/* Bind to loopback port 0 and test sending a datagram to the same socket. */ #include "udp.h" int main(void) { int fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP); if ( fd < 0 ) err(1, "socket"); struct sockaddr_in sin; memset(&sin, 0, sizeof(sin)); sin.sin_family = AF_INET; sin.sin_addr.s_addr = htobe32(INADDR_LOOPBACK); sin.sin_port = htobe16(0); if ( bind(fd, (const struct sockaddr*) &sin, sizeof(sin)) < 0 ) err(1, "bind"); struct sockaddr_in local; socklen_t locallen = sizeof(local); if ( getsockname(fd, (struct sockaddr*) &local, &locallen) < 0 ) err(1, "getsockname"); char x = 'x'; if ( sendto(fd, &x, sizeof(x), 0, (const struct sockaddr*) &local, locallen) < 0 ) err(1, "sendto"); return 0; }