我正在尝试在Linux中创建一个客户端以允许发送UDP数据包。到目前为止，该程序似乎正确地形成了所有部分，但是当我尝试发送数据时，程序无法发送数据包。
I've put the code here，代码的示例输出如下：
jeremiah@ubuntu:~/Documents/Networking 2/Lab3/client$ sudo ./a.out 192.168.1.128 22222 great success Imperial Soviet Comrade: SVN -> sin_family: 2 Imperial Soviet Comrade: SVN -> sin_port: 52822 Imperial Soviet Comrade: SVN -> sin_addr: -2147374912 Attention Comrade: Enter Message: red Imperial Soviet Comrade: Data in packet dump ::::::::::::::::::::::::::::::::::::::::: start Imperial Soviet Comrade: the size of the UPC is 1576 Imperial Soviet Comrade: Socket: 3 Imperial Soviet Comrade: UPC -> flags: 1 Imperial Soviet Comrade: UPC -> offset: 0 Imperial Soviet Comrade: UPC -> length: 8 Imperial Soviet Comrade: UPC -> filename: red Imperial Soviet Comrade: UPC -> data: 00000000000000000000000000000000000000000000000000000000000000000000000000000000 Imperial Soviet Comrade: UPC -> data: 00000000000000000000000000000000000000000000000000000000000000000000000000000000 Imperial Soviet Comrade: UPC -> data: 00000000000000000000000000000000000000000000000000000000000000000000000000000000 Imperial Soviet Comrade: UPC -> data: 00000000000000000000000000000000000000000000000000000000000000000000000000000000 Imperial Soviet Comrade: UPC -> data: 00000000000000000000000000000000000000000000000000000000000000000000000000000000 Imperial Soviet Comrade: UPC -> data: 00000000000000000000000000000000000000000000000000000000000000000000000000000000 Imperial Soviet Comrade: UPC -> data: 00000000000000000000000000000000000000000000000000000000000000000000000000000000 Imperial Soviet Comrade: UPC -> data: 00000000000000000000000000000000000000000000000000000000000000000000000000000000 Imperial Soviet Comrade: UPC -> data: 00000000000000000000000000000000000000000000000000000000000000000000000000000000 Imperial Soviet Comrade: UPC -> data: 00000000000000000000000000000000000000000000000000000000000000000000000000000000 Imperial Soviet Comrade: UPC -> data: 00000000000000000000000000000000000000000000000000000000000000000000000000000000 Imperial Soviet Comrade: UPC -> data: 00000000000000000000000000000000000000000000000000000000000000000000000000000000 Imperial Soviet Comrade: UPC -> data: 00000000000000000000000000000000000000000000000000000000000000000000000000000000 Imperial Soviet Comrade: UPC -> data: 00000000000000000000000000000000000000000000000000000000000000000000000000000000 Imperial Soviet Comrade: UPC -> data: 00000000000000000000000000000000000000000000000000000000000000000000000000000000 Imperial Soviet Comrade: UPC -> data: 00000000000000000000000000000000000000000000000000000000000000000000000000000000 Imperial Soviet Comrade: UPC -> data: 00000000000000000000000000000000000000000000000000000000000000000000000000000000 Imperial Soviet Comrade: UPC -> data: 0000000000000000000000000000000000000000 Imperial Soviet Comrade: sizeof(UPC): 8 Imperial Soviet Comrade: sockaddr.sin_family: 2 Imperial Soviet Comrade: sockaddr.sin_port: 52822 Imperial Soviet Comrade: sockaddr.sin_addr.s_addr: -2147374912 Imperial Soviet Comrade: sizeof(sockaddr): 8 Imperial Soviet Comrade: Data in packet dump ::::::::::::::::::::::::::::::::::::::::::: end Imperial Soviet Comrade: size_sent: -1 Alert Comrade: Data not sent: Invalid argument
它完全编译没有错误，但是printf函数中的casting会有警告。我们将非常感谢您提供的任何帮助。
答案 0 :(得分：1)
这真的很可疑：
int size_sent = sendto(SOCKET, UPC, sizeof(UPC)+2*MAX_MESSAGE, 0,
(struct sockaddr*) &TARGET, sizeof(TARGET)+2*MAX_MESSAGE);
为什么要在消息长度和sockaddr结构的大小上添加2 * MAX_MESSAGE？
最后一个很可能是你的sendto()调用返回-1的原因。
还要记住，sizeof（UPC）将是4或8，而不是你想要的。