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/*********************************************************************\
* 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 *
* "recv_udp&". *
* 2) Invoke send_udp as many times as desired on the *
* remote host. *
* 3) When done, MAKE SURE TO KILL THIS BACKGROUND PROCESS! *
* *
* Phil Kearns *
* April 11, 1987 *
* *
* Modified February 2009: use getaddrinfo() *
\*********************************************************************/
#include <stdlib.h>
#include <signal.h>
#include <errno.h>
#include <string.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
void printsin(struct sockaddr_in*, char*, char*);
int main()
{
int socket_fd, cc, ecode;
socklen_t fsize;
struct sockaddr_in *s_in, from;
struct addrinfo hints, *addrlist;
void printsin();
struct {
char head;
u_long body;
char tail;
} msg;
/*
In order to attach a name to the socket created above, first fill
in the appropriate blanks in an inet socket address data structure
called "s_in". We blindly pick port number 0x3333. The second step
is to BIND the address to the socket. If port 0x3333 is in use, the
bind system call will fail detectably.
*/
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;
/*
getaddrinfo() should return a single result, denoting
a SOCK_DGRAM socket on any interface of this system at
port 0x3333.
*/
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, "RECV_UDP", "Local socket is:"); fflush(stdout);
/*
Create the socket to be used for datagram reception. Initially,
it has no name in the internet (or any other) domain.
*/
socket_fd = socket (addrlist->ai_family, addrlist->ai_socktype, 0);
if (socket_fd < 0) {
perror ("recv_udp:socket");
exit (1);
}
/*
bind port 0x3333 on the current host to the socket accessed through
socket_fd. If port in use, bind() will fail and we die.
*/
if (bind(socket_fd, (struct sockaddr *)s_in, sizeof(struct sockaddr_in)) < 0) {
perror("recv_udp:bind");
exit(1);
}
for(;;) {
fsize = sizeof(from);
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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