嵌入式Linux实现TCP/IP通信

实现client向server发送数据。

server里面的rev要用nsockfd

client里面的send用sockfd

tcp_server代码：

#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <unistd.h>  
#include <arpa/inet.h>       
                         
#define PORT 		8088       		// The port which is communicate with server
#define BACKLOG 	10

#define LENGTH 512              		// Buffer length                                                                                 
int main ()
{  
	int iR;
	int sockfd;                        // Socket file descriptor
    	int nsockfd;               		// New Socket file descriptor
    	int num;
    	int sin_size;                      	// to store struct size
    	char sdbuf[LENGTH];          	// Send buffer
		char revbuf[LENGTH];       		// Receive buffer
    	struct sockaddr_in addr_local; 
    	struct sockaddr_in addr_remote; 
    //	char sendstr[16]= {"123456789 abcde"}; 
               
    	/* Get the Socket file descriptor */  
    	if( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1 )  
    	{   
        	printf ("ERROR: Failed to obtain Socket Despcritor.\n");
        	return (0);
    	} else {
        	printf ("OK: Obtain Socket Despcritor sucessfully.\n");
    	}
    
    	/* Fill the local socket address struct */
    	addr_local.sin_family = AF_INET;           	// Protocol Family
    	addr_local.sin_port = htons (PORT);         	// Port number
    	addr_local.sin_addr.s_addr  = htonl (INADDR_ANY);  // AutoFill local address
    	memset (addr_local.sin_zero,0,8);          		// Flush the rest of struct

    	/*  Blind a special Port */
    	if( bind(sockfd, (struct sockaddr*)&addr_local, sizeof(struct sockaddr)) == -1 )
    	{  
    	  	printf ("ERROR: Failed to bind Port %d.\n",PORT);
        	return (0);
    	} else {
        	printf("OK: Bind the Port %d sucessfully.\n",PORT);
    	}
   
    	/*  Listen remote connect/calling */
    	if(listen(sockfd,BACKLOG) == -1)    
    	{  
        	printf ("ERROR: Failed to listen Port %d.\n", PORT);
        	return (0);
    	} else {
        	printf ("OK: Listening the Port %d sucessfully.\n", PORT);
    	}
   
    	while(1)
    	{  
        	sin_size = sizeof(struct sockaddr_in);  
        
        	/*  Wait a connection, and obtain a new socket file despriptor for single connection */
        	if ((nsockfd = accept(sockfd, (struct sockaddr *)&addr_remote, (socklen_t *__restrict)&sin_size)) == -1)
        	{  
            	printf ("ERROR: Obtain new Socket Despcritor error.\n");
            	continue;
        	} else {
            	printf ("OK: Server has got connect from %s.\n", inet_ntoa(addr_remote.sin_addr)); 
        	}
        
		
        	/* Child process */
        	if(!fork())                    
        	{  
            	
            	<span style="white-space:pre">	</span>while (strcmp(revbuf,"exit") != 0)
            	<span style="white-space:pre">	</span>{ 
					//接收数据
					memset (revbuf,0,LENGTH);
					
					if((num = recv(nsockfd, revbuf, LENGTH, 0))>0)
					{
<span style="white-space:pre">						</span>printf ("OK: Receviced numbytes = %d\n", num);
						revbuf[num] = '\0';
						printf ("OK: Receviced string is: %s\n", revbuf);
					}
					
					
            	<span style="white-space:pre">	</span>}
         	}  
			
         	close(nsockfd);  
         	while(waitpid(-1, NULL, WNOHANG) > 0);   

     }    
}

tcp_client代码：

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <netdb.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <arpa/inet.h>

#define PORT 		8088    		// The port which is communicate with server
#define LENGTH 	256          		// Buffer length

int main(int argc, char *argv[])
{
	    int iR;					         //
		int nsockfd;               		// New Socket file descriptor
    	int sockfd;                        	// Socket file descriptor
    	int num;                    		// Counter of received bytes  
    	char revbuf[LENGTH];       		// Receive buffer
	char sdbuf[LENGTH];                     // Send buffer
    	struct sockaddr_in remote_addr;    	// Host address information

    	/* Check parameters number */
    	if (argc != 2)                     
    	{    
        	printf ("Usage: client HOST IP (ex: ./client 192.168.7.239).\n");
        	return (0);
    	}

    	/* Get the Socket file descriptor */
    	if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
    	{
        	printf("ERROR: Failed to obtain Socket Descriptor!\n");
        	return (0);
    	}
    
    	/* Fill the socket address struct */
    	remote_addr.sin_family = AF_INET;              	// Protocol Family
    	remote_addr.sin_port = htons(PORT);           		// Port number
    	inet_pton(AF_INET, argv[1], &remote_addr.sin_addr); 	// Net Address
    	memset (remote_addr.sin_zero,0,8);                 	// Flush the rest of struct

    	/* Try to connect the remote */
    	if (nsockfd=connect(sockfd, (struct sockaddr *)&remote_addr,  sizeof(struct sockaddr)) == -1) 
    	{
        	printf ("ERROR: Failed to connect to the host!\n");
        	return (0);
    	} else {
        	printf ("OK: Have connected to the %s\n",argv[1]);
    	}

		
        
			/* Try to connect the server */
			printf("You can enter string to send, and press 'exit' to end the connect.\n");
			 
			while(strcmp(sdbuf,"exit") != 0)
			{      
				
				/* 发送数据------------ */
				iR=(int)scanf("%s",sdbuf);
				if(iR>512)break;
				if((num=send(sockfd,sdbuf,strlen(sdbuf),0))==-1)
				{
					printf("ERROR:Fail to send string\n");
					close(nsockfd);
					exit(1);
				}
				printf("OK:Sent %d bytes sucessful,please enter again.\n",num);
			}
			
		
    	
		printf("Exit connect,Byebye!\n");
    	close (sockfd);
    	return (0);
}

开发板上执行tcp_client，主机上执行tcp_server

在Linux系统上编译tcp_client指令：arm-none-linux-gnueabi-gcc tcp_client.c -o client

编译tcp_server指令：gcc tcp_server.c -o tcp_server