這是最簡單的tcp的架構，server只有接受(accept)一個client，然後收送資料，接著就結束。Server
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <arpa/inet.h> // inet_xx()
#include <unistd.h> // close()
#include <netinet/in.h>
#define handle_error(msg) \
do { perror(msg); exit(EXIT_FAILURE); } while (0)
int main(int argc, char *argv[])
{
int sd, af, asd; // socket descriptor, address family, accepted sd
struct sockaddr_in sa, peer; // socket address
uint16_t port = 0;
char *ip = NULL, buf[128];
socklen_t addrlen;
ssize_t len;
if (argc > 1) {
ip = argv[1];
}
af = AF_INET;
if ((sd = socket(af, SOCK_STREAM, 0)) < 0) {
handle_error("socket");
}
memset(&sa, 0, sizeof(sa));
sa.sin_family = af;
sa.sin_port = htons(port);
sa.sin_addr.s_addr = INADDR_ANY;
if (ip) {
if (inet_pton(af, ip, &sa.sin_addr) != 1) {
handle_error("inet_pton");
}
}
if (bind(sd, (struct sockaddr*) &sa, sizeof(sa)) < 0) {
handle_error("bind");
}
addrlen = sizeof(sa);
if (getsockname(sd, (struct sockaddr*)&sa, &addrlen) < 0) {
handle_error("getsockname");
}
printf("bind on %s/%d\n",
inet_ntop(sa.sin_family, &sa.sin_addr, buf, sizeof(buf)),
ntohs(sa.sin_port));
if (listen(sd, 1) < -1) { // waiting to be accepted
handle_error("listen");
}
addrlen = sizeof(peer);
if ((asd = accept(sd, (struct sockaddr*) &peer, &addrlen)) < 0) {
handle_error("accept");
}
if ((len = recv(asd, buf, sizeof(buf), 0)) < 0) {
handle_error("recv");
}
buf[len] = 0;
printf("Server recv: %s\n", buf);
strcpy(buf, "bye bye, peer!");
if (send(asd, buf, strlen(buf), 0) < 0) {
handle_error("send");
}
close(asd);
close(sd);
return 0;
}
Client
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <arpa/inet.h> // inet_xx()
#include <unistd.h> // close()
#include <netinet/in.h>
#define handle_error(msg) \
do { perror(msg); exit(EXIT_FAILURE); } while (0)
int main(int argc, char *argv[])
{
int sd, af = AF_INET; // socket descriptor, address family
struct sockaddr_in serv; // socket address
char *serv_ip = NULL, buf[128];
socklen_t addrlen;
ssize_t len;
uint16_t port;
if (argc <= 2) {
fprintf(stderr, "Usage: %s <serv-ip> <port>\n", argv[0]);
exit(EXIT_FAILURE);
}
serv_ip = argv[1];
port = atoi(argv[2]);
if ((sd = socket(af, SOCK_STREAM, 0)) < 0) {
handle_error("socket");
}
memset(&serv, 0, sizeof(serv));
serv.sin_family = af;
serv.sin_port = htons(port);
if (inet_pton(af, serv_ip, &serv.sin_addr) != 1) {
handle_error("inet_pton");
}
if (connect(sd, (struct sockaddr*) &serv, sizeof(serv)) < 0) {
handle_error("connect");
}
strcpy(buf, "hello server!");
if (send(sd, buf, strlen(buf), 0) < 0) {
handle_error("send");
}
if ((len = recv(sd, buf, sizeof(buf), 0)) < 0) {
handle_error("recv");
}
buf[len] = 0;
printf("Client recv: %s", buf);
close(sd);
return 0;
}
