#include "configreader.h"
#include "socket.h"
+#define DN_COMP_BITMASK 0xC000 /* highest 6 bits in a DN label header */
+
/** Masks to mask off the responses we get from the DNSRequest methods
*/
enum QueryInfo
DNSRequest(DNS* dns, int id, const std::string &original);
~DNSRequest();
- DNSInfo ResultIsReady(DNSHeader &h, int length);
+ DNSInfo ResultIsReady(DNSHeader &h, unsigned length);
int SendRequests(const DNSHeader *header, const int length, QueryType qt);
};
/* Allocate the processing buffer */
DNSRequest::DNSRequest(DNS* dns, int rid, const std::string &original) : dnsobj(dns)
{
- res = new unsigned char[512];
+ /* hardening against overflow here: make our work buffer twice the theoretical
+ * maximum size so that hostile input doesn't screw us over.
+ */
+ res = new unsigned char[sizeof(DNSHeader) * 2];
*res = 0;
orig = original;
RequestTimeout* RT = new RequestTimeout(ServerInstance->Config->dns_timeout ? ServerInstance->Config->dns_timeout : 5, this, rid);
void DNS::Rehash()
{
- int portpass = 0;
-
if (this->GetFd() > -1)
{
- if (ServerInstance && ServerInstance->SE)
- ServerInstance->SE->DelFd(this);
+ ServerInstance->SE->DelFd(this);
ServerInstance->SE->Shutdown(this, 2);
ServerInstance->SE->Close(this);
this->SetFd(-1);
{
ServerInstance->SE->SetReuse(s);
ServerInstance->SE->NonBlocking(s);
- /* Bind the port - port 0 INADDR_ANY */
- if (!ServerInstance->BindSocket(this->GetFd(), portpass, "", false))
+ irc::sockets::sockaddrs bindto;
+ memset(&bindto, 0, sizeof(bindto));
+ bindto.sa.sa_family = myserver.sa.sa_family;
+ if (ServerInstance->SE->Bind(this->GetFd(), bindto) < 0)
{
/* Failed to bind */
- ServerInstance->Logs->Log("RESOLVER",DEBUG,"Error binding dns socket");
+ ServerInstance->Logs->Log("RESOLVER",SPARSE,"Error binding dns socket - hostnames will NOT resolve");
ServerInstance->SE->Shutdown(this, 2);
ServerInstance->SE->Close(this);
this->SetFd(-1);
}
-
- if (this->GetFd() >= 0)
+ else if (!ServerInstance->SE->AddFd(this, FD_WANT_POLL_READ | FD_WANT_NO_WRITE))
{
- /* Hook the descriptor into the socket engine */
- if (ServerInstance && ServerInstance->SE)
- {
- if (!ServerInstance->SE->AddFd(this, FD_WANT_POLL_READ | FD_WANT_NO_WRITE))
- {
- ServerInstance->Logs->Log("RESOLVER",SPARSE,"Internal error starting DNS - hostnames will NOT resolve.");
- ServerInstance->SE->Shutdown(this, 2);
- ServerInstance->SE->Close(this);
- this->SetFd(-1);
- }
- }
+ ServerInstance->Logs->Log("RESOLVER",SPARSE,"Internal error starting DNS - hostnames will NOT resolve.");
+ ServerInstance->SE->Shutdown(this, 2);
+ ServerInstance->SE->Close(this);
+ this->SetFd(-1);
}
}
else
/* Did we get the whole header? */
if (length < 12)
{
+ ServerInstance->Logs->Log("RESOLVER",DEBUG,"GetResult didn't get a full packet (len=%d)", length);
/* Nope - something screwed up. */
return DNSResult(-1,"",0,"");
}
*
* -- Thanks jilles for pointing this one out.
*/
- if (memcmp(&from, &myserver, sizeof(irc::sockets::sockaddrs)))
+ if (from != myserver)
{
+ ServerInstance->Logs->Log("RESOLVER",DEBUG,"Got a result from the wrong server! Bad NAT or DNS forging attempt? '%s' != '%s'",
+ from.str().c_str(), myserver.str().c_str());
return DNSResult(-1,"",0,"");
}
if (!requests[this_id])
{
/* Somehow we got a DNS response for a request we never made... */
+ ServerInstance->Logs->Log("RESOLVER",DEBUG,"Hmm, got a result that we didn't ask for (id=%lx). Ignoring.", this_id);
return DNSResult(-1,"",0,"");
}
else
}
/** A result is ready, process it */
-DNSInfo DNSRequest::ResultIsReady(DNSHeader &header, int length)
+DNSInfo DNSRequest::ResultIsReady(DNSHeader &header, unsigned length)
{
- int i = 0;
+ unsigned i = 0, o;
int q = 0;
- int curanswer, o;
+ int curanswer;
ResourceRecord rr;
unsigned short ptr;
else i += header.payload[i] + 1; /* skip length and label */
}
}
- if (length - i < 10)
+ if (static_cast<int>(length - i) < 10)
return std::make_pair((unsigned char*)NULL,"Incorrectly sized DNS reply");
/* XXX: We actually initialise 'rr' here including its ttl field */
switch (rr.type)
{
+ /*
+ * CNAME and PTR are compressed. We need to decompress them.
+ */
case DNS_QUERY_CNAME:
- /* CNAME and PTR have the same processing code */
case DNS_QUERY_PTR:
+ {
+ unsigned short lowest_pos = length;
o = 0;
q = 0;
while (q == 0 && i < length && o + 256 < 1023)
{
+ /* DN label found (byte over 63) */
if (header.payload[i] > 63)
{
memcpy(&ptr,&header.payload[i],2);
- i = ntohs(ptr) - 0xC000 - 12;
+
+ i = ntohs(ptr);
+
+ /* check that highest two bits are set. if not, we've been had */
+ if ((i & DN_COMP_BITMASK) != DN_COMP_BITMASK)
+ return std::make_pair((unsigned char *) NULL, "DN label decompression header is bogus");
+
+ /* mask away the two highest bits. */
+ i &= ~DN_COMP_BITMASK;
+
+ /* and decrease length by 12 bytes. */
+ i -= 12;
+
+ if (i >= lowest_pos)
+ return std::make_pair((unsigned char *) NULL, "Invalid decompression pointer");
+ lowest_pos = i;
}
else
{
res[o] = 0;
if (o != 0)
res[o++] = '.';
- memcpy(&res[o],&header.payload[i + 1],header.payload[i]);
+
+ if (o + header.payload[i] > sizeof(DNSHeader))
+ return std::make_pair((unsigned char *) NULL, "DN label decompression is impossible -- malformed/hostile packet?");
+
+ memcpy(&res[o], &header.payload[i + 1], header.payload[i]);
o += header.payload[i];
i += header.payload[i] + 1;
}
}
}
res[o] = 0;
+ }
break;
case DNS_QUERY_AAAA:
+ if (rr.rdlength != sizeof(struct in6_addr))
+ return std::make_pair((unsigned char *) NULL, "rr.rdlength is larger than 16 bytes for an ipv6 entry -- malformed/hostile packet?");
+
memcpy(res,&header.payload[i],rr.rdlength);
res[rr.rdlength] = 0;
break;
case DNS_QUERY_A:
+ if (rr.rdlength != sizeof(struct in_addr))
+ return std::make_pair((unsigned char *) NULL, "rr.rdlength is larger than 4 bytes for an ipv4 entry -- malformed/hostile packet?");
+
memcpy(res,&header.payload[i],rr.rdlength);
res[rr.rdlength] = 0;
break;
default:
- memcpy(res,&header.payload[i],rr.rdlength);
- res[rr.rdlength] = 0;
+ return std::make_pair((unsigned char *) NULL, "don't know how to handle undefined type (" + ConvToStr(rr.type) + ") -- rejecting");
break;
}
return std::make_pair(res,"No error");
projects / user / henk / code / inspircd.git / blobdiff