UDP服务器没有收到数据

Question

UDP服务器没有收到UDP客户端程序发送的数据。我感觉在UDP服务器程序中有什么问题。谢谢。

send_client_message = malloc(message_size); 
    recv_client_message = malloc(message_size); 
    sockaddr_in_length = sizeof(struct sockaddr_in); 

    /* Create a datagram socket.*/ 
    server_sock = socket(AF_INET,SOCK_DGRAM,0); 
    if (server_sock == return_error) 
    { 
    printf("Error in opening a datagram socket\n"); 
    exit(0); 
    } 
    printf("Host sock = %d\n",server_sock); 

    /* Bind a local name to the socket.*/ 
    server_sockaddr_in.sin_family  = AF_INET; 
    server_sockaddr_in.sin_port  = 4999; 
    server_sockaddr_in.sin_addr.s_addr = INADDR_ANY; 
    rc = bind(server_sock,(struct sockaddr *)&server_sockaddr_in, 
      sockaddr_in_length); 
    if (rc == return_error) 
    { 
    printf("Error in binding - \n"); 
    (void)close(server_sock); 
    exit(0); 
    } 

    /* Get the server information, and print its data out.*/ 
    rc = getsockname(server_sock,(struct sockaddr *)&server_sockaddr_in, 
        &sockaddr_in_length); 
    if (rc != return_error) 
    { 
    printf("Server Information\n"); 
    printf("--------------------------------\n"); 
    printf("Server sock  - %d\n",server_sock); 
    printf("Server IP address - %x\n", 
            server_sockaddr_in.sin_addr.s_addr); 
    printf("Server port #  - %d\n\n", 
            server_sockaddr_in.sin_port); 
    } 

    optval = message_size; 
    optlen = sizeof(optval); 
    rc = setsockopt(server_sock,SOL_SOCKET,SO_SNDBUF,(char *)&optval, 
        optlen); 
    if (rc == return_error) 
    { 
    //printf("Error in setsockopt - %d\n",sock_errno()); 
    printf("Error in setsockopt - \n"); 
    (void)close(server_sock); 
    exit(0); 
    } 

    printf(".... Ready for clients ....\n"); 

    /* Loop forever */ 
    for (;;) 
    { 
    /* Monitor incoming buffers. */ 
    rc = recvfrom(server_sock,recv_client_message,message_size,0, 
        (struct sockaddr *)&client_sockaddr_in, 
        &sockaddr_in_length); 

    printf("Recieved packet from %s: %d\nData: %s\n\n", inet_ntoa(client_sockaddr_in.sin_addr), ntohs(client_sockaddr_in.sin_port), recv_client_message); 
    fflush(stdout); 

    if (rc == return_error) 
    { 
     printf("Error in receiving message \n"); 
     break; 
    } 
    } /* end of for(;;) */ 

    /* Return the socket back to the system and exit normally. */ 
    rc = close(server_sock); 
    if (rc == return_error) 
    { 
    printf("Error in closing the socket \n"); 
    exit(0); 
    } 

    printf("Datagram server terminated\n"); 
    exit(0); 
} 


    for(i = 0; i < NPACK; i += 1) { 
     printf("Sending packet %d\n", i); 
     sprintf(buf, "This is packet %d\n", i); 
     if(sendto(s, buf, BUFLEN, 0, (struct sockaddr *) &si_other, slen) == -1) 
      diep("sendto()"); 
    } 

    close(s); 
    return 0; 
} 

Answer 1

server_sockaddr_in.sin_port  = 4999; 

你可能想htons是4999