Question

当我注释掉关闭阻止一切正常的代码时，但是当我离开非阻塞代码时，我从来没有从recvfrom获得任何数据。（接收的字节总是0）这是带有阻塞语句的代码。我是Xcode和IOS的新手，但是已经为.NET创建了UDP代码。

 // Create Socket
int Handle = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
if (Handle <=0){
    printf("Failed to create socket\n");
}

// Bind Socket
struct sockaddr_in address;
address.sin_family = AF_INET;
address.sin_addr.s_addr = INADDR_ANY;
address.sin_port = htons((unsigned short) 4966);
if (bind(Handle,(struct sockaddr *) &address, sizeof(struct sockaddr_in))< 0){
    printf("Failed to Bind\n");
}//end if
printf("Bind Done\n");

// Set to non Blocking
int NonBlocking = 1;
//if (fcntl(Handle, F_SETFL, O_NONBLOCK, NonBlocking) == -1){
    printf("Faile to set nonblocking\n");
//}
Boolean ContinueLoop = true;

    unsigned char Packet_Data[256];
    unsigned int Maximum_Packet_Size = sizeof(Packet_Data);

    struct sockaddr_in From_Address;
    socklen_t FromLength = sizeof(From_Address);

     while (ContinueLoop){
    int Received_Bytes = recvfrom(Handle, (char *)Packet_Data, Maximum_Packet_Size, 0, (struct sockaddr *)&From_Address, &FromLength);



    if (Received_Bytes > 0){
        ContinueLoop = false;
        printf("Got Data \n");
    } else {
        perror("Now");
        printf(".");
    }



    close(Handle);

}//wend

Answer 1

发现问题。我不小心在while循环中包含了close语句。将它移出它所属的循环，现在一切正常。阻止和非阻塞。

IOS UDP recvfrom在阻塞时工作，但在非阻塞时不工作

1 个答案: