1 files changed, 44 insertions, 50 deletions

diff --git a/src/core/lib/channel/compress_filter.c b/src/core/lib/channel/compress_filter.c
index c860d60d88..337c194b79 100644
--- a/src/core/lib/channel/compress_filter.c
+++ b/src/core/lib/channel/compress_filter.c
@@ -45,7 +45,6 @@
 #include "src/core/lib/compression/message_compress.h"
 #include "src/core/lib/profiling/timers.h"
 #include "src/core/lib/slice/slice_internal.h"
-#include "src/core/lib/slice/slice_string_helpers.h"
 #include "src/core/lib/support/string.h"
 #include "src/core/lib/transport/static_metadata.h"
 
@@ -81,6 +80,39 @@ typedef struct channel_data {
   uint32_t supported_compression_algorithms;
 } channel_data;
 
+/** For each \a md element from the incoming metadata, filter out the entry for
+ * "grpc-encoding", using its value to populate the call data's
+ * compression_algorithm field. */
+static grpc_mdelem *compression_md_filter(grpc_exec_ctx *exec_ctx,
+                                          void *user_data, grpc_mdelem *md) {
+  grpc_call_element *elem = user_data;
+  call_data *calld = elem->call_data;
+  channel_data *channeld = elem->channel_data;
+
+  if (md->key == GRPC_MDSTR_GRPC_INTERNAL_ENCODING_REQUEST) {
+    const char *md_c_str = grpc_mdstr_as_c_string(md->value);
+    if (!grpc_compression_algorithm_parse(md_c_str, strlen(md_c_str),
+                                          &calld->compression_algorithm)) {
+      gpr_log(GPR_ERROR,
+              "Invalid compression algorithm: '%s' (unknown). Ignoring.",
+              md_c_str);
+      calld->compression_algorithm = GRPC_COMPRESS_NONE;
+    }
+    if (!GPR_BITGET(channeld->enabled_algorithms_bitset,
+                    calld->compression_algorithm)) {
+      gpr_log(GPR_ERROR,
+              "Invalid compression algorithm: '%s' (previously disabled). "
+              "Ignoring.",
+              md_c_str);
+      calld->compression_algorithm = GRPC_COMPRESS_NONE;
+    }
+    calld->has_compression_algorithm = 1;
+    return NULL;
+  }
+
+  return md;
+}
+
 static int skip_compression(grpc_call_element *elem, uint32_t flags) {
   call_data *calld = elem->call_data;
   channel_data *channeld = elem->channel_data;
@@ -99,65 +131,32 @@ static int skip_compression(grpc_call_element *elem, uint32_t flags) {
 }
 
 /** Filter initial metadata */
-static grpc_error *process_send_initial_metadata(
-    grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-    grpc_metadata_batch *initial_metadata) GRPC_MUST_USE_RESULT;
-static grpc_error *process_send_initial_metadata(
+static void process_send_initial_metadata(
     grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
     grpc_metadata_batch *initial_metadata) {
-  grpc_error *error;
   call_data *calld = elem->call_data;
   channel_data *channeld = elem->channel_data;
   /* Parse incoming request for compression. If any, it'll be available
    * at calld->compression_algorithm */
-  if (initial_metadata->idx.named.grpc_internal_encoding_request != NULL) {
-    grpc_mdelem md =
-        initial_metadata->idx.named.grpc_internal_encoding_request->md;
-    if (!grpc_compression_algorithm_parse(GRPC_MDVALUE(md),
-                                          &calld->compression_algorithm)) {
-      char *val = grpc_slice_to_c_string(GRPC_MDVALUE(md));
-      gpr_log(GPR_ERROR,
-              "Invalid compression algorithm: '%s' (unknown). Ignoring.", val);
-      gpr_free(val);
-      calld->compression_algorithm = GRPC_COMPRESS_NONE;
-    }
-    if (!GPR_BITGET(channeld->enabled_algorithms_bitset,
-                    calld->compression_algorithm)) {
-      char *val = grpc_slice_to_c_string(GRPC_MDVALUE(md));
-      gpr_log(GPR_ERROR,
-              "Invalid compression algorithm: '%s' (previously disabled). "
-              "Ignoring.",
-              val);
-      gpr_free(val);
-      calld->compression_algorithm = GRPC_COMPRESS_NONE;
-    }
-    calld->has_compression_algorithm = 1;
-
-    grpc_metadata_batch_remove(
-        exec_ctx, initial_metadata,
-        initial_metadata->idx.named.grpc_internal_encoding_request);
-  } else {
+  grpc_metadata_batch_filter(exec_ctx, initial_metadata, compression_md_filter,
+                             elem);
+  if (!calld->has_compression_algorithm) {
     /* If no algorithm was found in the metadata and we aren't
      * exceptionally skipping compression, fall back to the channel
      * default */
     calld->compression_algorithm = channeld->default_compression_algorithm;
     calld->has_compression_algorithm = 1; /* GPR_TRUE */
   }
-
   /* hint compression algorithm */
-  error = grpc_metadata_batch_add_tail(
-      exec_ctx, initial_metadata, &calld->compression_algorithm_storage,
+  grpc_metadata_batch_add_tail(
+      initial_metadata, &calld->compression_algorithm_storage,
       grpc_compression_encoding_mdelem(calld->compression_algorithm));
 
-  if (error != GRPC_ERROR_NONE) return error;
-
   /* convey supported compression algorithms */
-  error = grpc_metadata_batch_add_tail(
-      exec_ctx, initial_metadata, &calld->accept_encoding_storage,
-      GRPC_MDELEM_ACCEPT_ENCODING_FOR_ALGORITHMS(
-          channeld->supported_compression_algorithms));
-
-  return error;
+  grpc_metadata_batch_add_tail(initial_metadata,
+                               &calld->accept_encoding_storage,
+                               GRPC_MDELEM_ACCEPT_ENCODING_FOR_ALGORITHMS(
+                                   channeld->supported_compression_algorithms));
 }
 
 static void continue_send_message(grpc_exec_ctx *exec_ctx,
@@ -248,12 +247,7 @@ static void compress_start_transport_stream_op(grpc_exec_ctx *exec_ctx,
   GPR_TIMER_BEGIN("compress_start_transport_stream_op", 0);
 
   if (op->send_initial_metadata) {
-    grpc_error *error = process_send_initial_metadata(
-        exec_ctx, elem, op->send_initial_metadata);
-    if (error != GRPC_ERROR_NONE) {
-      grpc_transport_stream_op_finish_with_failure(exec_ctx, op, error);
-      return;
-    }
+    process_send_initial_metadata(exec_ctx, elem, op->send_initial_metadata);
   }
   if (op->send_message != NULL &&
       !skip_compression(elem, op->send_message->flags)) {