libdill: Structured Concurrency for C

NAME

ws_status - retrieves the status after protocol termination

SYNOPSIS

#include <libdill.h>

ssize_t ws_status(
    int s,
    int* status,
    void* buf,
    size_t len);

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.

When peer shuts down the protocol, receiving functions will start failing with EPIPE error. Once that happens ws_status function allows to retrieve the status and message sent by the peer when it closed the protocol.

s: The socket handle.

status: Out parameter. Status number sent by the peer. If zero, there was no status.

buf: Buffer to fill the terminal message into. If set to NULL the message won't be returned.

len: Size of the buffer, in bytes.

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

RETURN VALUE

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

ERRORS

EAGAIN: The connection wasn't yet terminated by the peer.
EBADF: Invalid handle.
EINVAL: Invalid argument.
EMSGSIZE: The message doesn't fit in the supplied buffer.
ENOTSUP: The handle does not support this operation.

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);