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/*********************************************************************\
* FANCY_RECV_UDP.C *
* Test of UDP/IP. Receive datagrams on internet socket bound to port *
* 0x3333 on the local host. *
* *
* To use: *
* 1) On the appropriate host, invoke this code by *
* "fancy_recv_udp&". *
* 2) Invoke send_udp as many times as desired on the *
* remote host. *
* *
* Phil Kearns *
* April 11, 1987 *
* *
* Modified: April 10, 1992 *
* responds to input (CR) on stdin by cleanly shutting down *
* also shuts down if no datagrams for a minute *
\*********************************************************************/
#include <signal.h>
#include <errno.h>
#include <string.h>
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <stdlib.h>
void printsin(struct sockaddr_in*, char*, char*);
int main()
{
int socket_fd, cc, hits, ecode;
socklen_t fsize;
fd_set mask;
struct timeval timeout;
struct sockaddr_in *s_in, from;
struct addrinfo hints, *addrlist;
struct {
char head;
u_long body;
char tail;
} msg;
memset(&hints, 0, sizeof(hints));
hints.ai_family = AF_INET; hints.ai_socktype = SOCK_DGRAM;
hints.ai_flags = AI_NUMERICSERV | AI_PASSIVE; hints.ai_protocol = 0;
hints.ai_canonname = NULL; hints.ai_addr = NULL;
hints.ai_next = NULL;
ecode = getaddrinfo(NULL, "13107", &hints, &addrlist);
if (ecode != 0) {
fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(ecode));
exit(1);
}
s_in = (struct sockaddr_in *) addrlist->ai_addr;
printsin(s_in, "FANCY_RECV_UDP", "Local socket is:"); fflush(stdout);
socket_fd = socket (addrlist->ai_family, addrlist->ai_socktype, 0);
if (socket_fd < 0) {
perror ("fancy_recv_udp:socket");
exit (1);
}
/*
bind port 0x3333 on the current host to the socket accessed through
socket_fd. If port in use, die.
*/
if (bind(socket_fd, (struct sockaddr *)s_in, sizeof(struct sockaddr_in)) < 0) {
perror("fancy_recv_udp:bind");
exit(1);
}
for(;;) {
fsize = sizeof(from);
/* Here's the new stuff. Hang a select on the file descriptors 0 (stdin)
and socket_fd looking to see if either descriptor is able to be read.
If it's stdin, shut down. If it's socket_fd, proceed as normal. If
Nothing happens for a minute, shut down also.
*/
FD_ZERO(&mask);
FD_SET(0,&mask);
FD_SET(socket_fd,&mask);
timeout.tv_sec = 60;
timeout.tv_usec = 0;
if ((hits = select(socket_fd+1, &mask, (fd_set *)0, (fd_set *)0,
&timeout)) < 0) {
perror("fancy_recv_udp:select");
exit(1);
}
if ( (hits==0) || ((hits>0) && (FD_ISSET(0,&mask))) ) {
printf("Shutting down\n");
exit(0);
}
cc = recvfrom(socket_fd,&msg,sizeof(msg),0,(struct sockaddr *)&from,&fsize);
if (cc < 0) perror("recv_udp:recvfrom");
printsin( &from, "recv_udp: ", "Packet from:");
printf("Got data ::%c%u%c\n",msg.head,ntohl(msg.body),msg.tail);
fflush(stdout);
}
exit(0);
}
void printsin(struct sockaddr_in *sin, char *m1, char *m2 )
{
char fromip[INET_ADDRSTRLEN];
printf ("%s %s:\n", m1, m2);
printf (" family %d, addr %s, port %d\n", sin -> sin_family,
inet_ntop(AF_INET, &(sin->sin_addr.s_addr), fromip, sizeof(fromip)),
ntohs((unsigned short)(sin -> sin_port)));
}
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