Fixed compression interop and re-enable for C++.

Also added some defense in depth for compression algorithms in the
receive path.

6 files changed, 28 insertions, 14 deletions

diff --git a/src/core/lib/channel/compress_filter.c b/src/core/lib/channel/compress_filter.c
index 5510c79b18..9769070cc1 100644
--- a/src/core/lib/channel/compress_filter.c
+++ b/src/core/lib/channel/compress_filter.c
@@ -189,8 +189,10 @@ static void finish_send_message(grpc_exec_ctx *exec_ctx,
       char *algo_name;
       GPR_ASSERT(grpc_compression_algorithm_name(calld->compression_algorithm,
                                                  &algo_name));
-      gpr_log(GPR_DEBUG, "Algorithm '%s' enabled but decided not to compress.",
-              algo_name);
+      gpr_log(
+          GPR_DEBUG,
+          "Algorithm '%s' enabled but decided not to compress. Input size: %d",
+          algo_name, calld->slices.length);
     }
   }
 
diff --git a/src/core/lib/compression/message_compress.c b/src/core/lib/compression/message_compress.c
index cbe0b5a285..699719a523 100644
--- a/src/core/lib/compression/message_compress.c
+++ b/src/core/lib/compression/message_compress.c
@@ -194,5 +194,5 @@ int grpc_msg_decompress(grpc_compression_algorithm algorithm,
       break;
   }
   gpr_log(GPR_ERROR, "invalid compression algorithm %d", algorithm);
-  return 0;
+  return -1; /* to distinguish it from GRPC_COMPRESS_NONE */
 }
diff --git a/src/core/lib/surface/byte_buffer_reader.c b/src/core/lib/surface/byte_buffer_reader.c
index 809fd5f1fa..c7f941525d 100644
--- a/src/core/lib/surface/byte_buffer_reader.c
+++ b/src/core/lib/surface/byte_buffer_reader.c
@@ -62,12 +62,19 @@ void grpc_byte_buffer_reader_init(grpc_byte_buffer_reader *reader,
     case GRPC_BB_RAW:
       gpr_slice_buffer_init(&decompressed_slices_buffer);
       if (is_compressed(reader->buffer_in)) {
-        grpc_msg_decompress(reader->buffer_in->data.raw.compression,
-                            &reader->buffer_in->data.raw.slice_buffer,
-                            &decompressed_slices_buffer);
-        reader->buffer_out =
-            grpc_raw_byte_buffer_create(decompressed_slices_buffer.slices,
-                                        decompressed_slices_buffer.count);
+        if (grpc_msg_decompress(reader->buffer_in->data.raw.compression,
+                                &reader->buffer_in->data.raw.slice_buffer,
+                                &decompressed_slices_buffer) < 0) {
+          gpr_log(GPR_ERROR,
+                  "Unexpected error decompressing data for algorithm with enum "
+                  "value '%d'. Reading data as if it were uncompressed.",
+                  reader->buffer_in->data.raw.compression);
+          reader->buffer_out = reader->buffer_in;
+        } else { /* all fine */
+          reader->buffer_out =
+              grpc_raw_byte_buffer_create(decompressed_slices_buffer.slices,
+                                          decompressed_slices_buffer.count);
+        }
         gpr_slice_buffer_destroy(&decompressed_slices_buffer);
       } else { /* not compressed, use the input buffer as output */
         reader->buffer_out = reader->buffer_in;
diff --git a/src/core/lib/surface/call.c b/src/core/lib/surface/call.c
index 9b2b94eedf..778557121d 100644
--- a/src/core/lib/surface/call.c
+++ b/src/core/lib/surface/call.c
@@ -408,6 +408,7 @@ static void set_status_code(grpc_call *call, status_source source,
 
 static void set_compression_algorithm(grpc_call *call,
                                       grpc_compression_algorithm algo) {
+  GPR_ASSERT(algo < GRPC_COMPRESS_ALGORITHMS_COUNT);
   call->compression_algorithm = algo;
 }
 
@@ -828,12 +829,16 @@ static uint32_t decode_status(grpc_mdelem *md) {
   return status;
 }
 
-static uint32_t decode_compression(grpc_mdelem *md) {
+static grpc_compression_algorithm decode_compression(grpc_mdelem *md) {
   grpc_compression_algorithm algorithm =
       grpc_compression_algorithm_from_mdstr(md->value);
   if (algorithm == GRPC_COMPRESS_ALGORITHMS_COUNT) {
     const char *md_c_str = grpc_mdstr_as_c_string(md->value);
-    gpr_log(GPR_ERROR, "Invalid compression algorithm: '%s'", md_c_str);
+    gpr_log(GPR_ERROR,
+            "Invalid incoming compression algorithm: '%s'. Interpreting "
+            "incoming data as uncompressed.",
+            md_c_str);
+    return GRPC_COMPRESS_NONE;
   }
   return algorithm;
 }
diff --git a/test/cpp/interop/interop_client.cc b/test/cpp/interop/interop_client.cc
index 22293d211f..314d6c8eae 100644
--- a/test/cpp/interop/interop_client.cc
+++ b/test/cpp/interop/interop_client.cc
@@ -60,7 +60,7 @@ static const char* kRandomFile = "test/cpp/interop/rnd.dat";
 namespace {
 // The same value is defined by the Java client.
 const std::vector<int> request_stream_sizes = {27182, 8, 1828, 45904};
-const std::vector<int> response_stream_sizes = {31415, 9, 2653, 58979};
+const std::vector<int> response_stream_sizes = {31415, 59, 2653, 58979};
 const int kNumResponseMessages = 2000;
 const int kResponseMessageSize = 1030;
 const int kReceiveDelayMilliSeconds = 20;
diff --git a/tools/run_tests/run_interop_tests.py b/tools/run_tests/run_interop_tests.py
index e813473421..edbdf05e2a 100755
--- a/tools/run_tests/run_interop_tests.py
+++ b/tools/run_tests/run_interop_tests.py
@@ -82,10 +82,10 @@ class CXXLanguage:
     return {}
 
   def unimplemented_test_cases(self):
-    return _SKIP_ADVANCED + _SKIP_COMPRESSION
+    return _SKIP_ADVANCED
 
   def unimplemented_test_cases_server(self):
-    return _SKIP_ADVANCED + _SKIP_COMPRESSION
+    return _SKIP_ADVANCED
 
   def __str__(self):
     return 'c++'