5 files changed, 65 insertions, 5 deletions

diff --git a/src/core/lib/channel/channelz.cc b/src/core/lib/channel/channelz.cc
index c1194ae872..47ba1492ea 100644
--- a/src/core/lib/channel/channelz.cc
+++ b/src/core/lib/channel/channelz.cc
@@ -157,6 +157,38 @@ ServerNode::ServerNode(grpc_server* server, size_t channel_tracer_max_nodes)
 
 ServerNode::~ServerNode() {}
 
+char* ServerNode::RenderServerSockets(intptr_t start_socket_id) {
+  grpc_json* top_level_json = grpc_json_create(GRPC_JSON_OBJECT);
+  grpc_json* json = top_level_json;
+  grpc_json* json_iterator = nullptr;
+  ChildRefsList socket_refs;
+  // uuids index into entities one-off (idx 0 is really uuid 1, since 0 is
+  // reserved). However, we want to support requests coming in with
+  // start_server_id=0, which signifies "give me everything."
+  size_t start_idx = start_socket_id == 0 ? 0 : start_socket_id - 1;
+  grpc_server_populate_listen_sockets(server_, &socket_refs, start_idx);
+  if (!socket_refs.empty()) {
+    // create list of socket refs
+    grpc_json* array_parent = grpc_json_create_child(
+        nullptr, json, "socketRef", nullptr, GRPC_JSON_ARRAY, false);
+    for (size_t i = 0; i < socket_refs.size(); ++i) {
+      json_iterator =
+          grpc_json_create_child(json_iterator, array_parent, nullptr, nullptr,
+                                 GRPC_JSON_OBJECT, false);
+      grpc_json_add_number_string_child(json_iterator, nullptr, "socketId",
+                                        socket_refs[i]);
+    }
+  }
+  // For now we do not have any pagination rules. In the future we could
+  // pick a constant for max_channels_sent for a GetServers request.
+  // Tracking: https://github.com/grpc/grpc/issues/16019.
+  json_iterator = grpc_json_create_child(nullptr, json, "end", nullptr,
+                                         GRPC_JSON_TRUE, false);
+  char* json_str = grpc_json_dump_to_string(top_level_json, 0);
+  grpc_json_destroy(top_level_json);
+  return json_str;
+}
+
 grpc_json* ServerNode::RenderJson() {
   // We need to track these three json objects to build our object
   grpc_json* top_level_json = grpc_json_create(GRPC_JSON_OBJECT);
@@ -187,7 +219,8 @@ grpc_json* ServerNode::RenderJson() {
   call_counter_.PopulateCallCounts(json);
   json = top_level_json;
   ChildRefsList listen_sockets;
-  grpc_server_populate_listen_sockets(server_, &listen_sockets);
+  grpc_server_populate_listen_sockets(server_, &listen_sockets,
+                                      0 /* start_idx*/);
   if (!listen_sockets.empty()) {
     grpc_json* array_parent = grpc_json_create_child(
         nullptr, json, "listenSocket", nullptr, GRPC_JSON_ARRAY, false);
diff --git a/src/core/lib/channel/channelz.h b/src/core/lib/channel/channelz.h
index 5edd90c813..9ae2e56ec8 100644
--- a/src/core/lib/channel/channelz.h
+++ b/src/core/lib/channel/channelz.h
@@ -74,6 +74,12 @@ class BaseNode : public RefCounted<BaseNode> {
   // All children must implement this function.
   virtual grpc_json* RenderJson() GRPC_ABSTRACT;
 
+  // Fat interface for functionality that will only ever be called on Servers.
+  // All other channelz entities will assert false.
+  virtual char* RenderServerSockets(intptr_t start_socket_id) {
+    GPR_ASSERT(false);
+  }
+
   // Renders the json and returns allocated string that must be freed by the
   // caller.
   char* RenderJsonString();
@@ -184,6 +190,10 @@ class ServerNode : public BaseNode {
 
   grpc_json* RenderJson() override;
 
+  // Server overrides this functionality to populate the JSON with
+  // the sockets it owns.
+  char* RenderServerSockets(intptr_t start_socket_id) override;
+
   // proxy methods to composed classes.
   void AddTraceEvent(ChannelTrace::Severity severity, grpc_slice data) {
     trace_.AddTraceEvent(severity, data);
diff --git a/src/core/lib/channel/channelz_registry.cc b/src/core/lib/channel/channelz_registry.cc
index 841f1c6104..820ed7bf8d 100644
--- a/src/core/lib/channel/channelz_registry.cc
+++ b/src/core/lib/channel/channelz_registry.cc
@@ -160,6 +160,18 @@ char* grpc_channelz_get_servers(intptr_t start_server_id) {
   return grpc_core::channelz::ChannelzRegistry::GetServers(start_server_id);
 }
 
+char* grpc_channelz_get_server_sockets(intptr_t server_id,
+                                       intptr_t start_socket_id) {
+  grpc_core::channelz::BaseNode* server_node =
+      grpc_core::channelz::ChannelzRegistry::Get(server_id);
+  if (server_node == nullptr ||
+      server_node->type() !=
+          grpc_core::channelz::BaseNode::EntityType::kServer) {
+    return nullptr;
+  }
+  return server_node->RenderServerSockets(start_socket_id);
+}
+
 char* grpc_channelz_get_channel(intptr_t channel_id) {
   grpc_core::channelz::BaseNode* channel_node =
       grpc_core::channelz::ChannelzRegistry::Get(channel_id);
diff --git a/src/core/lib/surface/server.cc b/src/core/lib/surface/server.cc
index a35d60e275..da643f54ef 100644
--- a/src/core/lib/surface/server.cc
+++ b/src/core/lib/surface/server.cc
@@ -1213,7 +1213,8 @@ void grpc_server_setup_transport(grpc_server* s, grpc_transport* transport,
 }
 
 void grpc_server_populate_listen_sockets(
-    grpc_server* s, grpc_core::ChildRefsList* listen_sockets) {
+    grpc_server* s, grpc_core::ChildRefsList* listen_sockets,
+    intptr_t start_idx) {
   gpr_mu_lock(&s->mu_global);
   channel_data* c = nullptr;
   for (c = s->root_channel_data.next; c != &s->root_channel_data; c = c->next) {
@@ -1221,8 +1222,11 @@ void grpc_server_populate_listen_sockets(
       grpc_channel_element* connected_channel_elem =
           grpc_channel_stack_last_element(
               grpc_channel_get_channel_stack(c->channel));
-      listen_sockets->push_back(
-          grpc_connected_channel_get_socket_uuid(connected_channel_elem));
+      intptr_t socket_uuid =
+          grpc_connected_channel_get_socket_uuid(connected_channel_elem);
+      if (socket_uuid >= start_idx) {
+        listen_sockets->push_back(socket_uuid);
+      }
     }
   }
   gpr_mu_unlock(&s->mu_global);
diff --git a/src/core/lib/surface/server.h b/src/core/lib/surface/server.h
index db47d8032b..b3fd45564e 100644
--- a/src/core/lib/surface/server.h
+++ b/src/core/lib/surface/server.h
@@ -48,7 +48,8 @@ void grpc_server_setup_transport(grpc_server* server, grpc_transport* transport,
                                  const grpc_channel_args* args);
 
 void grpc_server_populate_listen_sockets(
-    grpc_server* server, grpc_core::ChildRefsList* listen_sockets);
+    grpc_server* server, grpc_core::ChildRefsList* listen_sockets,
+    intptr_t start_idx);
 
 grpc_core::channelz::ServerNode* grpc_server_get_channelz_node(
     grpc_server* server);