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socket编程详解（二）——客户端
写在前面
上一小节我们讲了socket编程服务器端，也简单说了各个函数的使用说明，下面我们看看客户端是怎样完成的，以及互相聊天的实现。。。
首先我们再贴贴上一小节的图：
客户端编程的文字步骤：
1：加载套接字库，创建套接字(WSAStartup()/socket())；
2：向服务器发出连接请求(connect())；
3：和服务器端进行通信(send()/recv())；
4：关闭套接字，关闭加载的套接字库(closesocket()/WSACleanup())。
client函数api
connect ()函数
#include <sys/types.h> /* See NOTES */ #include <sys/socket.h> int connect(int sockfd, const struct sockaddr *addr,socklen_t addrlen);- 1
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补充第二套收发函数：send和recv函数
send()函数和recv()函数
客户端比较简单连接上收发消息就可以了。。。。
demo1示例
client.c #include <stdio.h> #include <sys/types.h> /* See NOTES */ #include <sys/socket.h> #include <stdlib.h> #include <arpa/inet.h> #include <netinet/in.h> #include <unistd.h> #include <string.h> int main(){ int c_fd; struct sockaddr_in c_addr; char readBuf[128]; char *msg = "msg from client"; //void *memset(void *s, int c, size_t n); memset(&c_addr,0,sizeof(struct sockaddr_in)); //1.scoket //int socket(int domain, int type, int protocol); c_fd = socket(AF_INET,SOCK_STREAM,0); if(c_fd == -1){ perror("socket"); exit(-1); } c_addr.sin_family = AF_INET; c_addr.sin_port = htons(8089); inet_aton("192.168.2.40",&c_addr.sin_addr); //2.connect //int connect(int sockfd, const struct sockaddr *addr,socklen_t addrlen); if(connect(c_fd,(struct sockaddr *)&c_addr,sizeof(struct sockaddr)) == -1){ perror("connect"); exit(-1); } //3.write //ssize_t write(int fd, const void *buf, size_t count); write(c_fd,msg,128); //4.read //ssize_t read(int fd, void *buf, size_t count); int n_read = read(c_fd,readBuf,128); if(n_read == -1){ perror("read"); }else{ printf("msg:%d,%s\n",n_read,readBuf); } return 0; }- 1
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目前基本的框架已经完成了，不足的是只能发送一次消息，不能够持续性的聊天，我们再改进下。。。
demo2示例
tserver.c服务器端 int main(int argc,char **argv){ int s_fd; int c_fd; struct sockaddr_in s_addr; struct sockaddr_in c_addr; char readBuf[128]; //char *msg = "msg from server"; char msg[128] = {0}; //void *memset(void *s, int c, size_t n); memset(&s_addr,0,sizeof(struct sockaddr_in)); memset(&c_addr,0,sizeof(struct sockaddr_in)); //加上参数判断 if(argc != 3){ printf("Parameter incomplete!\n"); exit(-1); } //1.scoket //int socket(int domain, int type, int protocol); s_fd = socket(AF_INET,SOCK_STREAM,0); if(s_fd == -1){ perror("socket"); exit(-1); } s_addr.sin_family = AF_INET; s_addr.sin_port = htons(atoi(argv[2])); inet_aton(argv[1],&s_addr.sin_addr); //2.bind //int bind(int sockfd, const struct sockaddr *addr,socklen_t addrlen); bind(s_fd,(struct sockaddr *)&s_addr,sizeof(struct sockaddr_in)); //3.listen //int listen(int sockfd, int backlog); listen(s_fd,10); //4.accept //int accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen); int len = sizeof(struct sockaddr_in); while(1){//监听后不断的接收连接 c_fd = accept(s_fd,(struct sockaddr *)&c_addr,&len); if(c_fd == -1){ perror("accept"); exit(-1); } printf("connect:%s\n",inet_ntoa(c_addr.sin_addr)); if(fork() == 0){ //创建子进程，父进程等待连接消息，子进程来完成读写操作，写和读不断循环，随时收发，同样的客户端也要循环匹配 if(fork() == 0){ while(1){ //6.write //ssize_t write(int fd, const void *buf, size_t count); memset(msg,0,sizeof(msg)); printf("input: "); gets(msg); write(c_fd,msg,strlen(msg)); } } while(1){ //5.read //ssize_t read(int fd, void *buf, size_t count); memset(readBuf,0,sizeof(readBuf)); int n_read = read(c_fd,readBuf,128); if(n_read == -1){ perror("read"); }else{ printf("msg from client:%d,%s\n",n_read,readBuf); } } } } return 0; }- 1
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tclient.c客户端 int main(int argc,char **argv){ int c_fd; struct sockaddr_in c_addr; char readBuf[128]; //char *msg = "msg from client"; char msg[128] = {0}; //void *memset(void *s, int c, size_t n); memset(&c_addr,0,sizeof(struct sockaddr_in)); //加上参数判断 if(argc != 3){ printf("Parameter incomplete!\n"); exit(-1); } //1.scoket //int socket(int domain, int type, int protocol); c_fd = socket(AF_INET,SOCK_STREAM,0); if(c_fd == -1){ perror("socket"); exit(-1); } c_addr.sin_family = AF_INET; c_addr.sin_port = htons(atoi(argv[2])); inet_aton(argv[1],&c_addr.sin_addr); //2.connect //int connect(int sockfd, const struct sockaddr *addr,socklen_t addrlen); if(connect(c_fd,(struct sockaddr *)&c_addr,sizeof(struct sockaddr)) == -1){ perror("connect"); exit(-1); } while(1){ //3.write //ssize_t write(int fd, const void *buf, size_t count); if(fork() == 0){ while(1){ memset(msg,0,sizeof(msg)); printf("input: "); gets(msg); write(c_fd,msg,strlen(msg)); } } while(1){ //4.read //ssize_t read(int fd, void *buf, size_t count); memset(readBuf,0,sizeof(readBuf)); int n_read = read(c_fd,readBuf,128); if(n_read == -1){ perror("read"); }else{ printf("msg from server:\n%s\n",readBuf); } } } return 0; }- 1
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关于上面的父子进程的创建：
运行结果如下：
上面的只是针对单个客户端，那么实现多个客户端的消息发送呢？？？
仅限客户端消息发送哈。。。。demo3示例
dserver.c服务器端 #include <stdio.h> #include <sys/types.h> /* See NOTES */ #include <sys/socket.h> #include <stdlib.h> #include <arpa/inet.h> #include <netinet/in.h> #include <unistd.h> #include <string.h> int main(int argc,char **argv){ int s_fd; int c_fd; struct sockaddr_in s_addr; struct sockaddr_in c_addr; char readBuf[128]; //char *msg = "msg from server"; char msg[128] = {0}; int mark = 0; //void *memset(void *s, int c, size_t n); memset(&s_addr,0,sizeof(struct sockaddr_in)); memset(&c_addr,0,sizeof(struct sockaddr_in)); if(argc != 3){ printf("Parameter incomplete!\n"); exit(-1); } //1.scoket //int socket(int domain, int type, int protocol); s_fd = socket(AF_INET,SOCK_STREAM,0); if(s_fd == -1){ perror("socket"); exit(-1); } s_addr.sin_family = AF_INET; s_addr.sin_port = htons(atoi(argv[2])); inet_aton(argv[1],&s_addr.sin_addr); //2.bind //int bind(int sockfd, const struct sockaddr *addr,socklen_t addrlen); bind(s_fd,(struct sockaddr *)&s_addr,sizeof(struct sockaddr_in)); //3.listen //int listen(int sockfd, int backlog); listen(s_fd,10); //4.accept //int accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen); int len = sizeof(struct sockaddr_in); while(1){ c_fd = accept(s_fd,(struct sockaddr *)&c_addr,&len); if(c_fd == -1){ perror("accept"); exit(-1); } mark++; printf("connect:%s\n",inet_ntoa(c_addr.sin_addr)); if(fork() == 0){ if(fork() == 0){ while(1){ //6.write //ssize_t write(int fd, const void *buf, size_t count); sprintf(msg,"welcome No.%d client",mark); write(c_fd,msg,strlen(msg)); sleep(10); } } while(1){ //5.read //ssize_t read(int fd, void *buf, size_t count); memset(readBuf,0,sizeof(readBuf)); int n_read = read(c_fd,readBuf,128); if(n_read == -1){ perror("read"); }else{ printf("msg from client:\n%s\n",readBuf); } } } } return 0; }- 1
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客户端不用改变，只需要在服务器端打印客户端号即可
效果比较鸡肋，记录下来看看。。。。
ending！
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- 原文地址：https://blog.csdn.net/qq_44333320/article/details/125451293