From f106fecc1d7d0250d1d76c2ba837dc0c870c5fff Mon Sep 17 00:00:00 2001 From: Michael Vogt Date: Tue, 20 May 2014 13:15:51 +0200 Subject: add GetSrvRecord helper to apt-pkg/contrib/srvrec.{cc,h} --- apt-pkg/contrib/srvrec.cc | 93 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 93 insertions(+) create mode 100644 apt-pkg/contrib/srvrec.cc (limited to 'apt-pkg/contrib/srvrec.cc') diff --git a/apt-pkg/contrib/srvrec.cc b/apt-pkg/contrib/srvrec.cc new file mode 100644 index 000000000..d5d89fc67 --- /dev/null +++ b/apt-pkg/contrib/srvrec.cc @@ -0,0 +1,93 @@ +// -*- mode: cpp; mode: fold -*- +// Description /*{{{*/ +/* ###################################################################### + + SRV record support + + ##################################################################### */ + /*}}}*/ +#include + +#include +#include +#include + +#include +#include "srvrec.h" + +bool GetSrvRecords(std::string name, std::vector &Result) +{ + unsigned char answer[PACKETSZ]; + int answer_len, compressed_name_len; + int answer_count; + + if (res_init() != 0) + return _error->Errno("res_init", "Failed to init resolver"); + + answer_len = res_query(name.c_str(), C_IN, T_SRV, answer, sizeof(answer)); + if (answer_len < (int)sizeof(HEADER)) + return _error->Warning("Not enough data from res_query (%i)", answer_len); + + // check the header + HEADER *header = (HEADER*)answer; + if (header->rcode != NOERROR) + return _error->Warning("res_query returned rcode %i", header->rcode); + answer_count = ntohs(header->ancount); + if (answer_count <= 0) + return _error->Warning("res_query returned no answers (%i) ", answer_count); + + // skip the header + compressed_name_len = dn_skipname(answer+sizeof(HEADER), answer+answer_len); + if(compressed_name_len < 0) + return _error->Warning("dn_skipname failed %i", compressed_name_len); + + // pt points to the first answer record, go over all of them now + unsigned char *pt = answer+sizeof(HEADER)+compressed_name_len+QFIXEDSZ; + while ((int)Result.size() < answer_count && pt < answer+answer_len) + { + SrvRec rec; + u_int16_t type, klass, priority, weight, port, dlen; + char buf[MAXDNAME]; + + compressed_name_len = dn_skipname(pt, answer+answer_len); + if (compressed_name_len < 0) + return _error->Warning("dn_skipname failed (2): %i", + compressed_name_len); + pt += compressed_name_len; + if (((answer+answer_len) - pt) < 16) + return _error->Warning("packet too short"); + + // extract the data out of the result buffer + #define extract_u16(target, p) target = *p++ << 8; target |= *p++; + + extract_u16(type, pt); + if(type != T_SRV) + return _error->Warning("Unexpected type excepted %x != %x", + T_SRV, type); + extract_u16(klass, pt); + if(klass != C_IN) + return _error->Warning("Unexpected class excepted %x != %x", + C_IN, klass); + pt += 4; // ttl + extract_u16(dlen, pt); + extract_u16(priority, pt); + extract_u16(weight, pt); + extract_u16(port, pt); + + #undef extract_u16 + + compressed_name_len = dn_expand(answer, answer+answer_len, pt, buf, sizeof(buf)); + if(compressed_name_len < 0) + return _error->Warning("dn_expand failed %i", compressed_name_len); + pt += compressed_name_len; + + // add it to our class + rec.priority = priority; + rec.weight = weight; + rec.port = port; + rec.target = buf; + Result.push_back(rec); + } + + return true; +} -- cgit v1.2.3