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 "src/core/server/xds_channel_stack_modifier.h"
20
21 #include <grpc/support/port_platform.h>
22
23 #include <algorithm>
24 #include <initializer_list>
25 #include <string>
26
27 #include "src/core/config/core_configuration.h"
28 #include "src/core/lib/channel/channel_args.h"
29 #include "src/core/lib/channel/channel_stack.h"
30 #include "src/core/lib/surface/channel_init.h"
31 #include "src/core/lib/surface/channel_stack_type.h"
32 #include "src/core/util/useful.h"
33
34 namespace grpc_core {
35 namespace {
36
XdsChannelStackModifierArgCopy(void * p)37 void* XdsChannelStackModifierArgCopy(void* p) {
38 XdsChannelStackModifier* arg = static_cast<XdsChannelStackModifier*>(p);
39 return arg->Ref().release();
40 }
41
XdsChannelStackModifierArgDestroy(void * p)42 void XdsChannelStackModifierArgDestroy(void* p) {
43 XdsChannelStackModifier* arg = static_cast<XdsChannelStackModifier*>(p);
44 arg->Unref();
45 }
46
XdsChannelStackModifierArgCmp(void * p,void * q)47 int XdsChannelStackModifierArgCmp(void* p, void* q) {
48 return QsortCompare(p, q);
49 }
50
51 const grpc_arg_pointer_vtable kChannelArgVtable = {
52 XdsChannelStackModifierArgCopy, XdsChannelStackModifierArgDestroy,
53 XdsChannelStackModifierArgCmp};
54
55 const char* kXdsChannelStackModifierChannelArgName =
56 "grpc.internal.xds_channel_stack_modifier";
57
58 } // namespace
59
ModifyChannelStack(ChannelStackBuilder & builder)60 void XdsChannelStackModifier::ModifyChannelStack(ChannelStackBuilder& builder) {
61 // Insert the filters after predicate filters if present.
62 auto insert_before = builder.mutable_stack()->end();
63 for (auto it = builder.mutable_stack()->begin();
64 it != builder.mutable_stack()->end(); ++it) {
65 for (absl::string_view predicate_name : {"server", "census_server"}) {
66 if (predicate_name == (*it)->name.name()) insert_before = it + 1;
67 }
68 }
69 for (const grpc_channel_filter* filter : filters_) {
70 insert_before = builder.mutable_stack()->insert(insert_before, filter);
71 ++insert_before;
72 }
73 }
74
MakeChannelArg() const75 grpc_arg XdsChannelStackModifier::MakeChannelArg() const {
76 return grpc_channel_arg_pointer_create(
77 const_cast<char*>(kXdsChannelStackModifierChannelArgName),
78 const_cast<XdsChannelStackModifier*>(this), &kChannelArgVtable);
79 }
80
ChannelArgName()81 absl::string_view XdsChannelStackModifier::ChannelArgName() {
82 return kXdsChannelStackModifierChannelArgName;
83 }
84
85 RefCountedPtr<XdsChannelStackModifier>
GetFromChannelArgs(const grpc_channel_args & args)86 XdsChannelStackModifier::GetFromChannelArgs(const grpc_channel_args& args) {
87 XdsChannelStackModifier* config_selector_provider =
88 grpc_channel_args_find_pointer<XdsChannelStackModifier>(
89 &args, kXdsChannelStackModifierChannelArgName);
90 return config_selector_provider != nullptr ? config_selector_provider->Ref()
91 : nullptr;
92 }
93
RegisterXdsChannelStackModifier(CoreConfiguration::Builder * builder)94 void RegisterXdsChannelStackModifier(CoreConfiguration::Builder* builder) {
95 builder->channel_init()->RegisterPostProcessor(
96 GRPC_SERVER_CHANNEL,
97 ChannelInit::PostProcessorSlot::kXdsChannelStackModifier,
98 [](ChannelStackBuilder& builder) {
99 auto channel_stack_modifier =
100 builder.channel_args().GetObjectRef<XdsChannelStackModifier>();
101 if (channel_stack_modifier != nullptr) {
102 return channel_stack_modifier->ModifyChannelStack(builder);
103 }
104 });
105 }
106
107 } // namespace grpc_core
108