Function recvfrom [src]

If sockfd is opened in non blocking mode, the function will return error.WouldBlock when EAGAIN is received.

Prototype

 pub fn recvfrom( sockfd: socket_t, buf: []u8, flags: u32, src_addr: ?*sockaddr, addrlen: ?*socklen_t, ) RecvFromError!usize

Parameters

sockfd: socket_tbuf: []u8flags: u32src_addr: ?*sockaddraddrlen: ?*socklen_t

Possible Errors

ConnectionRefused

A remote host refused to allow the network connection, typically because it is not running the requested service.

ConnectionResetByPeer

ConnectionTimedOut

MessageTooBig

The UDP message was too big for the buffer and part of it has been discarded

NetworkSubsystemFailed

The network subsystem has failed.

SocketNotBound

The socket has not been bound.

SocketNotConnected

The socket is not connected (connection-oriented sockets only).

SystemResources

Could not allocate kernel memory.

Unexpected UnexpectedError

The Operating System returned an undocumented error code.

This error is in theory not possible, but it would be better to handle this error than to invoke undefined behavior.

When this error code is observed, it usually means the Zig Standard Library needs a small patch to add the error code to the error set for the respective function.

WouldBlock

The socket is marked nonblocking and the requested operation would block, and there is no global event loop configured.

Source

  pub fn recvfrom(
    sockfd: socket_t,
    buf: []u8,
    flags: u32,
    src_addr: ?*sockaddr,
    addrlen: ?*socklen_t,
) RecvFromError!usize {
    while (true) {
        const rc = system.recvfrom(sockfd, buf.ptr, buf.len, flags, src_addr, addrlen);
        if (native_os == .windows) {
            if (rc == windows.ws2_32.SOCKET_ERROR) {
                switch (windows.ws2_32.WSAGetLastError()) {
                    .WSANOTINITIALISED => unreachable,
                    .WSAECONNRESET => return error.ConnectionResetByPeer,
                    .WSAEINVAL => return error.SocketNotBound,
                    .WSAEMSGSIZE => return error.MessageTooBig,
                    .WSAENETDOWN => return error.NetworkSubsystemFailed,
                    .WSAENOTCONN => return error.SocketNotConnected,
                    .WSAEWOULDBLOCK => return error.WouldBlock,
                    .WSAETIMEDOUT => return error.ConnectionTimedOut,
                    // TODO: handle more errors
                    else => |err| return windows.unexpectedWSAError(err),
                }
            } else {
                return @intCast(rc);
            }
        } else {
            switch (errno(rc)) {
                .SUCCESS => return @intCast(rc),
                .BADF => unreachable, // always a race condition
                .FAULT => unreachable,
                .INVAL => unreachable,
                .NOTCONN => return error.SocketNotConnected,
                .NOTSOCK => unreachable,
                .INTR => continue,
                .AGAIN => return error.WouldBlock,
                .NOMEM => return error.SystemResources,
                .CONNREFUSED => return error.ConnectionRefused,
                .CONNRESET => return error.ConnectionResetByPeer,
                .TIMEDOUT => return error.ConnectionTimedOut,
                else => |err| return unexpectedErrno(err),
            }
        }
    }
}  