chat2.c

基于BSD C的socket编程 采用udp协议,类似两个进程通信的聊天程序 压缩包包含两个文件,编译后运行是两个不同的聊天进程 运行环境linux

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <netdb.h>
#define MYPORT1 4950        //for chat1
#define MYPORT2 4951        //for chat2
#define MAXBUFLEN 100 

void mysend(char* buf);
void myreceive(char* buf);

char bufrecv[MAXBUFLEN];
char bufsend[MAXBUFLEN];

int main(int argc, char *argv[]) 
{ 
    if(!fork()){
        while(1){
            myreceive(bufrecv);
        }
    }
    
    while(1){
        scanf("%s",bufsend);
        mysend(bufsend);
    }

    return 0; 
} 

void mysend(char* buf){
    int sockfd;
    int numbytes;
    struct sockaddr_in their_addr;
    
    if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) { 
        perror("socket"); 
        exit(1); 
    } 
    
    their_addr.sin_family = AF_INET; /* host byte order */ 
    their_addr.sin_port = htons(MYPORT1);   //port of chat 1, send to chat 1
    their_addr.sin_addr.s_addr = inet_addr("192.168.206.193");
    bzero(&(their_addr.sin_zero),sizeof(their_addr.sin_zero)); /* zero the rest of the struct */
    
    if ((numbytes=sendto(sockfd, buf, strlen(buf), 0, \
        (struct sockaddr *)&their_addr, sizeof(struct sockaddr))) == -1) { 
        perror("sendto"); 
        exit(1); 
    }
    
    //printf("sent %d bytes to %s\n",numbytes,inet_ntoa(their_addr.sin_addr)); 
    close(sockfd); 
}

void myreceive(char* buf){
    int sockfd;
    int numbytes,addr_len;
    struct sockaddr_in my_addr,their_addr;
    
    if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) { 
        perror("socket"); 
        exit(1); 
    }
    
    my_addr.sin_family = AF_INET;           /* host byte order */ 
    my_addr.sin_port = htons(MYPORT2);      //port of chat 2
    my_addr.sin_addr.s_addr = inet_addr("192.168.206.193");
    bzero(&(my_addr.sin_zero),sizeof(my_addr.sin_zero)); /* zero the rest of the struct */
    
    if (bind(sockfd, (struct sockaddr *)&my_addr, sizeof(struct sockaddr)) == -1) { 
        perror("bind"); 
        exit(1); 
    }
    
    addr_len = sizeof(struct sockaddr); 
    if ((numbytes=recvfrom(sockfd, buf, MAXBUFLEN, 0, \
        (struct sockaddr *)&their_addr, &addr_len)) == -1) { 
        perror("recvfrom"); 
        exit(1); 
    }
    
    //printf("got packet from %s\n",inet_ntoa(their_addr.sin_addr));
    printf("%d>>>",ntohs(their_addr.sin_port));
    buf[numbytes] = '\0'; 
    //printf("packet contains \"%s\"\n",buf); 
    printf("%s\n",buf);
    close(sockfd); 
}