我正在尝试使用下面的代码连接到UDP跟踪服务器，但我没有收到跟踪器的任何回复......
我通过这个链接收集了我的内容： http://xbtt.sourceforge.net/udp_tracker_protocol.html
我认为我得到了......但显然不是。代码执行正常，然后在调用RecvFrom时挂起。所以我猜我要么不发送正确的数据，要么就是把它发送到错误的地方......struct ConnectionIdRequest_t {
uint64_t connectionId;
uint32_t action;
int32_t transactionId;
} typedef ConnectionIdRequest;
const bool UdpTorrentTrackerComm::initiateConnection(const int amountUploaded,
const int amountDownloaded,
const int amountLeft) {
struct sockaddr_in serverAddress, clientAddress;
struct hostent * host;
struct in_addr address;
//Setup dummy client address
clientAddress.sin_family = AF_INET;
clientAddress.sin_addr.s_addr = htonl(INADDR_ANY);
clientAddress.sin_port = htons(0);
//Setup server address
serverAddress.sin_family = AF_INET;
serverAddress.sin_port = htons(portNumber);
//SETUP in_addr server address
//If we have an IP
if (trackerAddress) {
if (isIp4Address(*trackerAddress)) {
//retrieve hostname from ip address
if (inet_aton(trackerAddress->c_str(), &address)) {
host = gethostbyaddr((const char *) &address, sizeof(address), AF_INET);
trackerHostname = new std::string(host->h_name);
}
else {
return false;
}
}
else {
return false;
}
}
else {
//retrieve ip address from hostname
host = gethostbyname(trackerHostname->c_str());
address.s_addr = ((struct in_addr *) host->h_addr_list)->s_addr;
trackerAddress = new std::string(inet_ntoa(address));
}
std::cout << *trackerAddress << std::endl;
//Convert trackerAddress to network format
if(!inet_aton(trackerAddress->c_str(), &serverAddress.sin_addr)) {
return false;
}
int sockFd = -1;
//Add IPv6 in the future
if ((sockFd = Socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
return false;
}
//Bind my address to the socket
if (Bind(sockFd, (struct sockaddr *) &clientAddress, sizeof(clientAddress)) == - 1) {
return false;
}
std::cout << "SendTo\n";
ConnectionIdRequest * idRequest = createConnectionIdRequest();
if (SendTo(sockFd, idRequest, sizeof(*idRequest), 0,
(struct sockaddr *) &serverAddress, sizeof(serverAddress)) == -1) {
return false;
}
timeRequestSent = clock();
std::cout << "Sent: " << idRequest->connectionId << "|||" << idRequest->action << "|||" << idRequest->transactionId << std::endl;
std::cout << "RecvFrom\n";
char buffer[3000];
socklen_t serverAddressLength = sizeof(serverAddress);
while(true) {
if (RecvFrom(sockFd, buffer, 3000, 0,
(struct sockaddr *) &serverAddress, &serverAddressLength) == - 1) {
break;
std::cout << "breaking...\n";
}
}
std::cout << "The buffer is: " << buffer << std::endl;
Close(sockFd);
return true;
}
ConnectionIdRequest * UdpTorrentTrackerComm::createConnectionIdRequest() {
ConnectionIdRequest * idRequest = new ConnectionIdRequest;
generatePeerId();
idRequest->connectionId = htonll(0x41727101980);
idRequest->action = htonl(CONNECT);
idRequest->transactionId = htonl(*peerId);
return idRequest;
}
编辑：好吧，我做了Arvid建议的一个改变，但这没有任何帮助。我正在经历并确保我将所有发送的字节转换为网络字节顺序...也许我错过了一些......
答案 0 :(得分：1)
看起来你正在混淆交易ID和对等ID。它们是不同的。事务ID是您发送的cookie，以便将返回的数据包与正确的请求进行匹配。
看起来您还没有初始化connectionID。您必须在初始连接消息中将其设置为魔术64位数。 0x41727101980
您可以找到替代协议说明here。
答案 1 :(得分：1)
我最终让它上班了。问题主要在于我没有转换所有需要转换为big endian（网络排序）的值，以及使用过时的函数（gethostbyname等）。
如果您想了解更多详情，请发表评论。
这是我可以与跟踪服务器建立链接的代码：
注意：serverAddress和clientAddress是类型的类字段：struct sockaddr_in
const bool UdpTorrentTrackerComm::initiateConnection() {
//Setup dummy client address
clientAddress.sin_family = AF_INET;
clientAddress.sin_addr.s_addr = htonl(INADDR_ANY);
clientAddress.sin_port = htons(51413);
//Setup server address
serverAddress.sin_family = AF_INET;
serverAddress.sin_port = htons(portNumber);
//SETUP in_addr server address
//If we have an IP
if (trackerAddress) {
if (isIp4Address(*trackerAddress)) {
//Convert human readable trackerAddress to network byte order ip address and place in serverAddress.sin_addr
if (inet_pton(AF_INET, trackerAddress->c_str(), &(serverAddress.sin_addr))) {
//retrieve hostname and service type from ip address
char hostBuffer[100], serviceBuffer[100];
getnameinfo((struct sockaddr *) &serverAddress, sizeof(serverAddress),
hostBuffer, sizeof(hostBuffer),
serviceBuffer, sizeof(serviceBuffer),
NI_NAMEREQD | NI_DGRAM);
trackerHostname = new std::string(hostBuffer);
}
else {
return false;
}
}
else {
return false;
}
}
else {
//Setup structs to be used in getaddrinfo
struct addrinfo hints;
struct addrinfo * result, * resultPointer;
hints.ai_family = AF_INET;
hints.ai_socktype = SOCK_DGRAM;
hints.ai_flags = 0;
hints.ai_protocol = 0;
//Convert port number to string to pass to getaddrinfo
std::stringstream ss;
ss << portNumber;
std::string portNumberString = ss.str();
//retrieve ip address from hostname--------
if (GetAddrInfo(trackerHostname->c_str(), portNumberString.c_str(), &hints, &result) != 0) {
return false;
}
//Iterate over results for IP address V4 (ADD V6 later!)
char ipBuffer[INET_ADDRSTRLEN];
for (resultPointer = result; resultPointer != NULL; resultPointer = resultPointer->ai_next) {
//If we have an IPv4 address
if (resultPointer->ai_family == AF_INET) {
//convert to presentation format and store in ipBuffer
inet_ntop(AF_INET, &((struct sockaddr_in *) resultPointer->ai_addr)->sin_addr, ipBuffer, INET_ADDRSTRLEN);
}
}
//Free result
freeaddrinfo(result);
//Convert ipBuffer to std::string and store in trackerAddress field
trackerAddress = new std::string(ipBuffer);
//Convert trackerAddress to network format
if(!inet_pton(AF_INET, trackerAddress->c_str(), &serverAddress.sin_addr)) {
return false;
}
}
int sockFd = -1;
//Add IPv6 in the future
if ((sockFd = Socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
return false;
}
//Bind my address to the socket
if (Bind(sockFd, (struct sockaddr *) &clientAddress, sizeof(clientAddress)) == - 1) {
return false;
}
//Send a request to the tracker
ConnectionIdRequest * idRequest = createConnectionIdRequest();
if (SendTo(sockFd, idRequest, sizeof(*idRequest), 0,
(struct sockaddr *) &serverAddress, sizeof(serverAddress)) == -1) {
return false;
}
timeRequestSent = clock();
//Re-send until timeout.....
ConnectionIdResponse idResponse;
socklen_t serverAddressLength = sizeof(serverAddress);
while((timeRequestSent - clock()) / 1000 < SECONDS_UNTIL_TIMEOUT) {
//Response received!
if (RecvFrom(sockFd, &idResponse, sizeof(idResponse), 0,
(struct sockaddr *) &serverAddress, &serverAddressLength) > 0) {
break;
}
}
//Set class fields that will persist
activeSocket = sockFd;
connectionId = ntohll(idResponse.connectionId);
delete idRequest;
return true;
}
两个结构的位置，ConnectionIdResponse和ConnectionIdRequest定义为：
/* Struct used to send a request for a connectionId to the tracker server.*/
struct ConnectionIdRequest_t {
uint64_t connectionId;
uint32_t action;
uint32_t transactionId;
} typedef ConnectionIdRequest;
/* Struct used in receipt of a request for a connectionId from the tracker server. */
struct ConnectionIdResponse_t {
uint32_t action;
uint32_t transactionId;
uint64_t connectionId;
} typedef ConnectionIdResponse;