Question UnpackQuestion(const unsigned char* input, unsigned short input_size, unsigned short& pos)
{
- Question question;
+ Question q;
- question.name = this->UnpackName(input, input_size, pos);
+ q.name = this->UnpackName(input, input_size, pos);
if (pos + 4 > input_size)
throw Exception("Unable to unpack question");
- question.type = static_cast<QueryType>(input[pos] << 8 | input[pos + 1]);
+ q.type = static_cast<QueryType>(input[pos] << 8 | input[pos + 1]);
pos += 2;
- question.qclass = input[pos] << 8 | input[pos + 1];
+ // Skip over query class code
pos += 2;
- return question;
+ return q;
}
ResourceRecord UnpackResourceRecord(const unsigned char* input, unsigned short input_size, unsigned short& pos)
static const int HEADER_LENGTH = 12;
/* ID for this packet */
- unsigned short id;
+ RequestId id;
/* Flags on the packet */
unsigned short flags;
this->id = (input[packet_pos] << 8) | input[packet_pos + 1];
packet_pos += 2;
- if (this->id >= MAX_REQUEST_ID)
- throw Exception("Query ID too large?");
-
this->flags = (input[packet_pos] << 8) | input[packet_pos + 1];
packet_pos += 2;
ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "qdcount: " + ConvToStr(qdcount) + " ancount: " + ConvToStr(ancount) + " nscount: " + ConvToStr(nscount) + " arcount: " + ConvToStr(arcount));
- for (unsigned i = 0; i < qdcount; ++i)
- this->questions.push_back(this->UnpackQuestion(input, len, packet_pos));
+ if (qdcount != 1)
+ throw Exception("Question count != 1 in incoming packet");
+
+ this->question = this->UnpackQuestion(input, len, packet_pos);
for (unsigned i = 0; i < ancount; ++i)
this->answers.push_back(this->UnpackResourceRecord(input, len, packet_pos));
output[pos++] = this->id & 0xFF;
output[pos++] = this->flags >> 8;
output[pos++] = this->flags & 0xFF;
- output[pos++] = this->questions.size() >> 8;
- output[pos++] = this->questions.size() & 0xFF;
- output[pos++] = this->answers.size() >> 8;
- output[pos++] = this->answers.size() & 0xFF;
+ output[pos++] = 0; // Question count, high byte
+ output[pos++] = 1; // Question count, low byte
+ output[pos++] = 0; // Answer count, high byte
+ output[pos++] = 0; // Answer count, low byte
output[pos++] = 0;
output[pos++] = 0;
output[pos++] = 0;
output[pos++] = 0;
- for (unsigned i = 0; i < this->questions.size(); ++i)
{
- Question& q = this->questions[i];
+ Question& q = this->question;
if (q.type == QUERY_PTR)
{
memcpy(&output[pos], &s, 2);
pos += 2;
- s = htons(q.qclass);
- memcpy(&output[pos], &s, 2);
- pos += 2;
- }
-
- for (unsigned int i = 0; i < answers.size(); i++)
- {
- ResourceRecord& rr = answers[i];
-
- this->PackName(output, output_size, pos, rr.name);
-
- if (pos + 8 >= output_size)
- throw Exception("Unable to pack packet");
-
- short s = htons(rr.type);
- memcpy(&output[pos], &s, 2);
- pos += 2;
-
- s = htons(rr.qclass);
- memcpy(&output[pos], &s, 2);
- pos += 2;
-
- long l = htonl(rr.ttl);
- memcpy(&output[pos], &l, 4);
- pos += 4;
-
- switch (rr.type)
- {
- case QUERY_A:
- {
- if (pos + 6 > output_size)
- throw Exception("Unable to pack packet");
-
- irc::sockets::sockaddrs a;
- irc::sockets::aptosa(rr.rdata, 0, a);
-
- s = htons(4);
- memcpy(&output[pos], &s, 2);
- pos += 2;
-
- memcpy(&output[pos], &a.in4.sin_addr, 4);
- pos += 4;
- break;
- }
- case QUERY_AAAA:
- {
- if (pos + 18 > output_size)
- throw Exception("Unable to pack packet");
-
- irc::sockets::sockaddrs a;
- irc::sockets::aptosa(rr.rdata, 0, a);
-
- s = htons(16);
- memcpy(&output[pos], &s, 2);
- pos += 2;
-
- memcpy(&output[pos], &a.in6.sin6_addr, 16);
- pos += 16;
- break;
- }
- case QUERY_CNAME:
- case QUERY_PTR:
- {
- if (pos + 2 >= output_size)
- throw Exception("Unable to pack packet");
-
- unsigned short packet_pos_save = pos;
- pos += 2;
-
- this->PackName(output, output_size, pos, rr.rdata);
-
- s = htons(pos - packet_pos_save - 2);
- memcpy(&output[packet_pos_save], &s, 2);
- break;
- }
- default:
- break;
- }
+ // Query class, always IN
+ output[pos++] = 0;
+ output[pos++] = 1;
}
return pos;
{
const ResourceRecord& rr = r.answers[0];
ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "cache: added cache for " + rr.name + " -> " + rr.rdata + " ttl: " + ConvToStr(rr.ttl));
- this->cache[r.questions[0]] = r;
+ this->cache[r.question] = r;
}
public:
- DNS::Request* requests[MAX_REQUEST_ID];
+ DNS::Request* requests[MAX_REQUEST_ID+1];
MyManager(Module* c) : Manager(c), Timer(3600, true)
{
- for (int i = 0; i < MAX_REQUEST_ID; ++i)
+ for (unsigned int i = 0; i <= MAX_REQUEST_ID; ++i)
requests[i] = NULL;
ServerInstance->Timers.AddTimer(this);
}
~MyManager()
{
- for (int i = 0; i < MAX_REQUEST_ID; ++i)
+ for (unsigned int i = 0; i <= MAX_REQUEST_ID; ++i)
{
DNS::Request* request = requests[i];
if (!request)
/* Create an id */
unsigned int tries = 0;
+ int id;
do
{
- req->id = ServerInstance->GenRandomInt(DNS::MAX_REQUEST_ID);
+ id = ServerInstance->GenRandomInt(DNS::MAX_REQUEST_ID+1);
if (++tries == DNS::MAX_REQUEST_ID*5)
{
// If we couldn't find an empty slot this many times, do a sequential scan as a last
// resort. If an empty slot is found that way, go on, otherwise throw an exception
- req->id = 0;
- for (int i = 1; i < DNS::MAX_REQUEST_ID; i++)
+ id = -1;
+ for (unsigned int i = 0; i <= DNS::MAX_REQUEST_ID; i++)
{
if (!this->requests[i])
{
- req->id = i;
+ id = i;
break;
}
}
- if (req->id == 0)
+ if (id == -1)
throw Exception("DNS: All ids are in use");
break;
}
}
- while (!req->id || this->requests[req->id]);
+ while (this->requests[id]);
+ req->id = id;
this->requests[req->id] = req;
Packet p;
p.flags = QUERYFLAGS_RD;
p.id = req->id;
- p.questions.push_back(*req);
+ p.question = *req;
unsigned char buffer[524];
unsigned short len = p.Pack(buffer, sizeof(buffer));
- /* Note that calling Pack() above can actually change the contents of p.questions[0].name, if the query is a PTR,
+ /* Note that calling Pack() above can actually change the contents of p.question.name, if the query is a PTR,
* to contain the value that would be in the DNS cache, which is why this is here.
*/
- if (req->use_cache && this->CheckCache(req, p.questions[0]))
+ if (req->use_cache && this->CheckCache(req, p.question))
{
ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Using cached result");
delete req;
return;
}
+ // Update name in the original request so question checking works for PTR queries
+ req->name = p.question.name;
+
if (SocketEngine::SendTo(this, buffer, len, 0, &this->myserver.sa, this->myserver.sa_size()) != len)
throw Exception("DNS: Unable to send query");
}
if (length < Packet::HEADER_LENGTH)
return;
+ if (myserver != from)
+ {
+ std::string server1 = from.str();
+ std::string server2 = myserver.str();
+ ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Got a result from the wrong server! Bad NAT or DNS forging attempt? '%s' != '%s'",
+ server1.c_str(), server2.c_str());
+ return;
+ }
+
Packet recv_packet;
try
return;
}
- if (myserver != from)
+ DNS::Request* request = this->requests[recv_packet.id];
+ if (request == NULL)
{
- std::string server1 = from.str();
- std::string server2 = myserver.str();
- ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Got a result from the wrong server! Bad NAT or DNS forging attempt? '%s' != '%s'",
- server1.c_str(), server2.c_str());
+ ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Received an answer for something we didn't request");
return;
}
- DNS::Request* request = this->requests[recv_packet.id];
- if (request == NULL)
+ if (static_cast<Question&>(*request) != recv_packet.question)
{
- ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Received an answer for something we didn't request");
+ // This can happen under high latency, drop it silently, do not fail the request
+ ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Received an answer that isn't for a question we asked");
return;
}
recv_packet.error = error;
request->OnError(&recv_packet);
}
- else if (recv_packet.questions.empty() || recv_packet.answers.empty())
+ else if (recv_packet.answers.empty())
{
ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "No resource records returned");
ServerInstance->stats.DnsBad++;
void OnUnloadModule(Module* mod)
{
- for (int i = 0; i < MAX_REQUEST_ID; ++i)
+ for (unsigned int i = 0; i <= MAX_REQUEST_ID; ++i)
{
DNS::Request* req = this->manager.requests[i];
if (!req)
projects / user / henk / code / inspircd.git / blobdiff