Linux下的C语言编程——简单实现tcp客户端和服务器

怼烎@ 2022-07-14 08:57 184阅读 0赞

以下程序均未做错误处理，等有时间一定完善

客户端

#include <stdio.h>
    #include <sys/socket.h>
    #include <stdlib.h>
    #include <netinet/in.h>
    #include <string.h>
    
    int main(int argc,char **argv)
    {
    	int sockfd;
    	int n;
    	struct sockaddr_in servaddr,cliaddr;
    	char sendbuf[1000];
    	char recvbuf[1000];
    
    	if(argc != 2)
    	{
    		printf("usage:client <ip address>\n");
    		exit(-1);
    	}
    
    	sockfd = socket(AF_INET,SOCK_STREAM,0);
    	bzero(&servaddr,sizeof(servaddr));
    
    	servaddr.sin_family = AF_INET;
    	servaddr.sin_addr.s_addr = inet_addr(argv[1]);
    	servaddr.sin_port = htons(3200);
    
    	connect(sockfd,(struct sockaddr*)&servaddr,sizeof(servaddr));
    
    	while(fgets(sendbuf,1000,stdin) != NULL)
    	{
    		sendto(sockfd,sendbuf,strlen(sendbuf),0,(struct sockaddr *)&servaddr,sizeof(servaddr));
    		n = recvfrom(sockfd,recvbuf,1000,0,NULL,NULL);//(struct sockaddr*)&cliaddr,
    		recvbuf[n] = '\0';
    		fputs(recvbuf,stdout);
    	}
    
    	close(sockfd);
    
        return 0;
    }

服务器

#include <stdio.h>
    #include <string.h>
    #include <stdlib.h>
    #include <netinet/in.h>
    #include <sys/socket.h>
    
    void strlwr(char *str)
    {
    	char *p;
    
    	p = str;
    
    	while(*p != '\0')
    	{
    		if((*p >= 'a') && (*p <= 'z'))
    		{
    			*p -= 32;
    		}
    
    		p++;
    	}
    }
    
    int main()
    {
    	pid_t pid;
    	int listenfd,connfd;
    	int n;
    	struct sockaddr_in servaddr,cliaddr;
    	socklen_t clilen;
    
    	char mesg[1000];
    
    	listenfd = socket(AF_INET,SOCK_STREAM,0);
    	bzero(&servaddr,sizeof(servaddr));
    	servaddr.sin_family = AF_INET;
    	servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    	servaddr.sin_port = htons(3200);
    
    	int opt = 1;
    	setsockopt(listenfd,SOL_SOCKET,SO_REUSEADDR,&opt,sizeof(opt));
    	
    	bind(listenfd,(struct sockaddr *)&servaddr,sizeof(servaddr));
    	listen(listenfd,1024);
    	
    	for(;;)
    	{
    		clilen = sizeof(cliaddr);
    		connfd = accept(listenfd,(struct sockaddr*)&cliaddr,&clilen);
    
    		if((pid = fork()) == 0)
    		{
    			close(listenfd);
    			
    			for(;;)
    			{
    				n = recvfrom(connfd,mesg,1000,0,(struct sockaddr*)&cliaddr,&clilen);
    
    				if(n == 0)
    				{
    					printf("client closed!\n");
    					exit(-1);
    				}
    
    				printf("********************\n");
    				mesg[n] = '\0';
    				printf("%s\n",mesg);
    				printf("*********************\n");
    		
    				strlwr(mesg);
    
    				sendto(connfd,mesg,n,0,(struct sockaddr *)&cliaddr,sizeof(cliaddr));
    			}
    
    			close(connfd);
    		}
    	}
    	close(listenfd);
    
        return 0;
    }