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Optional Query Callbacks #4

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Optional Query Callbacks #4

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2ff9a01
add optional domain query callbacks
connectiblutz Jun 10, 2021
db5efeb
add ifdef around this method too, as its only used when report querie…
connectiblutz Jun 10, 2021
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3 changes: 3 additions & 0 deletions include/dnsparser.h
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,9 @@ class DnsParserListener
*/
virtual void onDnsRec(in_addr addr, std::string name, std::string path) = 0;
virtual void onDnsRec(in6_addr addr, std::string name, std::string path) = 0;
#ifdef REPORT_QUERIES
virtual void onDnsReq(uint16_t type, std::string name) = 0;
#endif
};

class DnsParser
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39 changes: 37 additions & 2 deletions src/dnsparse.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@ class DnsParserImpl : public DnsParser
private:

int dnsReadAnswers(char *payload, int payloadLen, char *ptr, int remaining, int numAnswers);
int dnsReadQueries(char *payload, int payloadLen, char *ptr, int remaining, int numQueries);

DnsParserListener* _listener;
bool _ignoreCnames;
Expand Down Expand Up @@ -75,19 +76,49 @@ int skip_name(char *ptr, int remaining)
return -1;
}

#ifdef REPORT_QUERIES
void reDotName(char* ptr, int remaining) {
char *p = ptr;
char *end = p + remaining;
while (p < end) {
int dotLen = *p;
if (dotLen < 0 || dotLen >= remaining) return;
if (dotLen == 0) return;
*p='.';
p += dotLen + 1;
remaining -= dotLen + 1;
}
}
#endif

//-------------------------------------------------------------------------
// Read query records
// @returns -1 on error
// @returns Number of bytes taken up by query records
//-------------------------------------------------------------------------
int dnsReadQueries(char *payload, int payloadLen, char *ptr, int remaining, int numQueries)
int DnsParserImpl::dnsReadQueries(char *payload, int payloadLen, char *ptr, int remaining, int numQueries)
{
int rem = remaining;
char *p = ptr;
while(numQueries > 0)
{
int nameLen = skip_name(p, remaining);
if (nameLen <= 0) return -1;

#ifdef REPORT_QUERIES
// copy the queried host, change dotlen specifiers to dots, and feed it (minus the leading dot) to our listener
char* nameTmp=(char*)malloc(nameLen+1);
if (nameTmp) {
memcpy(nameTmp,p,nameLen);
nameTmp[nameLen]=0;
reDotName(nameTmp,nameLen);
uint16_t type;
memcpy(&type,(p+nameLen),sizeof(uint16_t));
if (0L != _listener) _listener->onDnsReq(ntohs(type),nameTmp+1);
free(nameTmp);
}
#endif

remaining -= nameLen + 4;
p += nameLen + 4;
if (remaining < 0) return -1;
Expand Down Expand Up @@ -306,12 +337,16 @@ int DnsParserImpl::parse(char *payload, int payloadLen)

if (DNS_FLAG_OPCODE(hdr._flags) != 0) return -1; // not a standard query.

#ifndef REPORT_QUERIES
if ((hdr._flags & DNS_FLAG_RESPONSE) == 0) return 0;
#endif

{
// response


#ifndef REPORT_QUERIES
if (hdr._numAnswers <= 0) return 0; // only care about answers
#endif

if (hdr._numQueries > 4 || hdr._numAnswers > 20) return -1; // unreasonable?

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