From e626ceeb3336db66121395b4c4c2a3b37f52032f Mon Sep 17 00:00:00 2001 From: Sadie Powell Date: Mon, 18 Jan 2021 09:39:00 +0000 Subject: Improve the robustness of the DNSBL module. - Handle DNSBLs that return invalid lookup results. - Fix DNSBLs that return non-local addresses blocking connections. - Fix silently failing when a DNSBL returns no IPv4 results. - General code cleanup. --- src/modules/m_dnsbl.cpp | 56 ++++++++++++++++++++++++++++++------------------- 1 file changed, 35 insertions(+), 21 deletions(-) (limited to 'src/modules/m_dnsbl.cpp') diff --git a/src/modules/m_dnsbl.cpp b/src/modules/m_dnsbl.cpp index 37819c05c..f8bbb1a04 100644 --- a/src/modules/m_dnsbl.cpp +++ b/src/modules/m_dnsbl.cpp @@ -78,41 +78,55 @@ class DNSBLResolver : public DNS::Request if (!them || them->client_sa != theirsa) return; + int i = countExt.get(them); + if (i) + countExt.set(them, i - 1); + + // The DNSBL reply must contain an A result. const DNS::ResourceRecord* const ans_record = r->FindAnswerOfType(DNS::QUERY_A); if (!ans_record) + { + ConfEntry->stats_misses++; + ServerInstance->SNO->WriteGlobalSno('d', "%s returned an result with no IPv4 address.", + ConfEntry->name.c_str()); return; + } - // All replies should be in 127.0.0.0/8 - if (ans_record->rdata.compare(0, 4, "127.") != 0) + // The DNSBL reply must be a valid IPv4 address. + in_addr resultip; + if (inet_pton(AF_INET, ans_record->rdata.c_str(), &resultip) != 1) { - ServerInstance->SNO->WriteGlobalSno('d', "DNSBL: %s returned address outside of acceptable subnet 127.0.0.0/8: %s", ConfEntry->domain.c_str(), ans_record->rdata.c_str()); ConfEntry->stats_misses++; + ServerInstance->SNO->WriteGlobalSno('d', "%s returned an invalid IPv4 address: %s", + ConfEntry->name.c_str(), ans_record->rdata.c_str()); return; } - int i = countExt.get(them); - if (i) - countExt.set(them, i - 1); - - // Now we calculate the bitmask: 256*(256*(256*a+b)+c)+d + // The DNSBL reply should be in the 127.0.0.0/8 range. + if ((resultip.s_addr & 0xFF) != 127) + { + ConfEntry->stats_misses++; + ServerInstance->SNO->WriteGlobalSno('d', "%s returned an IPv4 address which is outside of the 127.0.0.0/8 subnet: %s", + ConfEntry->name.c_str(), ans_record->rdata.c_str()); + return; + } - unsigned int bitmask = 0, record = 0; bool match = false; - in_addr resultip; - - inet_pton(AF_INET, ans_record->rdata.c_str(), &resultip); - + unsigned int result = 0; switch (ConfEntry->type) { case DNSBLConfEntry::A_BITMASK: - bitmask = resultip.s_addr >> 24; /* Last octet (network byte order) */ - bitmask &= ConfEntry->bitmask; - match = (bitmask != 0); - break; + { + result = (resultip.s_addr >> 24) & ConfEntry->bitmask; + match = (result != 0); + break; + } case DNSBLConfEntry::A_RECORD: - record = resultip.s_addr >> 24; /* Last octet */ - match = (ConfEntry->records[record] == 1); - break; + { + result = resultip.s_addr >> 24; + match = (ConfEntry->records[result] == 1); + break; + } } if (match) @@ -212,7 +226,7 @@ class DNSBLResolver : public DNS::Request } ServerInstance->SNO->WriteGlobalSno('d', "Connecting user %s (%s) detected as being on the '%s' DNS blacklist with result %d", - them->GetFullRealHost().c_str(), them->GetIPString().c_str(), ConfEntry->name.c_str(), (ConfEntry->type==DNSBLConfEntry::A_BITMASK) ? bitmask : record); + them->GetFullRealHost().c_str(), them->GetIPString().c_str(), ConfEntry->name.c_str(), result); } else ConfEntry->stats_misses++; -- cgit v1.3.1-10-gc9f91 From 4a126ad130b0a51449343de2f2db6becca0d2819 Mon Sep 17 00:00:00 2001 From: Sadie Powell Date: Mon, 18 Jan 2021 10:22:05 +0000 Subject: Add a separate stats class for DNSBL errors. --- src/modules/m_dnsbl.cpp | 31 +++++++++++++++++++++---------- 1 file changed, 21 insertions(+), 10 deletions(-) (limited to 'src/modules/m_dnsbl.cpp') diff --git a/src/modules/m_dnsbl.cpp b/src/modules/m_dnsbl.cpp index f8bbb1a04..9ad3b05e7 100644 --- a/src/modules/m_dnsbl.cpp +++ b/src/modules/m_dnsbl.cpp @@ -43,8 +43,16 @@ class DNSBLConfEntry : public refcountbase unsigned long duration; unsigned int bitmask; unsigned char records[256]; - unsigned long stats_hits, stats_misses; - DNSBLConfEntry(): type(A_BITMASK),duration(86400),bitmask(0),stats_hits(0), stats_misses(0) {} + unsigned long stats_hits, stats_misses, stats_errors; + DNSBLConfEntry() + : type(A_BITMASK) + , duration(86400) + , bitmask(0) + , stats_hits(0) + , stats_misses(0) + , stats_errors(0) + { + } }; @@ -86,7 +94,7 @@ class DNSBLResolver : public DNS::Request const DNS::ResourceRecord* const ans_record = r->FindAnswerOfType(DNS::QUERY_A); if (!ans_record) { - ConfEntry->stats_misses++; + ConfEntry->stats_errors++; ServerInstance->SNO->WriteGlobalSno('d', "%s returned an result with no IPv4 address.", ConfEntry->name.c_str()); return; @@ -96,7 +104,7 @@ class DNSBLResolver : public DNS::Request in_addr resultip; if (inet_pton(AF_INET, ans_record->rdata.c_str(), &resultip) != 1) { - ConfEntry->stats_misses++; + ConfEntry->stats_errors++; ServerInstance->SNO->WriteGlobalSno('d', "%s returned an invalid IPv4 address: %s", ConfEntry->name.c_str(), ans_record->rdata.c_str()); return; @@ -105,7 +113,7 @@ class DNSBLResolver : public DNS::Request // The DNSBL reply should be in the 127.0.0.0/8 range. if ((resultip.s_addr & 0xFF) != 127) { - ConfEntry->stats_misses++; + ConfEntry->stats_errors++; ServerInstance->SNO->WriteGlobalSno('d', "%s returned an IPv4 address which is outside of the 127.0.0.0/8 subnet: %s", ConfEntry->name.c_str(), ans_record->rdata.c_str()); return; @@ -248,6 +256,7 @@ class DNSBLResolver : public DNS::Request return; } + ConfEntry->stats_errors++; ServerInstance->SNO->WriteGlobalSno('d', "An error occurred whilst checking whether %s (%s) is on the '%s' DNS blacklist: %s", them->GetFullRealHost().c_str(), them->GetIPString().c_str(), ConfEntry->name.c_str(), this->manager->GetErrorStr(q->error).c_str()); } @@ -478,20 +487,22 @@ class ModuleDNSBL : public Module, public Stats::EventListener if (stats.GetSymbol() != 'd') return MOD_RES_PASSTHRU; - unsigned long total_hits = 0, total_misses = 0; - + unsigned long total_hits = 0; + unsigned long total_misses = 0; + unsigned long total_errors = 0; for (std::vector >::const_iterator i = DNSBLConfEntries.begin(); i != DNSBLConfEntries.end(); ++i) { total_hits += (*i)->stats_hits; total_misses += (*i)->stats_misses; + total_errors += (*i)->stats_errors; - stats.AddRow(304, "DNSBLSTATS DNSbl \"" + (*i)->name + "\" had " + - ConvToStr((*i)->stats_hits) + " hits and " + ConvToStr((*i)->stats_misses) + " misses"); + stats.AddRow(304, InspIRCd::Format("DNSBLSTATS \"%s\" had %lu hits, %lu misses, and %lu errors", + (*i)->name.c_str(), (*i)->stats_hits, (*i)->stats_misses, (*i)->stats_errors)); } stats.AddRow(304, "DNSBLSTATS Total hits: " + ConvToStr(total_hits)); stats.AddRow(304, "DNSBLSTATS Total misses: " + ConvToStr(total_misses)); - + stats.AddRow(304, "DNSBLSTATS Total errors: " + ConvToStr(total_errors)); return MOD_RES_PASSTHRU; } }; -- cgit v1.3.1-10-gc9f91