Propagate PrivacyLibAgenticContext through Carbon requests and Thrift transport headers (#479)

Summary:
Pull Request resolved: #479

X-link: facebook/hhvm#9778

X-link: facebookresearch/DCPerf#621

Propagate the `PrivacyLibAgenticContext` as a `privacylib-propagation` Thrift header from clients through mcrouter to DevProxy.

We capture the context before enqueuing the request in the mcrouter message queue. And then we set the header in the mcrouter Thrift transport layer.

Diagram:

```
Caller thread (RequestContext available)
    │
    ├── CacheClientImplBase::buildSingleRequest()  ← captures context here
    │   └── carbonReq.setPrivacyLibAgenticContext(serialized)
    │
    ├── RequestBuilderHelper::updateTaoRequestCommonPart()  ← also captures here (TAO-specific)
    │   └── carbonReq.setPrivacyLibAgenticContext(serialized)
    │
    ╧ ── MessageQueue ──────────────────── (RequestContext lost, but field survives)
    │
    └── ThriftTransport::sendSyncHelper()
        └── request.getPrivacyLibAgenticContext().has_value()
            └── rpcOptions.setWriteHeader("privacylib-propagation", value)
```

We are focusing on Thrift transport exclusively as we are trying to close gaps in DevProxy layer.

Reviewed By: ghostonhuang

Differential Revision: D105269091

fbshipit-source-id: d362d4053651b95db31e758665922a8883b6a5af

Author: speb-meta

mcrouter/lib/carbon/MessageCommon.h

@@ -42,6 +42,9 @@ class MessageCommon {
 
   static constexpr std::string_view kKcbIdentityHeader = "kcb_identity";
 
+  static constexpr std::string_view kPrivacyLibAgenticContextHeader =
+      "privacylib-propagation";
+
  protected:
   std::string traceContext_;
 };

mcrouter/lib/carbon/RequestCommon.cpp

@@ -22,6 +22,7 @@ RequestCommon::RequestCommon(const RequestCommon& other)
   cryptoAuthToken_ = other.cryptoAuthToken_;
   replyBitMask_ = other.replyBitMask_;
   clientIdentifier_ = other.clientIdentifier_;
+  privacyLibAgenticContext_ = other.privacyLibAgenticContext_;
 }
 
 RequestCommon& RequestCommon::operator=(const RequestCommon& other) {
@@ -30,6 +31,7 @@ RequestCommon& RequestCommon::operator=(const RequestCommon& other) {
     cryptoAuthToken_ = other.cryptoAuthToken_;
     replyBitMask_ = other.replyBitMask_;
     clientIdentifier_ = other.clientIdentifier_;
+    privacyLibAgenticContext_ = other.privacyLibAgenticContext_;
     uniqueId_ = other.uniqueId_;
   }
   return *this;
@@ -81,6 +83,15 @@ void RequestCommon::setClientIdentifier(
   clientIdentifier_ = clientIdentifier.str();
 }
 
+const std::optional<std::string>& RequestCommon::getPrivacyLibAgenticContext()
+    const {
+  return privacyLibAgenticContext_;
+}
+
+void RequestCommon::setPrivacyLibAgenticContext(std::string&& context) {
+  privacyLibAgenticContext_.emplace(std::move(context));
+}
+
 const std::optional<folly::IPAddress>& RequestCommon::getSourceIpAddr()
     const noexcept {
   return sourceIpAddr_;

mcrouter/lib/carbon/RequestCommon.h

@@ -72,6 +72,10 @@ class RequestCommon : public MessageCommon {
 
   void setClientIdentifier(folly::StringPiece clientIdentifier) noexcept;
 
+  const std::optional<std::string>& getPrivacyLibAgenticContext() const;
+
+  void setPrivacyLibAgenticContext(std::string&& context);
+
   const std::optional<folly::IPAddress>& getSourceIpAddr() const noexcept;
 
   void setSourceIpAddr(const folly::IPAddress& sourceIpAddr) noexcept;
@@ -95,6 +99,8 @@ class RequestCommon : public MessageCommon {
   std::optional<std::string> cryptoAuthToken_;
   // Hash string of primary (non-host) tls client identities
   std::optional<std::string> clientIdentifier_;
+  // Privacylib agentic context in base64-encoded serialized format
+  std::optional<std::string> privacyLibAgenticContext_;
   // Source ip address.
   std::optional<folly::IPAddress> sourceIpAddr_;
   // write timestamp

mcrouter/lib/carbon/example/gen/HelloGoodbyeThriftTransport.h

@@ -56,6 +56,10 @@ folly::Try<apache::thrift::RpcResponseComplete<hellogoodbye::GoodbyeReply>> send
     rpcOptions.setWriteHeader(
         std::string{carbon::MessageCommon::kClientIdentifierHeader}, request.getClientIdentifier().value());
   }
+  if (FOLLY_UNLIKELY(request.getPrivacyLibAgenticContext().has_value())) {
+    rpcOptions.setWriteHeader(
+        std::string{carbon::MessageCommon::kPrivacyLibAgenticContextHeader}, request.getPrivacyLibAgenticContext().value());
+  }
   rpcOptions.setContextPropMask(0);
 
 #ifndef LIBMC_FBTRACE_DISABLE
@@ -96,6 +100,10 @@ folly::Try<apache::thrift::RpcResponseComplete<hellogoodbye::HelloReply>> sendSy
     rpcOptions.setWriteHeader(
         std::string{carbon::MessageCommon::kClientIdentifierHeader}, request.getClientIdentifier().value());
   }
+  if (FOLLY_UNLIKELY(request.getPrivacyLibAgenticContext().has_value())) {
+    rpcOptions.setWriteHeader(
+        std::string{carbon::MessageCommon::kPrivacyLibAgenticContextHeader}, request.getPrivacyLibAgenticContext().value());
+  }
   rpcOptions.setContextPropMask(0);
 
 #ifndef LIBMC_FBTRACE_DISABLE
@@ -139,6 +147,10 @@ folly::Try<apache::thrift::RpcResponseComplete<McVersionReply>> sendSyncHelper(
     rpcOptions.setWriteHeader(
         std::string{carbon::MessageCommon::kClientIdentifierHeader}, request.getClientIdentifier().value());
   }
+  if (FOLLY_UNLIKELY(request.getPrivacyLibAgenticContext().has_value())) {
+    rpcOptions.setWriteHeader(
+        std::string{carbon::MessageCommon::kPrivacyLibAgenticContextHeader}, request.getPrivacyLibAgenticContext().value());
+  }
   rpcOptions.setContextPropMask(0);
 
 #ifndef LIBMC_FBTRACE_DISABLE

mcrouter/lib/carbon/test/gen/AThriftTransport.h

@@ -54,6 +54,10 @@ folly::Try<apache::thrift::RpcResponseComplete<carbon::test::A::TestAReply>> sen
     rpcOptions.setWriteHeader(
         std::string{carbon::MessageCommon::kClientIdentifierHeader}, request.getClientIdentifier().value());
   }
+  if (FOLLY_UNLIKELY(request.getPrivacyLibAgenticContext().has_value())) {
+    rpcOptions.setWriteHeader(
+        std::string{carbon::MessageCommon::kPrivacyLibAgenticContextHeader}, request.getPrivacyLibAgenticContext().value());
+  }
   rpcOptions.setContextPropMask(0);
 
 #ifndef LIBMC_FBTRACE_DISABLE
@@ -94,6 +98,10 @@ folly::Try<apache::thrift::RpcResponseComplete<McVersionReply>> sendSyncHelper(
     rpcOptions.setWriteHeader(
         std::string{carbon::MessageCommon::kClientIdentifierHeader}, request.getClientIdentifier().value());
   }
+  if (FOLLY_UNLIKELY(request.getPrivacyLibAgenticContext().has_value())) {
+    rpcOptions.setWriteHeader(
+        std::string{carbon::MessageCommon::kPrivacyLibAgenticContextHeader}, request.getPrivacyLibAgenticContext().value());
+  }
   rpcOptions.setContextPropMask(0);
 
 #ifndef LIBMC_FBTRACE_DISABLE

mcrouter/lib/carbon/test/gen/BThriftTransport.h

@@ -54,6 +54,10 @@ folly::Try<apache::thrift::RpcResponseComplete<carbon::test::B::TestBReply>> sen
     rpcOptions.setWriteHeader(
         std::string{carbon::MessageCommon::kClientIdentifierHeader}, request.getClientIdentifier().value());
   }
+  if (FOLLY_UNLIKELY(request.getPrivacyLibAgenticContext().has_value())) {
+    rpcOptions.setWriteHeader(
+        std::string{carbon::MessageCommon::kPrivacyLibAgenticContextHeader}, request.getPrivacyLibAgenticContext().value());
+  }
   rpcOptions.setContextPropMask(0);
 
 #ifndef LIBMC_FBTRACE_DISABLE
@@ -94,6 +98,10 @@ folly::Try<apache::thrift::RpcResponseComplete<McVersionReply>> sendSyncHelper(
     rpcOptions.setWriteHeader(
         std::string{carbon::MessageCommon::kClientIdentifierHeader}, request.getClientIdentifier().value());
   }
+  if (FOLLY_UNLIKELY(request.getPrivacyLibAgenticContext().has_value())) {
+    rpcOptions.setWriteHeader(
+        std::string{carbon::MessageCommon::kPrivacyLibAgenticContextHeader}, request.getPrivacyLibAgenticContext().value());
+  }
   rpcOptions.setContextPropMask(0);
 
 #ifndef LIBMC_FBTRACE_DISABLE

mcrouter/lib/carbon/test/gen/CarbonTestThriftTransport.h

@@ -54,6 +54,10 @@ folly::Try<apache::thrift::RpcResponseComplete<carbon::test::TestReply>> sendSyn
     rpcOptions.setWriteHeader(
         std::string{carbon::MessageCommon::kClientIdentifierHeader}, request.getClientIdentifier().value());
   }
+  if (FOLLY_UNLIKELY(request.getPrivacyLibAgenticContext().has_value())) {
+    rpcOptions.setWriteHeader(
+        std::string{carbon::MessageCommon::kPrivacyLibAgenticContextHeader}, request.getPrivacyLibAgenticContext().value());
+  }
   rpcOptions.setContextPropMask(0);
 
 #ifndef LIBMC_FBTRACE_DISABLE
@@ -94,6 +98,10 @@ folly::Try<apache::thrift::RpcResponseComplete<carbon::test::TestReplyStringKey>
     rpcOptions.setWriteHeader(
         std::string{carbon::MessageCommon::kClientIdentifierHeader}, request.getClientIdentifier().value());
   }
+  if (FOLLY_UNLIKELY(request.getPrivacyLibAgenticContext().has_value())) {
+    rpcOptions.setWriteHeader(
+        std::string{carbon::MessageCommon::kPrivacyLibAgenticContextHeader}, request.getPrivacyLibAgenticContext().value());
+  }
   rpcOptions.setContextPropMask(0);
 
 #ifndef LIBMC_FBTRACE_DISABLE
@@ -134,6 +142,10 @@ folly::Try<apache::thrift::RpcResponseComplete<McVersionReply>> sendSyncHelper(
     rpcOptions.setWriteHeader(
         std::string{carbon::MessageCommon::kClientIdentifierHeader}, request.getClientIdentifier().value());
   }
+  if (FOLLY_UNLIKELY(request.getPrivacyLibAgenticContext().has_value())) {
+    rpcOptions.setWriteHeader(
+        std::string{carbon::MessageCommon::kPrivacyLibAgenticContextHeader}, request.getPrivacyLibAgenticContext().value());
+  }
   rpcOptions.setContextPropMask(0);
 
 #ifndef LIBMC_FBTRACE_DISABLE

mcrouter/lib/carbon/test/gen/CarbonThriftTestThriftTransport.h

@@ -54,6 +54,10 @@ folly::Try<apache::thrift::RpcResponseComplete<carbon::test::CustomReply>> sendS
     rpcOptions.setWriteHeader(
         std::string{carbon::MessageCommon::kClientIdentifierHeader}, request.getClientIdentifier().value());
   }
+  if (FOLLY_UNLIKELY(request.getPrivacyLibAgenticContext().has_value())) {
+    rpcOptions.setWriteHeader(
+        std::string{carbon::MessageCommon::kPrivacyLibAgenticContextHeader}, request.getPrivacyLibAgenticContext().value());
+  }
   rpcOptions.setContextPropMask(0);
 
 #ifndef LIBMC_FBTRACE_DISABLE
@@ -94,6 +98,10 @@ folly::Try<apache::thrift::RpcResponseComplete<carbon::test::DummyThriftReply>>
     rpcOptions.setWriteHeader(
         std::string{carbon::MessageCommon::kClientIdentifierHeader}, request.getClientIdentifier().value());
   }
+  if (FOLLY_UNLIKELY(request.getPrivacyLibAgenticContext().has_value())) {
+    rpcOptions.setWriteHeader(
+        std::string{carbon::MessageCommon::kPrivacyLibAgenticContextHeader}, request.getPrivacyLibAgenticContext().value());
+  }
   rpcOptions.setContextPropMask(0);
 
 #ifndef LIBMC_FBTRACE_DISABLE
@@ -134,6 +142,10 @@ folly::Try<apache::thrift::RpcResponseComplete<carbon::test::ThriftTestReply>> s
     rpcOptions.setWriteHeader(
         std::string{carbon::MessageCommon::kClientIdentifierHeader}, request.getClientIdentifier().value());
   }
+  if (FOLLY_UNLIKELY(request.getPrivacyLibAgenticContext().has_value())) {
+    rpcOptions.setWriteHeader(
+        std::string{carbon::MessageCommon::kPrivacyLibAgenticContextHeader}, request.getPrivacyLibAgenticContext().value());
+  }
   rpcOptions.setContextPropMask(0);
 
 #ifndef LIBMC_FBTRACE_DISABLE
@@ -174,6 +186,10 @@ folly::Try<apache::thrift::RpcResponseComplete<McVersionReply>> sendSyncHelper(
     rpcOptions.setWriteHeader(
         std::string{carbon::MessageCommon::kClientIdentifierHeader}, request.getClientIdentifier().value());
   }
+  if (FOLLY_UNLIKELY(request.getPrivacyLibAgenticContext().has_value())) {
+    rpcOptions.setWriteHeader(
+        std::string{carbon::MessageCommon::kPrivacyLibAgenticContextHeader}, request.getPrivacyLibAgenticContext().value());
+  }
   rpcOptions.setContextPropMask(0);
 
 #ifndef LIBMC_FBTRACE_DISABLE