100 lines
2.3 KiB
C
100 lines
2.3 KiB
C
/*
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** client.c -- a stream socket client demo
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <errno.h>
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#include <string.h>
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#include <netdb.h>
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#include <sys/types.h>
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#include <netinet/in.h>
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#include <sys/socket.h>
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#include <arpa/inet.h>
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#define PORT "3490" // the port client will be connecting to
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#define MAXDATASIZE 100 // max number of bytes we can get at once
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// get sockaddr, IPv4 or IPv6:
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void *get_in_addr(struct sockaddr *sa)
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{
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if (sa->sa_family == AF_INET) {
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return &(((struct sockaddr_in*)sa)->sin_addr);
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}
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return &(((struct sockaddr_in6*)sa)->sin6_addr);
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}
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int main(int argc, char *argv[])
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{
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int sockfd, numbytes;
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char buf[MAXDATASIZE];
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struct addrinfo hints, *servinfo, *p;
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int rv;
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char s[INET6_ADDRSTRLEN];
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if (argc != 2) {
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fprintf(stderr,"usage: client hostname\n");
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exit(1);
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}
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memset(&hints, 0, sizeof hints);
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hints.ai_family = AF_UNSPEC;
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hints.ai_socktype = SOCK_STREAM;
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if ((rv = getaddrinfo(argv[1], PORT, &hints, &servinfo)) != 0) {
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fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
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return 1;
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}
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// loop through all the results and connect to the first we can
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for(p = servinfo; p != NULL; p = p->ai_next) {
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if ((sockfd = socket(p->ai_family, p->ai_socktype,
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p->ai_protocol)) == -1) {
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perror("client: socket");
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continue;
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}
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inet_ntop(p->ai_family,
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get_in_addr((struct sockaddr *)p->ai_addr),
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s, sizeof s);
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printf("client: attempting connection to %s\n", s);
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if (connect(sockfd, p->ai_addr, p->ai_addrlen) == -1) {
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perror("client: connect");
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close(sockfd);
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continue;
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}
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break;
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}
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if (p == NULL) {
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fprintf(stderr, "client: failed to connect\n");
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return 2;
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}
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inet_ntop(p->ai_family,
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get_in_addr((struct sockaddr *)p->ai_addr),
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s, sizeof s);
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printf("client: connected to %s\n", s);
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freeaddrinfo(servinfo); // all done with this structure
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if ((numbytes = recv(sockfd, buf, MAXDATASIZE-1, 0)) == -1) {
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perror("recv");
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exit(1);
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}
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buf[numbytes] = '\0';
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printf("client: received '%s'\n",buf);
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close(sockfd);
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return 0;
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}
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