client.cc

#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 MAXDATASIZE 1000

int main(int argc, char *argv[]) {
	int sockfd;
	int numbytes;
	char buf[MAXDATASIZE];
	struct addrinfo hints, *servinfo;
	int rv;
	char s[INET_ADDRSTRLEN];

	if (argc != 3){
		fprintf(stderr, "usage: client hostname portnum\n");
		exit(1);
	}

	memset(&hints, 0, sizeof hints);
	hints.ai_family = AF_UNSPEC;
	hints.ai_socktype = SOCK_STREAM;

	if ((rv = getaddrinfo(argv[1], argv[2], &hints, &servinfo)) != 0) {
		fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
		return 1;
	}

	// create socket
	if ((sockfd = socket(servinfo->ai_family, servinfo->ai_socktype, servinfo->ai_protocol)) == -1){
		perror("client: socket");
		return 2;
	}

	// connect to server
	if (connect(sockfd, servinfo->ai_addr, servinfo->ai_addrlen) == -1) {
		close(sockfd);
		perror("client: connect");
		return 2;
	}

	// print to screen
	inet_ntop(servinfo->ai_family, &((struct sockaddr_in*)servinfo->ai_addr)->sin_addr, s, sizeof s);
	printf("client: connecting to %s\n", s);

	// free allocated memory for servinfo
	freeaddrinfo(servinfo);

	// send message
	strcpy(buf, "hello");
	if (send(sockfd, buf, strlen(buf), 0) == -1) {
		perror("send");
		close(sockfd);
		exit(1);	
	}

	// recv message (blocking)
	if ((numbytes = recv(sockfd, buf, sizeof buf, 0)) == -1){
		perror("recv");
		close(sockfd);
		exit(1);
	}

	buf[numbytes] = '\0'; // add null character at the end
	printf("client: received '%s'\n", buf);

	close(sockfd);

	return 0;
}