libdill: Structured Concurrency for C


udp_send - sends an UDP packet


#include <libdill.h>

int udp_send(
    int s,
    const struct ipaddr* addr,
    const void* buf,
    size_t len);


UDP is an unreliable message-based protocol defined in RFC 768. The size of the message is limited. The protocol has no initial or terminal handshake. A single socket can be used to different destinations.

This function sends an UDP packet.

Given that UDP protocol is unreliable the function has no deadline. If packet cannot be sent it will be silently dropped.

s: Handle of the UDP socket.

addr: IP address to send the packet to. If set to NULL remote address specified in udp_open function will be used.

buf: Data to send.

len: Number of bytes to send.

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


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



struct ipaddr local;
ipaddr_local(&local, NULL, 5555, 0);
struct ipaddr remote;
ipaddr_remote(&remote, "", 5555, 0, -1);
int s = udp_open(&local, &remote);
udp_send(s1, NULL, "ABC", 3);
char buf[2000];
ssize_t sz = udp_recv(s, NULL, buf, sizeof(buf), -1);


mrecv(3) mrecvl(3) msend(3) msendl(3) udp_open(3) udp_open_mem(3) udp_recv(3) udp_recvl(3) udp_sendl(3)