一、服务端-server.c

#include <stdio.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <netinet/in.h>
#define MAXPENDING 5
#define BUFFSIZE 32
void Die(char *mess)
{
perror(mess);
exit(1);
}
void HandleClient(int sock)
{
char buffer[BUFFSIZE];
int received = -1;
if ((received = recv(sock, buffer, BUFFSIZE, 0)) < 0) {
Die("Failed to recevie inital bytes from client");
}
while (received > 0) {
if (send(sock, buffer, received, 0) != received) {
Die("Failed to send bytes to client");
}
if ((received = recv(sock, buffer, BUFFSIZE, 0)) < 0) {
Die("Failed to receive additional bytes from client");
}
}
close(sock);
}
int main(int argc, char *argv[])
{
int serversock, clientsock;
struct sockaddr_in echoserver, echoclient;
if (argc != 2) {
fprintf(stderr, "USAGE: echoserver <port>/n");
exit(1);
}
if ((serversock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0) {
Die("Failed to create socket");
}
memset(&echoserver, 0, sizeof(echoserver));
echoserver.sin_family = AF_INET;
echoserver.sin_addr.s_addr = htonl(INADDR_ANY);
echoserver.sin_port = htons(atoi(argv[1]));

if (bind(serversock, (struct sockaddr *) &echoserver, sizeof(echoserver)) < 0) {
Die("Failed to bind the server socket");
}
if (listen(serversock, MAXPENDING) < 0) {
Die("Failed to listen on server socket");
}

while (1) {
unsigned int clientlen = sizeof(echoclient);
if ((clientsock = accept(serversock, (struct sockaddr *) &echoclient, &clientlen)) < 0 ) {
Die("Failed to accept client connection");
}
fprintf(stdout, "Client connected:%s/n", inet_ntoa(echoclient.sin_addr));
HandleClient(clientsock);
}
}

二、客户端-client.c

#include <stdio.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <netinet/in.h>
#define BUFFSIZE 32
#define FP fprintf
void Die(char *mess)
{
perror(mess);
exit(1);
}
int main(int argc, char *argv[])
{
int sock;
struct sockaddr_in echoserver;
char buffer[BUFFSIZE];
unsigned int echolen;
int received = 0;
if (argc != 4) {
FP(stderr, "USAGE: TCP echo <server_ip> <word> <port>/n");
exit(1);
}
if ((sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0) {
Die("Failed to create socket");
}
memset(&echoserver, 0, sizeof(echoserver));
echoserver.sin_family = AF_INET;
echoserver.sin_addr.s_addr = inet_addr(argv[1]);
echoserver.sin_port = htons(atoi(argv[3]));
if (connect(sock, (struct sockaddr *) &echoserver, sizeof(echoserver)) < 0) {
Die("Failed to connect with server");
}
echolen = strlen(argv[2]);
if (send(sock, argv[2], echolen, 0) != echolen) {
Die("Mismatch in number of sent bytes");
}
FP(stdout, "Received: ");
while (received < echolen) {
int bytes = 0;
if ((bytes = recv(sock, buffer, BUFFSIZE-1, 0)) < 1) {
Die("Failed to receive bytes from server");
}
received += bytes;
buffer[bytes] = '/0';
FP(stdout, buffer);
}

FP(stdout, "/n");
close(sock);
exit(0);
}