Stream socket client demo

/*

** client.c -- a stream socket client demo

*/



#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <errno.h>

#include <string.h>

#include <netdb.h>

#include <sys h="">

#include <netinet h="">

#include <sys h="">



#include 



#define PORT "3490" // the port client will be connecting to



#define MAXDATASIZE 100 // max number of bytes we can get at once



// get sockaddr, IPv4 or IPv6:

void *get_in_addr(struct sockaddr *sa)

{

 if (sa->sa_family == AF_INET) {

     return &(((struct sockaddr_in*)sa)->sin_addr);

 }



 return &(((struct sockaddr_in6*)sa)->sin6_addr);

}



int main(int argc, char *argv[])

{

 int sockfd, numbytes;

 char buf[MAXDATASIZE];

 struct addrinfo hints, *servinfo, *p;

 int rv;

 char s[INET6_ADDRSTRLEN];



 if (argc != 2) {

     fprintf(stderr,"usage: client hostname\n");

     exit(1);

 }



 memset(&hints, 0, sizeof hints);

 hints.ai_family = AF_UNSPEC;

 hints.ai_socktype = SOCK_STREAM;



 if ((rv = getaddrinfo(argv[1], PORT, &hints, &servinfo)) != 0) {

     fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));

     return 1;

 }



 // loop through all the results and connect to the first we can

 for(p = servinfo; p != NULL; p = p->ai_next) {

     if ((sockfd = socket(p->ai_family, p->ai_socktype,

             p->ai_protocol)) == -1) {

         perror("client: socket");

         continue;

     }



     if (connect(sockfd, p->ai_addr, p->ai_addrlen) == -1) {

         close(sockfd);

         perror("client: connect");

         continue;

     }



     break;

 }



 if (p == NULL) {

     fprintf(stderr, "client: failed to connect\n");

     return 2;

 }



 inet_ntop(p->ai_family, get_in_addr((struct sockaddr *)p->ai_addr),

         s, sizeof s);

 printf("client: connecting to %s\n", s);



 freeaddrinfo(servinfo); // all done with this structure



 if ((numbytes = recv(sockfd, buf, MAXDATASIZE-1, 0)) == -1) {

     perror("recv");

     exit(1);

 }



 buf[numbytes] = '\0';



 printf("client: received '%s'\n",buf);



 close(sockfd);



 return 0;

}