text:
#ifndef NGHTTP2_H
#define NGHTTP2_H

#include "config.h"

#ifdef  __cplusplus
extern "C" {
#endif

#include <stdlib.h>
#include <stdint.h>
#include <sys/types.h>

#include "nghttp2ver.h"

/**
 * @macro
 *
 * The protocol version identification string of this library
 * supports.  This identifier is used if HTTP/2 is used over TLS.
 */
#define NGHTTP2_PROTO_VERSION_ID "h2-13"
/**
 * @macro
 *
 * The length of :macro:`NGHTTP2_PROTO_VERSION_ID`.
 */
#define NGHTTP2_PROTO_VERSION_ID_LEN 5

/**
 * @macro
 *
 * The protocol version identification string of this library
 * supports.  This identifier is used if HTTP/2 is used over cleartext
 * TCP.
 */
#define NGHTTP2_CLEARTEXT_PROTO_VERSION_ID "h2c-13"

/**
 * @macro
 *
 * The length of :macro:`NGHTTP2_CLEARTEXT_PROTO_VERSION_ID`.
 */
#define NGHTTP2_CLEARTEXT_PROTO_VERSION_ID_LEN 6

struct nghttp2_session;
/**
 * @struct
 *
 * The primary structure to hold the resources needed for a HTTP/2
 * session.  The details of this structure are intentionally hidden
 * from the public API.
 */
typedef struct nghttp2_session nghttp2_session;

/**
 * @macro
 *
 * The age of :type:`nghttp2_info`
 */
#define NGHTTP2_VERSION_AGE 1

/**
 * @struct
 *
 * This struct is what `nghttp2_version()` returns.  It holds
 * information about the particular nghttp2 version.
 */
typedef struct {
  /**
   * Age of this struct.  This instance of nghttp2 sets it to
   * :macro:`NGHTTP2_VERSION_AGE` but a future version may bump it and
   * add more struct fields at the bottom
   */
  int age;
  /**
   * the :macro:`NGHTTP2_VERSION_NUM` number (since age ==1)
   */
  int version_num;
  /**
   * points to the :macro:`NGHTTP2_VERSION` string (since age ==1)
   */
  const char *version_str;
  /**
   * points to the :macro:`NGHTTP2_PROTO_VERSION_ID` string this
   * instance implements (since age ==1)
   */
  const char *proto_str;
  /* -------- the above fields all exist when age == 1 */
} nghttp2_info;

/**
 * @macro
 *
 * The default weight of stream dependency.
 */
#define NGHTTP2_DEFAULT_WEIGHT 16

/**
 * @macro
 *
 * The maximum weight of stream dependency.
 */
#define NGHTTP2_MAX_WEIGHT 256

/**
 * @macro
 *
 * The minimum weight of stream dependency.
 */
#define NGHTTP2_MIN_WEIGHT 1

/**
 * @macro
 *
 * The maximum window size
 */
#define NGHTTP2_MAX_WINDOW_SIZE ((int32_t)((1U << 31) - 1))

/**
 * @macro
 *
 * The initial window size for stream level flow control.
 */
#define NGHTTP2_INITIAL_WINDOW_SIZE ((1 << 16) - 1)
/**
 * @macro
 *
 * The initial window size for connection level flow control.
 */
#define NGHTTP2_INITIAL_CONNECTION_WINDOW_SIZE ((1 << 16) - 1)

/**
 * @macro
 *
 * The default header table size.
 */
#define NGHTTP2_DEFAULT_HEADER_TABLE_SIZE (1 << 12)

/**
 * @macro
 *
 * The client connection preface.
 */
#define NGHTTP2_CLIENT_CONNECTION_PREFACE "PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n"

/**
 * @macro
 *
 * The length of :macro:`NGHTTP2_CLIENT_CONNECTION_PREFACE`.
 */
#define NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN 24

/**
 * @macro
 *
 * The client connection header.  This macro is obsoleted by
 * NGHTTP2_CLIENT_CONNECTION_PREFACE.
 */
#define NGHTTP2_CLIENT_CONNECTION_HEADER NGHTTP2_CLIENT_CONNECTION_PREFACE

/**
 * @macro
 *
 * The length of :macro:`NGHTTP2_CLIENT_CONNECTION_HEADER`.
 */
#define NGHTTP2_CLIENT_CONNECTION_HEADER_LEN    \
  NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN

/**
 * @enum
 *
 * Error codes used in this library.  The code range is [-999, -500],
 * inclusive. The following values are defined:
 */
typedef enum {
  /**
   * Invalid argument passed.
   */
  NGHTTP2_ERR_INVALID_ARGUMENT = -501,
  /**
   * Ouf of buffer space.
   */
  NGHTTP2_ERR_BUFFER_ERROR = -502,
  /**
   * The specified protocol version is not supported.
   */
  NGHTTP2_ERR_UNSUPPORTED_VERSION = -503,
  /**
   * Used as a return value from :type:`nghttp2_send_callback` and
   * :type:`nghttp2_recv_callback` to indicate that the operation
   * would block.
   */
  NGHTTP2_ERR_WOULDBLOCK = -504,
  /**
   * General protocol error
   */
  NGHTTP2_ERR_PROTO = -505,
  /**
   * The frame is invalid.
   */
  NGHTTP2_ERR_INVALID_FRAME = -506,
  /**
   * The peer performed a shutdown on the connection.
   */
  NGHTTP2_ERR_EOF = -507,
  /**
   * Used as a return value from
   * :func:`nghttp2_data_source_read_callback` to indicate that data
   * transfer is postponed.  See
   * :func:`nghttp2_data_source_read_callback` for details.
   */
  NGHTTP2_ERR_DEFERRED = -508,
  /**
   * Stream ID has reached the maximum value.  Therefore no stream ID
   * is available.
   */
  NGHTTP2_ERR_STREAM_ID_NOT_AVAILABLE = -509,
  /**
   * The stream is already closed; or the stream ID is invalid.
   */
  NGHTTP2_ERR_STREAM_CLOSED = -510,
  /**
   * RST_STREAM has been added to the outbound queue.  The stream is
   * in closing state.
   */
  NGHTTP2_ERR_STREAM_CLOSING = -511,
  /**
   * The transmission is not allowed for this stream (e.g., a frame
   * with END_STREAM flag set has already sent).
   */
  NGHTTP2_ERR_STREAM_SHUT_WR = -512,
  /**
   * The stream ID is invalid.
   */
  NGHTTP2_ERR_INVALID_STREAM_ID = -513,
  /**
   * The state of the stream is not valid (e.g., DATA cannot be sent
   * to the stream if response HEADERS has not been sent).
   */
  NGHTTP2_ERR_INVALID_STREAM_STATE = -514,
  /**
   * Another DATA frame has already been deferred.
   */
  NGHTTP2_ERR_DEFERRED_DATA_EXIST = -515,
  /**
   * Starting new stream is not allowed (e.g., GOAWAY has been sent
   * and/or received).
   */
  NGHTTP2_ERR_START_STREAM_NOT_ALLOWED = -516,
  /**
   * GOAWAY has already been sent.
   */
  NGHTTP2_ERR_GOAWAY_ALREADY_SENT = -517,
  /**
   * The received frame contains the invalid header block (e.g., There
   * are duplicate header names; or the header names are not encoded
   * in US-ASCII character set and not lower cased; or the header name
   * is zero-length string; or the header value contains multiple
   * in-sequence NUL bytes).
   */
  NGHTTP2_ERR_INVALID_HEADER_BLOCK = -518,
  /**
   * Indicates that the context is not suitable to perform the
   * requested operation.
   */
  NGHTTP2_ERR_INVALID_STATE = -519,
  /**
   * The user callback function failed due to the temporal error.
   */
  NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE = -521,
  /**
   * The length of the frame is invalid, either too large or too small.
   */
  NGHTTP2_ERR_FRAME_SIZE_ERROR = -522,
  /**
   * Header block inflate/deflate error.
   */
  NGHTTP2_ERR_HEADER_COMP = -523,
  /**
   * Flow control error
   */
  NGHTTP2_ERR_FLOW_CONTROL = -524,
  /**
   * Insufficient buffer size given to function.
   */
  NGHTTP2_ERR_INSUFF_BUFSIZE = -525,
  /**
   * Callback was paused by the application
   */
  NGHTTP2_ERR_PAUSE = -526,
  /**
   * There are too many in-flight SETTING frame and no more
   * transmission of SETTINGS is allowed.
   */
  NGHTTP2_ERR_TOO_MANY_INFLIGHT_SETTINGS = -527,
  /**
   * The server push is disabled.
   */
  NGHTTP2_ERR_PUSH_DISABLED = -528,
  /**
   * DATA frame for a given stream has been already submitted and has
   * not been fully processed yet.
   */
  NGHTTP2_ERR_DATA_EXIST = -529,
  /**
   * The errors < :enum:`NGHTTP2_ERR_FATAL` mean that the library is
   * under unexpected condition and processing was terminated (e.g.,
   * out of memory).  If application receives this error code, it must
   * stop using that :type:`nghttp2_session` object and only allowed
   * operation for that object is deallocate it using
   * `nghttp2_session_del()`.
   */
  NGHTTP2_ERR_FATAL = -900,
  /**
   * Out of memory.  This is a fatal error.
   */
  NGHTTP2_ERR_NOMEM = -901,
  /**
   * The user callback function failed.  This is a fatal error.
   */
  NGHTTP2_ERR_CALLBACK_FAILURE = -902
} nghttp2_error;

typedef enum {
  NGHTTP2_MSG_MORE
} nghttp2_io_flag;

/**
 * @enum
 *
 * The flags for header field name/value pair.
 */
typedef enum {
  /**
   * No flag set.
   */
  NGHTTP2_NV_FLAG_NONE = 0,
  /**
   * Indicates that this name/value pair must not be indexed.
   */
  NGHTTP2_NV_FLAG_NO_INDEX = 0x01
} nghttp2_nv_flag;

/**
 * @struct
 *
 * The name/value pair, which mainly used to represent header fields.
 */
typedef struct {
  /**
   * The |name| byte string, which is not necessarily ``NULL``
   * terminated.
   */
  uint8_t *name;
  /**
   * The |value| byte string, which is not necessarily ``NULL``
   * terminated.
   */
  uint8_t *value;
  /**
   * The length of the |name|.
   */
  size_t namelen;
  /**
   * The length of the |value|.
   */
  size_t valuelen;
  /**
   * Bitwise OR of one or more of :type:`nghttp2_nv_flag`.
   */
  uint8_t flags;
} nghttp2_nv;

/**
 * @enum
 *
 * The frame types in HTTP/2 specification.
 */
typedef enum {
  /**
   * The DATA frame.
   */
  NGHTTP2_DATA = 0,
  /**
   * The HEADERS frame.
   */
  NGHTTP2_HEADERS = 0x01,
  /**
   * The PRIORITY frame.
   */
  NGHTTP2_PRIORITY = 0x02,
  /**
   * The RST_STREAM frame.
   */
  NGHTTP2_RST_STREAM = 0x03,
  /**
   * The SETTINGS frame.
   */
  NGHTTP2_SETTINGS = 0x04,
  /**
   * The PUSH_PROMISE frame.
   */
  NGHTTP2_PUSH_PROMISE = 0x05,
  /**
   * The PING frame.
   */
  NGHTTP2_PING = 0x06,
  /**
   * The GOAWAY frame.
   */
  NGHTTP2_GOAWAY = 0x07,
  /**
   * The WINDOW_UPDATE frame.
   */
  NGHTTP2_WINDOW_UPDATE = 0x08,
  /**
   * The CONTINUATION frame.
   */
  NGHTTP2_CONTINUATION = 0x09
} nghttp2_frame_type;

/**
 * @enum
 *
 * The extension frame types.
 *
 * TODO: The assigned frame types were carried from draft-12, and now
 * actually TBD.
 */
typedef enum {
  /**
   * The ALTSVC extension frame.
   */
  NGHTTP2_EXT_ALTSVC = 0x0a
} nghttp2_ext_frame_type;

/**
 * @enum
 *
 * The flags for HTTP/2 frames.  This enum defines all flags for all
 * frames.
 */
typedef enum {
  /**
   * No flag set.
   */
  NGHTTP2_FLAG_NONE = 0,
  /**
   * The END_STREAM flag.
   */
  NGHTTP2_FLAG_END_STREAM = 0x01,
  /**
   * The END_HEADERS flag.
   */
  NGHTTP2_FLAG_END_HEADERS = 0x04,
  /**
   * The ACK flag.
   */
  NGHTTP2_FLAG_ACK = 0x01,
  /**
   * The END_SEGMENT flag.
   */
  NGHTTP2_FLAG_END_SEGMENT = 0x02,
  /**
   * The PADDED flag.
   */
  NGHTTP2_FLAG_PADDED = 0x08,
  /**
   * The PRIORITY flag.
   */
  NGHTTP2_FLAG_PRIORITY = 0x20
} nghttp2_flag;

/**
 * @enum
 * The SETTINGS ID.
 */
typedef enum {
  /**
   * SETTINGS_HEADER_TABLE_SIZE
   */
  NGHTTP2_SETTINGS_HEADER_TABLE_SIZE = 0x01,
  /**
   * SETTINGS_ENABLE_PUSH
   */
  NGHTTP2_SETTINGS_ENABLE_PUSH = 0x02,
  /**
   * SETTINGS_MAX_CONCURRENT_STREAMS
   */
  NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS = 0x03,
  /**
   * SETTINGS_INITIAL_WINDOW_SIZE
   */
  NGHTTP2_SETTINGS_INITIAL_WINDOW_SIZE = 0x04
} nghttp2_settings_id;

/**
 * @macro
 * Default maximum concurrent streams.
 */
#define NGHTTP2_INITIAL_MAX_CONCURRENT_STREAMS ((1U << 31) - 1)

/**
 * @enum
 * The status codes for the RST_STREAM and GOAWAY frames.
 */
typedef enum {
  /**
   * No errors.
   */
  NGHTTP2_NO_ERROR = 0x00,
  /**
   * PROTOCOL_ERROR
   */
  NGHTTP2_PROTOCOL_ERROR = 0x01,
  /**
   * INTERNAL_ERROR
   */
  NGHTTP2_INTERNAL_ERROR = 0x02,
  /**
   * FLOW_CONTROL_ERROR
   */
  NGHTTP2_FLOW_CONTROL_ERROR = 0x03,
  /**
   * SETTINGS_TIMEOUT
   */
  NGHTTP2_SETTINGS_TIMEOUT = 0x04,
  /**
   * STREAM_CLOSED
   */
  NGHTTP2_STREAM_CLOSED = 0x05,
  /**
   * FRAME_SIZE_ERROR
   */
  NGHTTP2_FRAME_SIZE_ERROR = 0x06,
  /**
   * REFUSED_STREAM
   */
  NGHTTP2_REFUSED_STREAM = 0x07,
  /**
   * CANCEL
   */
  NGHTTP2_CANCEL = 0x08,
  /**
   * COMPRESSION_ERROR
   */
  NGHTTP2_COMPRESSION_ERROR = 0x09,
  /**
   * CONNECT_ERROR
   */
  NGHTTP2_CONNECT_ERROR = 0x0a,
  /**
   * ENHANCE_YOUR_CALM
   */
  NGHTTP2_ENHANCE_YOUR_CALM = 0x0b,
  /**
   * INADEQUATE_SECURITY
   */
  NGHTTP2_INADEQUATE_SECURITY = 0x0c
} nghttp2_error_code;

/**
 * @struct
 * The frame header.
 */
typedef struct {
  /**
   * The length field of this frame, excluding frame header.
   */
  size_t length;
  /**
   * The stream identifier (aka, stream ID)
   */
  int32_t stream_id;
  /**
   * The type of this frame.  See `nghttp2_frame`.
   */
  uint8_t type;
  /**
   * The flags.
   */
  uint8_t flags;
} nghttp2_frame_hd;

/**
 * @union
 *
 * This union represents the some kind of data source passed to
 * :type:`nghttp2_data_source_read_callback`.
 */
typedef union {
  /**
   * The integer field, suitable for a file descriptor.
   */
  int fd;
  /**
   * The pointer to an arbitrary object.
   */
  void *ptr;
} nghttp2_data_source;

/**
 * @enum
 *
 * The flags used to set in |data_flags| output parameter in
 * :type:`nghttp2_data_source_read_callback`.
 */
typedef enum {
  /**
   * No flag set.
   */
  NGHTTP2_DATA_FLAG_NONE = 0,
  /**
   * Indicates EOF was sensed.
   */
  NGHTTP2_DATA_FLAG_EOF = 0x01
} nghttp2_data_flag;

/**
 * @functypedef
 *
 * Callback function invoked when the library wants to read data from
 * the |source|.  The read data is sent in the stream |stream_id|.
 * The implementation of this function must read at most |length|
 * bytes of data from |source| (or possibly other places) and store
 * them in |buf| and return number of data stored in |buf|.  If EOF is
 * reached, set :enum:`NGHTTP2_DATA_FLAG_EOF` flag in |*data_flags|.
 *
 * If the application wants to postpone DATA frames (e.g.,
 * asynchronous I/O, or reading data blocks for long time), it is
 * achieved by returning :enum:`NGHTTP2_ERR_DEFERRED` without reading
 * any data in this invocation.  The library removes DATA frame from
 * the outgoing queue temporarily.  To move back deferred DATA frame
 * to outgoing queue, call `nghttp2_session_resume_data()`.  In case
 * of error, there are 2 choices. Returning
 * :enum:`NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE` will close the stream
 * by issuing RST_STREAM with :enum:`NGHTTP2_INTERNAL_ERROR`.
 * Returning :enum:`NGHTTP2_ERR_CALLBACK_FAILURE` will signal the
 * entire session failure.
 */
typedef ssize_t (*nghttp2_data_source_read_callback)
(nghttp2_session *session, int32_t stream_id,
 uint8_t *buf, size_t length, uint32_t *data_flags,
 nghttp2_data_source *source, void *user_data);

/**
 * @struct
 *
 * This struct represents the data source and the way to read a chunk
 * of data from it.
 */
typedef struct {
  /**
   * The data source.
   */
  nghttp2_data_source source;
  /**
   * The callback function to read a chunk of data from the |source|.
   */
  nghttp2_data_source_read_callback read_callback;
} nghttp2_data_provider;

/**
 * @struct
 *
 * The DATA frame.  The received data is delivered via
 * :type:`nghttp2_on_data_chunk_recv_callback`.
 */
typedef struct {
  nghttp2_frame_hd hd;
  /**
   * The length of the padding in this frame.  This includes PAD_HIGH
   * and PAD_LOW.
   */
  size_t padlen;
} nghttp2_data;

/**
 * @enum
 *
 * The category of HEADERS, which indicates the role of the frame.  In
 * HTTP/2 spec, request, response, push response and other arbitrary
 * headers (e.g., trailers) are all called just HEADERS.  To give the
 * application the role of incoming HEADERS frame, we define several
 * categories.
 */
typedef enum {
  /**
   * The HEADERS frame is opening new stream, which is analogous to
   * SYN_STREAM in SPDY.
   */
  NGHTTP2_HCAT_REQUEST = 0,
  /**
   * The HEADERS frame is the first response headers, which is
   * analogous to SYN_REPLY in SPDY.
   */
  NGHTTP2_HCAT_RESPONSE = 1,
  /**
   * The HEADERS frame is the first headers sent against reserved
   * stream.
   */
  NGHTTP2_HCAT_PUSH_RESPONSE = 2,
  /**
   * The HEADERS frame which does not apply for the above categories,
   * which is analogous to HEADERS in SPDY.
   */
  NGHTTP2_HCAT_HEADERS = 3
} nghttp2_headers_category;

/**
 * @struct
 *
 * The structure to specify stream dependency.
 */
typedef struct {
  /**
   * The stream ID of the stream to depend on.  Specifying 0 makes
   * stream not depend any other stream.
   */
  int32_t stream_id;
  /**
   * The weight of this dependency.
   */
  int32_t weight;
  /**
   * nonzero means exclusive dependency
   */
  uint8_t exclusive;
} nghttp2_priority_spec;

/**
 * @struct
 *
 * The HEADERS frame.  It has the following members:
 */
typedef struct {
  /**
   * The frame header.
   */
  nghttp2_frame_hd hd;
  /**
   * The length of the padding in this frame.  This includes PAD_HIGH
   * and PAD_LOW.
   */
  size_t padlen;
  /**
   * The priority specification
   */
  nghttp2_priority_spec pri_spec;
  /**
   * The name/value pairs.
   */
  nghttp2_nv *nva;
  /**
   * The number of name/value pairs in |nva|.
   */
  size_t nvlen;
  /**
   * The category of this HEADERS frame.
   */
  nghttp2_headers_category cat;
} nghttp2_headers;

/**
 * @struct
 *
 * The PRIORITY frame.  It has the following members:
 */
typedef struct {
  /**
   * The frame header.
   */
  nghttp2_frame_hd hd;
  /**
   * The priority specification.
   */
  nghttp2_priority_spec pri_spec;
} nghttp2_priority;

/**
 * @struct
 *
 * The RST_STREAM frame.  It has the following members:
 */
typedef struct {
  /**
   * The frame header.
   */
  nghttp2_frame_hd hd;
  /**
   * The error code.  See :type:`nghttp2_error_code`.
   */
  nghttp2_error_code error_code;
} nghttp2_rst_stream;

/**
 * @struct
 *
 * The SETTINGS ID/Value pair.  It has the following members:
 */
typedef struct {
  /**
   * The SETTINGS ID.  See :type:`nghttp2_settings_id`.
   */
  int32_t settings_id;
  /**
   * The value of this entry.
   */
  uint32_t value;
} nghttp2_settings_entry;

/**
 * @struct
 *
 * The SETTINGS frame.  It has the following members:
 */
typedef struct {
  /**
   * The frame header.
   */
  nghttp2_frame_hd hd;
  /**
   * The number of SETTINGS ID/Value pairs in |iv|.
   */
  size_t niv;
  /**
   * The pointer to the array of SETTINGS ID/Value pair.
   */
  nghttp2_settings_entry *iv;
} nghttp2_settings;

/**
 * @struct
 *
 * The PUSH_PROMISE frame.  It has the following members:
 */
typedef struct {
  /**
   * The frame header.
   */
  nghttp2_frame_hd hd;
  /**
   * The length of the padding in this frame.  This includes PAD_HIGH
   * and PAD_LOW.
   */
  size_t padlen;
  /**
   * The name/value pairs.
   */
  nghttp2_nv *nva;
  /**
   * The number of name/value pairs in |nva|.
   */
  size_t nvlen;
  /**
   * The promised stream ID
   */
  int32_t promised_stream_id;
} nghttp2_push_promise;

/**
 * @struct
 *
 * The PING frame.  It has the following members:
 */
typedef struct {
  /**
   * The frame header.
   */
  nghttp2_frame_hd hd;
  /**
   * The opaque data
   */
  uint8_t opaque_data[8];
} nghttp2_ping;

/**
 * @struct
 *
 * The GOAWAY frame.  It has the following members:
 */
typedef struct {
  /**
   * The frame header.
   */
  nghttp2_frame_hd hd;
  /**
   * The last stream stream ID.
   */
  int32_t last_stream_id;
  /**
   * The error code.  See :type:`nghttp2_error_code`.
   */
  nghttp2_error_code error_code;
  /**
   * The additional debug data
   */
  uint8_t *opaque_data;
  /**
   * The length of |opaque_data| member.
   */
  size_t opaque_data_len;
} nghttp2_goaway;

/**
 * @struct
 *
 * The WINDOW_UPDATE frame.  It has the following members:
 */
typedef struct {
  /**
   * The frame header.
   */
  nghttp2_frame_hd hd;
  /**
   * The window size increment.
   */
  int32_t window_size_increment;
} nghttp2_window_update;

/**
 * @struct
 *
 * The extension frame.  It has following members:
 */
typedef struct {
  /**
   * The frame header.
   */
  nghttp2_frame_hd hd;
  /**
   * The pointer to extension payload.  The exact pointer type is
   * determined by hd.type.
   *
   * If hd.type == :enum:`NGHTTP2_EXT_ALTSVC`, it is a pointer to
   * :type:`nghttp2_ext_altsvc`.
   */
  void *payload;
} nghttp2_extension;

/**
 * @struct
 *
 * The ALTSVC extension frame payload.  It has following members:
 */
typedef struct {
  /**
   * Protocol ID
   */
  uint8_t *protocol_id;
  /**
   * Host
   */
  uint8_t *host;
  /**
   * Origin
   */
  uint8_t *origin;
  /**
   * The length of |protocol_id|
   */
  size_t protocol_id_len;
  /**
   * The length of |host|
   */
  size_t host_len;
  /**
   * The length of |origin|
   */
  size_t origin_len;
  /**
   * Max-Age
   */
  uint32_t max_age;
  /**
   * Port
   */
  uint16_t port;
} nghttp2_ext_altsvc;

/**
 * @union
 *
 * This union includes all frames to pass them to various function
 * calls as nghttp2_frame type.  The CONTINUATION frame is omitted
 * from here because the library deals with it internally.
 */
typedef union {
  /**
   * The frame header, which is convenient to inspect frame header.
   */
  nghttp2_frame_hd hd;
  /**
   * The DATA frame.
   */
  nghttp2_data data;
  /**
   * The HEADERS frame.
   */
  nghttp2_headers headers;
  /**
   * The PRIORITY frame.
   */
  nghttp2_priority priority;
  /**
   * The RST_STREAM frame.
   */
  nghttp2_rst_stream rst_stream;
  /**
   * The SETTINGS frame.
   */
  nghttp2_settings settings;
  /**
   * The PUSH_PROMISE frame.
   */
  nghttp2_push_promise push_promise;
  /**
   * The PING frame.
   */
  nghttp2_ping ping;
  /**
   * The GOAWAY frame.
   */
  nghttp2_goaway goaway;
  /**
   * The WINDOW_UPDATE frame.
   */
  nghttp2_window_update window_update;
  /**
   * The extension frame.
   */
  nghttp2_extension ext;
} nghttp2_frame;

/**
 * @functypedef
 *
 * Callback function invoked when |session| wants to send data to the
 * remote peer.  The implementation of this function must send at most
 * |length| bytes of data stored in |data|.  The |flags| is currently
 * not used and always 0. It must return the number of bytes sent if
 * it succeeds.  If it cannot send any single byte without blocking,
 * it must return :enum:`NGHTTP2_ERR_WOULDBLOCK`.  For other errors,
 * it must return :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`.  The
 * |user_data| pointer is the third argument passed in to the call to
 * `nghttp2_session_client_new()` or `nghttp2_session_server_new()`.
 *
 * This callback is required if the application uses
 * `nghttp2_session_send()` to send data to the remote endpoint.  If
 * the application uses solely `nghttp2_session_mem_send()` instead,
 * this callback function is unnecessary.
 */
typedef ssize_t (*nghttp2_send_callback)
(nghttp2_session *session,
 const uint8_t *data, size_t length, int flags, void *user_data);

/**
 * @functypedef
 *
 * Callback function invoked when |session| wants to receive data from
 * the remote peer.  The implementation of this function must read at
 * most |length| bytes of data and store it in |buf|.  The |flags| is
 * currently not used and always 0.  It must return the number of
 * bytes written in |buf| if it succeeds.  If it cannot read any
 * single byte without blocking, it must return
 * :enum:`NGHTTP2_ERR_WOULDBLOCK`.  If it gets EOF before it reads any
 * single byte, it must return :enum:`NGHTTP2_ERR_EOF`.  For other
 * errors, it must return :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`.
 * Returning 0 is treated as :enum:`NGHTTP2_ERR_WOULDBLOCK`.  The
 * |user_data| pointer is the third argument passed in to the call to
 * `nghttp2_session_client_new()` or `nghttp2_session_server_new()`.
 *
 * This callback is required if the application uses
 * `nghttp2_session_recv()` to receive data from the remote endpoint.
 * If the application uses solely `nghttp2_session_mem_recv()`
 * instead, this callback function is unnecessary.
 */
typedef ssize_t (*nghttp2_recv_callback)
(nghttp2_session *session,
 uint8_t *buf, size_t length, int flags, void *user_data);

/**
 * @functypedef
 *
 * Callback function invoked by `nghttp2_session_recv()` when a frame
 * is received.  The |user_data| pointer is the third argument passed
 * in to the call to `nghttp2_session_client_new()` or
 * `nghttp2_session_server_new()`.
 *
 * If frame is HEADERS or PUSH_PROMISE, the ``nva`` and ``nvlen``
 * member of their data structure are always ``NULL`` and 0
 * respectively.  The header name/value pairs are emitted via
 * :type:`nghttp2_on_header_callback`.
 *
 * For HEADERS, PUSH_PROMISE and DATA frames, this callback may be
 * called after stream is closed (see
 * :type:`nghttp2_on_stream_close_callback`).  The application should
 * check that stream is still alive using its own stream management or
 * :func:`nghttp2_session_get_stream_user_data()`.
 *
 * Only HEADERS and DATA frame can signal the end of incoming data.
 * If ``frame->hd.flags & NGHTTP2_FLAG_END_STREAM`` is nonzero, the
 * |frame| is the last frame from the remote peer in this stream.
 *
 * The implementation of this function must return 0 if it succeeds.
 * If nonzero value is returned, it is treated as fatal error and
 * `nghttp2_session_recv()` and `nghttp2_session_mem_recv()` functions
 * immediately return :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`.
 */
typedef int (*nghttp2_on_frame_recv_callback)
(nghttp2_session *session, const nghttp2_frame *frame, void *user_data);

/**
 * @functypedef
 *
 * Callback function invoked by `nghttp2_session_recv()` when an
 * invalid non-DATA frame is received.  The |error_code| is one of the
 * :enum:`nghttp2_error_code` and indicates the error.  When this
 * callback function is invoked, the library automatically submits
 * either RST_STREAM or GOAWAY frame.  The |user_data| pointer is the
 * third argument passed in to the call to
 * `nghttp2_session_client_new()` or `nghttp2_session_server_new()`.
 *
 * If frame is HEADERS or PUSH_PROMISE, the ``nva`` and ``nvlen``
 * member of their data structure are always ``NULL`` and 0
 * respectively.
 *
 * The implementation of this function must return 0 if it succeeds.
 * If nonzero is returned, it is treated as fatal error and
 * `nghttp2_session_recv()` and `nghttp2_session_send()` functions
 * immediately return :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`.
 */
typedef int (*nghttp2_on_invalid_frame_recv_callback)
(nghttp2_session *session, const nghttp2_frame *frame,
 nghttp2_error_code error_code, void *user_data);

/**
 * @functypedef
 *
 * Callback function invoked when a chunk of data in DATA frame is
 * received.  The |stream_id| is the stream ID this DATA frame belongs
 * to.  The |flags| is the flags of DATA frame which this data chunk
 * is contained.  ``(flags & NGHTTP2_FLAG_END_STREAM) != 0`` does not
 * necessarily mean this chunk of data is the last one in the stream.
 * You should use :type:`nghttp2_on_frame_recv_callback` to know all
 * data frames are received.  The |user_data| pointer is the third
 * argument passed in to the call to `nghttp2_session_client_new()` or
 * `nghttp2_session_server_new()`.
 *
 * If the application uses `nghttp2_session_mem_recv()`, it can return
 * :enum:`NGHTTP2_ERR_PAUSE` to make `nghttp2_session_mem_recv()`
 * return without processing further input bytes.  The memory by
 * pointed by the |data| is retained until
 * `nghttp2_session_mem_recv()` or `nghttp2_session_recv()` is called.
 * The application must retain the input bytes which was used to
 * produce the |data| parameter, because it may refer to the memory
 * region included in the input bytes.
 *
 * The implementation of this function must return 0 if it succeeds.
 * If nonzero is returned, it is treated as fatal error and
 * `nghttp2_session_recv()` and `nghttp2_session_mem_recv()` functions
 * immediately return :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`.
 */
typedef int (*nghttp2_on_data_chunk_recv_callback)
(nghttp2_session *session, uint8_t flags, int32_t stream_id,
 const uint8_t *data, size_t len, void *user_data);

/**
 * @functypedef
 *
 * Callback function invoked just before the non-DATA frame |frame| is
 * sent.  The |user_data| pointer is the third argument passed in to
 * the call to `nghttp2_session_client_new()` or
 * `nghttp2_session_server_new()`.
 *
 * The implementation of this function must return 0 if it succeeds.
 * If nonzero is returned, it is treated as fatal error and
 * `nghttp2_session_recv()` and `nghttp2_session_send()` functions
 * immediately return :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`.
 */
typedef int (*nghttp2_before_frame_send_callback)
(nghttp2_session *session, const nghttp2_frame *frame, void *user_data);

/**
 * @functypedef
 *
 * Callback function invoked after the frame |frame| is sent.  The
 * |user_data| pointer is the third argument passed in to the call to
 * `nghttp2_session_client_new()` or `nghttp2_session_server_new()`.
 *
 * The implementation of this function must return 0 if it succeeds.
 * If nonzero is returned, it is treated as fatal error and
 * `nghttp2_session_recv()` and `nghttp2_session_send()` functions
 * immediately return :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`.
 */
typedef int (*nghttp2_on_frame_send_callback)
(nghttp2_session *session, const nghttp2_frame *frame, void *user_data);

/**
 * @functypedef
 *
 * Callback function invoked after the non-DATA frame |frame| is not
 * sent because of the error.  The error is indicated by the
 * |lib_error_code|, which is one of the values defined in
 * :type:`nghttp2_error`.  The |user_data| pointer is the third
 * argument passed in to the call to `nghttp2_session_client_new()` or
 * `nghttp2_session_server_new()`.
 *
 * The implementation of this function must return 0 if it succeeds.
 * If nonzero is returned, it is treated as fatal error and
 * `nghttp2_session_recv()` and `nghttp2_session_send()` functions
 * immediately return :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`.
 */
typedef int (*nghttp2_on_frame_not_send_callback)
(nghttp2_session *session, const nghttp2_frame *frame, int lib_error_code,
 void *user_data);

/**
 * @functypedef
 *
 * Callback function invoked when the stream |stream_id| is closed.
 * The reason of closure is indicated by the |error_code|.  The
 * stream_user_data, which was specified in `nghttp2_submit_request()`
 * or `nghttp2_submit_headers()`, is still available in this function.
 * The |user_data| pointer is the third argument passed in to the call
 * to `nghttp2_session_client_new()` or
 * `nghttp2_session_server_new()`.
 *
 * This function is also called for a stream in reserved state.
 *
 * The implementation of this function must return 0 if it succeeds.
 * If nonzero is returned, it is treated as fatal error and
 * `nghttp2_session_recv()` and `nghttp2_session_send()` functions
 * immediately return :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`.
 */
typedef int (*nghttp2_on_stream_close_callback)
(nghttp2_session *session, int32_t stream_id, nghttp2_error_code error_code,
 void *user_data);

/**
 * @functypedef
 *
 * Callback function invoked when the received frame type is unknown.
 * The |head| is the pointer to the header of the received frame.  The
 * |headlen| is the length of the |head|.  According to the spec, the
 * |headlen| is always 8.  In other words, the |head| is the first 8
 * bytes of the received frame.  The |payload| is the pointer to the
 * data portion of the received frame.  The |payloadlen| is the length
 * of the |payload|.  This is the data after the length field.  The
 * |user_data| pointer is the third argument passed in to the call to
 * `nghttp2_session_client_new()` or `nghttp2_session_server_new()`.
 *
 * The implementation of this function must return 0 if it succeeds.
 * If nonzero is returned, it is treated as fatal error and
 * `nghttp2_session_recv()` and `nghttp2_session_send()` functions
 * immediately return :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`.
 */
typedef int (*nghttp2_on_unknown_frame_recv_callback)
(nghttp2_session *session,
 const uint8_t *head, size_t headlen,
 const uint8_t *payload, size_t payloadlen,
 void *user_data);

/**
 * @functypedef
 *
 * Callback function invoked when the reception of header block in
 * HEADERS or PUSH_PROMISE is started.  Each header name/value pair
 * will be emitted by :type:`nghttp2_on_header_callback`.
 *
 * The ``frame->hd.flags`` may not have
 * :enum:`NGHTTP2_FLAG_END_HEADERS` flag set, which indicates that one
 * or more CONTINUATION frames are involved.  But the application does
 * not need to care about that because the header name/value pairs are
 * emitted transparently regardless of CONTINUATION frames.
 *
 * The implementation of this function must return 0 if it succeeds or
 * :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`.  If nonzero value other than
 * :enum:`NGHTTP2_ERR_CALLBACK_FAILURE` is returned, it is treated as
 * if :enum:`NGHTTP2_ERR_CALLBACK_FAILURE` is returned.  If
 * :enum:`NGHTTP2_ERR_CALLBACK_FAILURE` is returned,
 * `nghttp2_session_mem_recv()` function will immediately return
 * :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`.
 */
typedef int (*nghttp2_on_begin_headers_callback)
(nghttp2_session *session, const nghttp2_frame *frame, void *user_data);

/**
 * @functypedef
 *
 * Callback function invoked when a header name/value pair is received
 * for the |frame|.  The |name| of length |namelen| is header name.
 * The |value| of length |valuelen| is header value.  The |flags| is
 * bitwise OR of one or more of :type:`nghttp2_nv_flag`.
 *
 * If :enum:`NGHTTP2_NV_FLAG_NO_INDEX` is set in |flags|, the receiver
 * must not index this name/value pair when forwarding it to the next
 * hop.
 *
 * When this callback is invoked, ``frame->hd.type`` is either
 * :enum:`NGHTTP2_HEADERS` or :enum:`NGHTTP2_PUSH_PROMISE`.  After all
 * header name/value pairs are processed with this callback, and no
 * error has been detected, :type:`nghttp2_on_frame_recv_callback`
 * will be invoked.  If there is an error in decompression,
 * :type:`nghttp2_on_frame_recv_callback` for the |frame| will not be
 * invoked.
 *
 * The |name| may be ``NULL`` if the |namelen| is 0.  The same thing
 * can be said about the |value|.
 *
 * Please note that nghttp2 library does not perform any validity
 * check against the |name| and the |value|.  For example, the
 * |namelen| could be 0, and/or the |value| contains ``0x0a`` or
 * ``0x0d``.  The application must check them if it matters.  The
 * helper function `nghttp2_check_header_name()` and
 * `nghttp2_check_header_value()` provide simple validation against
 * HTTP2 header field construction rule.
 *
 * One more thing to note is that the |value| may contain ``NULL``
 * (``0x00``) characters.  It is used to concatenate header values
 * which share the same header field name.  The application should
 * split these values if it wants to get individual value.  This
 * concatenation is used in order to keep the ordering of headers.
 *
 * If the application uses `nghttp2_session_mem_recv()`, it can return
 * :enum:`NGHTTP2_ERR_PAUSE` to make `nghttp2_session_mem_recv()`
 * return without processing further input bytes.  The memory pointed
 * by |frame|, |name| and |value| parameters are retained until
 * `nghttp2_session_mem_recv()` or `nghttp2_session_recv()` is called.
 * The application must retain the input bytes which was used to
 * produce these parameters, because it may refer to the memory region
 * included in the input bytes.
 *
 * Returning :enum:`NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE` will close
 * the stream by issuing RST_STREAM with
 * :enum:`NGHTTP2_INTERNAL_ERROR`.  In this case,
 * :type:`nghttp2_on_frame_recv_callback` will not be invoked.
 *
 * The implementation of this function must return 0 if it succeeds.
 * It may return :enum:`NGHTTP2_ERR_PAUSE` or
 * :enum:`NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE`.  For other critical
 * failures, it must return :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`.  If
 * the other nonzero value is returned, it is treated as
 * :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`.  If
 * :enum:`NGHTTP2_ERR_CALLBACK_FAILURE` is returned,
 * `nghttp2_session_recv()` and `nghttp2_session_mem_recv()` functions
 * immediately return :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`.
 */
typedef int (*nghttp2_on_header_callback)
(nghttp2_session *session,
 const nghttp2_frame *frame,
 const uint8_t *name, size_t namelen,
 const uint8_t *value, size_t valuelen,
 uint8_t flags,
 void *user_data);

/**
 * @functypedef
 *
 * Callback function invoked when the library asks application how
 * many padding bytes are required for the transmission of the
 * |frame|.  The application must choose the total length of payload
 * including padded bytes in range [frame->hd.length, max_payloadlen],
 * inclusive.  Choosing number not in this range will be treated as
 * :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`.  Returning
 * ``frame->hd.length`` means no padding is added.  Returning
 * :enum:`NGHTTP2_ERR_CALLBACK_FAILURE` will make
 * `nghttp2_session_send()` function immediately return
 * :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`.
 */
typedef ssize_t (*nghttp2_select_padding_callback)
(nghttp2_session *session,
 const nghttp2_frame *frame,
 size_t max_payloadlen,
 void *user_data);

/**
 * @struct
 *
 * Callback functions.
 */
typedef struct {
  /**
   * Callback function invoked when the |session| wants to send data
   * to the remote peer.  This callback is not necessary if the
   * application uses solely `nghttp2_session_mem_send()` to serialize
   * data to transmit.
   */
  nghttp2_send_callback send_callback;
  /**
   * Callback function invoked when the |session| wants to receive
   * data from the remote peer.  This callback is not necessary if the
   * application uses solely `nghttp2_session_mem_recv()` to process
   * received data.
   */
  nghttp2_recv_callback recv_callback;
  /**
   * Callback function invoked by `nghttp2_session_recv()` when a
   * frame is received.
   */
  nghttp2_on_frame_recv_callback on_frame_recv_callback;
  /**
   * Callback function invoked by `nghttp2_session_recv()` when an
   * invalid non-DATA frame is received.
   */
  nghttp2_on_invalid_frame_recv_callback on_invalid_frame_recv_callback;
  /**
   * Callback function invoked when a chunk of data in DATA frame is
   * received.
   */
  nghttp2_on_data_chunk_recv_callback on_data_chunk_recv_callback;
  /**
   * Callback function invoked before a non-DATA frame is sent.
   */
  nghttp2_before_frame_send_callback before_frame_send_callback;
  /**
   * Callback function invoked after a frame is sent.
   */
  nghttp2_on_frame_send_callback on_frame_send_callback;
  /**
   * The callback function invoked when a non-DATA frame is not sent
   * because of an error.
   */
  nghttp2_on_frame_not_send_callback on_frame_not_send_callback;
  /**
   * Callback function invoked when the stream is closed.
   */
  nghttp2_on_stream_close_callback on_stream_close_callback;
  /**
   * Callback function invoked when the received frame type is
   * unknown.
   */
  nghttp2_on_unknown_frame_recv_callback on_unknown_frame_recv_callback;
  /**
   * Callback function invoked when the reception of header block in
   * HEADERS or PUSH_PROMISE is started.
   */
  nghttp2_on_begin_headers_callback on_begin_headers_callback;
  /**
   * Callback function invoked when a header name/value pair is
   * received.
   */
  nghttp2_on_header_callback on_header_callback;
  /**
   * Callback function invoked when the library asks application how
   * many padding bytes are required for the transmission of the given
   * frame.
   */
  nghttp2_select_padding_callback select_padding_callback;
} nghttp2_session_callbacks;

struct nghttp2_option;

/**
 * @struct
 *
 * Configuration options for :type:`nghttp2_session`.  The details of
 * this structure are intentionally hidden from the public API.
 */
typedef struct nghttp2_option nghttp2_option;

/**
 * @function
 *
 * Initializes |*option_ptr| with default values.
 *
 * When the application finished using this object, it can use
 * `nghttp2_option_del()` to free its memory.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 */
int nghttp2_option_new(nghttp2_option **option_ptr);

/**
 * @function
 *
 * Frees any resources allocated for |option|.  If |option| is
 * ``NULL``, this function does nothing.
 */
void nghttp2_option_del(nghttp2_option *option);

/**
 * @function
 *
 * This option prevents the library from sending WINDOW_UPDATE for a
 * stream automatically.  If this option is set to nonzero, the
 * library won't send WINDOW_UPDATE for a stream and the application
 * is responsible for sending WINDOW_UPDATE using
 * `nghttp2_submit_window_update`.  By default, this option is set to
 * zero.
 */
void nghttp2_option_set_no_auto_stream_window_update(nghttp2_option *option,
                                                     int val);

/**
 * @function
 *
 * This option prevents the library from sending WINDOW_UPDATE for a
 * connection automatically.  If this option is set to nonzero, the
 * library won't send WINDOW_UPDATE for a connection and the
 * application is responsible for sending WINDOW_UPDATE with stream ID
 * 0 using `nghttp2_submit_window_update`.  By default, this option is
 * set to zero.
 */
void nghttp2_option_set_no_auto_connection_window_update
(nghttp2_option *option, int val);

/**
 * @function
 *
 * This option sets the SETTINGS_MAX_CONCURRENT_STREAMS value of
 * remote endpoint as if it is received in SETTINGS frame.  Without
 * specifying this option, before the local endpoint receives
 * SETTINGS_MAX_CONCURRENT_STREAMS in SETTINGS frame from remote
 * endpoint, SETTINGS_MAX_CONCURRENT_STREAMS is unlimited.  This may
 * cause problem if local endpoint submits lots of requests initially
 * and sending them at once to the remote peer may lead to the
 * rejection of some requests.  Specifying this option to the sensible
 * value, say 100, may avoid this kind of issue. This value will be
 * overwritten if the local endpoint receives
 * SETTINGS_MAX_CONCURRENT_STREAMS from the remote endpoint.
 */
void nghttp2_option_set_peer_max_concurrent_streams(nghttp2_option *option,
                                                    uint32_t val);

/**
 * @function
 *
 * Initializes |*session_ptr| for client use.  The all members of
 * |callbacks| are copied to |*session_ptr|.  Therefore |*session_ptr|
 * does not store |callbacks|.  The |user_data| is an arbitrary user
 * supplied data, which will be passed to the callback functions.
 *
 * The :member:`nghttp2_session_callbacks.send_callback` must be
 * specified.  If the application code uses `nghttp2_session_recv()`,
 * the :member:`nghttp2_session_callbacks.recv_callback` must be
 * specified.  The other members of |callbacks| can be ``NULL``.
 *
 * If this function fails, |*session_ptr| is left untouched.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 */
int nghttp2_session_client_new(nghttp2_session **session_ptr,
                               const nghttp2_session_callbacks *callbacks,
                               void *user_data);

/**
 * @function
 *
 * Initializes |*session_ptr| for server use.  The all members of
 * |callbacks| are copied to |*session_ptr|. Therefore |*session_ptr|
 * does not store |callbacks|.  The |user_data| is an arbitrary user
 * supplied data, which will be passed to the callback functions.
 *
 * The :member:`nghttp2_session_callbacks.send_callback` must be
 * specified.  If the application code uses `nghttp2_session_recv()`,
 * the :member:`nghttp2_session_callbacks.recv_callback` must be
 * specified.  The other members of |callbacks| can be ``NULL``.
 *
 * If this function fails, |*session_ptr| is left untouched.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 */
int nghttp2_session_server_new(nghttp2_session **session_ptr,
                               const nghttp2_session_callbacks *callbacks,
                               void *user_data);

/**
 * @function
 *
 * Like `nghttp2_session_client_new()`, but with additional options
 * specified in the |option|.
 *
 * The |option| can be ``NULL`` and the call is equivalent to
 * `nghttp2_session_client_new()`.
 *
 * This function does not take ownership |option|.  The application is
 * responsible for freeing |option| if it finishes using the object.
 *
 * The library code does not refer to |option| after this function
 * returns.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 */
int nghttp2_session_client_new2(nghttp2_session **session_ptr,
                                const nghttp2_session_callbacks *callbacks,
                                void *user_data,
                                const nghttp2_option *option);

/**
 * @function
 *
 * Like `nghttp2_session_server_new()`, but with additional options
 * specified in the |option|.
 *
 * The |option| can be ``NULL`` and the call is equivalent to
 * `nghttp2_session_server_new()`.
 *
 * This function does not take ownership |option|.  The application is
 * responsible for freeing |option| if it finishes using the object.
 *
 * The library code does not refer to |option| after this function
 * returns.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 */
int nghttp2_session_server_new2(nghttp2_session **session_ptr,
                                const nghttp2_session_callbacks *callbacks,
                                void *user_data,
                                const nghttp2_option *option);

/**
 * @function
 *
 * Frees any resources allocated for |session|.  If |session| is
 * ``NULL``, this function does nothing.
 */
void nghttp2_session_del(nghttp2_session *session);

/**
 * @function
 *
 * Sends pending frames to the remote peer.
 *
 * This function retrieves the highest prioritized frame from the
 * outbound queue and sends it to the remote peer.  It does this as
 * many as possible until the user callback
 * :member:`nghttp2_session_callbacks.send_callback` returns
 * :enum:`NGHTTP2_ERR_WOULDBLOCK` or the outbound queue becomes empty.
 * This function calls several callback functions which are passed
 * when initializing the |session|.  Here is the simple time chart
 * which tells when each callback is invoked:
 *
 * 1. Get the next frame to send from outbound queue.
 * 2. Prepare transmission of the frame.
 * 3. If the control frame cannot be sent because some preconditions
 *    are not met (e.g., request HEADERS cannot be sent after GOAWAY),
 *    :member:`nghttp2_session_callbacks.on_frame_not_send_callback`
 *    is invoked.  Abort the following steps.
 * 4. If the frame is HEADERS, PUSH_PROMISE or DATA,
 *    :member:`nghttp2_session_callbacks.select_padding_callback` is
 *    invoked.
 * 5. If the frame is request HEADERS, the stream is opened here.
 * 6. :member:`nghttp2_session_callbacks.before_frame_send_callback` is
 *    invoked.
 * 7. :member:`nghttp2_session_callbacks.send_callback` is invoked one
 *    or more times to send the frame.
 * 8. :member:`nghttp2_session_callbacks.on_frame_send_callback` is
 *    invoked.
 * 9. If the transmission of the frame triggers closure of the stream,
 *    the stream is closed and
 *    :member:`nghttp2_session_callbacks.on_stream_close_callback` is
 *    invoked.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 * :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`
 *     The callback function failed.
 */
int nghttp2_session_send(nghttp2_session *session);

/**
 * @function
 *
 * Returns the serialized data to send.
 *
 * This function behaves like `nghttp2_session_send()` except that it
 * does not use :member:`nghttp2_session_callbacks.send_callback` to
 * transmit data.  Instead, it assigns the pointer to the serialized
 * data to the |*data_ptr| and returns its length.  The other
 * callbacks are called in the same way as they are in
 * `nghttp2_session_send()`.
 *
 * If no data is available to send, this function returns 0.
 *
 * This function may not return all serialized data in one invocation.
 * To get all data, call this function repeatedly until it returns 0
 * or one of negative error codes.
 *
 * The assigned |*data_ptr| is valid until the next call of
 * `nghttp2_session_mem_send()` or `nghttp2_session_send()`.
 *
 * The caller must send all data before sending the next chunk of
 * data.
 *
 * This function returns the length of the data pointed by the
 * |*data_ptr| if it succeeds, or one of the following negative error
 * codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 */
ssize_t nghttp2_session_mem_send(nghttp2_session *session,
                                 const uint8_t **data_ptr);

/**
 * @function
 *
 * Receives frames from the remote peer.
 *
 * This function receives as many frames as possible until the user
 * callback :member:`nghttp2_session_callbacks.recv_callback` returns
 * :enum:`NGHTTP2_ERR_WOULDBLOCK`.  This function calls several
 * callback functions which are passed when initializing the
 * |session|.  Here is the simple time chart which tells when each
 * callback is invoked:
 *
 * 1. :member:`nghttp2_session_callbacks.recv_callback` is invoked one
 *    or more times to receive frame header.
 * 2. If the frame is DATA frame:
 *
 *    1. :member:`nghttp2_session_callbacks.recv_callback` is invoked
 *       to receive DATA payload. For each chunk of data,
 *       :member:`nghttp2_session_callbacks.on_data_chunk_recv_callback`
 *       is invoked.
 *    2. If one DATA frame is completely received,
 *       :member:`nghttp2_session_callbacks.on_frame_recv_callback` is
 *       invoked.  If the reception of the frame triggers the
 *       closure of the stream,
 *       :member:`nghttp2_session_callbacks.on_stream_close_callback`
 *       is invoked.
 *
 * 3. If the frame is the control frame:
 *
 *    1. :member:`nghttp2_session_callbacks.recv_callback` is invoked
 *       one or more times to receive whole frame.
 *
 *    2. If the received frame is valid, then following actions are
 *       taken.  If the frame is either HEADERS or PUSH_PROMISE,
 *       :member:`nghttp2_session_callbacks.on_begin_headers_callback`
 *       is invoked.  Then
 *       :member:`nghttp2_session_callbacks.on_header_callback` is
 *       invoked for each header name/value pair.  After all name/value
 *       pairs are emitted successfully,
 *       :member:`nghttp2_session_callbacks.on_frame_recv_callback` is
 *       invoked.  For other frames,
 *       :member:`nghttp2_session_callbacks.on_frame_recv_callback` is
 *       invoked.
 *       If the reception of the frame triggers the closure of the
 *       stream,
 *       :member:`nghttp2_session_callbacks.on_stream_close_callback`
 *       is invoked.
 *    3. If the received frame is unpacked but is interpreted as
 *       invalid,
 *       :member:`nghttp2_session_callbacks.on_invalid_frame_recv_callback`
 *       is invoked.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * :enum:`NGHTTP2_ERR_EOF`
 *     The remote peer did shutdown on the connection.
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 * :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`
 *     The callback function failed.
 */
int nghttp2_session_recv(nghttp2_session *session);

/**
 * @function
 *
 * Processes data |in| as an input from the remote endpoint.  The
 * |inlen| indicates the number of bytes in the |in|.
 *
 * This function behaves like `nghttp2_session_recv()` except that it
 * does not use :member:`nghttp2_session_callbacks.recv_callback` to
 * receive data; the |in| is the only data for the invocation of this
 * function.  If all bytes are processed, this function returns.  The
 * other callbacks are called in the same way as they are in
 * `nghttp2_session_recv()`.
 *
 * In the current implementation, this function always tries to
 * processes all input data unless either an error occurs or
 * :enum:`NGHTTP2_ERR_PAUSE` is returned from
 * :member:`nghttp2_session_callbacks.on_header_callback` or
 * :member:`nghttp2_session_callbacks.on_data_chunk_recv_callback`.
 * If :enum:`NGHTTP2_ERR_PAUSE` is used, the return value includes the
 * number of bytes which was used to produce the data or frame for the
 * callback.
 *
 * This function returns the number of processed bytes, or one of the
 * following negative error codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 * :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`
 *     The callback function failed.
 */
ssize_t nghttp2_session_mem_recv(nghttp2_session *session,
                                 const uint8_t *in, size_t inlen);

/**
 * @function
 *
 * Puts back previously deferred DATA frame in the stream |stream_id|
 * to the outbound queue.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * :enum:`NGHTTP2_ERR_INVALID_ARGUMENT`
 *     The stream does not exist; or no deferred data exist; or data
 *     was deferred by flow control.
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 */
int nghttp2_session_resume_data(nghttp2_session *session, int32_t stream_id);

/**
 * @function
 *
 * Returns nonzero value if |session| wants to receive data from the
 * remote peer.
 *
 * If both `nghttp2_session_want_read()` and
 * `nghttp2_session_want_write()` return 0, the application should
 * drop the connection.
 */
int nghttp2_session_want_read(nghttp2_session *session);

/**
 * @function
 *
 * Returns nonzero value if |session| wants to send data to the remote
 * peer.
 *
 * If both `nghttp2_session_want_read()` and
 * `nghttp2_session_want_write()` return 0, the application should
 * drop the connection.
 */
int nghttp2_session_want_write(nghttp2_session *session);

/**
 * @function
 *
 * Returns stream_user_data for the stream |stream_id|.  The
 * stream_user_data is provided by `nghttp2_submit_request()`,
 * `nghttp2_submit_headers()` or
 * `nghttp2_session_set_stream_user_data()`.  Unless it is set using
 * `nghttp2_session_set_stream_user_data()`, if the stream is
 * initiated by the remote endpoint, stream_user_data is always
 * ``NULL``.  If the stream does not exist, this function returns
 * ``NULL``.
 */
void* nghttp2_session_get_stream_user_data(nghttp2_session *session,
                                           int32_t stream_id);

/**
 * @function
 *
 * Sets the |stream_user_data| to the stream denoted by the
 * |stream_id|.  If a stream user data is already set to the stream,
 * it is replaced with the |stream_user_data|.  It is valid to specify
 * ``NULL`` in the |stream_user_data|, which nullifies the associated
 * data pointer.
 *
 * It is valid to set the |stream_user_data| to the stream reserved by
 * PUSH_PROMISE frame.
 *
 * This function returns 0 if it succeeds, or one of following
 * negative error codes:
 *
 * :enum:`NGHTTP2_ERR_INVALID_ARGUMENT`
 *     The stream does not exist
 */
int nghttp2_session_set_stream_user_data(nghttp2_session *session,
                                         int32_t stream_id,
                                         void *stream_user_data);

/**
 * @function
 *
 * Returns the number of frames in the outbound queue.  This does not
 * include the deferred DATA frames.
 */
size_t nghttp2_session_get_outbound_queue_size(nghttp2_session *session);

/**
 * @function
 *
 * Returns the number of DATA payload in bytes received without
 * WINDOW_UPDATE transmission for the stream |stream_id|.  The local
 * (receive) window size can be adjusted by
 * `nghttp2_submit_window_update()`.  This function takes into account
 * that and returns effective data length.  In particular, if the
 * local window size is reduced by submitting negative
 * window_size_increment with `nghttp2_submit_window_update()`, this
 * function returns the number of bytes less than actually received.
 *
 * This function returns -1 if it fails.
 */
int32_t nghttp2_session_get_stream_effective_recv_data_length
(nghttp2_session *session, int32_t stream_id);

/**
 * @function
 *
 * Returns the local (receive) window size for the stream |stream_id|.
 * The local window size can be adjusted by
 * `nghttp2_submit_window_update()`.  This function takes into account
 * that and returns effective window size.
 *
 * This function returns -1 if it fails.
 */
int32_t nghttp2_session_get_stream_effective_local_window_size
(nghttp2_session *session, int32_t stream_id);

/**
 * @function
 *
 * Returns the number of DATA payload in bytes received without
 * WINDOW_UPDATE transmission for a connection.  The local (receive)
 * window size can be adjusted by `nghttp2_submit_window_update()`.
 * This function takes into account that and returns effective data
 * length.  In particular, if the local window size is reduced by
 * submitting negative window_size_increment with
 * `nghttp2_submit_window_update()`, this function returns the number
 * of bytes less than actually received.
 *
 * This function returns -1 if it fails.
 */
int32_t nghttp2_session_get_effective_recv_data_length
(nghttp2_session *session);

/**
 * @function
 *
 * Returns the local (receive) window size for a connection.  The
 * local window size can be adjusted by
 * `nghttp2_submit_window_update()`.  This function takes into account
 * that and returns effective window size.
 *
 * This function returns -1 if it fails.
 */
int32_t nghttp2_session_get_effective_local_window_size
(nghttp2_session *session);

/**
 * @function
 *
 * Returns the remote window size for a given stream |stream_id|.
 * This is the amount of flow-controlled payload (e.g., DATA) that the
 * local endpoint can send without WINDOW_UPDATE.
 *
 * This function returns -1 if it fails.
 */
int32_t nghttp2_session_get_stream_remote_window_size(nghttp2_session* session,
                                                      int32_t stream_id);

/**
 * @function
 *
 * Returns 1 if local peer half closed the given stream |stream_id|.
 * Returns 0 if it did not.  Returns -1 if no such stream exists.
 */
int nghttp2_session_get_stream_local_close(nghttp2_session* session,
                                           int32_t stream_id);

/**
 * @function
 *
 * Returns 1 if remote peer half closed the given stream |stream_id|.
 * Returns 0 if it did not.  Returns -1 if no such stream exists.
 */
int nghttp2_session_get_stream_remote_close(nghttp2_session* session,
                                            int32_t stream_id);

/**
 * @function
 *
 * Signals the session so that the connection should be terminated.
 *
 * The last stream ID is the ID of a stream for which
 * :type:`nghttp2_on_frame_recv_callback` was called most recently.
 *
 * The |error_code| is the error code of this GOAWAY frame.
 *
 * After the transmission, both `nghttp2_session_want_read()` and
 * `nghttp2_session_want_write()` return 0.
 *
 * This function should be called when the connection should be
 * terminated after sending GOAWAY.  If the remaining streams should
 * be processed after GOAWAY, use `nghttp2_submit_goaway()` instead.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 */
int nghttp2_session_terminate_session(nghttp2_session *session,
                                      nghttp2_error_code error_code);

/**
 * @function
 *
 * Signals the session so that the connection should be terminated.
 *
 * This function behaves like `nghttp2_session_terminate_session()`,
 * but the last stream ID can be specified by the application for fine
 * grained control of stream.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 */
int nghttp2_session_terminate_session2(nghttp2_session *session,
                                       int32_t last_stream_id,
                                       nghttp2_error_code error_code);

/**
 * @function
 *
 * Returns the value of SETTINGS |id| notified by a remote endpoint.
 * The |id| must be one of values defined in
 * :enum:`nghttp2_settings_id`.
 */
uint32_t nghttp2_session_get_remote_settings(nghttp2_session *session,
                                             nghttp2_settings_id id);

/**
 * @function
 *
 * Performs post-process of HTTP Upgrade request.  This function can
 * be called from both client and server, but the behavior is very
 * different in each other.
 *
 * If called from client side, the |settings_payload| must be the
 * value sent in ``HTTP2-Settings`` header field and must be decoded
 * by base64url decoder.  The |settings_payloadlen| is the length of
 * |settings_payload|.  The |settings_payload| is unpacked and its
 * setting values will be submitted using `nghttp2_submit_settings()`.
 * This means that the client application code does not need to submit
 * SETTINGS by itself.  The stream with stream ID=1 is opened and the
 * |stream_user_data| is used for its stream_user_data.  The opened
 * stream becomes half-closed (local) state.
 *
 * If called from server side, the |settings_payload| must be the
 * value received in ``HTTP2-Settings`` header field and must be
 * decoded by base64url decoder.  The |settings_payloadlen| is the
 * length of |settings_payload|.  It is treated as if the SETTINGS
 * frame with that payload is received.  Thus, callback functions for
 * the reception of SETTINGS frame will be invoked.  The stream with
 * stream ID=1 is opened.  The |stream_user_data| is ignored.  The
 * opened stream becomes half-closed (remote).
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 * :enum:`NGHTTP2_ERR_INVALID_ARGUMENT`
 *     The |settings_payload| is badly formed.
 * :enum:`NGHTTP2_ERR_PROTO`
 *     The stream ID 1 is already used or closed; or is not available.
 */
int nghttp2_session_upgrade(nghttp2_session *session,
                            const uint8_t *settings_payload,
                            size_t settings_payloadlen,
                            void *stream_user_data);

/**
 * @function
 *
 * Serializes the SETTINGS values |iv| in the |buf|.  The size of the
 * |buf| is specified by |buflen|.  The number of entries in the |iv|
 * array is given by |niv|.  The required space in |buf| for the |niv|
 * entries is ``8*niv`` bytes and if the given buffer is too small, an
 * error is returned.  This function is used mainly for creating a
 * SETTINGS payload to be sent with the ``HTTP2-Settings`` header
 * field in an HTTP Upgrade request.  The data written in |buf| is NOT
 * base64url encoded and the application is responsible for encoding.
 *
 * This function returns the number of bytes written in |buf|, or one
 * of the following negative error codes:
 *
 * :enum:`NGHTTP2_ERR_INVALID_ARGUMENT`
 *     The |iv| contains duplicate settings ID or invalid value.
 *
 * :enum:`NGHTTP2_ERR_INSUFF_BUFSIZE`
 *     The provided |buflen| size is too small to hold the output.
 */
ssize_t nghttp2_pack_settings_payload(uint8_t *buf,
                                      size_t buflen,
                                      const nghttp2_settings_entry *iv,
                                      size_t niv);

/**
 * @function
 *
 * Returns string describing the |lib_error_code|.  The
 * |lib_error_code| must be one of the :enum:`nghttp2_error`.
 */
const char* nghttp2_strerror(int lib_error_code);

/**
 * @function
 *
 * Initializes |pri_spec| with the |stream_id| of the stream to depend
 * on with |weight| and its exclusive flag.  If |exclusive| is
 * nonzero, exclusive flag is set.
 *
 * The |weight| must be in [:enum:`NGHTTP2_MIN_WEIGHT`,
 * :enum:`NGHTTP2_MAX_WEIGHT`], inclusive.
 */
void nghttp2_priority_spec_init(nghttp2_priority_spec *pri_spec,
                                int32_t stream_id, int32_t weight,
                                int exclusive);

/**
 * @function
 *
 * Initializes |pri_spec| with the default values.  The default values
 * are: stream_id = 0, weight = :macro:`NGHTTP2_DEFAULT_WEIGHT` and
 * exclusive = 0.
 */
void nghttp2_priority_spec_default_init(nghttp2_priority_spec *pri_spec);

/**
 * @function
 *
 * Returns nonzero if the |pri_spec| is filled with default values.
 */
int nghttp2_priority_spec_check_default(const nghttp2_priority_spec *pri_spec);

/**
 * @function
 *
 * Submits HEADERS frame and optionally one or more DATA frames.
 *
 * The |pri_spec| is priority specification of this request.  ``NULL``
 * means the default priority (see
 * `nghttp2_priority_spec_default_init()`).  To specify the priority,
 * use `nghttp2_priority_spec_init()`.  If |pri_spec| is not ``NULL``,
 * this function will copy its data members.
 *
 * The `pri_spec->weight` must be in [:enum:`NGHTTP2_MIN_WEIGHT`,
 * :enum:`NGHTTP2_MAX_WEIGHT`], inclusive.  If `pri_spec->weight` is
 * strictly less than :enum:`NGHTTP2_MIN_WEIGHT`, it becomes
 * :enum:`NGHTTP2_MIN_WEIGHT`.  If it is strictly greater than
 * :enum:`NGHTTP2_MAX_WEIGHT`, it becomes :enum:`NGHTTP2_MAX_WEIGHT`.
 *
 * The |nva| is an array of name/value pair :type:`nghttp2_nv` with
 * |nvlen| elements.  The value is opaque sequence of bytes and
 * therefore can contain NULL byte (0x0).  If the application requires
 * that the ordering of values for a single header field name
 * appearing in different header fields, it has to concatenate them
 * using NULL byte (0x0) before passing them to this function.
 *
 * HTTP/2 specification has requirement about header fields in the
 * request HEADERS.  See the specification for more details.
 *
 * This function creates copies of all name/value pairs in |nva|.  It
 * also lower-cases all names in |nva|.
 *
 * If |data_prd| is not ``NULL``, it provides data which will be sent
 * in subsequent DATA frames.  In this case, a method that allows
 * request message bodies
 * (http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html#sec9) must
 * be specified with ``:method`` key in |nva| (e.g. ``POST``).  This
 * function does not take ownership of the |data_prd|.  The function
 * copies the members of the |data_prd|.  If |data_prd| is ``NULL``,
 * HEADERS have END_STREAM set.  The |stream_user_data| is data
 * associated to the stream opened by this request and can be an
 * arbitrary pointer, which can be retrieved later by
 * `nghttp2_session_get_stream_user_data()`.
 *
 * This function returns assigned stream ID if it succeeds, or one of
 * the following negative error codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 * :enum:`NGHTTP2_ERR_STREAM_ID_NOT_AVAILABLE`
 *     No stream ID is available because maximum stream ID was
 *     reached.
 *
 * .. warning::
 *
 *   This function returns assigned stream ID if it succeeds.  But
 *   that stream is not opened yet.  The application must not submit
 *   frame to that stream ID before
 *   :member:`nghttp2_session_callbacks.before_frame_send_callback` is
 *   called for this frame.
 *
 */
int32_t nghttp2_submit_request(nghttp2_session *session,
                               const nghttp2_priority_spec *pri_spec,
                               const nghttp2_nv *nva, size_t nvlen,
                               const nghttp2_data_provider *data_prd,
                               void *stream_user_data);

/**
 * @function
 *
 * Submits response HEADERS frame and optionally one or more DATA
 * frames against the stream |stream_id|.
 *
 * The |nva| is an array of name/value pair :type:`nghttp2_nv` with
 * |nvlen| elements.  The value is opaque sequence of bytes and
 * therefore can contain NULL byte (0x0).  If the application requires
 * that the ordering of values for a single header field name
 * appearing in different header fields, it has to concatenate them
 * using NULL byte (0x0) before passing them to this function.
 *
 * HTTP/2 specification has requirement about header fields in the
 * response HEADERS.  See the specification for more details.
 *
 * This function creates copies of all name/value pairs in |nva|.  It
 * also lower-cases all names in |nva|.
 *
 * If |data_prd| is not ``NULL``, it provides data which will be sent
 * in subsequent DATA frames.  This function does not take ownership
 * of the |data_prd|.  The function copies the members of the
 * |data_prd|.  If |data_prd| is ``NULL``, HEADERS will have
 * END_STREAM flag set.
 *
 * This method can be used as normal HTTP response and push response.
 * When pushing a resource using this function, the |session| must be
 * configured using `nghttp2_session_server_new()` or its variants and
 * the target stream denoted by the |stream_id| must be reserved using
 * `nghttp2_submit_push_promise()`.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 * :enum:`NGHTTP2_ERR_INVALID_ARGUMENT`
 *     The |stream_id| is 0.
 */
int nghttp2_submit_response(nghttp2_session *session,
                            int32_t stream_id,
                            const nghttp2_nv *nva, size_t nvlen,
                            const nghttp2_data_provider *data_prd);

/**
 * @function
 *
 * Submits HEADERS frame. The |flags| is bitwise OR of the
 * following values:
 *
 * * :enum:`NGHTTP2_FLAG_END_STREAM`
 *
 * If |flags| includes :enum:`NGHTTP2_FLAG_END_STREAM`, this frame has
 * END_STREAM flag set.
 *
 * The library handles the CONTINUATION frame internally and it
 * correctly sets END_HEADERS to the last sequence of the PUSH_PROMISE
 * or CONTINUATION frame.
 *
 * If the |stream_id| is -1, this frame is assumed as request (i.e.,
 * request HEADERS frame which opens new stream).  In this case, the
 * assigned stream ID will be returned.  Otherwise, specify stream ID
 * in |stream_id|.
 *
 * The |pri_spec| is priority specification of this request.  ``NULL``
 * means the default priority (see
 * `nghttp2_priority_spec_default_init()`).  To specify the priority,
 * use `nghttp2_priority_spec_init()`.  If |pri_spec| is not ``NULL``,
 * this function will copy its data members.
 *
 * The `pri_spec->weight` must be in [:enum:`NGHTTP2_MIN_WEIGHT`,
 * :enum:`NGHTTP2_MAX_WEIGHT`], inclusive.  If `pri_spec->weight` is
 * strictly less than :enum:`NGHTTP2_MIN_WEIGHT`, it becomes
 * :enum:`NGHTTP2_MIN_WEIGHT`.  If it is strictly greater than
 * :enum:`NGHTTP2_MAX_WEIGHT`, it becomes :enum:`NGHTTP2_MAX_WEIGHT`.
 *
 * The |nva| is an array of name/value pair :type:`nghttp2_nv` with
 * |nvlen| elements.  The value is opaque sequence of bytes and
 * therefore can contain NULL byte (0x0).  If the application requires
 * that the ordering of values for a single header field name
 * appearing in different header fields, it has to concatenate them
 * using NULL byte (0x0) before passing them to this function.
 *
 * This function creates copies of all name/value pairs in |nva|.  It
 * also lower-cases all names in |nva|.
 *
 * The |stream_user_data| is a pointer to an arbitrary data which is
 * associated to the stream this frame will open.  Therefore it is
 * only used if this frame opens streams, in other words, it changes
 * stream state from idle or reserved to open.
 *
 * This function is low-level in a sense that the application code can
 * specify flags directly.  For usual HTTP request,
 * `nghttp2_submit_request()` is useful.
 *
 * This function returns newly assigned stream ID if it succeeds and
 * |stream_id| is -1.  Otherwise, this function returns 0 if it
 * succeeds, or one of the following negative error codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 * :enum:`NGHTTP2_ERR_STREAM_ID_NOT_AVAILABLE`
 *     No stream ID is available because maximum stream ID was
 *     reached.
 * :enum:`NGHTTP2_ERR_INVALID_ARGUMENT`
 *     The |stream_id| is 0.
 *
 * .. warning::
 *
 *   This function returns assigned stream ID if it succeeds and
 *   |stream_id| is -1.  But that stream is not opened yet.  The
 *   application must not submit frame to that stream ID before
 *   :member:`nghttp2_session_callbacks.before_frame_send_callback` is
 *   called for this frame.
 *
 */
int32_t nghttp2_submit_headers(nghttp2_session *session, uint8_t flags,
                               int32_t stream_id,
                               const nghttp2_priority_spec *pri_spec,
                               const nghttp2_nv *nva, size_t nvlen,
                               void *stream_user_data);

/**
 * @function
 *
 * Submits one or more DATA frames to the stream |stream_id|.  The
 * data to be sent are provided by |data_prd|.  If |flags| contains
 * :enum:`NGHTTP2_FLAG_END_STREAM`, the last DATA frame has END_STREAM
 * flag set.  If |flags| contains :enum:`NGHTTP2_FLAG_END_SEGMENT`,
 * the last DATA frame has END_SEGMENT flag set.
 *
 * This function does not take ownership of the |data_prd|.  The
 * function copies the members of the |data_prd|.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 * :enum:`NGHTTP2_ERR_DATA_EXIST`
 *     DATA has been already submitted and not fully processed yet.
 * :enum:`NGHTTP2_ERR_INVALID_ARGUMENT`
 *     The |stream_id| is 0.
 */
int nghttp2_submit_data(nghttp2_session *session, uint8_t flags,
                        int32_t stream_id,
                        const nghttp2_data_provider *data_prd);

/**
 * @function
 *
 * Submits PRIORITY frame to change the priority of stream |stream_id|
 * to the priority specification |pri_spec|.
 *
 * The |flags| is currently ignored and should be
 * :enum:`NGHTTP2_FLAG_NONE`.
 *
 * The |pri_spec| is priority specification of this request.  ``NULL``
 * is not allowed for this function. To specify the priority, use
 * `nghttp2_priority_spec_init()`.  This function will copy its data
 * members.
 *
 * The `pri_spec->weight` must be in [:enum:`NGHTTP2_MIN_WEIGHT`,
 * :enum:`NGHTTP2_MAX_WEIGHT`], inclusive.  If `pri_spec->weight` is
 * strictly less than :enum:`NGHTTP2_MIN_WEIGHT`, it becomes
 * :enum:`NGHTTP2_MIN_WEIGHT`.  If it is strictly greater than
 * :enum:`NGHTTP2_MAX_WEIGHT`, it becomes :enum:`NGHTTP2_MAX_WEIGHT`.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 * :enum:`NGHTTP2_ERR_INVALID_ARGUMENT`
 *     The |stream_id| is 0; or the |pri_spec| is NULL; or trying to
 *     depend on itself.
 */
int nghttp2_submit_priority(nghttp2_session *session, uint8_t flags,
                            int32_t stream_id,
                            const nghttp2_priority_spec *pri_spec);

/**
 * @function
 *
 * Submits RST_STREAM frame to cancel/reject the stream |stream_id|
 * with the error code |error_code|.
 *
 * The |flags| is currently ignored and should be
 * :enum:`NGHTTP2_FLAG_NONE`.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 * :enum:`NGHTTP2_ERR_INVALID_ARGUMENT`
 *     The |stream_id| is 0.
 */
int nghttp2_submit_rst_stream(nghttp2_session *session, uint8_t flags,
                              int32_t stream_id,
                              nghttp2_error_code error_code);

/**
 * @function
 *
 * Stores local settings and submits SETTINGS frame.  The |iv| is the
 * pointer to the array of :type:`nghttp2_settings_entry`.  The |niv|
 * indicates the number of :type:`nghttp2_settings_entry`.
 *
 * The |flags| is currently ignored and should be
 * :enum:`NGHTTP2_FLAG_NONE`.
 *
 * This function does not take ownership of the |iv|.  This function
 * copies all the elements in the |iv|.
 *
 * While updating individual stream's local window size, if the window
 * size becomes strictly larger than NGHTTP2_MAX_WINDOW_SIZE,
 * RST_STREAM is issued against such a stream.
 *
 * SETTINGS with :enum:`NGHTTP2_FLAG_ACK` is automatically submitted
 * by the library and application could not send it at its will.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * :enum:`NGHTTP2_ERR_INVALID_ARGUMENT`
 *     The |iv| contains invalid value (e.g., initial window size
 *     strictly greater than (1 << 31) - 1.
 * :enum:`NGHTTP2_ERR_TOO_MANY_INFLIGHT_SETTINGS`
 *     There is already another in-flight SETTINGS.  Note that the
 *     current implementation only allows 1 in-flight SETTINGS frame
 *     without ACK flag set.
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 */
int nghttp2_submit_settings(nghttp2_session *session, uint8_t flags,
                            const nghttp2_settings_entry *iv, size_t niv);

/**
 * @function
 *
 * Submits PUSH_PROMISE frame.
 *
 * The |flags| is currently ignored.  The library handles the
 * CONTINUATION frame internally and it correctly sets END_HEADERS to
 * the last sequence of the PUSH_PROMISE or CONTINUATION frame.
 *
 * The |stream_id| must be client initiated stream ID.
 *
 * The |nva| is an array of name/value pair :type:`nghttp2_nv` with
 * |nvlen| elements.  The value is opaque sequence of bytes and
 * therefore can contain NULL byte (0x0).  If the application requires
 * that the ordering of values for a single header field name
 * appearing in different header fields, it has to concatenate them
 * using NULL byte (0x0) before passing them to this function.
 *
 * This function creates copies of all name/value pairs in |nva|.  It
 * also lower-cases all names in |nva|.
 *
 * The |promised_stream_user_data| is a pointer to an arbitrary data
 * which is associated to the promised stream this frame will open and
 * make it in reserved state.  It is available using
 * `nghttp2_session_get_stream_user_data()`.  The application can
 * access it in :type:`nghttp2_before_frame_send_callback` and
 * :type:`nghttp2_on_frame_send_callback` of this frame.
 *
 * The client side is not allowed to use this function.
 *
 * This function returns assigned promised stream ID if it succeeds,
 * or one of the following negative error codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 * :enum:`NGHTTP2_ERR_PROTO`
 *     This function was invoked when |session| is initialized as
 *     client.
 * :enum:`NGHTTP2_ERR_STREAM_ID_NOT_AVAILABLE`
 *     No stream ID is available because maximum stream ID was
 *     reached.
 * :enum:`NGHTTP2_ERR_INVALID_ARGUMENT`
 *     The |stream_id| is 0.
 *
 * .. warning::
 *
 *   This function returns assigned promised stream ID if it succeeds.
 *   But that stream is not opened yet.  The application must not
 *   submit frame to that stream ID before
 *   :member:`nghttp2_session_callbacks.before_frame_send_callback` is
 *   called for this frame.
 *
 */
int32_t nghttp2_submit_push_promise(nghttp2_session *session, uint8_t flags,
                                    int32_t stream_id,
                                    const nghttp2_nv *nva, size_t nvlen,
                                    void *promised_stream_user_data);

/**
 * @function
 *
 * Submits PING frame.  You don't have to send PING back when you
 * received PING frame.  The library automatically submits PING frame
 * in this case.
 *
 * The |flags| is currently ignored and should be
 * :enum:`NGHTTP2_FLAG_NONE`.
 *
 * If the |opaque_data| is non ``NULL``, then it should point to the 8
 * bytes array of memory to specify opaque data to send with PING
 * frame.  If the |opaque_data| is ``NULL``, zero-cleared 8 bytes will
 * be sent as opaque data.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 */
int nghttp2_submit_ping(nghttp2_session *session, uint8_t flags,
                        const uint8_t *opaque_data);

/**
 * @function
 *
 * Submits GOAWAY frame with the last stream ID |last_stream_id| and
 * the error code |error_code|.
 *
 * The |flags| is currently ignored and should be
 * :enum:`NGHTTP2_FLAG_NONE`.
 *
 * If the |opaque_data| is not ``NULL`` and |opaque_data_len| is not
 * zero, those data will be sent as additional debug data.  The
 * library makes a copy of the memory region pointed by |opaque_data|
 * with the length |opaque_data_len|, so the caller does not need to
 * keep this memory after the return of this function.  If the
 * |opaque_data_len| is 0, the |opaque_data| could be ``NULL``.
 *
 * To shutdown gracefully, first send GOAWAY with ``last_stream_id =
 * (1u << 31) - 1``.  After 1 RTT, call either
 * `nghttp2_submit_goaway()`, `nghttp2_session_terminate_session()` or
 * `nghttp2_session_terminate_session2()`.  The latter 2 will close
 * HTTP/2 session immediately after transmission of the frame.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 * :enum:`NGHTTP2_ERR_INVALID_ARGUMENT`
 *     The |opaque_data_len| is too large.
 */
int nghttp2_submit_goaway(nghttp2_session *session, uint8_t flags,
                          int32_t last_stream_id,
                          nghttp2_error_code error_code,
                          const uint8_t *opaque_data, size_t opaque_data_len);

/**
 * @function
 *
 * Submits WINDOW_UPDATE frame.
 *
 * The |flags| is currently ignored and should be
 * :enum:`NGHTTP2_FLAG_NONE`.
 *
 * If the |window_size_increment| is positive, the WINDOW_UPDATE with
 * that value as window_size_increment is queued.  If the
 * |window_size_increment| is larger than the received bytes from the
 * remote endpoint, the local window size is increased by that
 * difference.
 *
 * If the |window_size_increment| is negative, the local window size
 * is decreased by -|window_size_increment|.  If
 * :enum:`NGHTTP2_OPT_NO_AUTO_STREAM_WINDOW_UPDATE` (or
 * :enum:`NGHTTP2_OPT_NO_AUTO_CONNECTION_WINDOW_UPDATE` if |stream_id|
 * is 0) is not set and the library decided that the WINDOW_UPDATE
 * should be submitted, then WINDOW_UPDATE is queued with the current
 * received bytes count.
 *
 * If the |window_size_increment| is 0, the function does nothing and
 * returns 0.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * :enum:`NGHTTP2_ERR_FLOW_CONTROL`
 *     The local window size overflow or gets negative.
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 */
int nghttp2_submit_window_update(nghttp2_session *session, uint8_t flags,
                                 int32_t stream_id,
                                 int32_t window_size_increment);

/**
 * @function
 *
 * Submits ALTSVC frame with given parameters.
 *
 * The |flags| is currently ignored and should be
 * :enum:`NGHTTP2_FLAG_NONE`.
 *
 * Only the server can send the ALTSVC frame.  If |session| is
 * initialized as client, this function fails and returns
 * :enum:`NGHTTP2_ERR_INVALID_STATE`.
 *
 * If the |protocol_id_len| is 0, the |protocol_id| could be ``NULL``.
 *
 * If the |host_len| is 0, the |host| could be ``NULL``.
 *
 * If the |origin_len| is 0, the |origin| could be ``NULL``.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 * :enum:`NGHTTP2_ERR_PROTO`
 *     The function is invoked with |session| which was initialized as
 *     client.
 * :enum:`NGHTTP2_ERR_INVALID_ARGUMENT`
 *     The combined length of |protocol_id_len|, |host_len| and
 *     |origin_len| is is too large.
 */
int nghttp2_submit_altsvc(nghttp2_session *session, uint8_t flags,
                          int32_t stream_id,
                          uint32_t max_age, uint16_t port,
                          const uint8_t *protocol_id, size_t protocol_id_len,
                          const uint8_t *host, size_t host_len,
                          const uint8_t *origin, size_t origin_len);

/**
 * @function
 *
 * Compares ``lhs->name`` of length ``lhs->namelen`` bytes and
 * ``rhs->name`` of length ``rhs->namelen`` bytes.  Returns negative
 * integer if ``lhs->name`` is found to be less than ``rhs->name``; or
 * returns positive integer if ``lhs->name`` is found to be greater
 * than ``rhs->name``; or returns 0 otherwise.
 */
int nghttp2_nv_compare_name(const nghttp2_nv *lhs, const nghttp2_nv *rhs);

/**
 * @function
 *
 * A helper function for dealing with NPN in client side or ALPN in
 * server side.  The |in| contains peer's protocol list in preferable
 * order.  The format of |in| is length-prefixed and not
 * null-terminated.  For example, ``HTTP-draft-04/2.0`` and
 * ``http/1.1`` stored in |in| like this::
 *
 *     in[0] = 17
 *     in[1..17] = "HTTP-draft-04/2.0"
 *     in[18] = 8
 *     in[19..26] = "http/1.1"
 *     inlen = 27
 *
 * The selection algorithm is as follows:
 *
 * 1. If peer's list contains HTTP/2 protocol the library supports,
 *    it is selected and returns 1. The following step is not taken.
 *
 * 2. If peer's list contains ``http/1.1``, this function selects
 *    ``http/1.1`` and returns 0.  The following step is not taken.
 *
 * 3. This function selects nothing and returns -1 (So called
 *    non-overlap case).  In this case, |out| and |outlen| are left
 *    untouched.
 *
 * Selecting ``HTTP-draft-04/2.0`` means that ``HTTP-draft-04/2.0`` is
 * written into |*out| and its length (which is 17) is assigned to
 * |*outlen|.
 *
 * For ALPN, refer to
 * https://tools.ietf.org/html/draft-ietf-tls-applayerprotoneg-05
 *
 * See http://technotes.googlecode.com/git/nextprotoneg.html for more
 * details about NPN.
 *
 * For NPN, to use this method you should do something like::
 *
 *     static int select_next_proto_cb(SSL* ssl,
 *                                     unsigned char **out,
 *                                     unsigned char *outlen,
 *                                     const unsigned char *in,
 *                                     unsigned int inlen,
 *                                     void *arg)
 *     {
 *         int rv;
 *         rv = nghttp2_select_next_protocol(out, outlen, in, inlen);
 *         if(rv == 1) {
 *             ((MyType*)arg)->http2_selected = 1;
 *         }
 *         return SSL_TLSEXT_ERR_OK;
 *     }
 *     ...
 *     SSL_CTX_set_next_proto_select_cb(ssl_ctx, select_next_proto_cb, my_obj);
 *
 */
int nghttp2_select_next_protocol(unsigned char **out, unsigned char *outlen,
                                 const unsigned char *in, unsigned int inlen);

/**
 * @function
 *
 * Returns a pointer to a nghttp2_info struct with version information
 * about the run-time library in use.  The |least_version| argument
 * can be set to a 24 bit numerical value for the least accepted
 * version number and if the condition is not met, this function will
 * return a ``NULL``.  Pass in 0 to skip the version checking.
 */
nghttp2_info *nghttp2_version(int least_version);

/**
 * @function
 *
 * Returns nonzero if the :type:`nghttp2_error` library error code
 * |lib_error| is fatal.
 */
int nghttp2_is_fatal(int lib_error);

/**
 * @function
 *
 * Returns nonzero if HTTP header field name |name| of length |len| is
 * valid according to
 * http://tools.ietf.org/html/draft-ietf-httpbis-p1-messaging-25#section-3.2
 *
 * Because this is a header field name in HTTP2, the upper cased alphabet
 * is treated as error.
 */
int nghttp2_check_header_name(const uint8_t *name, size_t len);

/**
 * @function
 *
 * Returns nonzero if HTTP header field value |value| of length |len|
 * is valid according to
 * http://tools.ietf.org/html/draft-ietf-httpbis-p1-messaging-25#section-3.2
 *
 * Because this is HTTP2 header field value, it can contain NULL
 * character (0x00).
 */
int nghttp2_check_header_value(const uint8_t *value, size_t len);

/* HPACK API */

struct nghttp2_hd_deflater;

/**
 * @struct
 *
 * HPACK deflater object.
 */
typedef struct nghttp2_hd_deflater nghttp2_hd_deflater;

/**
 * @function
 *
 * Initializes |*deflater_ptr| for deflating name/values pairs.
 *
 * The |deflate_hd_table_bufsize_max| is the upper bound of header
 * table size the deflater will use.
 *
 * If this function fails, |*deflater_ptr| is left untouched.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 */
int nghttp2_hd_deflate_new(nghttp2_hd_deflater **deflater_ptr,
                           size_t deflate_hd_table_bufsize_max);

/**
 * @function
 *
 * Deallocates any resources allocated for |deflater|.
 */
void nghttp2_hd_deflate_del(nghttp2_hd_deflater *deflater);

/**
 * @function
 *
 * Sets the availability of reference set in the |deflater|.  If
 * |no_refset| is nonzero, the deflater will first emit "Reference Set
 * Emptying" in the each subsequent invocation of
 * `nghttp2_hd_deflate_hd()` to clear up reference set.  By default,
 * the deflater uses reference set.
 */
void nghttp2_hd_deflate_set_no_refset(nghttp2_hd_deflater *deflater,
                                      uint8_t no_refset);

/**
 * @function
 *
 * Changes header table size of the |deflater| to
 * |settings_hd_table_bufsize_max| bytes.  This may trigger eviction
 * in the dynamic table.
 *
 * The |settings_hd_table_bufsize_max| should be the value received in
 * SETTINGS_HEADER_TABLE_SIZE.
 *
 * The deflater never uses more memory than
 * ``deflate_hd_table_bufsize_max`` bytes specified in
 * `nghttp2_hd_deflate_new()`.  Therefore, if
 * |settings_hd_table_bufsize_max| > ``deflate_hd_table_bufsize_max``,
 * resulting maximum table size becomes
 * ``deflate_hd_table_bufsize_max``.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 */
int nghttp2_hd_deflate_change_table_size(nghttp2_hd_deflater *deflater,
                                         size_t settings_hd_table_bufsize_max);

/**
 * @function
 *
 * Deflates the |nva|, which has the |nvlen| name/value pairs, into
 * the |buf| of length |buflen|.
 *
 * If |buf| is not large enough to store the deflated header block,
 * this function fails with :enum:`NGHTTP2_ERR_INSUFF_BUFSIZE`.  The
 * caller should use `nghttp2_hd_deflate_bound()` to know the upper
 * bound of buffer size required to deflate given header name/value
 * pairs.
 *
 * Once this function fails, subsequent call of this function always
 * returns :enum:`NGHTTP2_ERR_HEADER_COMP`.
 *
 * After this function returns, it is safe to delete the |nva|.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 * :enum:`NGHTTP2_ERR_HEADER_COMP`
 *     Deflation process has failed.
 * :enum:`NGHTTP2_ERR_INSUFF_BUFSIZE`
 *     The provided |buflen| size is too small to hold the output.
 */
ssize_t nghttp2_hd_deflate_hd(nghttp2_hd_deflater *deflater,
                              uint8_t *buf, size_t buflen,
                              const nghttp2_nv *nva, size_t nvlen);

/**
 * @function
 *
 * Returns an upper bound on the compressed size after deflation of
 * |nva| of length |nvlen|.
 */
size_t nghttp2_hd_deflate_bound(nghttp2_hd_deflater *deflater,
                                const nghttp2_nv *nva, size_t nvlen);

struct nghttp2_hd_inflater;

/**
 * @struct
 *
 * HPACK inflater object.
 */
typedef struct nghttp2_hd_inflater nghttp2_hd_inflater;

/**
 * @function
 *
 * Initializes |*inflater_ptr| for inflating name/values pairs.
 *
 * If this function fails, |*inflater_ptr| is left untouched.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 */
int nghttp2_hd_inflate_new(nghttp2_hd_inflater **inflater_ptr);

/**
 * @function
 *
 * Deallocates any resources allocated for |inflater|.
 */
void nghttp2_hd_inflate_del(nghttp2_hd_inflater *inflater);

/**
 * @function
 *
 * Changes header table size in the |inflater|.  This may trigger
 * eviction in the dynamic table.
 *
 * The |settings_hd_table_bufsize_max| should be the value transmitted
 * in SETTINGS_HEADER_TABLE_SIZE.
 *
 * This function returns 0 if it succeeds, or one of the following
 * negative error codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 */
int nghttp2_hd_inflate_change_table_size(nghttp2_hd_inflater *inflater,
                                         size_t settings_hd_table_bufsize_max);

/**
 * @enum
 *
 * The flags for header inflation.
 */
typedef enum {
  /**
   * No flag set.
   */
  NGHTTP2_HD_INFLATE_NONE = 0,
  /**
   * Indicates all headers were inflated.
   */
  NGHTTP2_HD_INFLATE_FINAL = 0x01,
  /**
   * Indicates a header was emitted.
   */
  NGHTTP2_HD_INFLATE_EMIT = 0x02
} nghttp2_hd_inflate_flag;

/**
 * @function
 *
 * Inflates name/value block stored in |in| with length |inlen|.  This
 * function performs decompression.  For each successful emission of
 * header name/value pair, :enum:`NGHTTP2_HD_INFLATE_EMIT` is set in
 * |*inflate_flags| and name/value pair is assigned to the |nv_out|
 * and the function returns.  The caller must not free the members of
 * |nv_out|.
 *
 * The |nv_out| may include pointers to the memory region in the |in|.
 * The caller must retain the |in| while the |nv_out| is used.
 *
 * The application should call this function repeatedly until the
 * ``(*inflate_flags) & NGHTTP2_HD_INFLATE_FINAL`` is nonzero and
 * return value is non-negative.  This means the all input values are
 * processed successfully.  Then the application must call
 * `nghttp2_hd_inflate_end_headers()` to prepare for the next header
 * block input.
 *
 * The caller can feed complete compressed header block.  It also can
 * feed it in several chunks.  The caller must set |in_final| to
 * nonzero if the given input is the last block of the compressed
 * header.
 *
 * This function returns the number of bytes processed if it succeeds,
 * or one of the following negative error codes:
 *
 * :enum:`NGHTTP2_ERR_NOMEM`
 *     Out of memory.
 * :enum:`NGHTTP2_ERR_HEADER_COMP`
 *     Inflation process has failed.
 * :enum:`NGHTTP2_ERR_BUFFER_ERROR`
 *     The heder field name or value is too large.
 *
 * Example follows::
 *
 *     int inflate_header_block(nghttp2_hd_inflater *hd_inflater,
 *                              uint8_t *in, size_t inlen, int final)
 *     {
 *         ssize_t rv;
 *
 *         for(;;) {
 *             nghttp2_nv nv;
 *             int inflate_flags = 0;
 *
 *             rv = nghttp2_hd_inflate_hd(hd_inflater, &nv, &inflate_flags,
 *                                        in, inlen, final);
 *
 *             if(rv < 0) {
 *                 fprintf(stderr, "inflate failed with error code %zd", rv);
 *                 return -1;
 *             }
 *
 *             in += rv;
 *             inlen -= rv;
 *
 *             if(inflate_flags & NGHTTP2_HD_INFLATE_EMIT) {
 *                 fwrite(nv.name, nv.namelen, 1, stderr);
 *                 fprintf(stderr, ": ");
 *                 fwrite(nv.value, nv.valuelen, 1, stderr);
 *                 fprintf(stderr, "\n");
 *             }
 *             if(inflate_flags & NGHTTP2_HD_INFLATE_FINAL) {
 *                 nghttp2_hd_inflate_end_headers(hd_inflater);
 *                 break;
 *             }
 *             if((inflate_flags & NGHTTP2_HD_INFLATE_EMIT) == 0 &&
 *                inlen == 0) {
 *                break;
 *             }
 *         }
 *
 *         return 0;
 *     }
 *
 */
ssize_t nghttp2_hd_inflate_hd(nghttp2_hd_inflater *inflater,
                              nghttp2_nv *nv_out, int *inflate_flags,
                              uint8_t *in, size_t inlen, int in_final);

/**
 * @function
 *
 * Signals the end of decompression for one header block.
 *
 * This function returns 0 if it succeeds. Currently this function
 * always succeeds.
 */
int nghttp2_hd_inflate_end_headers(nghttp2_hd_inflater *inflater);

#ifdef __cplusplus
}
#endif

#endif /* NGHTTP2_H */

redpajama_set_name: RedPajamaGithub


Our new healthcare aides can even provide urgent care!
Doctors are in short supply across rural India, since most prefer to work abroad or in urban areas after their medical training. As a result, many of India's remote tribal villages are left without any access to health care. Depending on a tribal family's financial resources, sick or injured family members may need to be carried long distances on foot, before finally being transported by bus or taxi to the nearest hospital. But even then, they are likely to find the hospital overcrowded, understaffed, or lacking adequate supplies and equipment.
Our volunteers are now pursuing a solution to this problem. Our own Amrita Hospital and Amrita Kalpetta Tribal Hospital trained 8 young men and women on how to provide basic medical services to tribal villages. These new healthcare aides were trained to measure patients' vital signs, draw blood samples, and give first aid. They also learned about the symptoms and effects of diseases like sickle cell anemia, measles and chicken pox, and about the dangers of addiction. They even went to medical camps where they learned to dress various kinds of wounds, and had rotations in the pharmacy, patient registration, and the lab in which they practiced lab tests for cholesterol, pregnancy, and urine sugar levels.
Our new healthcare aides can even provide urgent care to tribal villagers, and educate them about healthy habits like good nutrition and hand-washing, and about the dangers of addiction, spitting, and open defecation. They have learned tablet technology as well, which they will use to access special health care apps, to screen medical awareness videos, and for record keeping. The aides also will be a valuable link between the remote villages and our medical establishment, as they can make use of telemedicine link-ups (medical treatment at a distance) and can call for organized medical camps, if needed.
These new healthcare aides are the very first graduates of our tribal medical training program. Despite having an education through high school, these youth reported that, prior to their training, they were unable to find work other than occasional manual or agricultural labor. Yet, these new graduates will have regular work. They will be placed in remote tribal villages in the Wyanad area. With the strong dedication the aides showed in their training, we expect them to accomplish great things and raise the standard of health in Wyanad.