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/* udp-broadcast-client.c
* udp datagram client
* Get datagram stock market quotes from UDP broadcast:
* see below the step by step explanation
*/
#ifdef WIN32
#include <winsock2.h>
#include <windows.h>
#else
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <time.h>
#include <signal.h>
#ifndef TRUE
#define TRUE 1
#define FALSE 0
#endif
/*
* This function reports the error and
* exits back to the shell:
*/
static void
displayError(const char *on_what) {
fputs(strerror(errno),stderr);
fputs(": ",stderr);
fputs(on_what,stderr);
fputc('\n',stderr);
exit(1);
}
int
main(int argc,char **argv) {
int z;
#ifdef WIN32
int x;
#else
socklen_t x;
#endif
struct sockaddr_in adr; /* AF_INET */
int len_inet; /* length */
int s; /* Socket */
char dgram[512]; /* Recv buffer */
/*
* Form the broadcast address:
*/
len_inet = sizeof adr;
adr.sin_family = AF_INET;
if (inet_pton(AF_INET, "127.0.0.1", &adr.sin_addr.s_addr) != 1) {
displayError("inet_pton");
}
adr.sin_port = htons(8124);
struct addrinfo hints;
memset(&hints, 0, sizeof(hints));
hints.ai_family = AF_INET;
hints.ai_socktype = SOCK_DGRAM;
hints.ai_protocol = 0;
hints.ai_flags = AI_PASSIVE;
/* WORKS
struct addrinfo *res;
if (getaddrinfo(NULL, "8124", &hints, &res) < 0) {
displayError("getaddrinfo");
}
*/
/* TEST */
adr.sin_family = AF_INET;
adr.sin_addr.s_addr = htonl(INADDR_ANY);
adr.sin_port = htons(8124);
/*
* Create a UDP socket to use:
*/
s = socket(AF_INET,SOCK_DGRAM,0);
if (s == -1)
displayError("socket()");
/*
* Bind our socket to the broadcast address:
*/
z = bind(s, /*TEST*/ (struct sockaddr *) &adr, sizeof(adr));
/* WORKS
res->ai_addr,
res->ai_addrlen);
*/
if (z == -1)
displayError("bind(2)");
for (;;) {
/*
* Wait for a broadcast message:
*/
x = sizeof(adr);
z = recvfrom(s, /* Socket */
dgram, /* Receiving buffer */
sizeof dgram,/* Max rcv buf size */
0, /* Flags: no options */
(struct sockaddr *)&adr, /* Addr */
&x); /* Addr len, in & out */
if (z < 0)
displayError("recvfrom(2)"); /* else err */
fwrite(dgram, z, 1, stdout);
putchar('\n');
fflush(stdout);
}
return 0;
}
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