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网站备案哪个省,网络营销swot分析,做国外网站销售,深圳网站建设外贸服务端流程步骤socket函数创建监听套接字lfdbind函数将监听套接字绑定ip和端口listen函数设置服务器为被动监听状态，同时创建一条未完成连接队列（没走完tcp三次握手流程的连接），和一条已完成连接队列（已完成tcp三次握手…

服务端流程步骤

socket函数创建监听套接字lfd

bind函数将监听套接字绑定ip和端口

listen函数设置服务器为被动监听状态，同时创建一条未完成连接队列（没走完tcp三次握手流程的连接），和一条已完成连接队列（已完成tcp三次握手的连接）

accept函数循环的从已完成连接队列中提取连接，并返回一个新的套接字cfd跟客户端进行通信

fork函数创建一个子进程，让子进程与客户端进行通信

子进程：read函数循环的从r缓冲区读取客户端发送的数据，write函数将要发送的数据写入w缓冲区

close函数关闭套接字

客户端流程步骤

socket函数创建套接字

connect函数连接服务器

write函数将要发送的数据写入w缓冲区，read函数从r缓冲区读取服务器发送给客户端的数据

close函数关闭套接字

客户端跟服务器通信流程图

服务端代码

#include <stdio.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <errno.h>#define BUF_SIZE 256void do_sigchld(int signo, siginfo_t *siginfo, void *p)
{int status;pid_t pid;while((pid = waitpid(0, &status, WNOHANG)) > 0) //0:回收跟调用进程同组的子进程的资源，WNOHANG:不阻塞{if (WIFEXITED(status))printf("pid = %d, parent pid = %d, child pid = %d, exit status %d\n", pid, getpid(), siginfo->si_pid, WEXITSTATUS(status));else if (WEXITSTATUS(status))printf("pid = %d, parent pid = %d, child pid = %d, exit by signal %d\n ", pid, getpid(), siginfo->si_pid, WIFSIGNALED(status));}
}void sys_err(const char *str, int err)
{perror(str);exit(err);
}int main(int argc, char *argv[])
{if (argc < 2){printf("%s port\n", argv[0]);exit(1);}//创建流式套接字int lfd = socket(AF_INET, SOCK_STREAM, 0);if (lfd < 0)sys_err("socket", 1);//绑定ip端口    struct sockaddr_in server_addr;server_addr.sin_family = AF_INET;server_addr.sin_port = htons((unsigned short)atoi(argv[1]));server_addr.sin_addr.s_addr = 0; //0表示将本机所有ip都绑定上int ret = bind(lfd, (struct sockaddr *)&server_addr, sizeof(server_addr));if (ret < 0)sys_err("bind", 1);//监听ret = listen(lfd, 128);if (ret < 0)sys_err("listen", 1);//阻塞SIGCHLD信号sigset_t set;sigemptyset(&set);sigaddset(&set, SIGCHLD);sigprocmask(SIG_BLOCK, &set, NULL);int block = 1;//循环提取int cfd;pid_t pid;struct sockaddr_in client_addr; socklen_t len = sizeof(client_addr);char buf[BUF_SIZE];ssize_t size;char ip[INET_ADDRSTRLEN] = "";while(1){cfd = accept(lfd, (struct sockaddr *)&client_addr, &len);if (cfd < 0){if (errno == EINTR)continue;sys_err("accept", 1);}printf("client ip = %s, port = %d connect success\n", inet_ntop(AF_INET, &client_addr.sin_addr.s_addr, ip, sizeof(ip)), ntohs(client_addr.sin_port));pid = fork();if (pid == 0){//in childclose(lfd); //关闭不用了的监听套接字//解除阻塞SIGCHLD信号sigprocmask(SIG_UNBLOCK, &set, NULL);block = 0;while(1){memset(buf, 0, sizeof(buf));size = read(cfd, buf, sizeof(buf));if (size == 0) //客户端断开连接{printf("client close\n");break;}printf("%s\n", buf);write(cfd, buf, size);}break;}else if (pid > 0){//in parentclose(cfd); //关闭不用了的跟客户端通讯的套接字if (1 == block){//先捕捉struct sigaction sa;sa.sa_sigaction = do_sigchld;sigemptyset(&sa.sa_mask);sa.sa_flags = SA_SIGINFO;sigaction(SIGCHLD, &sa, NULL);//后解除阻塞sigprocmask(SIG_UNBLOCK, &set, NULL);block = 0;}}elsesys_err("fork", 1);}//关闭套接字if (pid == 0)close(cfd);else if (pid > 0)close(lfd);return 0;
}

客户端代码

#include <stdio.h>
#include <unistd.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <string.h>int main(int argc, char *argv[])
{if (argc < 3){printf("%s sever_ip server_port\n", argv[0]);exit(1);}//创建流式套接字int fd = socket(AF_INET, SOCK_STREAM, 0);if (fd < 0){perror("socket");exit(1);}//连接服务器struct sockaddr_in addr;addr.sin_family = AF_INET;addr.sin_port = htons((unsigned short)atoi(argv[2]));addr.sin_addr.s_addr = inet_addr(argv[1]);int ret = connect(fd, (struct sockaddr *)&addr, sizeof(addr));printf("connect ret = %d\n", ret);if (ret < 0){perror("connect");exit(1);}//读写数据char buf_w[128] = "";char buf_r[128] = "";ssize_t size_r = 0;while(1){fgets(buf_w, sizeof(buf_w), stdin);buf_w[strlen(buf_w) - 1] = 0;write(fd, buf_w, strlen(buf_w));size_r = read(fd, buf_r, sizeof(buf_r));if (size_r == 0) //服务器断开break;elseprintf("%s\n", buf_r);memset(buf_w, 0, sizeof(buf_w));memset(buf_r, 0, sizeof(buf_r));}//关闭套接字close(fd);return 0;
}