我的眩晕绑定请求哪里出错了？

Question

我向stun.l.google.com:19305发送udp请求，但没有从google服务器获得任何响应。我省略了这段代码中的所有错误检查。我的程序挂在recvfrom上。

int stun_socket = socket(AF_INET, SOCK_DGRAM, 0);

struct sockaddr_in stun_client;
memset(&stun_client, 0, sizeof(stun_client));

stun_client.sin_family = AF_INET;
stun_client.sin_port = htons(local_port);

int rc = bind(stun_socket, (struct sockaddr *)&stun_client, sizeof(stun_client));

struct sockaddr_in stun_server;
memset(&stun_server, 0, sizeof(stun_server));

stun_server.sin_family = AF_INET;
stun_server.sin_port = htons(remote_port);
inet_pton(AF_INET, server, &stun_server.sin_addr);

typedef struct stun_header_tag {
    uint16_t message_type;
    uint16_t message_length;
    unsigned char transaction_id[16];
} stun_header_t;

stun_header_t header;
header.message_type = htons(0x0001); /* Binding Request */
header.message_length = htons(0);
*(int *)(&header.transaction_id[8]) = 0xFFEEFFEE; /* transaction id in the response should keep consistent with this one */

rc = sendto(stun_socket, (void *)&header, sizeof(header), 0, (struct sockaddr *)&stun_server, sizeof(stun_server));

char response[64];
rc = recvfrom(stun_socket, response, 64, 0, NULL, 0);

Answer 1

我猜您正在为发送数据做类似的或等效的事情：

sendto(sock, &header, sizeof(header), (sockaddr*)&addr, addrlen);

如果是这样的话，您可能忘记将您的message_type值转换为网络字节顺序(大端)。

试试这个：

header.message_type = htons(0x0001);

但是，如果您想要一个更好的解决方案，并且可以使用C++，请使用内置到特技演员中的客户端库。您可以使用C++类CStunMessageBuilder生成绑定请求，该类在特技核心/特技建筑文件中声明。

CStunMessageBuilder builder;
StunTransactionId transId;

builder.AddBindingRequestHeader();
builder.AddRandomTransactionId(&transID);
unsigned char* msg = builder.GetStream().GetDataPointerUnsafe();
size_t len = builder.GetStream().GetSize();

sendto(sock, msg, len, (sockaddr*)&addr, addrlen);