Created
September 9, 2014 14:30
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A Simple Stream Client
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/* | |
** 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/types.h> | |
#include <netinet/in.h> | |
#include <sys/socket.h> | |
#include <arpa/inet.h> | |
#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; | |
} |
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