Adding upstream version 2.2.4.upstream/2.2.4upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 204 insertions, 0 deletions

diff --git a/apt-pkg/contrib/srvrec.cc b/apt-pkg/contrib/srvrec.cc
new file mode 100644
index 0000000..4ca2082
--- /dev/null
+++ b/apt-pkg/contrib/srvrec.cc
@@ -0,0 +1,204 @@
+// -*- mode: cpp; mode: fold -*-
+// Description								/*{{{*/
+/* ######################################################################
+
+   SRV record support
+
+   ##################################################################### */
+									/*}}}*/
+#include <config.h>
+
+#include <netdb.h>
+
+#include <arpa/nameser.h>
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <resolv.h>
+#include <time.h>
+
+#include <algorithm>
+#include <memory>
+#include <tuple>
+
+#include <apt-pkg/configuration.h>
+#include <apt-pkg/error.h>
+#include <apt-pkg/strutl.h>
+
+#include "srvrec.h"
+
+bool SrvRec::operator==(SrvRec const &other) const
+{
+   return (std::tie(target, priority, weight, port) ==
+           std::tie(other.target, other.priority, other.weight, other.port));
+}
+
+bool GetSrvRecords(std::string host, int port, std::vector<SrvRec> &Result)
+{
+   // try SRV only for hostnames, not for IP addresses
+   {
+      struct in_addr addr4;
+      struct in6_addr addr6;
+      if (inet_pton(AF_INET, host.c_str(), &addr4) == 1 ||
+	  inet_pton(AF_INET6, host.c_str(), &addr6) == 1)
+	 return true;
+   }
+
+   std::string target;
+   int res;
+   struct servent s_ent_buf;
+   struct servent *s_ent = nullptr;
+   std::vector<char> buf(1024);
+
+   res = getservbyport_r(htons(port), "tcp", &s_ent_buf, buf.data(), buf.size(), &s_ent);
+   if (res != 0 || s_ent == nullptr)
+      return false;
+
+   strprintf(target, "_%s._tcp.%s", s_ent->s_name, host.c_str());
+   return GetSrvRecords(target, Result);
+}
+
+bool GetSrvRecords(std::string name, std::vector<SrvRec> &Result)
+{
+   unsigned char answer[PACKETSZ];
+   int answer_len, compressed_name_len;
+   int answer_count;
+   struct __res_state res;
+
+   if (res_ninit(&res) != 0)
+      return _error->Errno("res_init", "Failed to init resolver");
+
+   // Close on return
+   std::shared_ptr<void> guard(&res, res_nclose);
+
+   answer_len = res_nquery(&res, name.c_str(), C_IN, T_SRV, answer, sizeof(answer));
+   if (answer_len == -1)
+      return false;
+   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)
+   {
+      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
+      Result.emplace_back(buf, priority, weight, port);
+   }
+
+   // implement load balancing as specified in RFC-2782
+
+   // sort them by priority
+   std::stable_sort(Result.begin(), Result.end());
+
+   if (_config->FindB("Debug::Acquire::SrvRecs", false))
+      for(auto const &R : Result)
+	 std::cerr << "SrvRecs: got " << R.target
+		   << " prio: " << R.priority
+		   << " weight: " << R.weight
+		   << '\n';
+
+   return true;
+}
+
+SrvRec PopFromSrvRecs(std::vector<SrvRec> &Recs)
+{
+   // FIXME: instead of the simplistic shuffle below use the algorithm
+   //        described in rfc2782 (with weights)
+   //        and figure out how the weights need to be adjusted if
+   //        a host refuses connections
+
+#if 0  // all code below is only needed for the weight adjusted selection 
+   // assign random number ranges
+   int prev_weight = 0;
+   int prev_priority = 0;
+   for(std::vector<SrvRec>::iterator I = Result.begin();
+      I != Result.end(); ++I)
+   {
+      if(prev_priority != I->priority)
+         prev_weight = 0;
+      I->random_number_range_start = prev_weight;
+      I->random_number_range_end = prev_weight + I->weight;
+      prev_weight = I->random_number_range_end;
+      prev_priority = I->priority;
+
+      if (_config->FindB("Debug::Acquire::SrvRecs", false) == true)
+         std::cerr << "SrvRecs: got " << I->target
+                   << " prio: " << I->priority
+                   << " weight: " << I->weight
+                   << std::endl;
+   }
+
+   // go over the code in reverse order and note the max random range
+   int max = 0;
+   prev_priority = 0;
+   for(std::vector<SrvRec>::iterator I = Result.end();
+      I != Result.begin(); --I)
+   {
+      if(prev_priority != I->priority)
+         max = I->random_number_range_end;
+      I->random_number_range_max = max;
+   }
+#endif
+
+   // shuffle in a very simplistic way for now (equal weights)
+   std::vector<SrvRec>::iterator I = Recs.begin();
+   std::vector<SrvRec>::iterator const J = std::find_if(Recs.begin(), Recs.end(),
+	 [&I](SrvRec const &J) { return I->priority != J.priority; });
+
+   // clock seems random enough.
+   I += std::max(static_cast<clock_t>(0), clock()) % std::distance(I, J);
+   SrvRec const selected = std::move(*I);
+   Recs.erase(I);
+
+   if (_config->FindB("Debug::Acquire::SrvRecs", false) == true)
+      std::cerr << "PopFromSrvRecs: selecting " << selected.target << std::endl;
+
+   return selected;
+}