UDP编程

偏执的太偏执、 2022-09-09 06:03 175阅读 0赞

## UDP编程 ##

本文内容来源于《TCP/IP网络编程第六章》。主要需要了解UDP常用两个函数：sendto()和recvfrom(),其中两个函数调用次数要相同，如下面例子所示：  
server端

#include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #include <unistd.h>
    #include <arpa/inet.h>
    #include <sys/socket.h>
    
    #define BUF_SIZE 30
    void error_handling(char * message);
    
    int main(int argc,char *argv[]){
        
        int sock;
        char message[BUF_SIZE];
        int str_len,i;
        socklen_t adr_sz;
    
        struct sockaddr_in my_adr,your_adr;
        if(argc!=2){
        
            printf("usage : %s <port>\n",argv[0]);
            exit(1);
        }
        sock = socket(PF_INET,SOCK_DGRAM,0);
        if(sock == -1)
         error_handling("UDP socket creation error");
    			        
        memset(&my_adr,0,sizeof(my_adr));
        my_adr.sin_family = AF_INET;
        my_adr.sin_addr.s_addr=htonl(INADDR_ANY);
        my_adr.sin_port=htons(atoi(argv[1]));		
        if(bind(sock,(struct sockaddr*)&my_adr,sizeof(my_adr))==-1)
               error_handling("bind() error");
        for(i=0;i<3;i++){
        
            sleep(5);
    	adr_sz = sizeof(your_adr);
    	str_len=recvfrom(sock,message,BUF_SIZE,0,(struct sockaddr*)&your_adr,&adr_sz);
    	printf("message %d: %s\n",i+1,message);
    	}
          close(sock);
          return 0;
     }
    
    void error_handling(char *message){
        
        fputs(message,stderr);
        fputc('\n',stderr);
        exit(1);
    }

客户端

#include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #include <unistd.h>
    #include <arpa/inet.h>
    #include <sys/socket.h>
    
    #define BUF_SIZE 30
    void error_handling(char * message);
    
    int main(int argc,char *argv[]){
        
        int sock;
        char msg1[] = "Hi!";
        char msg2[]="I 'm zzy";
        char msg3[] = "Nicw to meet you";
    
        socklen_t your_adr_sz;
    
        struct sockaddr_in your_adr;
        if(argc!=3){
        
            printf("usage : %s <port>\n",argv[0]);
            exit(1);
        }
    
        sock = socket(PF_INET,SOCK_DGRAM,0);
        if(sock == -1)
            error_handling("socket() error");
        
        memset(&your_adr,0,sizeof(your_adr));
        your_adr.sin_family = AF_INET;
        your_adr.sin_addr.s_addr=inet_addr(argv[1]);
        your_adr.sin_port=htons(atoi(argv[2]));
    
        sendto(sock,msg1,sizeof(msg1),0,(struct sockaddr*)&your_adr,sizeof(your_adr));
        sendto(sock,msg2,sizeof(msg2),0,(struct sockaddr*)&your_adr,sizeof(your_adr));
        sendto(sock,msg3,sizeof(msg3),0,(struct sockaddr*)&your_adr,sizeof(your_adr));
        close(sock);
        return 0;
    }
    
    void error_handling(char *message){
        
        fputs(message,stderr);
        fputc('\n',stderr);
        exit(1);
    }