linux下TCP编程示例（服务端/客户端）

1. 前言

1.1 TCP编程模型(服务端/客户端)

1.2 编程步骤

(1)服务端:
    ①创建套接字
    ②绑定本地地址和端口号
    ③侦听客户端的连接请求
    ④接受客户端的连接请求
    ⑤接收客户端发来的消息
    ⑥发送消息给客户端
    ⑦关闭套接字

(2)客户端

    ①创建套接字
    ②连接服务器
    ③发送消息给服务器
    ④接收服务器的回应
    ⑤关闭套接字

2. 服务端示例程序

2.1 单服务器

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdio.h>
#include <string.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <stdlib.h>

#define PORT 10000

int main(){
//1.创建套接字
int sid = socket(AF_INET,SOCK_STREAM,0);
if(sid < 0 ){
perror("socket");
exit(-1);
}

struct sockaddr_in saddr,caddr;
saddr.sin_family = AF_INET;
saddr.sin_port = htons(PORT);
saddr.sin_addr.s_addr = INADDR_ANY;

//2.绑定本地地址和端口号
int iRet = bind(sid,(struct sockaddr*)&saddr,sizeof(saddr));
if(iRet != 0){
perror("bind");
exit(-1);
}

//3.侦听客户端的连接
iRet = listen(sid,5);
if(iRet != 0){
perror("listen");
exit(-1);
}

//4.接受客户端的连接
int addrsize = sizeof(struct sockaddr_in);
int pid = accept(sid,(struct sockaddr *)&caddr,&addrsize);
if(pid < 0){
perror("accept");
exit(-1);
}

char buffer[1024] = {0};
int len = -1;

while(1){
bzero(buffer,sizeof(buffer));

//5.接收客户端发送的消息
len = recv(pid,buffer,sizeof(buffer),0);
if(len < 0)
{
perror("recv");
exit(-1);
}
else
{
buffer[len] = 0;//加结束符
printf("Receive: %s\n",buffer);
}

bzero(buffer,sizeof(buffer));
strcpy(buffer, "Welcome to access the server!");

//6.发送消息给客户端
len = send(pid,buffer,strlen(buffer),0);
if(len < 0){
perror("send");
exit(-1);
}
}
close(pid);
close(sid);

return 0;
}

2.2 基于多线程的并发服务器示例程序(编译：gcc server.c -o server lpthread)

#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<stdio.h>
#include<string.h>
#include<unistd.h>
#include<pthread.h>
#include<stdlib.h>

#define PORT 10000

void thread_process(const int * socketid)
{
int cid = *socketid;
char buffer[1024] = {0};
int iLen = -1;

while(1)
{
bzero(buffer,sizeof(buffer));

//5.接收客户端发来的消息
iLen = recv(cid,buffer,sizeof(buffer),0);
if(iLen < 0)
{
perror("recv");
exit(-1);
}
else
{
buffer[iLen] = 0;//加结束符
printf("Receive: %s\n",buffer);
}

bzero(buffer,sizeof(buffer));
strcpy(buffer, "Welcome to access the server!");
//6.发送消息给客户端
iLen = send(cid,buffer,strlen(buffer),0);
if(iLen < 0)
{
perror("send");
exit(-1);
}
}

close(cid);
}

int main()
{
//1.创建套接字
int sid = socket(AF_INET,SOCK_STREAM,0);
if(sid < 0 ){
perror("socket");
exit(-1);
}

struct sockaddr_in saddr,caddr;
saddr.sin_family = AF_INET;
saddr.sin_port = htons(PORT);
saddr.sin_addr.s_addr = INADDR_ANY;

//2.绑定本地地址和端口号
int iRet = bind(sid,(struct sockaddr*)&saddr,sizeof(saddr));
if(iRet != 0){
perror("bind");
exit(-1);
}

//3.侦听客户端的连接
iRet = listen(sid,5);
if(iRet != 0){
perror("listen");
exit(-1);
}

while(1)
{
//4.接受客户端的连接
int addrsize = sizeof(struct sockaddr_in);
int cid = accept(sid,(struct sockaddr *)&caddr,&addrsize);
if(cid < 0)
{
perror("accept");
exit(-1);
}

//创建线程
pthread_t tid;
int err = pthread_create(&tid,NULL,(void*)thread_process,(void*)&cid);
if (err != 0)
{
printf("can't create thread: %s\n", strerror(err));
exit(-1);
}
}

//7.关闭套接字
close(sid);
}

3. 客户端示例程序

#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include <unistd.h>
#include <arpa/inet.h>

#define PORT 10000
#define IP "192.168.1.101"

int main(){
//1.创建套接字
int cid = socket(AF_INET,SOCK_STREAM,0);
if(cid < 0 ){
perror("socket");
exit(-1);
}

struct sockaddr_in saddr;
saddr.sin_family = AF_INET;
saddr.sin_port = htons(PORT);
saddr.sin_addr.s_addr = inet_addr(IP);

//2.连接服务器
int iRet = connect(cid,(struct sockaddr*)&saddr,sizeof(struct sockaddr));
if(iRet < 0 ){
perror("connect");
exit(-1);
}

char buffer[100] = {0};
int len = -1;

while(strncmp(buffer,"quit",4) != 0){
bzero(buffer,sizeof(buffer));
fgets(buffer,1024,stdin);

//3.发送消息给服务器
len = send(cid,buffer,strlen(buffer),0);
if(len < 0)
{
perror("send");
exit(-1);
}

bzero(buffer,sizeof(buffer));

//4.接收服务器的回应
len = recv(cid,buffer,sizeof(buffer),0);
if(len < 0)
{
perror("recv");
exit(-1);
}
else
{
buffer[len] = 0;//加结束符
printf("\nReceive: %s\n",buffer);
}
}

//5.关闭套接字
close(cid);
}