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linux网络编程实战

news 文章来源：https://blog.csdn.net/xiexieyuchen/article/details/142622090 2025/5/4 21:50:14

前言

之前找工作的之后写了一些网络编程的笔记和代码，然后现在放到csdn上保存一下。有几个版本的，看看就好。就是简单的实现一下服务端和客户端之间的交互的，还没有我之前上linux编程课写的代码复杂。

哦对了，这个网络编程的代码对错误处理函数进行了一些封装，就是将select、accept等函数进一步封装了一下，问题不大。要是有朋友看到这篇博客想学习啥的，有问题可以问我。这个其实是在b站上看视频写的代码，嗯，其实没必要看我的代码的。

最后，客户端的代码都是一样的，不用客户端的代码其实也可以，启动服务端后直接用nc命令进行测试就行。

使用环境

makefile文件

直接将所有文件复制到同一个目录下，然后打开终端使用make命令就全部编译好了。

# 定义编译器
CXX=gcc# 定义编译选项，-Wall表示将所有警告打开，这里注释掉
# CFLAGS=-Wall# 定义多个目标文件
TARGET=client
TARGET1=server1
TARGET2=server2
TARGET3=server3
TARGET4=server4
TARGET5=server5
TARGET6=server6# 定义多个源文件
SRC=client.c wrap.c
SRC1=server1.c wrap.c
SRC2=server2.c wrap.c
SRC3=server3.c wrap.c
SRC4=server4.c wrap.c
SRC5=server5.c wrap.c
SRC6=server6.c wrap.c# 默认目标
all: $(TARGET) $(TARGET1) $(TARGET2) $(TARGET3) $(TARGET4) $(TARGET5) $(TARGET6)# 编译第一个文件
$(TARGET): $(SRC)$(CXX) -o $(TARGET) $(SRC)
# 编译其他文件
$(TARGET1): $(SRC1)$(CXX) -o $(TARGET1) $(SRC1)
$(TARGET2): $(SRC2)$(CXX) -o $(TARGET2) $(SRC2)
$(TARGET3): $(SRC3)$(CXX) -o $(TARGET3) $(SRC3) -pthread
$(TARGET4): $(SRC4)$(CXX) -o $(TARGET4) $(SRC4)
$(TARGET5): $(SRC5)$(CXX) -o $(TARGET5) $(SRC5)
$(TARGET6): $(SRC6)$(CXX) -o $(TARGET6) $(SRC6)# 清理编译生成的文件
.PHONY: clean
clean:rm -f  $(TARGET) $(TARGET1) $(TARGET2) $(TARGET3) $(TARGET4) $(TARGET5) $(TARGET6)

错误处理函数封装头文件wrap.h

#ifndef __WRAP_H_
#define __WRAP_H_
void perr_exit(const char *s);
int Accept(int fd, struct sockaddr *sa, socklen_t *salenptr);
int Bind(int fd, const struct sockaddr *sa, socklen_t salen);
int Connect(int fd, const struct sockaddr *sa, socklen_t salen);
int Listen(int fd, int backlog);
int Socket(int family, int type, int protocol);
ssize_t Read(int fd, void *ptr, size_t nbytes);
ssize_t Write(int fd, const void *ptr, size_t nbytes);
int Close(int fd);
ssize_t Readn(int fd, void *vptr, size_t n);
ssize_t Writen(int fd, const void *vptr, size_t n);
ssize_t my_read(int fd, char *ptr);
ssize_t Readline(int fd, void *vptr, size_t maxlen);
#endif

错误处理函数封装wrap.c：

#include <stdlib.h>
#include <errno.h>
#include <sys/socket.h>
void perr_exit(const char *s)
{perror(s);exit(1);
}
int Accept(int fd, struct sockaddr *sa, socklen_t *salenptr)
{int n;again:if ( (n = accept(fd, sa, salenptr)) < 0) {if ((errno == ECONNABORTED) || (errno == EINTR))goto again;elseperr_exit("accept error");}return n;
}
int Bind(int fd, const struct sockaddr *sa, socklen_t salen)
{int n;if ((n = bind(fd, sa, salen)) < 0)perr_exit("bind error");return n;
}
int Connect(int fd, const struct sockaddr *sa, socklen_t salen)
{int n;if ((n = connect(fd, sa, salen)) < 0)perr_exit("connect error");return n;
}
int Listen(int fd, int backlog)
{int n;if ((n = listen(fd, backlog)) < 0)perr_exit("listen error");return n;
}
int Socket(int family, int type, int protocol)
{int n;if ( (n = socket(family, type, protocol)) < 0)perr_exit("socket error");return n;
}
ssize_t Read(int fd, void *ptr, size_t nbytes)
{ssize_t n;
again:if ( (n = read(fd, ptr, nbytes)) == -1) {if (errno == EINTR)goto again;elsereturn -1;}return n;
}
ssize_t Write(int fd, const void *ptr, size_t nbytes)
{ssize_t n;
again:if ( (n = write(fd, ptr, nbytes)) == -1) {if (errno == EINTR)goto again;elsereturn -1;}return n;
}
int Close(int fd)
{int n;if ((n = close(fd)) == -1)perr_exit("close error");return n;
}
ssize_t Readn(int fd, void *vptr, size_t n)
{size_t nleft;ssize_t nread;char *ptr;ptr = vptr;nleft = n;while (nleft > 0) {if ( (nread = read(fd, ptr, nleft)) < 0) {if (errno == EINTR)nread = 0;elsereturn -1;} else if (nread == 0)break;nleft -= nread;ptr += nread;}return n - nleft;
}ssize_t Writen(int fd, const void *vptr, size_t n)
{size_t nleft;ssize_t nwritten;const char *ptr;ptr = vptr;nleft = n;while (nleft > 0) {if ( (nwritten = write(fd, ptr, nleft)) <= 0) {if (nwritten < 0 && errno == EINTR)nwritten = 0;elsereturn -1;}nleft -= nwritten;ptr += nwritten;}return n;
}static ssize_t my_read(int fd, char *ptr)
{static int read_cnt;static char *read_ptr;static char read_buf[100];if (read_cnt <= 0) {
again:if ((read_cnt = read(fd, read_buf, sizeof(read_buf))) < 0) {if (errno == EINTR)goto again;return -1;	} else if (read_cnt == 0)return 0;read_ptr = read_buf;}read_cnt--;*ptr = *read_ptr++;return 1;
}ssize_t Readline(int fd, void *vptr, size_t maxlen)
{ssize_t n, rc;char c, *ptr;ptr = vptr;for (n = 1; n < maxlen; n++) {if ( (rc = my_read(fd, &c)) == 1) {*ptr++ = c;if (c == '\n')break;} else if (rc == 0) {*ptr = 0;return n - 1;} elsereturn -1;}*ptr = 0;return n;
}

客户端代码client.c

#include <stdio.h>
#include <string.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <signal.h>
#include <sys/wait.h>
#include <sys/types.h>
#include "wrap.h"#define SERVER_PORT 8888 //需要与服务器相同int main(int argc, char *argv[])
{int sc=0,err=0,slen=0;char message[1024]={0};struct sockaddr_in server_addr;bzero(&server_addr,sizeof(server_addr));server_addr.sin_family=AF_INET;server_addr.sin_port=htons(SERVER_PORT);server_addr.sin_addr.s_addr=htonl(INADDR_ANY);//或inet_pton(AF_INET,"127.0.0.1",&server_addr.sin_addr.s_addr);sc=Socket(AF_INET,SOCK_STREAM,0);err = Connect(sc,(struct sockaddr*)&server_addr,sizeof(struct sockaddr));while(1){//持续进行通信slen=Read(0,message,sizeof(message));slen=Write(sc,message,slen);slen=Read(sc,message,slen);slen=Write(1,message,slen);}Close(sc);return 0;
}

第一版服务器（直接发送接受，只能一次且一个客户端）server1.c

#include <stdio.h>
#include <string.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <signal.h>
#include <sys/wait.h>
#include <sys/types.h>
#include "wrap.h"//宏定义
#define MAXLEN 100  //设置监听上限
#define SERVER_PORT 8888  //绑定的端口int main(int argc, char *argv[])
{int ss=0,sc=0,slen=0,err=0;//创建套接字char message[1024]={0},client_ip[1024]={0};//创建字符串来作为缓冲区,或用BUFSIZ=4096struct sockaddr_in server_addr,client_addr;//创建服务器端和客户端的地址结构socklen_t addrlen;//地址结构的长度bzero(&server_addr,sizeof server_addr);//清零server_addr.sin_family = AF_INET;//协议族server_addr.sin_port = htons(SERVER_PORT);//绑定端口server_addr.sin_addr.s_addr = htonl(INADDR_ANY);//绑定IPss = Socket(AF_INET,SOCK_STREAM,0);int opt=1;setsockopt(ss,SOL_SOCKET,SO_REUSEADDR,&opt,sizeof(opt));//设置端口复用err = Bind(ss,(struct sockaddr*)&server_addr,sizeof server_addr);//给socket绑定地址结构err = Listen(ss,MAXLEN);//设置监听上限addrlen = sizeof(struct sockaddr);sc=Accept(ss,(struct sockaddr*)&client_addr,&addrlen);printf("client ip:%s,port:%d\n",inet_ntop(AF_INET,&client_addr.sin_addr.s_addr,client_ip,sizeof(client_ip)),ntohs(client_addr.sin_port));//inet_ntop:将网络字节序转为本地字节序//ntohs:将网络端口转为本地端口while(1){slen = Read(sc,message,1024);//接收信息Write(1,message,slen);//将收到的信息输出，STDOUT_FILENO=1,STDIN_FILENO=0;for(int i=0;i<slen;i++)//进行大小写转换if(message[i]>='a'&&message[i]<='z')message[i]=message[i]-'a'+'A';//message[i]=toupper(message[i]);slen=Write(sc,message,slen);//将转换后的信息发回给客户端}Close(sc);//关闭文件描述符Close(ss);return 0;
}

第二版服务器（多进程多并发服务器，直接用fork创建子进程处理客户端请求）server2.c

#include <stdio.h>
#include <string.h>
#include <strings.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <signal.h>
#include <sys/wait.h>
#include <sys/types.h>
#include "wrap.h"//宏定义
#define MAXLEN 100  //设置监听上限
#define SERVER_PORT 8888  //绑定的端口void catch_child(int signum){while(waitpid(0, NULL,WNOHANG)>0);return ;
}int main(int argc, char *argv[])
{int lfd=0,cfd=0,slen=0,ret;//创建套接字pid_t pid;//创建子进程char message[1024]={0},client_ip[1024]={0};//创建字符串来作为缓冲区,或用BUFSIZ=4096struct sockaddr_in server_addr,client_addr;//创建服务器端和客户端的地址结构socklen_t addrlen;//地址结构的长度bzero(&server_addr,sizeof server_addr);//清零server_addr.sin_family = AF_INET;//协议族server_addr.sin_port = htons(SERVER_PORT);//绑定端口server_addr.sin_addr.s_addr = htonl(INADDR_ANY);//绑定IPint opt=1;setsockopt(lfd,SOL_SOCKET,SO_REUSEADDR,&opt,sizeof(opt));//设置端口复用lfd = Socket(AF_INET,SOCK_STREAM,0);Bind(lfd,(struct sockaddr*)&server_addr,sizeof server_addr);//给socket绑定地址结构Listen(lfd,MAXLEN);//设置监听上限addrlen = sizeof(struct sockaddr);printf("Accepting connections ...\n");while(1){cfd = Accept(lfd,(struct sockaddr*)&client_addr,&addrlen);printf("client ip:%s,port:%d 进入\n",inet_ntop(AF_INET,&client_addr.sin_addr.s_addr,client_ip,sizeof(client_ip)),ntohs(client_addr.sin_port));//inet_ntop:将网络字节序转为本地字节序//ntohs:将网络端口转为本地端口pid=fork();if(pid==0){Close(lfd);while(1){slen = Read(cfd,message,1024);//接收信息if(slen==0){Close(cfd);exit(1);}Write(1,message,slen);//将收到的信息输出，STDOUT_FILENO=1,STDIN_FILENO=0;for(int i=0;i<slen;i++)//进行大小写转换if(message[i]>='a'&&message[i]<='z')message[i]=message[i]-'a'+'A';//message[i]=toupper(message[i]);slen=Write(cfd,message,slen);//将转换后的信息发回给客户端}Close(cfd);break;}else if(pid < 0) perr_exit("fork error");else{struct sigaction act;//-----还不知道这是在干嘛act.sa_handler=catch_child;sigemptyset(&act.sa_mask);act.sa_flags = 0;ret = sigaction(SIGCHLD,&act,NULL);if(ret!=0) perr_exit("sigaction error");Close(cfd);continue;	}}Close(lfd);//关闭文件描述符return 0;
}

第三版服务器（多线程多并发服务器，创建子线程处理客户端请求，多线程在编译时要加-pthread,在makefile文件中加上即可）server3.c

#include <stdio.h>
#include <string.h>
#include <strings.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <signal.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <pthread.h>
#include "wrap.h"#define MAXLISTEN 100  //设置监听上限
#define MAXLINE 80  //缓冲区大小
#define SERVER_PORT 8888  //绑定的端口
#define MAXCLIENT 256 //最大客户端数量struct client_info{struct sockaddr_in client_addr;int connfd;
};
void *do_work(void *arg){int slen;struct client_info *temp = (struct client_info*)arg;char buf[MAXLINE],client_ip[1024];char str[INET_ADDRSTRLEN];pthread_detach(pthread_self());while(1){slen=Read(temp->connfd, buf, MAXLINE);if(slen == 0){printf("client ip:%s quit\n",inet_ntop(AF_INET,&(*temp).client_addr.sin_addr,client_ip,sizeof(client_ip)));break;}Write(1,buf,slen);//输出到本地printf(" received ip:%s at port:%d :",inet_ntop(AF_INET,&(*temp).client_addr.sin_addr,client_ip,sizeof(client_ip)),ntohs((*temp).client_addr.sin_port));//进行处理for(int i=0;i<slen;i++)if(buf[i]>='a'&&buf[i]<='z')buf[i]=buf[i]-'a'+'A';Write(temp->connfd,buf,slen);//将改好的信息发回客户端}Close(temp->connfd);return (void*)0;
}
int main(int argc, char *argv[])
{int lfd=0,cfd=0;//创建套接字int i=0;//i为线程编号struct sockaddr_in server_addr,client_addr;//创建服务器端的地址结构socklen_t addrlen;//地址结构的长度char client_ip[1024];pthread_t tid;struct client_info client[MAXCLIENT];//创建客户端地址结构bzero(&server_addr,sizeof server_addr);//清零server_addr.sin_family = AF_INET;//协议族server_addr.sin_port = htons(SERVER_PORT);//绑定端口server_addr.sin_addr.s_addr = htonl(INADDR_ANY);//绑定IPint opt=1;setsockopt(lfd,SOL_SOCKET,SO_REUSEADDR,&opt,sizeof(opt));//设置端口复用lfd = Socket(AF_INET,SOCK_STREAM,0);Bind(lfd,(struct sockaddr*)&server_addr,sizeof server_addr);//给socket绑定地址结构Listen(lfd,MAXLISTEN);//设置监听上限addrlen = sizeof(struct sockaddr);printf("Accepting connections ...\n");while(1){cfd = Accept(lfd,(struct sockaddr*)&client_addr,&addrlen);printf("client ip:%s,port:%d 进入\n",inet_ntop(AF_INET,&client_addr.sin_addr.s_addr,client_ip,sizeof(client_ip)),ntohs(client_addr.sin_port));client[i].client_addr=client_addr;client[i].connfd=cfd;/*达到线程最大数时，pthread_create出错处理，增加服务器稳定性*/pthread_create(&tid, NULL, do_work, (void*)&client[i]);i++;}Close(lfd);return 0;
}

第四版服务器（使用select多路IO转接（借助内核，select用来监听客户端请求））server4.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include "wrap.h"#define MAXLISTEN 100  //设置监听上限
#define MAXLINE 80  //缓冲区大小
#define SERVER_PORT 8888  //设置服务端的端口int main(int argc, char *argv[])
{int lfd,cfd,sockfd,slen,ret,i;//创建套接字int maxi;//用来保存最大的文件描述符int maxfd,client[FD_SETSIZE];//最大文件描述符、客户端文件描述符集合,FD_SETSIZE默认为1024pid_t pid;//创建子进程char buf[MAXLINE],str[INET_ADDRSTRLEN];//创建字符串来作为缓冲区,或用BUFSIZ=4096,str用来使用inet_ntop函数struct sockaddr_in server_addr,client_addr;//创建服务器端和客户端的地址结构socklen_t addrlen;//地址结构的长度fd_set rset,allset;//文件描述符集合,创建监听集合int opt=1;setsockopt(lfd,SOL_SOCKET,SO_REUSEADDR,&opt,sizeof(opt));//设置端口复用lfd = Socket(AF_INET,SOCK_STREAM,0);bzero(&server_addr,sizeof server_addr);//清零server_addr.sin_family = AF_INET;//协议族server_addr.sin_port = htons(SERVER_PORT);//绑定端口server_addr.sin_addr.s_addr = htonl(INADDR_ANY);//绑定IPBind(lfd,(struct sockaddr*)&server_addr,sizeof server_addr);//给socket绑定地址结构Listen(lfd,MAXLISTEN);//设置监听上限maxfd = lfd;maxi=-1;for(i=0;i<FD_SETSIZE;i++)client[i]=-1;//对客户端文件描述符集合进行初始化FD_ZERO(&allset); //将监听集合清空FD_SET(lfd,&allset);//将lfd添加到读集合中。addrlen = sizeof(struct sockaddr);printf("Accepting connections ...\n");while(1){rset=allset;//保存监听集合ret = select(maxfd+1,&rset,NULL,NULL,NULL); //监听文件描述符集合对应事件if(ret<0)perr_exit("select error");if(FD_ISSET(lfd,&rset)){//1 在，0 不在cfd = Accept(lfd,(struct sockaddr*)&client_addr,&addrlen);//建立连接，不会阻塞printf("client ip:%s at port:%d access\n",inet_ntop(AF_INET, &client_addr.sin_addr, str, sizeof(str)),ntohs(client_addr.sin_port));for(i=0;i<FD_SETSIZE;i++)if(client[i]<0){client[i]=cfd;break;}if (i == FD_SETSIZE) {/* 达到select能监控的文件个数上限 1024 */fputs("too many clients\n", stderr);exit(1);}FD_SET(cfd,&allset);//将新产生的fd添加到监听通信描述符集合中if(maxfd<cfd)maxfd=cfd;//select第一个参数需要if(i>maxi)maxi=i;//更新client[]数组中的最大文件描述符if(--ret == 0) continue;//只有lfd事件，后续的for不执行}for(i=0;i<=maxi;i++){//处理满足都事件的fdif((sockfd = client[i])<0) continue;//将client[i]赋值给sockfdif(FD_ISSET(sockfd,&rset)){//找到满足读事件的fdslen = Read(sockfd,buf,sizeof buf);if(slen == 0){//当客户端关闭连接时，服务端也关闭连接/*printf("client ip %s at port %d quit\n",inet_ntop(AF_INET, &client_addr.sin_addr, str, sizeof(str)),ntohs(client_addr.sin_port));*/Close(sockfd);FD_CLR(sockfd,&allset);//解除select对此文件描述符的监控client[i]=-1;}else if(slen>0){/*printf("received from %s at port %d :",inet_ntop(AF_INET, &client_addr.sin_addr, str, sizeof(str)),ntohs(client_addr.sin_port));*/Write(1,buf,slen);for(int j=0;j<slen;j++)//进行处理if(buf[j]>='a'&&buf[j]<='z')buf[j]=buf[j]-'a'+'A';slen = Write(sockfd,buf,slen);}if(--ret == 0)break;}	}}Close(lfd);//关闭文件描述符return 0;
}

第五版服务器（poll多路IO转接，poll是半成品，了解即可）server5.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <poll.h>
#include <errno.h>
#include "wrap.h"#define MAXLISTEN 100  //设置监听上限
#define MAXLINE 80  //缓冲区大小
#define SERVER_PORT 8888  //设置服务端的端口
#define OPEN_MAX 1024int main(int argc, char *argv[])
{int lfd,cfd,sockfd,slen,ret,i,maxi;//创建套接字,maxi为用来保存最大的文件描述符char buf[MAXLINE],str[INET_ADDRSTRLEN];//创建字符串来作为缓冲区,或用BUFSIZ=4096//str用来使用inet_ntop函数,INET_ADDESTRLEN=16struct sockaddr_in server_addr,client_addr;//创建服务器端和客户端的地址结构struct pollfd client[OPEN_MAX];socklen_t addrlen;//地址结构的长度int opt=1;setsockopt(lfd,SOL_SOCKET,SO_REUSEADDR,&opt,sizeof(opt));//设置端口复用lfd = Socket(AF_INET,SOCK_STREAM,0);bzero(&server_addr,sizeof server_addr);//清零server_addr.sin_family = AF_INET;//协议族server_addr.sin_port = htons(SERVER_PORT);//绑定端口server_addr.sin_addr.s_addr = htonl(INADDR_ANY);//绑定IPBind(lfd,(struct sockaddr*)&server_addr,sizeof server_addr);//给socket绑定地址结构Listen(lfd,MAXLISTEN);//设置监听上限maxi=0;client[0].fd=lfd;client[0].events=POLLRDNORM;for(i=1;i<OPEN_MAX;i++)client[i].fd=-1;addrlen = sizeof(struct sockaddr);printf("Accepting connections ...\n");while(1){ret=poll(client,maxi+1,-1);if(client[0].revents & POLLRDNORM){//处理lfdcfd=Accept(lfd,(struct sockaddr*)&client_addr,&addrlen);printf("client ip:%s at port:%d access\n",inet_ntop(AF_INET, &client_addr.sin_addr, str, sizeof(str)),ntohs(client_addr.sin_port));for(i=1;i<OPEN_MAX;i++)if(client[i].fd<0){client[i].fd=cfd;//找到client中空闲的位置并将客户端的文件描述符放入break;}if(i==OPEN_MAX) perr_exit("to many client");//客户端数量过多client[i].events=POLLRDNORM;if(i>maxi)maxi=i;if(--ret<=0)continue;}for(i=1;i<=maxi;i++){//处理cfdsockfd=client[i].fd;if(sockfd<0)continue;if(client[i].revents & (POLLRDNORM | POLLERR)){slen=Read(sockfd,buf,sizeof buf);if(slen<0){if(errno == ECONNRESET){//收到RST标志printf("client[%d](ip:%s) aborted connection\n",i,inet_ntop(AF_INET, &client_addr.sin_addr, str, sizeof(str)));Close(sockfd);client[i].fd=-1;}else perr_exit("read error");}else if(slen == 0){//说明客户端先关闭连接printf("client[%d](ip:%s) closed connection\n",i,inet_ntop(AF_INET, &client_addr.sin_addr, str, sizeof(str)));Close(sockfd);client[i].fd=-1;}else {for(int j=0;j<slen;j++)if(buf[j]>='a'&&buf[j]<='z')buf[j]=buf[j]-'a'+'A';slen=Write(sockfd,buf,slen);}if(--ret<=0)break;}}}Close(lfd);//关闭文件描述符return 0;
}

第六版服务器（epoll多路IO转接）server6.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/epoll.h>
#include <errno.h>
#include "wrap.h"#define MAXLISTEN 100  //设置listen监听上限
#define MAXLINE 80  //缓冲区大小
#define SERVER_PORT 8888  //设置服务端的端口
#define OPEN_MAX 1024int main(int argc, char *argv[])
{int lfd,cfd,sockfd,slen,ret,res,i,j,maxi,efd;//创建套接字,maxi为用来保存最大的文件描述符int client[OPEN_MAX];char buf[MAXLINE],str[INET_ADDRSTRLEN];//创建字符串来作为缓冲区,或用BUFSIZ=4096//str用来使用inet_ntop函数,INET_ADDESTRLEN=16struct sockaddr_in server_addr,client_addr;//创建服务器端和客户端的地址结构struct epoll_event tep,ep[OPEN_MAX];//tep为临时变量socklen_t addrlen;//地址结构的长度int opt=1;setsockopt(lfd,SOL_SOCKET,SO_REUSEADDR,&opt,sizeof(opt));//设置端口复用lfd = Socket(AF_INET,SOCK_STREAM,0);bzero(&server_addr,sizeof server_addr);//清零server_addr.sin_family = AF_INET;//协议族server_addr.sin_port = htons(SERVER_PORT);//绑定端口server_addr.sin_addr.s_addr = htonl(INADDR_ANY);//绑定IPBind(lfd,(struct sockaddr*)&server_addr,sizeof server_addr);//给socket绑定地址结构Listen(lfd,MAXLISTEN);//设置监听上限maxi = -1;for(i = 0;i < OPEN_MAX;i++) client[i] = -1;efd = epoll_create(OPEN_MAX);if(efd < 0) perr_exit("epoll_create error");tep.events = EPOLLIN;//设置临时变量tep.data.fd = lfd;res = epoll_ctl(efd,EPOLL_CTL_ADD,lfd,&tep);if(res < 0) perr_exit("epoll_ctl error");addrlen = sizeof(struct sockaddr);printf("Accepting connections ...\n");while(1){ret = epoll_wait(efd, ep, OPEN_MAX, -1);//阻塞监听,返回监听到的文件描述符数量if(ret < 0) perr_exit("epoll_wait error");for(i = 0;i < ret; i++){if(!(ep[i].events & EPOLLIN)) continue;if(ep[i].data.fd == lfd){cfd = Accept(lfd,(struct sockaddr *)&client_addr,&addrlen);printf("client ip:%s at port %d access\n",inet_ntop(AF_INET,&client_addr.sin_addr,str,sizeof str),ntohs(client_addr.sin_port));for(j=0;j<OPEN_MAX;j++)//找一个空位置存放客户端的文件描述符if(client[j] < 0){client[j]=cfd;break;}if(j == OPEN_MAX) perr_exit("too many clients");if(j > maxi) maxi=j;tep.events = EPOLLIN;tep.data.fd = cfd;res = epoll_ctl(efd,EPOLL_CTL_ADD,cfd,&tep);if(res < 0)perr_exit("epoll_ctl error");}else {sockfd = tep.data.fd;slen = Read(sockfd,buf,sizeof buf);if(slen == 0){for(j=0;j<=maxi;j++)if(client[j]==sockfd){client[j]=-1;break;}res = epoll_ctl(efd,EPOLL_CTL_DEL,sockfd,NULL);if(res < 0) perr_exit("eopll_ctl error");Close(sockfd);printf("client[%d] closed connection\n",j);}else{Write(1,buf,slen);for(j=0;j<slen;j++)if(buf[j]>='a'&&buf[j]<='z')buf[j]=buf[j]-'a'+'A';Write(sockfd,buf,slen);}}}}Close(lfd);//关闭文件描述符Close(efd);return 0;
}

结语

没啥好说的，找到工作之后就是当牛马了，也不知道能干几年，已经在想养老了（但是养老计算器说还要干40年，我想我真能活到那时候吗）。现在是还没转正，工作也是最近才找到的（因为考研失败摆烂了好长时间），是一家国企965，感觉还行。公司计算机不能接外网，所以我发个博客，用手机看（个人电脑不推荐带），到时候看一些函数作用啥的看自己的代码好想起。

前言