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#include <stdint.h>
#include <stdlib.h>
#include <nettle/sha1.h>
#include <nettle/base64.h>
/* Version defines */
#define WEBSOCKSY_API_VERSION 1
#define WEBSOCKSY_VERSION "0.1"
/* HTTP/WS read buffer size & limit */
#define WS_MAX_LINE 16384
/* Maximum number of HTTP headers to accept */
#define WS_HEADER_LIMIT 10
/*
* State machine for WebSocket connections
*/
typedef enum {
ws_new = 0, /* Initial state */
ws_http, /* HTTP Headers */
ws_open, /* Upgrade performed, forwarding */
ws_closed /* Close frame sent */
} ws_state;
/*
* WebSocket frame opcodes
* RFC Section 5.2
*/
typedef enum {
ws_frame_continuation = 0,
ws_frame_text = 1,
ws_frame_binary = 2,
ws_frame_close = 8,
ws_frame_ping = 9,
ws_frame_pong = 10
} ws_operation;
/*
* WebSocket close reasons / response codes
* RFC Section 7.4.1
*/
typedef enum {
ws_close_http = 100,
ws_close_normal = 1000,
ws_close_shutdown = 1001,
ws_close_proto = 1002,
ws_close_data = 1003,
ws_close_format = 1007,
ws_close_policy = 1008,
ws_close_limit = 1009,
ws_close_unexpected = 1011
} ws_close_reason;
/*
* HTTP header split into tag and value
*/
typedef struct /*_ws_http_header*/ {
char* tag;
char* value;
} ws_http_header;
/*
* Peer stream framing function
*
* Since the WebSocket protocol transfers its payload using discrete frames, unlike the peer's
* underlying TCP/Unix sockets (UDP is a different matter and may be framed directly), we need
* a method to indicate whether a complete frame to be forwarded has been received from the peer
* and with what WebSocket frame type to forward it (binary/text). Since this is largely
* protocol-dependent, this functionality needs to be user-extendable.
*
* We do however provide some default framing functions:
* * binary: Always forward all reads as binary frames
* * auto: Based on the content, forward every read result as binary/text
* * separator: Separate binary frames on a sequence of bytes
* * newline: Forward text frames separated by newlines (\r\n)
*
* The separator function is called once for every succesful read from the peer socket and called
* again when it indicates a frame boundary but there is still data in the buffer.
*/
typedef int64_t (*ws_framing)(void);
/*
* Peer connection model
*/
typedef struct /*_ws_peer_info*/ {
/* Peer protocol data */
int transport;
char* host;
char* port;
/* Framing function for this peer */
ws_framing framing;
/* WebSocket subprotocol indication index*/
size_t protocol;
} ws_peer_info;
/*
* Core connection model
*/
typedef struct /*_web_socket*/ {
/* WebSocket state & data */
int ws_fd;
uint8_t read_buffer[WS_MAX_LINE];
size_t read_buffer_offset;
ws_state state;
/* HTTP request headers */
size_t headers;
ws_http_header header[WS_HEADER_LIMIT];
/* WebSocket parameters */
char* request_path;
unsigned websocket_version;
char* socket_key;
unsigned want_upgrade;
/* WebSocket indicated subprotocols*/
size_t protocols;
char** protocol;
/* Peer data */
ws_peer_info peer;
int peer_fd;
} websocket;
/*
* Peer discovery backend API
*
* Peer discovery backends are used to dynamically select the peer based on parameters supplied by
* the WebSocket connection. The backend maps WebSocket characteristics (such as the endpoint used,
* the supported protocols and HTTP client headers) to a TCP/UDP/Unix socket peer endpoint using
* some form of possibly user-configurable provider (such as databases, files, crystal balls or
* sheer guesses).
*
* Backends are supplied as shared objects exporting the following symbols:
* * `init`: Optional, initialize any storage or connections required
* * `configure`: Optional, configure the backend
* * `query`: Required, find a peer for the given parameters
* * `cleanup`: Optional, Release any acquired resources prior to shutdown
*/
/*
* Called once for the initialization of backend resources if the backend shared objects exports it as
* the `init` symbol.
* Returns the WEBSOCKSY_API_VERSION used to compile the backend.
*/
typedef uint64_t (*ws_backend_init)();
/*
* Called once for every backend configuration variable if the backend shared object exports it as
* the `configure` symbol.
* Returns 0 on success, anything else fails configuration.
*/
typedef uint64_t (*ws_backend_configure)(char* key, char* value);
/*
* Called when a WebSocket successfully negotiates a connection upgrade and is to be connected with
* a peer. Exported as the `query` symbol from the backend shared object.
* The return value is a structure containing the destination address and transport to be connected to
* the Web Socket, as well as the indicated subprotocol to use (or none, if set to the provided maximum
* number of protocols).
* The fields within the structure should be allocated with `calloc` and will be free'd by websocky
* after use.
*/
typedef ws_peer_info (*ws_backend_query)(char* endpoint, size_t protocols, char** protocol, size_t headers, ws_http_header* header, websocket* ws);
/*
* Called once for the release of all backend-internal resources if exported as the `cleanup` symbol.
*/
typedef void (*ws_backend_cleanup)();
/*
* Composite backend model structure
*/
typedef struct /*_ws_backend*/ {
ws_backend_init init;
ws_backend_configure config;
ws_backend_query query;
ws_backend_cleanup cleanup;
} ws_backend;
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