Add HTTP2 header tracing

HPACK makes headers on the wire very difficult to read. Add a trace facility to print them on the receive path.
Later this will be expanded no doubt for sending headers, stream creation, etc...

3 files changed, 23 insertions, 8 deletions

diff --git a/src/core/debug/trace.c b/src/core/debug/trace.c
index 92acbe924d..b8eb755bff 100644
--- a/src/core/debug/trace.c
+++ b/src/core/debug/trace.c
@@ -81,6 +81,8 @@ static void parse(const char *s) {
       grpc_trace_bits |= GRPC_TRACE_TCP;
     } else if (0 == strcmp(s, "secure_endpoint")) {
       grpc_trace_bits |= GRPC_TRACE_SECURE_ENDPOINT;
+    } else if (0 == strcmp(s, "http")) {
+      grpc_trace_bits |= GRPC_TRACE_HTTP;
     } else if (0 == strcmp(s, "all")) {
       grpc_trace_bits = -1;
     } else {
diff --git a/src/core/debug/trace.h b/src/core/debug/trace.h
index 167ef3c6ea..bf9b8a3642 100644
--- a/src/core/debug/trace.h
+++ b/src/core/debug/trace.h
@@ -45,7 +45,8 @@ typedef enum {
   GRPC_TRACE_SURFACE = 1 << 0,
   GRPC_TRACE_CHANNEL = 1 << 1,
   GRPC_TRACE_TCP = 1 << 2,
-  GRPC_TRACE_SECURE_ENDPOINT = 1 << 3
+  GRPC_TRACE_SECURE_ENDPOINT = 1 << 3,
+  GRPC_TRACE_HTTP = 1 << 4
 } grpc_trace_bit_value;
 
 #if GRPC_ENABLE_TRACING
diff --git a/src/core/transport/chttp2_transport.c b/src/core/transport/chttp2_transport.c
index ccd8d0c376..e9f1cd7842 100644
--- a/src/core/transport/chttp2_transport.c
+++ b/src/core/transport/chttp2_transport.c
@@ -37,6 +37,7 @@
 #include <stdio.h>
 #include <string.h>
 
+#include "src/core/debug/trace.h"
 #include "src/core/support/string.h"
 #include "src/core/transport/chttp2/frame_data.h"
 #include "src/core/transport/chttp2/frame_goaway.h"
@@ -66,6 +67,12 @@
 typedef struct transport transport;
 typedef struct stream stream;
 
+#define IF_TRACING(stmt)                    \
+  if (!(grpc_trace_bits & GRPC_TRACE_HTTP)) \
+    ;                                       \
+  else                                      \
+  stmt
+
 /* streams are kept in various linked lists depending on what things need to
    happen to them... this enum labels each list */
 typedef enum {
@@ -552,7 +559,7 @@ static int init_stream(grpc_transport *gt, grpc_stream *gs,
     lock(t);
     s->id = 0;
   } else {
-    s->id = (gpr_uint32)(gpr_uintptr)server_data;
+    s->id = (gpr_uint32)(gpr_uintptr) server_data;
     t->incoming_stream = s;
     grpc_chttp2_stream_map_add(&t->stream_map, s->id, s);
   }
@@ -1206,6 +1213,11 @@ static void on_header(void *tp, grpc_mdelem *md) {
   stream *s = t->incoming_stream;
 
   GPR_ASSERT(s);
+
+  IF_TRACING(gpr_log(GPR_INFO, "HTTP:%d:HDR: %s: %s", s->id,
+                     grpc_mdstr_as_c_string(md->key),
+                     grpc_mdstr_as_c_string(md->value)));
+
   stream_list_join(t, s, PENDING_CALLBACKS);
   if (md->key == t->str_grpc_timeout) {
     gpr_timespec *cached_timeout = grpc_mdelem_get_user_data(md, free_timeout);
@@ -1269,7 +1281,7 @@ static int init_header_frame_parser(transport *t, int is_continuation) {
     t->incoming_stream = NULL;
     /* if stream is accepted, we set incoming_stream in init_stream */
     t->cb->accept_stream(t->cb_user_data, &t->base,
-                         (void *)(gpr_uintptr)t->incoming_stream_id);
+                         (void *)(gpr_uintptr) t->incoming_stream_id);
     s = t->incoming_stream;
     if (!s) {
       gpr_log(GPR_ERROR, "stream not accepted");
@@ -1534,8 +1546,8 @@ static int process_read(transport *t, gpr_slice slice) {
                   "Connect string mismatch: expected '%c' (%d) got '%c' (%d) "
                   "at byte %d",
                   CLIENT_CONNECT_STRING[t->deframe_state],
-                  (int)(gpr_uint8)CLIENT_CONNECT_STRING[t->deframe_state], *cur,
-                  (int)*cur, t->deframe_state);
+                  (int)(gpr_uint8) CLIENT_CONNECT_STRING[t->deframe_state],
+                  *cur, (int)*cur, t->deframe_state);
           drop_connection(t);
           return 0;
         }
@@ -1765,9 +1777,9 @@ static void add_to_pollset(grpc_transport *gt, grpc_pollset *pollset) {
  */
 
 static const grpc_transport_vtable vtable = {
-    sizeof(stream), init_stream, send_batch, set_allow_window_updates,
-    add_to_pollset, destroy_stream, abort_stream, goaway, close_transport,
-    send_ping, destroy_transport};
+    sizeof(stream),  init_stream,    send_batch,       set_allow_window_updates,
+    add_to_pollset,  destroy_stream, abort_stream,     goaway,
+    close_transport, send_ping,      destroy_transport};
 
 void grpc_create_chttp2_transport(grpc_transport_setup_callback setup,
                                   void *arg,