TCP通信——多线程并发回环服务器

思路

首先要考虑到服务器的流程，TCP服务器端程序流程：

socket
bind绑定
listen监听
accept等待连接
多线程并发服务器需要通过多个线程实现与多个客户端的连接，当每次有一个客户端连接来时，创建一个线程，用于与客户端的通信。
创建线程后，将所用参数传递给线程，tid，cfd，clientaddr；
最后将线程分离，方便线程结束回收子线程资源。

服务器代码

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <pthread.h>struct sockInfo
{int fd;pthread_t pthd;struct sockaddr_in clientaddr;
};void * pthreadCallback(void * arg)
{char rbuf[1024];struct sockInfo sockinfo = *(struct sockInfo *)arg;int cfd = sockinfo.fd;printf("the port is : %d\n", ntohs(sockinfo.clientaddr.sin_port));while(1){int len = read(cfd, rbuf, 1024);rbuf[len] = 0;if(len > 0){write(cfd, rbuf, len);printf("%d send:%s", cfd, rbuf);}else if(len == -1){perror("read");close(cfd);pthread_exit(NULL);}else{printf("%d client is closed...\n", cfd);close(cfd);pthread_exit(NULL);}}}int main()
{int lfd = socket(PF_INET, SOCK_STREAM, 0);if(lfd == -1){perror("socket");exit(-1);}struct sockaddr_in saddr;saddr.sin_family = AF_INET;inet_ntop(lfd, &saddr.sin_addr.s_addr, "192.168.1.108", sizeof(saddr));saddr.sin_port = htons(9999);int ret = bind(lfd, (struct sockaddr *)&saddr, sizeof(saddr));if(ret){perror("bind");exit(-1);}   ret = listen(lfd, 128);if(ret){perror("listen");exit(-1);}   int cfd;pthread_t pthd;while(1){struct sockaddr_in caddr;int clen = sizeof(caddr);cfd = accept(lfd, (struct sockaddr *)&caddr, &clen);struct sockInfo cinfo;cinfo.fd = cfd;//cinfo.clientaddr = caddr;memcpy(&cinfo.clientaddr, &caddr, sizeof(caddr));ret = pthread_create(&cinfo.pthd, NULL, pthreadCallback, (void *)&cinfo);if(ret == -1){perror("pthread_creat");printf("err is: %s\n", strerror(ret));}ret = pthread_detach(cinfo.pthd);if(ret == -1){printf("pthread error : %s\n", strerror(ret));}printf("the %d client link success!, pthd:%ld\n", cfd, cinfo.pthd);}return 0;
}

客户端代码

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <string.h>
#include <fcntl.h>int main()
{int lfd = socket(PF_INET, SOCK_STREAM, 0);if(lfd == -1){perror("socket");exit(-1);}struct sockaddr_in saddr;saddr.sin_family = AF_INET;int len = sizeof(saddr);inet_pton(AF_INET, "192.168.1.108", &saddr.sin_addr.s_addr);saddr.sin_port = htons(9999);int ret = connect(lfd, (struct sockaddr *)&saddr, sizeof(saddr));if(ret == -1){perror("connect");exit(-1);}printf("client link success!\n");//由于读操作会阻塞，客户端需要先发送数据，若先读取数据，一个进程就会阻塞住，一个进程就要先发数据，如果一次数据没有接收到，则会阻塞住。//可以采用两个进程，发、收互不影响pid_t pid = fork();if(pid==0){char rbuf[1024];while(1){//memset(rbuf, 0, 1024);int lent = read(lfd, rbuf, 1024);if(lent > 0){printf("send: %s", rbuf);}else if(lent == -1) perror("read");}}else if(pid > 0){int i = 0;char sbuf[1024];while(1){      i++;if(i > 255) i = 0;sprintf(sbuf, "the num is %d\n", i);write(lfd, sbuf,strlen(sbuf));sleep(1);}}close(lfd);return 0;
}