initial commit

Author: Władysław Bodzek

.gitignore

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+*~
+udp_relay

Makefile

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+udp_relay: udp_relay.c
+	gcc -o udp_relay udp_relay.c
+	

README.md

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+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+
+int to_sockaddr_in(char *ip, char *port, struct sockaddr_in *a) {
+	a->sin_family = AF_INET;
+	a->sin_port = htons(atoi(port));
+	a->sin_addr.s_addr = inet_addr(ip);
+	return 0;
+}
+
+int parse_address(char *s, struct sockaddr_in *a) {
+	int ret = 0;
+	char *c = strrchr(s,':');
+	if (c) {
+		*c = 0;
+		ret = to_sockaddr_in(s,c+1,a);
+		*c = ':';
+	} else {
+		ret = 1;
+	}
+	return ret;
+}
+
+
+int main(int argc, char **argv) {
+	if ( argc < 3 ) {
+		printf("usage: udp_relay <source> <dest1> [ <dest2> ... ]\n");
+		exit(1);
+	}
+
+	struct sockaddr_in s;
+	struct sockaddr_in d[10];
+	int dcount = 0, i;
+
+	if ( parse_address(argv[1],&s) ) {
+		printf("error: could not resolve source address: %s\n",argv[1]);
+		return 1;
+	}
+
+	for (i=2;i<argc&&dcount<10;i++) {
+		if ( parse_address(argv[i],&d[dcount]) ) {
+			printf("error: could not resolve destination address: %s\n",argv[i]);
+			return 1;
+		}
+		dcount++;
+	}
+
+	int sock = socket(PF_INET,SOCK_DGRAM,IPPROTO_IP);
+	if ( sock < 0 ) {
+		perror("socket()");
+		return 1;
+	}
+	if ( bind(sock,(struct sockaddr*)&s,sizeof(s)) ) {
+		perror("bind()");
+		return 1;
+	}
+
+
+	char buffer[65536];
+	while (1) {
+		int n = recv(sock,buffer,sizeof(buffer),0);
+		if ( n < 0 ) continue;
+		printf("got packet: length=%d\n",n);
+		for (i=0;i<dcount;i++) {
+			sendto(sock,buffer,n,0,(struct sockaddr*)&d[i],sizeof(d[i]));
+		}
+	}
+
+	return 0;	
+}