/*}}}*/
#include <config.h>
+#include <netdb.h>
+
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <resolv.h>
+#include <time.h>
+
+#include <algorithm>
+#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)
+{
+ 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];
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 == -1)
+ return false;
if (answer_len < (int)sizeof(HEADER))
return _error->Warning("Not enough data from res_query (%i)", answer_len);
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",
return _error->Warning("packet too short");
// extract the data out of the result buffer
- #define extract_u16(target, p) target = *p++ << 8; target |= *p++;
+ #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",
+ 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",
+ return _error->Warning("Unexpected class excepted %x != %x",
C_IN, klass);
pt += 4; // ttl
extract_u16(dlen, pt);
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);
+ 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());
+
+ for(std::vector<SrvRec>::iterator I = Result.begin();
+ I != Result.end(); ++I)
+ {
+ if (_config->FindB("Debug::Acquire::SrvRecs", false) == true)
+ {
+ std::cerr << "SrvRecs: got " << I->target
+ << " prio: " << I->priority
+ << " weight: " << I->weight
+ << std::endl;
+ }
}
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 += 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;
+}
projects / apt.git / blobdiff