API Reference¶

Includes¶

To use the public APIs, include nghttp2/nghttp2.h:

#include <nghttp2/nghttp2.h>

The header files are also available online: nghttp2.h and nghttp2ver.h.

Remarks¶

Do not call nghttp2_session_send(), nghttp2_session_mem_send(), nghttp2_session_recv() or nghttp2_session_mem_recv() from the nghttp2 callback functions directly or indirectly. It will lead to the crash. You can submit requests or frames in the callbacks then call these functions outside the callbacks.

Macros¶

NGHTTP2_VERSION¶: Version number of the nghttp2 library release

NGHTTP2_VERSION_NUM¶: Numerical representation of the version number of the nghttp2 library release. This is a 24 bit number with 8 bits for major number, 8 bits for minor and 8 bits for patch. Version 1.2.3 becomes 0x010203.

NGHTTP2_PROTO_VERSION_ID¶: The protocol version identification string of this library supports. This identifier is used if HTTP/2 is used over TLS.

NGHTTP2_PROTO_VERSION_ID_LEN¶: The length of NGHTTP2_PROTO_VERSION_ID.

NGHTTP2_CLEARTEXT_PROTO_VERSION_ID¶: The protocol version identification string of this library supports. This identifier is used if HTTP/2 is used over cleartext TCP.

NGHTTP2_CLEARTEXT_PROTO_VERSION_ID_LEN¶: The length of NGHTTP2_CLEARTEXT_PROTO_VERSION_ID.

NGHTTP2_VERSION_AGE¶: The age of nghttp2_info

NGHTTP2_DEFAULT_WEIGHT¶: The default weight of stream dependency.

NGHTTP2_MAX_WEIGHT¶: The maximum weight of stream dependency.

NGHTTP2_MIN_WEIGHT¶: The minimum weight of stream dependency.

NGHTTP2_MAX_WINDOW_SIZE¶: The maximum window size

NGHTTP2_INITIAL_WINDOW_SIZE¶: The initial window size for stream level flow control.

NGHTTP2_INITIAL_CONNECTION_WINDOW_SIZE¶: The initial window size for connection level flow control.

NGHTTP2_MAX_HEADER_TABLE_SIZE¶: The maximum header table size.

NGHTTP2_CLIENT_CONNECTION_PREFACE¶: The client connection preface.

NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN¶: The length of NGHTTP2_CLIENT_CONNECTION_PREFACE.

NGHTTP2_CLIENT_CONNECTION_HEADER¶: The client connection header. This macro is obsoleted by NGHTTP2_CLIENT_CONNECTION_PREFACE.

NGHTTP2_CLIENT_CONNECTION_HEADER_LEN¶: The length of NGHTTP2_CLIENT_CONNECTION_HEADER.

NGHTTP2_INITIAL_MAX_CONCURRENT_STREAMS¶: Default maximum concurrent streams.

Enums¶

nghttp2_error¶

Error codes used in this library. The code range is [-999, -500], inclusive. The following values are defined:

NGHTTP2_ERR_INVALID_ARGUMENT¶: (-501) Invalid argument passed.

NGHTTP2_ERR_UNSUPPORTED_VERSION¶: (-503) The specified protocol version is not supported.

NGHTTP2_ERR_WOULDBLOCK¶: (-504) Used as a return value from nghttp2_send_callback and nghttp2_recv_callback to indicate that the operation would block.

NGHTTP2_ERR_PROTO¶: (-505) General protocol error

NGHTTP2_ERR_INVALID_FRAME¶: (-506) The frame is invalid.

NGHTTP2_ERR_EOF¶: (-507) The peer performed a shutdown on the connection.

NGHTTP2_ERR_DEFERRED¶: (-508) Used as a return value from nghttp2_data_source_read_callback() to indicate that data transfer is postponed. See nghttp2_data_source_read_callback() for details.

NGHTTP2_ERR_STREAM_ID_NOT_AVAILABLE¶: (-509) Stream ID has reached the maximum value. Therefore no stream ID is available.

NGHTTP2_ERR_STREAM_CLOSED¶: (-510) The stream is already closed; or the stream ID is invalid.

NGHTTP2_ERR_STREAM_CLOSING¶: (-511) RST_STREAM has been added to the outbound queue. The stream is in closing state.

NGHTTP2_ERR_STREAM_SHUT_WR¶: (-512) The transmission is not allowed for this stream (e.g., a frame with END_STREAM flag set has already sent).

NGHTTP2_ERR_INVALID_STREAM_ID¶: (-513) The stream ID is invalid.

NGHTTP2_ERR_INVALID_STREAM_STATE¶: (-514) 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_DEFERRED_DATA_EXIST¶: (-515) Another DATA frame has already been deferred.

NGHTTP2_ERR_START_STREAM_NOT_ALLOWED¶: (-516) Starting new stream is not allowed (e.g., GOAWAY has been sent and/or received).

NGHTTP2_ERR_GOAWAY_ALREADY_SENT¶: (-517) GOAWAY has already been sent.

NGHTTP2_ERR_INVALID_HEADER_BLOCK¶: (-518) 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_STATE¶: (-519) Indicates that the context is not suitable to perform the requested operation.

NGHTTP2_ERR_GZIP¶: (-520) The gzip error.

NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE¶: (-521) The user callback function failed due to the temporal error.

NGHTTP2_ERR_FRAME_SIZE_ERROR¶: (-522) The length of the frame is invalid, either too large or too small.

NGHTTP2_ERR_HEADER_COMP¶: (-523) Header block inflate/deflate error.

NGHTTP2_ERR_FLOW_CONTROL¶: (-524) Flow control error

NGHTTP2_ERR_INSUFF_BUFSIZE¶: (-525) Insufficient buffer size given to function.

NGHTTP2_ERR_PAUSE¶: (-526) Callback was paused by the application

NGHTTP2_ERR_TOO_MANY_INFLIGHT_SETTINGS¶: (-527) There are too many in-flight SETTING frame and no more transmission of SETTINGS is allowed.

NGHTTP2_ERR_PUSH_DISABLED¶: (-528) The server push is disabled.

NGHTTP2_ERR_DATA_EXIST¶: (-529) DATA frame for a given stream has been already submitted and has not been fully processed yet.

NGHTTP2_ERR_FATAL¶: (-900) The errors < 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 nghttp2_session object and only allowed operation for that object is deallocate it using nghttp2_session_del().

NGHTTP2_ERR_NOMEM¶: (-901) Out of memory. This is a fatal error.

NGHTTP2_ERR_CALLBACK_FAILURE¶: (-902) The user callback function failed. This is a fatal error.

nghttp2_nv_flag¶

The flags for header field name/value pair.

NGHTTP2_NV_FLAG_NONE¶: (0) No flag set.

NGHTTP2_NV_FLAG_NO_INDEX¶: (0x1) Indicates that this name/value pair must not be indexed.

nghttp2_frame_type¶

The control frame types in HTTP/2.

NGHTTP2_DATA¶: (0) The DATA frame.

NGHTTP2_HEADERS¶: (0x01) The HEADERS frame.

NGHTTP2_PRIORITY¶: (0x02) The PRIORITY frame.

NGHTTP2_RST_STREAM¶: (0x03) The RST_STREAM frame.

NGHTTP2_SETTINGS¶: (0x04) The SETTINGS frame.

NGHTTP2_PUSH_PROMISE¶: (0x05) The PUSH_PROMISE frame.

NGHTTP2_PING¶: (0x06) The PING frame.

NGHTTP2_GOAWAY¶: (0x07) The GOAWAY frame.

NGHTTP2_WINDOW_UPDATE¶: (0x08) The WINDOW_UPDATE frame.

NGHTTP2_CONTINUATION¶: (0x09) The CONTINUATION frame.

NGHTTP2_ALTSVC¶: (0x0a) The ALTSVC frame.

NGHTTP2_BLOCKED¶: (0x0b) The BLOCKED frame.

nghttp2_flag¶

The flags for HTTP/2 frames. This enum defines all flags for all frames.

NGHTTP2_FLAG_NONE¶: (0) No flag set.

NGHTTP2_FLAG_END_STREAM¶: (0x01) The END_STREAM flag.

NGHTTP2_FLAG_END_HEADERS¶: (0x04) The END_HEADERS flag.

NGHTTP2_FLAG_ACK¶: (0x01) The ACK flag.

NGHTTP2_FLAG_END_SEGMENT¶: (0x02) The END_SEGMENT flag.

NGHTTP2_FLAG_PAD_LOW¶: (0x08) The PAD_LOW flag.

NGHTTP2_FLAG_PAD_HIGH¶: (0x10) The PAD_HIGH flag.

NGHTTP2_FLAG_PRIORITY¶: (0x20) The PRIORITY flag.

NGHTTP2_FLAG_COMPRESSED¶: (0x20) THE COMPRESSED flag.

nghttp2_settings_id¶

The SETTINGS ID.

NGHTTP2_SETTINGS_HEADER_TABLE_SIZE¶: (1) SETTINGS_HEADER_TABLE_SIZE

NGHTTP2_SETTINGS_ENABLE_PUSH¶: (2) SETTINGS_ENABLE_PUSH

NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS¶: (3) SETTINGS_MAX_CONCURRENT_STREAMS

NGHTTP2_SETTINGS_INITIAL_WINDOW_SIZE¶: (4) SETTINGS_INITIAL_WINDOW_SIZE

NGHTTP2_SETTINGS_COMPRESS_DATA¶: (5) SETTINGS_COMPRESS_DATA

NGHTTP2_SETTINGS_MAX¶: (5) Maximum ID of nghttp2_settings_id.

nghttp2_error_code¶

The status codes for the RST_STREAM and GOAWAY frames.

NGHTTP2_NO_ERROR¶: (0) No errors.

NGHTTP2_PROTOCOL_ERROR¶: (1) PROTOCOL_ERROR

NGHTTP2_INTERNAL_ERROR¶: (2) INTERNAL_ERROR

NGHTTP2_FLOW_CONTROL_ERROR¶: (3) FLOW_CONTROL_ERROR

NGHTTP2_SETTINGS_TIMEOUT¶: (4) SETTINGS_TIMEOUT

NGHTTP2_STREAM_CLOSED¶: (5) STREAM_CLOSED

NGHTTP2_FRAME_SIZE_ERROR¶: (6) FRAME_SIZE_ERROR

NGHTTP2_REFUSED_STREAM¶: (7) REFUSED_STREAM

NGHTTP2_CANCEL¶: (8) CANCEL

NGHTTP2_COMPRESSION_ERROR¶: (9) COMPRESSION_ERROR

NGHTTP2_CONNECT_ERROR¶: (10) CONNECT_ERROR

NGHTTP2_ENHANCE_YOUR_CALM¶: (11) ENHANCE_YOUR_CALM

NGHTTP2_INADEQUATE_SECURITY¶: (12) INADEQUATE_SECURITY

nghttp2_data_flag¶

The flags used to set in data_flags output parameter in nghttp2_data_source_read_callback.

NGHTTP2_DATA_FLAG_NONE¶: (0) No flag set.

NGHTTP2_DATA_FLAG_EOF¶: (0x01) Indicates EOF was sensed.

NGHTTP2_DATA_FLAG_COMPRESSED¶: (0x02) Indicates data was compressed by application.

nghttp2_headers_category¶

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.

NGHTTP2_HCAT_REQUEST¶: (0) The HEADERS frame is opening new stream, which is analogous to SYN_STREAM in SPDY.

NGHTTP2_HCAT_RESPONSE¶: (1) The HEADERS frame is the first response headers, which is analogous to SYN_REPLY in SPDY.

NGHTTP2_HCAT_PUSH_RESPONSE¶: (2) The HEADERS frame is the first headers sent against reserved stream.

NGHTTP2_HCAT_HEADERS¶: (3) The HEADERS frame which does not apply for the above categories, which is analogous to HEADERS in SPDY.

Types (structs, unions and typedefs)¶

nghttp2_session¶: 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.

nghttp2_info¶

This struct is what nghttp2_version() returns. It holds information about the particular nghttp2 version.

int age¶: Age of this struct. This instance of nghttp2 sets it to NGHTTP2_VERSION_AGE but a future version may bump it and add more struct fields at the bottom

int version_num¶: the NGHTTP2_VERSION_NUM number (since age ==1)

const char *version_str¶: points to the NGHTTP2_VERSION string (since age ==1)

const char *proto_str¶: points to the NGHTTP2_PROTO_VERSION_ID string this instance implements (since age ==1)

nghttp2_nv¶

The name/value pair, which mainly used to represent header fields.

uint8_t *name¶: The name byte string, which is not necessarily NULL terminated.

uint8_t *value¶: The value byte string, which is not necessarily NULL terminated.

uint16_t namelen¶: The length of the name.

uint16_t valuelen¶: The length of the value.

uint8_t flags¶: Bitwise OR of one or more of nghttp2_nv_flag.

nghttp2_frame_hd¶

The frame header.

size_t length¶: The length field of this frame, excluding frame header.

int32_t stream_id¶: The stream identifier (aka, stream ID)

uint8_t type¶: The type of this frame. See nghttp2_frame().

uint8_t flags¶: The flags.

nghttp2_data_source¶

This union represents the some kind of data source passed to nghttp2_data_source_read_callback.

int fd¶: The integer field, suitable for a file descriptor.

void *ptr¶: The pointer to an arbitrary object.

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)¶

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 NGHTTP2_DATA_FLAG_EOF flag in *data_flags.

To send compressed data payload without affecting content-length, set NGHTTP2_DATA_FLAG_COMPRESSED flag in *data_flags. Compression must be done by application prior to fill data in buf.

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 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 NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE will close the stream by issuing RST_STREAM with NGHTTP2_INTERNAL_ERROR. Returning NGHTTP2_ERR_CALLBACK_FAILURE will signal the entire session failure.

nghttp2_data_provider¶

This struct represents the data source and the way to read a chunk of data from it.

nghttp2_data_source source¶: The data source.

nghttp2_data_source_read_callback read_callback¶: The callback function to read a chunk of data from the source.

nghttp2_data¶

The DATA frame. The received data is delivered via nghttp2_on_data_chunk_recv_callback.

size_t padlen¶: The length of the padding in this frame. This includes PAD_HIGH and PAD_LOW.

nghttp2_priority_spec¶

The structure to specify stream dependency.

int32_t stream_id¶: The stream ID of the stream to depend on. Specifying 0 makes stream not depend any other stream.

int32_t weight¶: The weight of this dependency.

uint8_t exclusive¶: nonzero means exclusive dependency

nghttp2_headers¶

The HEADERS frame. It has the following members:

nghttp2_frame_hd hd¶: The frame header.

size_t padlen¶: The length of the padding in this frame. This includes PAD_HIGH and PAD_LOW.

nghttp2_priority_spec pri_spec¶: The priority specification

nghttp2_nv *nva¶: The name/value pairs.

size_t nvlen¶: The number of name/value pairs in nva.

nghttp2_headers_category cat¶: The category of this HEADERS frame.

nghttp2_priority¶

The PRIORITY frame. It has the following members:

nghttp2_frame_hd hd¶: The frame header.

nghttp2_priority_spec pri_spec¶: The priority specification.

nghttp2_rst_stream¶

The RST_STREAM frame. It has the following members:

nghttp2_frame_hd hd¶: The frame header.

nghttp2_error_code error_code¶: The error code. See nghttp2_error_code.

nghttp2_settings_entry¶

The SETTINGS ID/Value pair. It has the following members:

int32_t settings_id¶: The SETTINGS ID. See nghttp2_settings_id.

uint32_t value¶: The value of this entry.

nghttp2_settings¶

The SETTINGS frame. It has the following members:

nghttp2_frame_hd hd¶: The frame header.

size_t niv¶: The number of SETTINGS ID/Value pairs in iv.

nghttp2_settings_entry *iv¶: The pointer to the array of SETTINGS ID/Value pair.

nghttp2_push_promise¶

The PUSH_PROMISE frame. It has the following members:

nghttp2_frame_hd hd¶: The frame header.

size_t padlen¶: The length of the padding in this frame. This includes PAD_HIGH and PAD_LOW.

nghttp2_nv *nva¶: The name/value pairs.

size_t nvlen¶: The number of name/value pairs in nva.

int32_t promised_stream_id¶: The promised stream ID

nghttp2_ping¶

The PING frame. It has the following members:

nghttp2_frame_hd hd¶: The frame header.

uint8_t opaque_data[8]: The opaque data

nghttp2_goaway¶

The GOAWAY frame. It has the following members:

nghttp2_frame_hd hd¶: The frame header.

int32_t last_stream_id¶: The last stream stream ID.

nghttp2_error_code error_code¶: The error code. See nghttp2_error_code.

uint8_t *opaque_data¶: The additional debug data

size_t opaque_data_len¶: The length of opaque_data member.

nghttp2_window_update¶

The WINDOW_UPDATE frame. It has the following members:

nghttp2_frame_hd hd¶: The frame header.

int32_t window_size_increment¶: The window size increment.

nghttp2_altsvc¶

The ALTSVC frame. It has following members:

nghttp2_frame_hd hd¶: The frame header.

uint8_t *protocol_id¶: Protocol ID

uint8_t *host¶: Host

uint8_t *origin¶: Origin

size_t protocol_id_len¶: The length of protocol_id

size_t host_len¶: The length of host

size_t origin_len¶: The length of origin

uint32_t max_age¶: Max-Age

uint16_t port¶: Port

nghttp2_blocked¶

The BLOCKED frame. It has following members:

nghttp2_frame_hd hd¶: The frame header.

nghttp2_frame¶

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.

nghttp2_frame_hd hd¶: The frame header, which is convenient to inspect frame header.

nghttp2_data data¶: The DATA frame.

nghttp2_headers headers¶: The HEADERS frame.

nghttp2_priority priority¶: The PRIORITY frame.

nghttp2_rst_stream rst_stream¶: The RST_STREAM frame.

nghttp2_settings settings¶: The SETTINGS frame.

nghttp2_push_promise push_promise¶: The PUSH_PROMISE frame.

nghttp2_ping ping¶: The PING frame.

nghttp2_goaway goaway¶: The GOAWAY frame.

nghttp2_window_update window_update¶: The WINDOW_UPDATE frame.

nghttp2_altsvc altsvc¶: The ALTSVC frame.

nghttp2_blocked blocked¶: The BLOCKED frame.

typedef ssize_t (*nghttp2_send_callback)(nghttp2_session *session, const uint8_t *data, size_t length, int flags, void *user_data)¶

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 NGHTTP2_ERR_WOULDBLOCK. For other errors, it must return 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_recv_callback)(nghttp2_session *session, uint8_t *buf, size_t length, int flags, void *user_data)¶

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 NGHTTP2_ERR_WOULDBLOCK. If it gets EOF before it reads any single byte, it must return NGHTTP2_ERR_EOF. For other errors, it must return NGHTTP2_ERR_CALLBACK_FAILURE. Returning 0 is treated as 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 int (*nghttp2_on_frame_recv_callback)(nghttp2_session *session, const nghttp2_frame *frame, void *user_data)¶

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 nghttp2_on_header_callback.

For HEADERS, PUSH_PROMISE and DATA frames, this callback may be called after stream is closed (see nghttp2_on_stream_close_callback). The application should check that stream is still alive using its own stream management or 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 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)¶

Callback function invoked by nghttp2_session_recv() when an invalid non-DATA frame is received. The error_code is one of the 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 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)¶

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 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 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 NGHTTP2_ERR_CALLBACK_FAILURE.

typedef int (*nghttp2_before_frame_send_callback)(nghttp2_session *session, const nghttp2_frame *frame, void *user_data)¶

Callback function invoked before the non-DATA frame frame is sent. This may be useful, for example, to know the stream ID of HEADERS and PUSH_PROMISE frame (see also nghttp2_session_get_stream_user_data()), which is not assigned when it was queued. 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 NGHTTP2_ERR_CALLBACK_FAILURE.

typedef int (*nghttp2_on_frame_send_callback)(nghttp2_session *session, const nghttp2_frame *frame, void *user_data)¶

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 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)¶

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 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 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)¶

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 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)¶

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 NGHTTP2_ERR_CALLBACK_FAILURE.

typedef int (*nghttp2_on_begin_headers_callback)(nghttp2_session *session, const nghttp2_frame *frame, void *user_data)¶

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 nghttp2_on_header_callback.

The frame->hd.flags may not have 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 NGHTTP2_ERR_CALLBACK_FAILURE. If nonzero value other than NGHTTP2_ERR_CALLBACK_FAILURE is returned, it is treated as if NGHTTP2_ERR_CALLBACK_FAILURE is returned. If NGHTTP2_ERR_CALLBACK_FAILURE is returned, nghttp2_session_mem_recv() function will immediately return 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)¶

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 nghttp2_nv_flag.

If 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 NGHTTP2_HEADERS or NGHTTP2_PUSH_PROMISE. After all header name/value pairs are processed with this callback, and no error has been detected, nghttp2_on_frame_recv_callback will be invoked. If there is an error in decompression, 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 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 NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE will close the stream by issuing RST_STREAM with NGHTTP2_INTERNAL_ERROR. In this case, nghttp2_on_frame_recv_callback will not be invoked.

The implementation of this function must return 0 if it succeeds. It may return NGHTTP2_ERR_PAUSE or NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE. For other critical failures, it must return NGHTTP2_ERR_CALLBACK_FAILURE. If the other nonzero value is returned, it is treated as NGHTTP2_ERR_CALLBACK_FAILURE. If NGHTTP2_ERR_CALLBACK_FAILURE is returned, nghttp2_session_recv() and nghttp2_session_mem_recv() functions immediately return 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)¶: 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 NGHTTP2_ERR_CALLBACK_FAILURE. Returning frame->hd.length means no padding is added. Returning NGHTTP2_ERR_CALLBACK_FAILURE will make nghttp2_session_send() function immediately return NGHTTP2_ERR_CALLBACK_FAILURE.

typedef int (*nghttp2_adjust_priority_callback)(nghttp2_session *session, const nghttp2_frame *frame, nghttp2_priority_spec *pri_spec, void *user_data)¶

Callback function invoked to adjust priority value for request HEADERS. This callback is called only for request HEADERS (which means, frame->hd.type == NGHTTP2_HEADERS && frame->headers.cat == NGHTTP2_HCAT_REQUEST() hold) and before nghttp2_before_frame_send_callback(). The application can adjust priority value pri_spec. Initially, pri_spec is filled with the current priority value, which is equal to frame->headers.pri_spec(). If the application doesn’t alter priority value, just return 0 without updating pri_spec.

Since the application doesn’t know stream ID when it submits requests, it may not be able to add correct priority value to HEADERS frame and forced to use follwing PRIORITY frame. The purpose of this callback is give the chance to the application to adjust priority value with the latest information it has just before transmission so that correct priority is included in HEADERS frame and it doesn’t have to send additional PRIORITY frame.

Returning NGHTTP2_ERR_CALLBACK_FAILURE will make nghttp2_session_send() function immediately return NGHTTP2_ERR_CALLBACK_FAILURE.

nghttp2_session_callbacks¶

Callback functions.

nghttp2_send_callback send_callback¶: 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_recv_callback recv_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_on_frame_recv_callback on_frame_recv_callback¶: Callback function invoked by nghttp2_session_recv() when a frame is received.

nghttp2_on_invalid_frame_recv_callback on_invalid_frame_recv_callback¶: Callback function invoked by nghttp2_session_recv() when an invalid non-DATA frame is received.

nghttp2_on_data_chunk_recv_callback on_data_chunk_recv_callback¶: Callback function invoked when a chunk of data in DATA frame is received.

nghttp2_before_frame_send_callback before_frame_send_callback¶: Callback function invoked before a non-DATA frame is sent.

nghttp2_on_frame_send_callback on_frame_send_callback¶: Callback function invoked after a frame is sent.

nghttp2_on_frame_not_send_callback on_frame_not_send_callback¶: The callback function invoked when a non-DATA frame is not sent because of an error.

nghttp2_on_stream_close_callback on_stream_close_callback¶: Callback function invoked when the stream is closed.

nghttp2_on_unknown_frame_recv_callback on_unknown_frame_recv_callback¶: Callback function invoked when the received frame type is unknown.

nghttp2_on_begin_headers_callback on_begin_headers_callback¶: Callback function invoked when the reception of header block in HEADERS or PUSH_PROMISE is started.

nghttp2_on_header_callback on_header_callback¶: Callback function invoked when a header name/value pair is received.

nghttp2_select_padding_callback select_padding_callback¶: Callback function invoked when the library asks application how many padding bytes are required for the transmission of the given frame.

nghttp2_adjust_priority_callback adjust_priority_callback¶: Callback function invoked to adjust priority value just before request HEADERS is serialized to the wire format.

nghttp2_option¶: Configuration options for nghttp2_session. The details of this structure are intentionally hidden from the public API.

nghttp2_gzip¶: The gzip stream to inflate data. The details of this structure are intentionally hidden from the public API.

Functions¶

int nghttp2_option_new(nghttp2_option **option_ptr)¶

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:

NGHTTP2_ERR_NOMEM: Out of memory.

void nghttp2_option_del(nghttp2_option *option)¶: Frees any resources allocated for option. If option is NULL, this function does nothing.

void nghttp2_option_set_no_auto_stream_window_update(nghttp2_option *option, int val)¶: 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_connection_window_update(nghttp2_option *option, int val)¶: 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_peer_max_concurrent_streams(nghttp2_option *option, uint32_t val)¶: 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.

int nghttp2_session_client_new(nghttp2_session **session_ptr, const nghttp2_session_callbacks *callbacks, void *user_data)¶

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 nghttp2_session_callbacks.send_callback must be specified. If the application code uses nghttp2_session_recv(), the nghttp2_session_callbacks.recv_callback must be specified. The other members of callbacks can be NULL.

This function returns 0 if it succeeds, or one of the following negative error codes:

NGHTTP2_ERR_NOMEM: Out of memory.

int nghttp2_session_server_new(nghttp2_session **session_ptr, const nghttp2_session_callbacks *callbacks, void *user_data)¶

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 nghttp2_session_callbacks.send_callback must be specified. If the application code uses nghttp2_session_recv(), the nghttp2_session_callbacks.recv_callback must be specified. The other members of callbacks can be NULL.

This function returns 0 if it succeeds, or one of the following negative error codes:

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)¶

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:

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)¶

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:

NGHTTP2_ERR_NOMEM: Out of memory.

void nghttp2_session_del(nghttp2_session *session)¶: Frees any resources allocated for session. If session is NULL, this function does nothing.

int nghttp2_session_send(nghttp2_session *session)¶

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 nghttp2_session_callbacks.send_callback returns 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:

Get the next frame to send from outbound queue.
Prepare transmission of the frame.
If the control frame cannot be sent because some preconditions are not met (e.g., request HEADERS cannot be sent after GOAWAY), nghttp2_session_callbacks.on_frame_not_send_callback is invoked. Abort the following steps.
If the frame is request HEADERS, nghttp2_session_callbacks.adjust_priority_callback is invoked.
If the frame is HEADERS, PUSH_PROMISE or DATA, nghttp2_session_callbacks.select_padding_callback is invoked.
If the frame is request HEADERS, the stream is opened here.
nghttp2_session_callbacks.before_frame_send_callback is invoked.
nghttp2_session_callbacks.send_callback is invoked one or more times to send the frame.
nghttp2_session_callbacks.on_frame_send_callback is invoked.
If the transmission of the frame triggers closure of the stream, the stream is closed and nghttp2_session_callbacks.on_stream_close_callback is invoked.

This function returns 0 if it succeeds, or one of the following negative error codes:

NGHTTP2_ERR_NOMEM: Out of memory.
NGHTTP2_ERR_CALLBACK_FAILURE: The callback function failed.

ssize_t nghttp2_session_mem_send(nghttp2_session *session, const uint8_t **data_ptr)¶

Returns the serialized data to send.

This function behaves like nghttp2_session_send() except that it does not use 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:

NGHTTP2_ERR_NOMEM: Out of memory.

int nghttp2_session_recv(nghttp2_session *session)¶

Receives frames from the remote peer.

This function receives as many frames as possible until the user callback nghttp2_session_callbacks.recv_callback returns 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:

nghttp2_session_callbacks.recv_callback is invoked one or more times to receive frame header.
If the frame is DATA frame:
1. nghttp2_session_callbacks.recv_callback is invoked to receive DATA payload. For each chunk of data, nghttp2_session_callbacks.on_data_chunk_recv_callback is invoked.
2. If one DATA frame is completely received, nghttp2_session_callbacks.on_frame_recv_callback is invoked. If the reception of the frame triggers the closure of the stream, nghttp2_session_callbacks.on_stream_close_callback is invoked.
If the frame is the control frame:
1. 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, nghttp2_session_callbacks.on_begin_headers_callback is invoked. Then nghttp2_session_callbacks.on_header_callback is invoked for each header name/value pair. After all name/value pairs are emitted successfully, nghttp2_session_callbacks.on_frame_recv_callback is invoked. For other frames, nghttp2_session_callbacks.on_frame_recv_callback is invoked. If the reception of the frame triggers the closure of the stream, nghttp2_session_callbacks.on_stream_close_callback is invoked.
3. If the received frame is unpacked but is interpreted as invalid, nghttp2_session_callbacks.on_invalid_frame_recv_callback is invoked.
4. If the received frame type is unknown, nghttp2_session_callbacks.on_unknown_frame_recv_callback is invoked.

This function returns 0 if it succeeds, or one of the following negative error codes:

NGHTTP2_ERR_EOF: The remote peer did shutdown on the connection.
NGHTTP2_ERR_NOMEM: Out of memory.
NGHTTP2_ERR_CALLBACK_FAILURE: The callback function failed.

ssize_t nghttp2_session_mem_recv(nghttp2_session *session, const uint8_t *in, size_t inlen)¶

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 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 NGHTTP2_ERR_PAUSE is returned from nghttp2_session_callbacks.on_header_callback or nghttp2_session_callbacks.on_data_chunk_recv_callback. If 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:

NGHTTP2_ERR_NOMEM: Out of memory.
NGHTTP2_ERR_CALLBACK_FAILURE: The callback function failed.

int nghttp2_session_resume_data(nghttp2_session *session, int32_t stream_id)¶

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:

NGHTTP2_ERR_INVALID_ARGUMENT: The stream does not exist; or no deferred data exist; or data was deferred by flow control.
NGHTTP2_ERR_NOMEM: Out of memory.

int nghttp2_session_want_read(nghttp2_session *session)¶

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_write(nghttp2_session *session)¶

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.

void* nghttp2_session_get_stream_user_data(nghttp2_session *session, int32_t stream_id)¶: 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.

int nghttp2_session_set_stream_user_data(nghttp2_session *session, int32_t stream_id, void *stream_user_data)¶

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:

NGHTTP2_ERR_INVALID_ARGUMENT: The stream does not exist

size_t nghttp2_session_get_outbound_queue_size(nghttp2_session *session)¶: Returns the number of frames in the outbound queue. This does not include the deferred DATA frames.

int32_t nghttp2_session_get_stream_effective_recv_data_length(nghttp2_session *session, int32_t stream_id)¶

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_local_window_size(nghttp2_session *session, int32_t stream_id)¶

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_effective_recv_data_length(nghttp2_session *session)¶

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_local_window_size(nghttp2_session *session)¶

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_stream_remote_window_size(nghttp2_session* session, int32_t stream_id)¶

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.

int nghttp2_session_terminate_session(nghttp2_session *session, nghttp2_error_code error_code)¶

Signals the session so that the connection should be terminated.

GOAWAY frame with the given error_code will be submitted if it has not been transmitted. After the transmission, both nghttp2_session_want_read() and nghttp2_session_want_write() return 0. If GOAWAY frame has already transmitted at the time when this function is invoked, nghttp2_session_want_read() and nghttp2_session_want_write() returns 0 immediately after this function succeeds.

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:

NGHTTP2_ERR_NOMEM: Out of memory.

int nghttp2_session_upgrade(nghttp2_session *session, const uint8_t *settings_payload, size_t settings_payloadlen, void *stream_user_data)¶

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:

NGHTTP2_ERR_NOMEM: Out of memory.
NGHTTP2_ERR_INVALID_ARGUMENT: The settings_payload is badly formed.
NGHTTP2_ERR_PROTO: The stream ID 1 is already used or closed; or is not available.

ssize_t nghttp2_pack_settings_payload(uint8_t *buf, size_t buflen, const nghttp2_settings_entry *iv, size_t niv)¶

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:

NGHTTP2_ERR_INVALID_ARGUMENT: The iv contains duplicate settings ID or invalid value.
NGHTTP2_ERR_INSUFF_BUFSIZE: The provided buflen size is too small to hold the output.

const char* nghttp2_strerror(int lib_error_code)¶: Returns string describing the lib_error_code. The lib_error_code must be one of the nghttp2_error.

void nghttp2_priority_spec_init(nghttp2_priority_spec *pri_spec, int32_t stream_id, int32_t weight, int exclusive)¶

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 [NGHTTP2_MIN_WEIGHT, NGHTTP2_MAX_WEIGHT], inclusive.

void nghttp2_priority_spec_default_init(nghttp2_priority_spec *pri_spec)¶: Initializes pri_spec with the default values. The default values are: stream_id = 0, weight = NGHTTP2_DEFAULT_WEIGHT and exclusive = 0.

int nghttp2_priority_spec_check_default(const nghttp2_priority_spec *pri_spec)¶: Returns nonzero if the pri_spec is filled with default values.

int 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)¶

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 [NGHTTP2_MIN_WEIGHT, NGHTTP2_MAX_WEIGHT], inclusive. If pri_spec->weight() is strictly less than NGHTTP2_MIN_WEIGHT, it becomes NGHTTP2_MIN_WEIGHT. If it is strictly greater than NGHTTP2_MAX_WEIGHT, it becomes NGHTTP2_MAX_WEIGHT.

The nva is an array of name/value pair 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().

Since the library reorders the frames and tries to send the highest prioritized one first and the HTTP/2 specification requires the stream ID must be strictly increasing, the stream ID of this request cannot be known until it is about to sent. To know the stream ID of the request, the application can use nghttp2_session_callbacks.before_frame_send_callback. This callback is called just before the frame is sent. For HEADERS frame, the argument frame has the stream ID assigned. Also since the stream is already opened, nghttp2_session_get_stream_user_data() can be used to get stream_user_data to identify which HEADERS we are processing.

This function returns 0 if it succeeds, or one of the following negative error codes:

NGHTTP2_ERR_NOMEM: Out of memory.

int nghttp2_submit_response(nghttp2_session *session, int32_t stream_id, const nghttp2_nv *nva, size_t nvlen, const nghttp2_data_provider *data_prd)¶

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 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:

NGHTTP2_ERR_NOMEM: Out of memory.

int 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)¶

Submits HEADERS frame. The flags is bitwise OR of the following values:

NGHTTP2_FLAG_END_STREAM

If flags includes 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 actual stream ID is assigned just before the frame is sent. For response, 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 [NGHTTP2_MIN_WEIGHT, NGHTTP2_MAX_WEIGHT], inclusive. If pri_spec->weight() is strictly less than NGHTTP2_MIN_WEIGHT, it becomes NGHTTP2_MIN_WEIGHT. If it is strictly greater than NGHTTP2_MAX_WEIGHT, it becomes NGHTTP2_MAX_WEIGHT.

The nva is an array of name/value pair 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 0 if it succeeds, or one of the following negative error codes:

NGHTTP2_ERR_NOMEM: Out of memory.

int nghttp2_submit_data(nghttp2_session *session, uint8_t flags, int32_t stream_id, const nghttp2_data_provider *data_prd)¶

Submits one or more DATA frames to the stream stream_id. The data to be sent are provided by data_prd. If flags contains NGHTTP2_FLAG_END_STREAM, the last DATA frame has END_STREAM flag set. If flags contains 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:

NGHTTP2_ERR_NOMEM: Out of memory.
NGHTTP2_ERR_DATA_EXIST: DATA has been already submitted and not fully processed yet.

int nghttp2_submit_priority(nghttp2_session *session, uint8_t flags, int32_t stream_id, const nghttp2_priority_spec *pri_spec)¶

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 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 [NGHTTP2_MIN_WEIGHT, NGHTTP2_MAX_WEIGHT], inclusive. If pri_spec->weight() is strictly less than NGHTTP2_MIN_WEIGHT, it becomes NGHTTP2_MIN_WEIGHT. If it is strictly greater than NGHTTP2_MAX_WEIGHT, it becomes NGHTTP2_MAX_WEIGHT.

This function returns 0 if it succeeds, or one of the following negative error codes:

NGHTTP2_ERR_NOMEM: Out of memory.
NGHTTP2_ERR_INVALID_ARGUMENT: The pri_spec is NULL; or trying to depend on itself.

int nghttp2_submit_rst_stream(nghttp2_session *session, uint8_t flags, int32_t stream_id, nghttp2_error_code error_code)¶

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 NGHTTP2_FLAG_NONE.

This function returns 0 if it succeeds, or one of the following negative error codes:

NGHTTP2_ERR_NOMEM: Out of memory.

int nghttp2_submit_settings(nghttp2_session *session, uint8_t flags, const nghttp2_settings_entry *iv, size_t niv)¶

Stores local settings and submits SETTINGS frame. The iv is the pointer to the array of nghttp2_settings_entry. The niv indicates the number of nghttp2_settings_entry.

The flags is currently ignored and should be 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 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:

NGHTTP2_ERR_INVALID_ARGUMENT: The iv contains invalid value (e.g., initial window size strictly greater than (1 << 31) - 1.
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.
NGHTTP2_ERR_NOMEM: Out of memory.

int 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)¶

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 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 nghttp2_before_frame_send_callback and nghttp2_on_frame_send_callback of this frame.

Since the library reorders the frames and tries to send the highest prioritized one first and the HTTP/2 specification requires the stream ID must be strictly increasing, the promised stream ID cannot be known until it is about to sent. To know the promised stream ID, the application can use nghttp2_session_callbacks.before_frame_send_callback. This callback is called just before the frame is sent. For PUSH_PROMISE frame, the argument frame has the promised stream ID assigned.

The client side is not allowed to use this function.

This function returns 0 if it succeeds, or one of the following negative error codes:

NGHTTP2_ERR_NOMEM: Out of memory.
NGHTTP2_ERR_PROTO: This function was invoked when session is initialized as client.

int nghttp2_submit_ping(nghttp2_session *session, uint8_t flags, uint8_t *opaque_data)¶

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 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:

NGHTTP2_ERR_NOMEM: Out of memory.

int nghttp2_submit_goaway(nghttp2_session *session, uint8_t flags, nghttp2_error_code error_code, const uint8_t *opaque_data, size_t opaque_data_len)¶

Submits GOAWAY frame with the error code error_code.

The flags is currently ignored and should be 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.

This function returns 0 if it succeeds, or one of the following negative error codes:

NGHTTP2_ERR_NOMEM: Out of memory.
NGHTTP2_ERR_INVALID_ARGUMENT: The opaque_data_len is too large.

int nghttp2_submit_window_update(nghttp2_session *session, uint8_t flags, int32_t stream_id, int32_t window_size_increment)¶

Submits WINDOW_UPDATE frame.

The flags is currently ignored and should be 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 NGHTTP2_OPT_NO_AUTO_STREAM_WINDOW_UPDATE (or 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:

NGHTTP2_ERR_FLOW_CONTROL: The local window size overflow or gets negative.
NGHTTP2_ERR_NOMEM: Out of memory.

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)¶

Submits ALTSVC frame with given parameters.

The flags is currently ignored and should be NGHTTP2_FLAG_NONE.

Only the server can send the ALTSVC frame. If session is initialized as client, this function fails and returns 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:

NGHTTP2_ERR_NOMEM: Out of memory.
NGHTTP2_ERR_PROTO: The function is invoked with session which was initialized as client.
NGHTTP2_ERR_INVALID_ARGUMENT: The combined length of protocol_id_len, host_len and origin_len is is too large.

int nghttp2_nv_compare_name(const nghttp2_nv *lhs, const nghttp2_nv *rhs)¶: 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_select_next_protocol(unsigned char **out, unsigned char *outlen, const unsigned char *in, unsigned int inlen)¶

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:

If peer’s list contains HTTP/2 protocol the library supports, it is selected and returns 1. The following step is not taken.
If peer’s list contains http/1.1, this function selects http/1.1 and returns 0. The following step is not taken.
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_gzip_inflate_new(nghttp2_gzip **inflater_ptr)¶

A helper function to set up a per request gzip stream to inflate data.

This function returns 0 if it succeeds, or one of the following negative error codes:

NGHTTP2_ERR_GZIP: The initialization of gzip stream failed.
NGHTTP2_ERR_NOMEM: Out of memory.

void nghttp2_gzip_inflate_del(nghttp2_gzip *inflater)¶: Frees the inflate stream. The inflater may be NULL.

int nghttp2_gzip_inflate(nghttp2_gzip *inflater, uint8_t *out, size_t *outlen_ptr, const uint8_t *in, size_t *inlen_ptr)¶

Inflates data in in with the length *inlen_ptr and stores the inflated data to out which has allocated size at least *outlen_ptr. On return, *outlen_ptr is updated to represent the number of data written in out. Similarly, *inlen_ptr is updated to represent the number of input bytes processed.

This function returns 0 if it succeeds, or one of the following negative error codes:

NGHTTP2_ERR_GZIP: The inflation of gzip stream failed.

The example follows:

void 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)
{
    ...
    req = nghttp2_session_get_stream_user_data(session, stream_id);
    nghttp2_gzip *inflater = req->inflater;
    while(len > 0) {
        uint8_t out[MAX_OUTLEN];
        size_t outlen = MAX_OUTLEN;
        size_t tlen = len;
        int rv;
        rv = nghttp2_gzip_inflate(inflater, out, &outlen, data, &tlen);
        if(rv != 0) {
            nghttp2_submit_rst_stream(session, stream_id,
                                      NGHTTP2_INTERNAL_ERROR);
            break;
        }
        ... Do stuff ...
        data += tlen;
        len -= tlen;
    }
    ....
}

nghttp2_info *nghttp2_version(int least_version)¶: 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.

int nghttp2_is_fatal(int lib_error)¶: Returns nonzero if the nghttp2_error library error code lib_error is fatal.

int nghttp2_check_header_name(const uint8_t *name, size_t len)¶

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_value(const uint8_t *value, size_t len)¶

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).