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/* udp_o.c -- read packets from the network */
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#define BUFSIZE 1024
#define UDP_PORT 10094
main(argc, argv)
int argc;
char *argv[];
{
int sock, fromlen, l, i, portno;
char buf[BUFSIZE], *p;
struct sockaddr_in from;
portno = UDP_PORT;
/* Test arguments */
if(argc>2){
fprintf(stderr,"Usage: %s [<portnumber>]\n",argv[0]);
exit(1);
}
if(argc>1)portno = atoi(argv[1]);
/* Create socket */
sock = socket(AF_INET, SOCK_DGRAM, 0);
if (sock<0) {
perror("opening raw socket");
exit(1);
}
bzero((char *)&from, sizeof from);
from.sin_family = AF_INET;
from.sin_addr.s_addr = htonl(INADDR_ANY);
from.sin_port = htons(portno);
if (bind(sock, (struct sockaddr *)&from, sizeof from) < 0){
perror("binding UDP socket");
exit(1);
}
l = 0;
while(l>-1){
fromlen = sizeof from;
l = recvfrom(sock, buf, BUFSIZE, 0,
(struct sockaddr *)&from, &fromlen);
if(l<0){
perror("udp socket");
close(sock);
exit(2);
}
fprintf(stdout,"---------->recv %d bytes from port %d host %s\n", l,
ntohs(from.sin_port),
(char *)inet_ntoa(from.sin_addr));
fprintf(stdout,"{%d.%d.%d.%d->%d.%d.%d.%d}\n",buf[12],buf[13],
buf[14],buf[15],buf[16],buf[17],buf[18],buf[19]);
for(p=buf+40,i=0;i<(l-40);i++,p++){
if(isprint(*p))putc(*p,stdout);
else putc('.',stdout);
}
putc('\n',stdout);
fflush(stdout);
}
/* all done, close the socket and exit */
close(sock);
exit(0);
}
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