From 37e66fa610bd60465076119e09ab9ef885175afb Mon Sep 17 00:00:00 2001
From: jianminzhao <76990468+jianminzhao@users.noreply.github.com>
Date: Wed, 3 Dec 2025 11:57:04 -0800
Subject: [PATCH] CBL-7673: Better error message when Lite 4.0 talks to SGW 3.x

* CBL-7496: Better error message when Lite 4.0 talks to SGW 3.x

Starting in SGW 3.3.1, a request using "Sec-WebSocket-Protocol: BLIP_3+CBMobile_4" receives an HTTP 500 response with the message "I only speak BLIP_3+CBMobile_3,BLIP_3+CBMobile_2 protocols."
This PR propagates that message into LiteCore's C4Error, improving the clarity of the logs.
Ported from v4.1
---
 Networking/HTTP/HTTPLogic.cc                  | 20 +++++++++++++------
 .../tests/ReplicatorCollectionSGTest.cc       |  2 +-
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/Networking/HTTP/HTTPLogic.cc b/Networking/HTTP/HTTPLogic.cc
index ff997ef88..a353589b6 100644
--- a/Networking/HTTP/HTTPLogic.cc
+++ b/Networking/HTTP/HTTPLogic.cc
@@ -19,6 +19,7 @@
 #include "Error.hh"
 #include "SecureRandomize.hh"
 #include "SecureDigest.hh"
+#include "StringUtil.hh"
 #include "slice_stream.hh"
 #include "NumConversion.hh"
 #include "fleece/Fleece.hh"
@@ -351,12 +352,19 @@ namespace litecore::net {
         Disposition disposition = receivedResponse(response);
         if ( disposition == kFailure && _error.domain == WebSocketDomain && _error.code == int(_httpStatus) ) {
             // Look for a more detailed HTTP error message in the response body:
-            if ( _responseHeaders["Content-Type"_sl].hasPrefix("application/json"_sl) ) {
-                alloc_slice responseBody;
-                if ( socket.readHTTPBody(_responseHeaders, responseBody) ) {
-                    Doc json = Doc::fromJSON(responseBody);
-                    if ( slice reason = json["reason"].asString(); reason )
-                        _error = c4error_make(WebSocketDomain, int(_httpStatus), reason);
+            if ( bool isJSON = _responseHeaders["Content-Type"_sl].hasPrefix("application/json"_sl);
+                 isJSON || _responseHeaders["Content-Type"_sl].hasPrefix("text/plain"_sl) ) {
+                if ( alloc_slice responseBody; socket.readHTTPBody(_responseHeaders, responseBody) ) {
+                    slice reason;
+                    Doc   json;
+                    if ( isJSON ) {
+                        json   = Doc::fromJSON(responseBody);
+                        reason = json["reason"].asString();
+                    } else {  // text/plain
+                        // trimming the ending '\n's
+                        reason = trimWhitespace(responseBody);
+                    }
+                    _error = c4error_make(WebSocketDomain, int(_httpStatus), (slice)reason);
                 }
             }
         }
diff --git a/Replicator/tests/ReplicatorCollectionSGTest.cc b/Replicator/tests/ReplicatorCollectionSGTest.cc
index af56b4eff..099699d13 100644
--- a/Replicator/tests/ReplicatorCollectionSGTest.cc
+++ b/Replicator/tests/ReplicatorCollectionSGTest.cc
@@ -168,7 +168,7 @@ TEST_CASE_METHOD(ReplicatorCollectionSGTest, "Bad Configurations SG", "[.SyncSer
     for ( auto& coll : _collections ) { importJSONLines(sFixturesDir + "names_100.json", coll, 0, false, 2, idPrefix); }
     ReplParams replParams{_collectionSpecs};
 
-    C4Error expectedError;
+    C4Error expectedError{};
     slice   expectedErrorMsg;
 
     SECTION("Mixed OneShot and Continuous Modes") {