1 //
2 //
3 // Copyright 2021 gRPC authors.
4 //
5 // Licensed under the Apache License, Version 2.0 (the "License");
6 // you may not use this file except in compliance with the License.
7 // You may obtain a copy of the License at
8 //
9 // http://www.apache.org/licenses/LICENSE-2.0
10 //
11 // Unless required by applicable law or agreed to in writing, software
12 // distributed under the License is distributed on an "AS IS" BASIS,
13 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 // See the License for the specific language governing permissions and
15 // limitations under the License.
16 //
17 //
18
19 #include <grpc/support/port_platform.h>
20
21 #include "src/core/ext/xds/xds_channel_stack_modifier.h"
22
23 #include "src/core/lib/config/core_configuration.h"
24 #include "src/core/lib/surface/channel_init.h"
25
26 namespace grpc_core {
27 namespace {
28
XdsChannelStackModifierArgCopy(void * p)29 void* XdsChannelStackModifierArgCopy(void* p) {
30 XdsChannelStackModifier* arg = static_cast<XdsChannelStackModifier*>(p);
31 return arg->Ref().release();
32 }
33
XdsChannelStackModifierArgDestroy(void * p)34 void XdsChannelStackModifierArgDestroy(void* p) {
35 XdsChannelStackModifier* arg = static_cast<XdsChannelStackModifier*>(p);
36 arg->Unref();
37 }
38
XdsChannelStackModifierArgCmp(void * p,void * q)39 int XdsChannelStackModifierArgCmp(void* p, void* q) {
40 return QsortCompare(p, q);
41 }
42
43 const grpc_arg_pointer_vtable kChannelArgVtable = {
44 XdsChannelStackModifierArgCopy, XdsChannelStackModifierArgDestroy,
45 XdsChannelStackModifierArgCmp};
46
47 const char* kXdsChannelStackModifierChannelArgName =
48 "grpc.internal.xds_channel_stack_modifier";
49
50 } // namespace
51
ModifyChannelStack(grpc_channel_stack_builder * builder)52 bool XdsChannelStackModifier::ModifyChannelStack(
53 grpc_channel_stack_builder* builder) {
54 // Insert the filters after the census filter if present.
55 grpc_channel_stack_builder_iterator* it =
56 grpc_channel_stack_builder_create_iterator_at_first(builder);
57 while (grpc_channel_stack_builder_move_next(it)) {
58 if (grpc_channel_stack_builder_iterator_is_end(it)) break;
59 const char* filter_name_at_it =
60 grpc_channel_stack_builder_iterator_filter_name(it);
61 if (strcmp("census_server", filter_name_at_it) == 0 ||
62 strcmp("opencensus_server", filter_name_at_it) == 0) {
63 break;
64 }
65 }
66 if (grpc_channel_stack_builder_iterator_is_end(it)) {
67 // No census filter found. Reset iterator to the beginning. This will result
68 // in prepending the list of xDS HTTP filters to the current stack. Note
69 // that this stage is run before the stage that adds the top server filter,
70 // resulting in these filters being finally placed after the `server`
71 // filter.
72 grpc_channel_stack_builder_iterator_destroy(it);
73 it = grpc_channel_stack_builder_create_iterator_at_first(builder);
74 }
75 GPR_ASSERT(grpc_channel_stack_builder_move_next(it));
76 for (const grpc_channel_filter* filter : filters_) {
77 GPR_ASSERT(grpc_channel_stack_builder_add_filter_before(it, filter, nullptr,
78 nullptr));
79 }
80 grpc_channel_stack_builder_iterator_destroy(it);
81 return true;
82 }
83
MakeChannelArg() const84 grpc_arg XdsChannelStackModifier::MakeChannelArg() const {
85 return grpc_channel_arg_pointer_create(
86 const_cast<char*>(kXdsChannelStackModifierChannelArgName),
87 const_cast<XdsChannelStackModifier*>(this), &kChannelArgVtable);
88 }
89
90 RefCountedPtr<XdsChannelStackModifier>
GetFromChannelArgs(const grpc_channel_args & args)91 XdsChannelStackModifier::GetFromChannelArgs(const grpc_channel_args& args) {
92 XdsChannelStackModifier* config_selector_provider =
93 grpc_channel_args_find_pointer<XdsChannelStackModifier>(
94 &args, kXdsChannelStackModifierChannelArgName);
95 return config_selector_provider != nullptr ? config_selector_provider->Ref()
96 : nullptr;
97 }
98
RegisterXdsChannelStackModifier(CoreConfiguration::Builder * builder)99 void RegisterXdsChannelStackModifier(CoreConfiguration::Builder* builder) {
100 builder->channel_init()->RegisterStage(
101 GRPC_SERVER_CHANNEL, INT_MAX, [](grpc_channel_stack_builder* builder) {
102 grpc_core::RefCountedPtr<XdsChannelStackModifier>
103 channel_stack_modifier =
104 XdsChannelStackModifier::GetFromChannelArgs(
105 *grpc_channel_stack_builder_get_channel_arguments(builder));
106 if (channel_stack_modifier != nullptr) {
107 return channel_stack_modifier->ModifyChannelStack(builder);
108 }
109 return true;
110 });
111 }
112
113 } // namespace grpc_core
114