record reason for path fail and the full hops

llarp/messages/relay_status.cpp

@@ -273,4 +273,32 @@ namespace llarp
     return status == other.status;
   }
 
+  std::string
+  LRStatusCodeToString(uint64_t status)
+  {
+    std::map<uint64_t, std::string> codes = {
+        {LR_StatusRecord::SUCCESS, "success"},
+        {LR_StatusRecord::FAIL_TIMEOUT, "timeout"},
+        {LR_StatusRecord::FAIL_CONGESTION, "congestion"},
+        {LR_StatusRecord::FAIL_DEST_UNKNOWN, "destination unknown"},
+        {LR_StatusRecord::FAIL_DECRYPT_ERROR, "decrypt error"},
+        {LR_StatusRecord::FAIL_MALFORMED_RECORD, "malformed record"},
+        {LR_StatusRecord::FAIL_DEST_INVALID, "destination invalid"},
+        {LR_StatusRecord::FAIL_CANNOT_CONNECT, "cannot connect"},
+        {LR_StatusRecord::FAIL_DUPLICATE_HOP, "duplicate hop"}};
+    std::stringstream ss;
+    ss << "[";
+    bool found = false;
+    for (const auto& [val, message] : codes)
+    {
+      if ((status & val) == val)
+      {
+        ss << (found ? ", " : "") << message;
+        found = true;
+      }
+    }
+    ss << "]";
+    return ss.str();
+  }
+
 }  // namespace llarp

llarp/messages/relay_status.hpp

@@ -49,6 +49,9 @@ namespace llarp
     OnKey(llarp_buffer_t* buffer, llarp_buffer_t* key);
   };
 
+  std::string
+  LRStatusCodeToString(uint64_t status);
+
   struct LR_StatusMessage : public ILinkMessage
   {
     std::array<EncryptedFrame, 8> frames;

llarp/path/path.cpp

@@ -199,7 +199,14 @@ namespace llarp
         if (failedAt)
         {
           r->NotifyRouterEvent<tooling::PathBuildRejectedEvent>(Endpoint(), RXID(), *failedAt);
-          LogWarn(Name(), " build failed at ", *failedAt);
+          LogWarn(
+              Name(),
+              " build failed at ",
+              *failedAt,
+              " status=",
+              LRStatusCodeToString(currentStatus),
+              " hops=",
+              HopsString());
           r->routerProfiling().MarkHopFail(*failedAt);
         }
         else