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文章目录：

一：wrap常用函数封装

wrap.h 

wrap.c

server.c

client.c

二：多进程process并发服务器

实现思路

server.c服务器

client.c客户端

三：多线程thread并发服务器

实现思路

server.c服务器

client.c客户端

---

一：wrap常用函数封装

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

wrap.c

#include <stdlib.h>
#include <stdio.h>
#include <unistd.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;n = connect(fd, sa, salen);if (n < 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;
}/*参三: 应该读取的字节数  读 N 个字节*/                          //socket 4096  readn(cfd, buf, 4096)   nleft = 4096-1500
ssize_t Readn(int fd, void *vptr, size_t n)
{size_t  nleft;              //usigned int 剩余未读取的字节数ssize_t nread;              //int 实际读到的字节数char   *ptr;ptr = vptr;nleft = n;                  //n 未读取字节数while (nleft > 0) {if ((nread = read(fd, ptr, nleft)) < 0) {if (errno == EINTR)nread = 0;elsereturn -1;} else if (nread == 0)break;nleft -= nread;   //nleft = 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) {   //"hello\n"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;
}/*readline读一行 --- fgets*/    
//传出参数 vptr
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[] = hello\n*ptr++ = c;if (c == '\n')break;} else if (rc == 0) {*ptr = 0;return n-1;} elsereturn -1;}*ptr = 0;return n;
}

利用封装函数： 联合编译server.c 和 wrap.c 生成 server、 联合编译 client.c 和 wrap.c 生成 client

server.c

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <strings.h>
#include <string.h>
#include <ctype.h>
#include <arpa/inet.h>#include "wrap.h"#define SERV_PORT 6666int main(void)
{int sfd, cfd;int len, i;char buf[BUFSIZ], clie_IP[BUFSIZ];struct sockaddr_in serv_addr, clie_addr;socklen_t clie_addr_len;sfd = Socket(AF_INET, SOCK_STREAM, 0);int opt = 1;setsockopt(sfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));bzero(&serv_addr, sizeof(serv_addr));           serv_addr.sin_family = AF_INET;                 serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);  serv_addr.sin_port = htons(SERV_PORT);          Bind(sfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr));Listen(sfd, 2);                                printf("wait for client connect ...\n");clie_addr_len = sizeof(clie_addr_len);cfd = Accept(sfd, (struct sockaddr *)&clie_addr, &clie_addr_len);printf("cfd = ----%d\n", cfd);printf("client IP: %s  port:%d\n", inet_ntop(AF_INET, &clie_addr.sin_addr.s_addr, clie_IP, sizeof(clie_IP)), ntohs(clie_addr.sin_port));while (1) {len = Read(cfd, buf, sizeof(buf));Write(STDOUT_FILENO, buf, len);for (i = 0; i < len; i++)buf[i] = toupper(buf[i]);Write(cfd, buf, len); }Close(sfd);Close(cfd);return 0;
}

client.c

#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sys/socket.h>
#include <arpa/inet.h>#include "wrap.h"#define SERV_IP "127.0.0.1"
#define SERV_PORT 6666int main(void)
{int sfd, len;struct sockaddr_in serv_addr;char buf[BUFSIZ]; sfd = Socket(AF_INET, SOCK_STREAM, 0);bzero(&serv_addr, sizeof(serv_addr));                       serv_addr.sin_family = AF_INET;                             inet_pton(AF_INET, SERV_IP, &serv_addr.sin_addr.s_addr);    serv_addr.sin_port = htons(SERV_PORT);                      Connect(sfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr));while (1) {fgets(buf, sizeof(buf), stdin);int r = Write(sfd, buf, strlen(buf));       printf("Write r ======== %d\n", r);len = Read(sfd, buf, sizeof(buf));printf("Read len ========= %d\n", len);Write(STDOUT_FILENO, buf, len);}Close(sfd);return 0;
}

 read 函数的返回值

read 函数的返回值：1. > 0 实际读到的字节数2. = 0 已经读到结尾（对端已经关闭）【 ！重 ！点 ！】3. -1 应进一步判断errno的值：errno = EAGAIN or EWOULDBLOCK: 设置了非阻塞方式 读。 没有数据到达。 errno = EINTR 慢速系统调用被 中断。errno = “其他情况” 异常。

二：多进程process并发服务器

使用多进程并发服务器时要考虑以下几点：1.父进程最大文件描述个数(父进程中需要close关闭accept返回的新文件描述符)2.系统内创建进程个数(与内存大小相关)3.进程创建过多是否降低整体服务性能(进程调度)

实现思路

1. Socket();		        创建 监听套接字 lfd2. Bind()	                绑定地址结构 Strcut scokaddr_in addr;3. Listen();	4. while (1) {cfd = Accpet();			接收客户端连接请求。pid = fork();if (pid == 0){			子进程 read(cfd) --- 小-》大 --- write(cfd)close(lfd)		    关闭用于建立连接的套接字 lfdread()小--大write()} else if （pid > 0） {	close(cfd);		    关闭用于与客户端通信的套接字 cfd	contiue;}}5. 子进程：close(lfd)read()小--大write()	父进程：close(cfd);注册信号捕捉函数：	SIGCHLD在回调函数中， 完成子进程回收while （waitpid()）;

server.c服务器

#include <stdio.h>
#include <string.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <signal.h>
#include <sys/wait.h>
#include <ctype.h>
#include <unistd.h>#include "wrap.h"#define MAXLINE 8192
#define SERV_PORT 8000void do_sigchild(int num)
{while (waitpid(0, NULL, WNOHANG) > 0);
}int main(void)
{struct sockaddr_in servaddr, cliaddr;socklen_t cliaddr_len;int listenfd, connfd;char buf[MAXLINE];char str[INET_ADDRSTRLEN];int i, n;pid_t pid;struct sigaction newact;newact.sa_handler = do_sigchild;sigemptyset(&newact.sa_mask);newact.sa_flags = 0;sigaction(SIGCHLD, &newact, NULL);listenfd = Socket(AF_INET, SOCK_STREAM, 0);int opt = 1;setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));bzero(&servaddr, sizeof(servaddr));servaddr.sin_family = AF_INET;servaddr.sin_addr.s_addr = htonl(INADDR_ANY);servaddr.sin_port = htons(SERV_PORT);Bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr));Listen(listenfd, 20);printf("Accepting connections ...\n");while (1) {cliaddr_len = sizeof(cliaddr);connfd = Accept(listenfd, (struct sockaddr *)&cliaddr, &cliaddr_len);printf("-------------------------%d\n", connfd);pid = fork();if (pid == 0) {Close(listenfd);while (1) {n = Read(connfd, buf, MAXLINE);if (n == 0) {printf("the other side has been closed.\n");break;}printf("received from %s at PORT %d\n",inet_ntop(AF_INET, &cliaddr.sin_addr, str, sizeof(str)),ntohs(cliaddr.sin_port));for (i = 0; i < n; i++)buf[i] = toupper(buf[i]);Write(STDOUT_FILENO, buf, n);Write(connfd, buf, n);}Close(connfd);return 0;} else if (pid > 0) {Close(connfd);}  elseperr_exit("fork");}return 0;
}

client.c客户端

/* client.c */
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <netinet/in.h>
#include <arpa/inet.h>#include "wrap.h"#define MAXLINE 8192
#define SERV_PORT 8000int main(int argc, char *argv[])
{struct sockaddr_in servaddr;char buf[MAXLINE];int sockfd, n;sockfd = Socket(AF_INET, SOCK_STREAM, 0);bzero(&servaddr, sizeof(servaddr));servaddr.sin_family = AF_INET;inet_pton(AF_INET, "127.0.0.1", &servaddr.sin_addr);servaddr.sin_port = htons(SERV_PORT);Connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));while (fgets(buf, MAXLINE, stdin) != NULL) {Write(sockfd, buf, strlen(buf));n = Read(sockfd, buf, MAXLINE);if (n == 0) {printf("the other side has been closed.\n");break;}elseWrite(STDOUT_FILENO, buf, n);}Close(sockfd);return 0;
}

三：多线程thread并发服务器

在使用线程模型开发服务器时需考虑以下问题：1.调整进程内最大文件描述符上限2.线程如有共享数据，考虑线程同步3.服务于客户端线程退出时，退出处理。（退出值，分离态）4.系统负载，随着链接客户端增加，导致其它线程不能及时得到CPU

实现思路

	1. Socket();		            创建 监听套接字 lfd2. Bind()		                绑定地址结构 Strcut scokaddr_in addr;3. Listen();		4. while (1) {		cfd = Accept(lfd, );pthread_create(&tid, NULL, tfn, (void *)cfd);pthread_detach(tid);  		// pthead_join(tid, void **);  新线程---专用于回收子线程}5. 子线程：void *tfn(void *arg) {// close(lfd)			不能关闭。 主线程要使用lfdread(cfd)小--大write(cfd)pthread_exit（(void *)10）;	}

server.c服务器

#include <stdio.h>
#include <string.h>
#include <arpa/inet.h>
#include <pthread.h>
#include <ctype.h>
#include <unistd.h>
#include <fcntl.h>#include "wrap.h"#define MAXLINE 8192
#define SERV_PORT 8000struct s_info {                     //定义一个结构体, 将地址结构跟cfd捆绑struct sockaddr_in cliaddr;int connfd;
};void *do_work(void *arg)
{int n,i;struct s_info *ts = (struct s_info*)arg;char buf[MAXLINE];char str[INET_ADDRSTRLEN];      //#define INET_ADDRSTRLEN 16  可用"[+d"查看while (1) {n = Read(ts->connfd, buf, MAXLINE);                     //读客户端if (n == 0) {printf("the client %d closed...\n", ts->connfd);break;                                              //跳出循环,关闭cfd}printf("received from %s at PORT %d\n",inet_ntop(AF_INET, &(*ts).cliaddr.sin_addr, str, sizeof(str)),ntohs((*ts).cliaddr.sin_port));                 //打印客户端信息(IP/PORT)for (i = 0; i < n; i++) buf[i] = toupper(buf[i]);                           //小写-->大写Write(STDOUT_FILENO, buf, n);                           //写出至屏幕Write(ts->connfd, buf, n);                              //回写给客户端}Close(ts->connfd);return (void *)0;
}int main(void)
{struct sockaddr_in servaddr, cliaddr;socklen_t cliaddr_len;int listenfd, connfd;pthread_t tid;struct s_info ts[256];      //创建结构体数组.int i = 0;listenfd = Socket(AF_INET, SOCK_STREAM, 0);                     //创建一个socket, 得到lfdbzero(&servaddr, sizeof(servaddr));                             //地址结构清零servaddr.sin_family = AF_INET;servaddr.sin_addr.s_addr = htonl(INADDR_ANY);                               //指定本地任意IPservaddr.sin_port = htons(SERV_PORT);                                       //指定端口号 Bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr));             //绑定Listen(listenfd, 128);                                                      //设置同一时刻链接服务器上限数printf("Accepting client connect ...\n");while (1) {cliaddr_len = sizeof(cliaddr);connfd = Accept(listenfd, (struct sockaddr *)&cliaddr, &cliaddr_len);   //阻塞监听客户端链接请求ts[i].cliaddr = cliaddr;ts[i].connfd = connfd;pthread_create(&tid, NULL, do_work, (void*)&ts[i]);pthread_detach(tid);                                                    //子线程分离,防止僵线程产生.i++;}return 0;
}

client.c客户端

/* client.c */
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include "wrap.h"#define MAXLINE 80
#define SERV_PORT 8000int main(int argc, char *argv[])
{struct sockaddr_in servaddr;char buf[MAXLINE];int sockfd, n;sockfd = Socket(AF_INET, SOCK_STREAM, 0);bzero(&servaddr, sizeof(servaddr));servaddr.sin_family = AF_INET;inet_pton(AF_INET, "127.0.0.1", &servaddr.sin_addr.s_addr);servaddr.sin_port = htons(SERV_PORT);Connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));while (fgets(buf, MAXLINE, stdin) != NULL) {Write(sockfd, buf, strlen(buf));n = Read(sockfd, buf, MAXLINE);if (n == 0)printf("the other side has been closed.\n");elseWrite(STDOUT_FILENO, buf, n);}Close(sockfd);return 0;
}