mDNS: Add more detailed logging

This CL adds more detailed logging to help debug ongoing issues.

bug: b/157683753
Change-Id: Ibee54a379c95773571cd3e7ec0095aa5f4ac9152
Reviewed-on: https://chromium-review.googlesource.com/c/openscreen/+/2223828
Commit-Queue: Ryan Keane <rwkeane@google.com>
Reviewed-by: Jordan Bayles <jophba@chromium.org>

5 files changed, 54 insertions, 13 deletions

diff --git a/discovery/mdns/mdns_querier.cc b/discovery/mdns/mdns_querier.cc
index 800aef4a..7152be24 100644
--- a/discovery/mdns/mdns_querier.cc
+++ b/discovery/mdns/mdns_querier.cc
@@ -372,9 +372,7 @@ void MdnsQuerier::OnMessageReceived(const MdnsMessage& message) {
   for (const MdnsRecord& record : message.answers()) {
     if (ShouldAnswerRecordBeProcessed(record)) {
       ProcessRecord(record);
-      OSP_DVLOG << "\tProcessing answer record for domain '"
-                << record.name().ToString() << "' of type '"
-                << record.dns_type() << "'...";
+      OSP_DVLOG << "\tProcessing answer record (" << record.ToString() << ")";
       found_relevant_records = true;
       processed_count++;
     }
@@ -385,9 +383,8 @@ void MdnsQuerier::OnMessageReceived(const MdnsMessage& message) {
   // individual records relevant to this querier to update the cache.
   for (const MdnsRecord& record : message.additional_records()) {
     if (found_relevant_records || ShouldAnswerRecordBeProcessed(record)) {
-      OSP_DVLOG << "\tProcessing additional record for domain '"
-                << record.name().ToString() << "' of type '"
-                << record.dns_type() << "'...";
+      OSP_DVLOG << "\tProcessing additional record (" << record.ToString()
+                << ")";
       ProcessRecord(record);
       processed_count++;
     }
diff --git a/discovery/mdns/mdns_receiver.cc b/discovery/mdns/mdns_receiver.cc
index b21d748f..bb8634d2 100644
--- a/discovery/mdns/mdns_receiver.cc
+++ b/discovery/mdns/mdns_receiver.cc
@@ -4,6 +4,8 @@
 
 #include "discovery/mdns/mdns_receiver.h"
 
+#include <utility>
+
 #include "discovery/mdns/mdns_reader.h"
 #include "util/trace_logging.h"
 
@@ -66,6 +68,7 @@ void MdnsReceiver::OnRead(UdpSocket* socket,
   MdnsReader reader(config_, packet.data(), packet.size());
   MdnsMessage message;
   if (!reader.Read(&message)) {
+    OSP_DVLOG << "mDNS message failed to parse...";
     return;
   }
 
@@ -74,13 +77,14 @@ void MdnsReceiver::OnRead(UdpSocket* socket,
       client->OnMessageReceived(message);
     }
     if (response_clients_.empty()) {
-      OSP_DVLOG << "Response message dropped. No response client registered...";
+      OSP_DVLOG
+          << "mDNS response message dropped. No response client registered...";
     }
   } else {
     if (query_callback_) {
       query_callback_(message, packet.source());
     } else {
-      OSP_DVLOG << "Query message dropped. No query client registered...";
+      OSP_DVLOG << "mDNS query message dropped. No query client registered...";
     }
   }
 }
diff --git a/discovery/mdns/mdns_records.cc b/discovery/mdns/mdns_records.cc
index a04c2694..8be7fe00 100644
--- a/discovery/mdns/mdns_records.cc
+++ b/discovery/mdns/mdns_records.cc
@@ -5,6 +5,9 @@
 #include "discovery/mdns/mdns_records.h"
 
 #include <cctype>
+#include <limits>
+#include <sstream>
+#include <vector>
 
 #include "absl/strings/ascii.h"
 #include "absl/strings/match.h"
@@ -562,6 +565,34 @@ size_t MdnsRecord::MaxWireSize() const {
   return name_.MaxWireSize() + absl::visit(wire_size_visitor, rdata_) + 8;
 }
 
+std::string MdnsRecord::ToString() const {
+  std::stringstream ss;
+  ss << "name: '" << name_.ToString() << "'";
+  ss << ", type: " << dns_type_;
+
+  if (dns_type_ == DnsType::kPTR) {
+    const DomainName& target = absl::get<PtrRecordRdata>(rdata_).ptr_domain();
+    ss << ", target: '" << target.ToString() << "'";
+  } else if (dns_type_ == DnsType::kSRV) {
+    const DomainName& target = absl::get<SrvRecordRdata>(rdata_).target();
+    ss << ", target: '" << target.ToString() << "'";
+  } else if (dns_type_ == DnsType::kNSEC) {
+    const auto& nsec_rdata = absl::get<NsecRecordRdata>(rdata_);
+    std::vector<DnsType> types = nsec_rdata.types();
+    ss << ", representing [";
+    if (!types.empty()) {
+      auto it = types.begin();
+      ss << *it++;
+      while (it != types.end()) {
+        ss << ", " << *it++;
+      }
+      ss << "]";
+    }
+  }
+
+  return ss.str();
+}
+
 MdnsRecord CreateAddressRecord(DomainName name, const IPAddress& address) {
   Rdata rdata;
   DnsType type;
diff --git a/discovery/mdns/mdns_records.h b/discovery/mdns/mdns_records.h
index 8e9ac244..696eaf8c 100644
--- a/discovery/mdns/mdns_records.h
+++ b/discovery/mdns/mdns_records.h
@@ -419,6 +419,8 @@ class MdnsRecord {
                       record.ttl_.count(), record.rdata_);
   }
 
+  std::string ToString() const;
+
  private:
   static bool IsValidConfig(const DomainName& name,
                             DnsType dns_type,
diff --git a/discovery/mdns/mdns_responder.cc b/discovery/mdns/mdns_responder.cc
index 3627f2fd..faef9a18 100644
--- a/discovery/mdns/mdns_responder.cc
+++ b/discovery/mdns/mdns_responder.cc
@@ -513,7 +513,7 @@ void MdnsResponder::ProcessQueries(
   for (const auto& question : questions) {
     OSP_DVLOG << "\tProcessing mDNS Query for domain: '"
               << question.name().ToString() << "', type: '"
-              << question.dns_type() << "'";
+              << question.dns_type() << "' from '" << src << "'";
 
     // NSEC records should not be queried for.
     if (question.dns_type() == DnsType::kNSEC) {
@@ -586,18 +586,25 @@ void MdnsResponder::SendResponse(
     // method is called. Exclusive ownership cannot be gained for a record which
     // has previously been published, and if this host is the exclusive owner
     // then this method will have been called without any delay on the task
-    // runner
+    // runner.
     ApplyQueryResults(&message, record_handler_, question.name(), known_answers,
                       question.dns_type(), question.dns_class(),
                       is_exclusive_owner);
   }
 
   // Send the response only if it contains answers to the query.
+  OSP_DVLOG << "\tCompleted Processing mDNS Query for domain: '"
+            << question.name().ToString() << "', type: '" << question.dns_type()
+            << "', with " << message.answers().size() << " results:";
+  for (const auto& record : message.answers()) {
+    OSP_DVLOG << "\t\tanswer (" << record.ToString() << ")";
+  }
+  for (const auto& record : message.additional_records()) {
+    OSP_DVLOG << "\t\tadditional record ('" << record.ToString() << ")";
+  }
+
   if (!message.answers().empty()) {
-    OSP_DVLOG << "\tmDNS Query processed and response sent!";
     send_response(message);
-  } else {
-    OSP_DVLOG << "\tmDNS Query processed and no response sent!";
   }
 }