#include "dnswriter.hh"
#include "misc.hh"
#include "dnsparser.hh"
-
+#include <boost/container/static_vector.hpp>
+#include <boost/scoped_ptr.hpp>
#include <limits.h>
DNSPacketWriter::DNSPacketWriter(vector<uint8_t>& content, const DNSName& qname, uint16_t qtype, uint16_t qclass, uint8_t opcode)
memcpy(dptr, ptr, sizeof(dnsheader));
d_stuff=0;
-
+ d_positions.reserve(16);
xfrName(qname, false);
len=d_content.size();
memcpy(&*i, &qclass, 2);
d_stuff=0xffff;
- d_labelmap.reserve(16);
d_truncatemarker=d_content.size();
d_sor = 0;
d_rollbackmarker = 0;
d_record.insert(d_record.end(), text.c_str(), text.c_str() + text.length());
}
-/* FIXME400: check that this beats a map */
-DNSPacketWriter::lmap_t::iterator find(DNSPacketWriter::lmap_t& nmap, const DNSName& name)
+
+static constexpr bool l_verbose=false;
+uint16_t DNSPacketWriter::lookupName(const DNSName& name, uint16_t* matchLen)
{
- DNSPacketWriter::lmap_t::iterator ret;
- for(ret=nmap.begin(); ret != nmap.end(); ++ret)
- if(ret->first == name)
+ // iterate over the written labels, see if we find a match
+ const auto& raw = name.getStorage();
+
+ /* name might be a.root-servers.net, we need to be able to benefit from finding:
+ b.root-servers.net, or even:
+ b\xc0\x0c
+ */
+ unsigned int bestpos=0;
+ *matchLen=0;
+ boost::container::static_vector<uint16_t, 34> nvect, pvect;
+
+ for(auto riter= raw.cbegin(); riter < raw.cend(); ) {
+ if(!*riter)
break;
- return ret;
-}
+ nvect.push_back(riter - raw.cbegin());
+ riter+=*riter+1;
+ }
+
+ if(l_verbose) {
+ cout<<"Input vector for lookup "<<name<<": ";
+ for(const auto n : nvect)
+ cout << n<<" ";
+ cout<<endl;
+ cout<<makeHexDump(string(raw.c_str(), raw.c_str()+raw.size()))<<endl;
+ }
-// //! tokenize a label into parts, the parts describe a begin offset and an end offset
-// bool labeltokUnescape(labelparts_t& parts, const string& label)
-// {
-// string::size_type epos = label.size(), lpos(0), pos;
-// bool unescapedSomething = false;
-// const char* ptr=label.c_str();
-
-// parts.clear();
-
-// for(pos = 0 ; pos < epos; ++pos) {
-// if(ptr[pos]=='\\') {
-// pos++;
-// unescapedSomething = true;
-// continue;
-// }
-// if(ptr[pos]=='.') {
-// parts.push_back(make_pair(lpos, pos));
-// lpos=pos+1;
-// }
-// }
-
-// if(lpos < pos)
-// parts.push_back(make_pair(lpos, pos));
-// return unescapedSomething;
-// }
+ if(l_verbose)
+ cout<<"Have "<<d_positions.size()<<" to ponder"<<endl;
+ int counter=1;
+ for(auto p : d_positions) {
+ vector<uint8_t>* source=0;
+ if(p < d_content.size())
+ source = &d_content;
+ else {
+ source = &d_record;
+ p-= (d_content.size() + d_stuff);
+
+ }
+ if(l_verbose) {
+ if(source == &d_content) {
+ DNSName pname((const char*)&(*source)[0], (*source).size(), p, true); // only for debugging
+ cout<<"Looking at '"<<pname<<"' in packet at position "<<p<<"/"<<(*source).size()<<", option "<<counter<<"/"<<d_positions.size()<<endl;
+ }
+ else
+ {
+ cout<<"Looking at *record* at position "<<p<<"/"<<(*source).size()<<", option "<<counter<<"/"<<d_positions.size()<<endl;
+ }
+ ++counter;
+ }
+ // memcmp here makes things _slower_
+ pvect.clear();
+ for(auto iter = (*source).cbegin() + p; iter < (*source).cend();) {
+
+ uint8_t c=*iter;
+ if(l_verbose)
+ cout<<"Found label length: "<<(int)c<<endl;
+ if(c & 0xc0) {
+
+ uint16_t npos = 0x100*(c & (~0xc0)) + *++iter;
+ iter = (*source).begin() + npos;
+ if(l_verbose)
+ cout<<"Is compressed label to newpos "<<npos<<", going there"<<endl;
+ // check against going forward here
+ continue;
+ }
+ if(!c)
+ break;
+ pvect.push_back(iter - (*source).cbegin());
+ iter+=*iter+1;
+ }
+ if(l_verbose) {
+ cout<<"Packet vector: "<<endl;
+ for(const auto n : pvect)
+ cout << n<<" ";
+ cout<<endl;
+ }
+ auto niter=nvect.crbegin(), piter=pvect.crbegin();
+ unsigned int cmatchlen=1;
+ for(; niter != nvect.crend() && piter != pvect.crend(); ++niter, ++piter) {
+ // niter is an offset in raw, pvect an offset in packet
+ uint8_t nlen = raw[*niter], plen=(*source)[*piter];
+ if(l_verbose)
+ cout<<"nlnen="<<(int)nlen<<", plen="<<(int)plen<<endl;
+ if(nlen != plen)
+ break;
+ if(strncasecmp(raw.c_str()+*niter+1, (const char*)&(*source)[*piter]+1, nlen)) {
+ if(l_verbose)
+ cout<<"Mismatch: "<<string(raw.c_str()+*niter+1, raw.c_str()+*niter+nlen+1)<< " != "<<string((const char*)&(*source)[*piter]+1, (const char*)&(*source)[*piter]+nlen+1)<<endl;
+ break;
+ }
+ cmatchlen+=nlen+1;
+ if(cmatchlen == raw.length()) { // have matched all of it, can't improve
+ if(l_verbose)
+ cout<<"Stopping search, matched whole name"<<endl;
+ *matchLen = cmatchlen;
+ return *piter;
+ }
+ }
+ if(piter != pvect.crbegin() && *matchLen < cmatchlen) {
+ *matchLen = cmatchlen;
+ bestpos=*--piter;
+ }
+ }
+ return bestpos;
+}
// this is the absolute hottest function in the pdns recursor
void DNSPacketWriter::xfrName(const DNSName& name, bool compress, bool)
{
- //cerr<<"xfrName: name=["<<name.toString()<<"] compress="<<compress<<endl;
- // string label = d_lowerCase ? toLower(Label) : Label;
- // FIXME400: we ignore d_lowerCase for now
- // cerr<<"xfrName writing ["<<name.toString()<<"]"<<endl;
- std::vector<std::string> parts = name.getRawLabels();
- // labelparts_t parts;
- // cerr<<"labelcount: "<<parts.size()<<endl;
-
- if(d_canonic)
+ if(l_verbose)
+ cout<<"Wants to write "<<name<<", compress="<<compress<<", canonic="<<d_canonic<<", LC="<<d_lowerCase<<endl;
+ if(d_canonic || d_lowerCase) // d_lowerCase implies canonic
compress=false;
- if(!parts.size()) { // otherwise we encode '..'
+ if(name.empty() || name.isRoot()) { // for speed
d_record.push_back(0);
return;
}
- // d_stuff is amount of stuff that is yet to be written out - the dnsrecordheader for example
- unsigned int pos=d_content.size() + d_record.size() + d_stuff;
- // bool deDot = labellen && (label[labellen-1]=='.'); // make sure we don't store trailing dots in the labelmap
-
- unsigned int startRecordSize=d_record.size();
- unsigned int startPos;
-
- DNSName towrite = name;
- /* FIXME400: if we are not compressing, there is no reason to work per-label */
- for(auto &label: parts) {
- if(d_lowerCase) label=toLower(label);
- //cerr<<"xfrName labelpart ["<<label<<"], left to write ["<<towrite.toString()<<"]"<<endl;
-
- auto li=d_labelmap.end();
- // see if we've written out this domain before
- //cerr<<"compress="<<compress<<", searching? for compression pointer to '"<<towrite.toString()<<"', "<<d_labelmap.size()<<" cmp-records"<<endl;
- if(compress && (li=find(d_labelmap, towrite))!=d_labelmap.end()) {
- //cerr<<"doing compression, my label=["<<label<<"] found match ["<<li->first.toString()<<"]"<<endl;
- //cerr<<"\tFound a compression pointer to '"<<towrite.toString()<<"': "<<li->second<<endl;
- if (d_record.size() - startRecordSize + label.size() > 253) // chopped does not include a length octet for the first label and the root label
- throw MOADNSException("DNSPacketWriter::xfrName() found overly large (compressed) name");
- uint16_t offset=li->second;
- offset|=0xc000;
- d_record.push_back((char)(offset >> 8));
- d_record.push_back((char)(offset & 0xff));
- goto out; // skip trailing 0 in case of compression
+ uint16_t li=0;
+ uint16_t matchlen=0;
+ if(compress && (li=lookupName(name, &matchlen))) {
+ const auto& dns=name.getStorage();
+ if(l_verbose)
+ cout<<"Found a substring of "<<matchlen<<" bytes from the back, offset: "<<li<<", dnslen: "<<dns.size()<<endl;
+ // found a substring, if www.powerdns.com matched powerdns.com, we get back matchlen = 13
+
+ unsigned int pos=d_content.size() + d_record.size() + d_stuff;
+ if(pos < 16384 && matchlen != dns.size()) {
+ if(l_verbose)
+ cout<<"Inserting pos "<<pos<<" for "<<name<<" for compressed case"<<endl;
+ d_positions.push_back(pos);
}
- if(li==d_labelmap.end() && pos< 16384) {
- // cerr<<"\tStoring a compression pointer to '"<<chopped<<"': "<<pos<<endl;
- d_labelmap.push_back(make_pair(towrite, pos)); // if untrue, we need to count - also, don't store offsets > 16384, won't work
- //cerr<<"stored ["<<towrite.toString()<<"] at pos "<<pos<<endl;
- }
+ if(l_verbose)
+ cout<<"Going to write unique part: '"<<makeHexDump(string(dns.c_str(), dns.c_str() + dns.size() - matchlen)) <<"'"<<endl;
+ d_record.insert(d_record.end(), (const unsigned char*)dns.c_str(), (const unsigned char*)dns.c_str() + dns.size() - matchlen);
+ uint16_t offset=li;
+ offset|=0xc000;
- startPos=pos;
-
- char labelsize=label.size();
- //cerr<<"labelsize = "<<int(labelsize)<<" for label ["<<label<<"]"<<endl;
- d_record.push_back(labelsize);
- unsigned int len=d_record.size();
- d_record.resize(len + labelsize);
- memcpy(((&*d_record.begin()) + len), label.c_str(), labelsize); // FIXME400 do not want memcpy
- pos+=labelsize+1;
-
- if(pos - startPos == 1)
- throw MOADNSException("DNSPacketWriter::xfrName() found empty label in the middle of name");
- if(pos - startPos > 64)
- throw MOADNSException("DNSPacketWriter::xfrName() found overly large label in name");
- towrite.chopOff(); /* FIXME400: iterating the label vector while keeping this chopoff in sync is a hack */
+ d_record.push_back((char)(offset >> 8));
+ d_record.push_back((char)(offset & 0xff));
}
- d_record.push_back(0); // insert root label
+ else {
+ unsigned int pos=d_content.size() + d_record.size() + d_stuff;
+ if(l_verbose)
+ cout<<"Found nothing, we are at pos "<<pos<<", inserting whole name"<<endl;
+ if(pos < 16384) {
+ if(l_verbose)
+ cout<<"Inserting pos "<<pos<<" for "<<name<<" for uncompressed case"<<endl;
+ d_positions.push_back(pos);
+ }
- if (d_record.size() - startRecordSize > 255)
- throw MOADNSException("DNSPacketWriter::xfrName() found overly large name");
+ std::unique_ptr<DNSName> lc;
+ if(d_lowerCase)
+ lc = make_unique<DNSName>(name.makeLowerCase());
- out:;
+ const DNSName::string_t& raw = (lc ? *lc : name).getStorage();
+ if(l_verbose)
+ cout<<"Writing out the whole thing "<<makeHexDump(string(raw.c_str(), raw.c_str() + raw.length()))<<endl;
+ d_record.insert(d_record.end(), raw.c_str(), raw.c_str() + raw.size());
+ }
}
void DNSPacketWriter::xfrBlob(const string& blob, int )
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