libdill: Structured Concurrency for C

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NAME

ws_send - sends a WebSocket message

SYNOPSIS

#include <libdill.h>

int ws_send(
    int s,
    int flags,
    const void* buf,
    size_t len,
    int64_t deadline);

DESCRIPTION

WARNING: This is experimental functionality and the API may change in the future.

WebSocket is a message-based protocol defined in RFC 6455. It can be used as a bidirectional communication channel for communication with a web server.

This function works very much like msend except that it allows message type (text or binary) to be specified explicitly rather that using the type specified at attach time.

s: The socket handle.

flags: Type of message to send. Either WS_BINARY or WS_TEXT. This will override the type specified when attaching the socket.

buf: Data to send.

len: Number of bytes to send.

deadline: A point in time when the operation should time out, in milliseconds. Use the now function to get your current point in time. 0 means immediate timeout, i.e., perform the operation if possible or return without blocking if not. -1 means no deadline, i.e., the call will block forever if the operation cannot be performed.

This function is not available if libdill is compiled with --disable-sockets option.

RETURN VALUE

In case of success the function returns 0. In case of error it returns -1 and sets errno to one of the values below.

ERRORS

• EBADF: Invalid handle.
• EBUSY: The handle is currently being used by a different coroutine.
• ECANCELED: Current coroutine was canceled.
• ECONNRESET: Broken connection.
• EINVAL: Invalid argument.
• ENOTSUP: The handle does not support this operation.
• EPIPE: Closed connection.
• ETIMEDOUT: Deadline was reached.

EXAMPLE

struct ipaddr addr;
ipaddr_remote(&addr, "www.example.org", 80, 0, -1);
int s = tcp_connect(&addr, -1);
s = ws_attach_client(s, "/", "www.example.org", WS_TEXT, -1);
ws_send(s, WS_TEXT, "Hello, world!", 13, -1);
int flags;
char buf[256];
ssize_t sz = ws_recv(s, &flags, buf, sizeof(buf), -1);
assert(flags & WS_TEXT);
s = ws_detach(s, -1);
tcp_close(s, -1);

SEE ALSO

mrecv(3) mrecvl(3) msend(3) msendl(3) now(3) ws_attach_client(3) ws_attach_client_mem(3) ws_attach_server(3) ws_attach_server_mem(3) ws_detach(3) ws_done(3) ws_recv(3) ws_recvl(3) ws_request_key(3) ws_response_key(3) ws_sendl(3) ws_status(3)