[Feat] (P11 PAIR): the PairBind control message - the client's nonce and which of its two connections this is, the first frame on each - with the control revision 3 -> 4 and its pin

MobileGL/MG_Remote/Protocol/generated/protocol_generated.h

@@ -50,6 +50,9 @@ struct WelcomeBuilder;
 struct DataBind;
 struct DataBindBuilder;
 
+struct PairBind;
+struct PairBindBuilder;
+
 struct CapsSnapshot;
 struct CapsSnapshotBuilder;
 
@@ -552,11 +555,12 @@ enum class CtrlMsg : uint8_t {
   LogFlush = 12,
   DataBind = 13,
   SurfaceProgress = 14,
+  PairBind = 15,
   MIN = NONE,
-  MAX = SurfaceProgress
+  MAX = PairBind
 };
 
-inline const CtrlMsg (&EnumValuesCtrlMsg())[15] {
+inline const CtrlMsg (&EnumValuesCtrlMsg())[16] {
   static const CtrlMsg values[] = {
     CtrlMsg::NONE,
     CtrlMsg::Hello,
@@ -572,13 +576,14 @@ inline const CtrlMsg (&EnumValuesCtrlMsg())[15] {
     CtrlMsg::Refuse,
     CtrlMsg::LogFlush,
     CtrlMsg::DataBind,
-    CtrlMsg::SurfaceProgress
+    CtrlMsg::SurfaceProgress,
+    CtrlMsg::PairBind
   };
   return values;
 }
 
 inline const char * const *EnumNamesCtrlMsg() {
-  static const char * const names[16] = {
+  static const char * const names[17] = {
     "NONE",
     "Hello",
     "Welcome",
@@ -594,13 +599,14 @@ inline const char * const *EnumNamesCtrlMsg() {
     "LogFlush",
     "DataBind",
     "SurfaceProgress",
+    "PairBind",
     nullptr
   };
   return names;
 }
 
 inline const char *EnumNameCtrlMsg(CtrlMsg e) {
-  if (::flatbuffers::IsOutRange(e, CtrlMsg::NONE, CtrlMsg::SurfaceProgress)) return "";
+  if (::flatbuffers::IsOutRange(e, CtrlMsg::NONE, CtrlMsg::PairBind)) return "";
   const size_t index = static_cast<size_t>(e);
   return EnumNamesCtrlMsg()[index];
 }
@@ -665,6 +671,10 @@ template<> struct CtrlMsgTraits<MobileGL::Wire::SurfaceProgress> {
   static const CtrlMsg enum_value = CtrlMsg::SurfaceProgress;
 };
 
+template<> struct CtrlMsgTraits<MobileGL::Wire::PairBind> {
+  static const CtrlMsg enum_value = CtrlMsg::PairBind;
+};
+
 template <bool B = false>
 bool VerifyCtrlMsg(::flatbuffers::VerifierTemplate<B> &verifier, const void *obj, CtrlMsg type);
 template <bool B = false>
@@ -1478,6 +1488,76 @@ inline ::flatbuffers::Offset<DataBind> CreateDataBindDirect(
       nonce__);
 }
 
+struct PairBind FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
+  typedef PairBindBuilder Builder;
+  struct Traits;
+  enum FlatBuffersVTableOffset FLATBUFFERS_VTABLE_UNDERLYING_TYPE {
+    VT_NONCE = 4,
+    VT_AUX = 6
+  };
+  const ::flatbuffers::Vector<uint8_t> *nonce() const {
+    return GetPointer<const ::flatbuffers::Vector<uint8_t> *>(VT_NONCE);
+  }
+  bool aux() const {
+    return GetField<uint8_t>(VT_AUX, 0) != 0;
+  }
+  template <bool B = false>
+  bool Verify(::flatbuffers::VerifierTemplate<B> &verifier) const {
+    return VerifyTableStart(verifier) &&
+           VerifyOffset(verifier, VT_NONCE) &&
+           verifier.VerifyVector(nonce()) &&
+           VerifyField<uint8_t>(verifier, VT_AUX, 1) &&
+           verifier.EndTable();
+  }
+};
+
+struct PairBindBuilder {
+  typedef PairBind Table;
+  ::flatbuffers::FlatBufferBuilder &fbb_;
+  ::flatbuffers::uoffset_t start_;
+  void add_nonce(::flatbuffers::Offset<::flatbuffers::Vector<uint8_t>> nonce) {
+    fbb_.AddOffset(PairBind::VT_NONCE, nonce);
+  }
+  void add_aux(bool aux) {
+    fbb_.AddElement<uint8_t>(PairBind::VT_AUX, static_cast<uint8_t>(aux), 0);
+  }
+  explicit PairBindBuilder(::flatbuffers::FlatBufferBuilder &_fbb)
+        : fbb_(_fbb) {
+    start_ = fbb_.StartTable();
+  }
+  ::flatbuffers::Offset<PairBind> Finish() {
+    const auto end = fbb_.EndTable(start_);
+    auto o = ::flatbuffers::Offset<PairBind>(end);
+    return o;
+  }
+};
+
+inline ::flatbuffers::Offset<PairBind> CreatePairBind(
+    ::flatbuffers::FlatBufferBuilder &_fbb,
+    ::flatbuffers::Offset<::flatbuffers::Vector<uint8_t>> nonce = 0,
+    bool aux = false) {
+  PairBindBuilder builder_(_fbb);
+  builder_.add_nonce(nonce);
+  builder_.add_aux(aux);
+  return builder_.Finish();
+}
+
+struct PairBind::Traits {
+  using type = PairBind;
+  static auto constexpr Create = CreatePairBind;
+};
+
+inline ::flatbuffers::Offset<PairBind> CreatePairBindDirect(
+    ::flatbuffers::FlatBufferBuilder &_fbb,
+    const std::vector<uint8_t> *nonce = nullptr,
+    bool aux = false) {
+  auto nonce__ = nonce ? _fbb.CreateVector<uint8_t>(*nonce) : 0;
+  return MobileGL::Wire::CreatePairBind(
+      _fbb,
+      nonce__,
+      aux);
+}
+
 struct CapsSnapshot FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
   typedef CapsSnapshotBuilder Builder;
   struct Traits;
@@ -2416,6 +2496,9 @@ struct CtrlEnvelope FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
   const MobileGL::Wire::SurfaceProgress *msg_as_SurfaceProgress() const {
     return msg_type() == MobileGL::Wire::CtrlMsg::SurfaceProgress ? static_cast<const MobileGL::Wire::SurfaceProgress *>(msg()) : nullptr;
   }
+  const MobileGL::Wire::PairBind *msg_as_PairBind() const {
+    return msg_type() == MobileGL::Wire::CtrlMsg::PairBind ? static_cast<const MobileGL::Wire::PairBind *>(msg()) : nullptr;
+  }
   template <bool B = false>
   bool Verify(::flatbuffers::VerifierTemplate<B> &verifier) const {
     return VerifyTableStart(verifier) &&
@@ -2482,6 +2565,10 @@ template<> inline const MobileGL::Wire::SurfaceProgress *CtrlEnvelope::msg_as<Mo
   return msg_as_SurfaceProgress();
 }
 
+template<> inline const MobileGL::Wire::PairBind *CtrlEnvelope::msg_as<MobileGL::Wire::PairBind>() const {
+  return msg_as_PairBind();
+}
+
 struct CtrlEnvelopeBuilder {
   typedef CtrlEnvelope Table;
   ::flatbuffers::FlatBufferBuilder &fbb_;
@@ -2580,6 +2667,10 @@ inline bool VerifyCtrlMsg(::flatbuffers::VerifierTemplate<B> &verifier, const vo
       auto ptr = reinterpret_cast<const MobileGL::Wire::SurfaceProgress *>(obj);
       return verifier.VerifyTable(ptr);
     }
+    case CtrlMsg::PairBind: {
+      auto ptr = reinterpret_cast<const MobileGL::Wire::PairBind *>(obj);
+      return verifier.VerifyTable(ptr);
+    }
     default: return true;
   }
 }

MobileGL/MG_Remote/Protocol/mg_protocol_base.h

@@ -67,7 +67,9 @@ extern "C" {
 //   2  P7 (p7/spawnhang): the SurfaceProgress message.
 //   3  P12 (on-screen server window): WindowKind.ServerOwned, the SurfaceRefusal enum and
 //      SurfaceReply.width/height/refusal.
-#define MOBILEGL_PROTOCOL_CONTROL_REVISION 3
+//   4  P11 PAIR: the PairBind message - a socket client's control and aux connections pair by
+//      the nonce each presents first, not by arrival order.
+#define MOBILEGL_PROTOCOL_CONTROL_REVISION 4
 
 #define MOBILEGL_ABI_VERSION(major, minor) (((uint32_t)(major) << 16) | (uint32_t)(minor))
 #define MOBILEGL_ABI_MAJOR_OF(version) ((uint32_t)(version) >> 16)

MobileGL/MG_Remote/Protocol/protocol.fbs

@@ -142,6 +142,19 @@ table DataBind {
   nonce: [ubyte];
 }
 
+// P11 PAIR. The FIRST frame on each of the two connections a socket client opens with
+// SocketTransport::ConnectTo - control, then aux (the SCM_RIGHTS socket; the data connection on a
+// tcp:// ConnectTo) - and on control the only frame before the Hello. `nonce` is 128 bits from the
+// client's CSPRNG, the same on both; `aux` says which of the two this connection is. The server
+// holds every accepted connection until it has presented this and pairs the two halves by the
+// nonce, never by arrival order (Server/PairAcceptor.h): a stray connection, or a second client
+// connecting at the same moment, cannot become half of this client's session. A control connection
+// whose first frame is a Hello is a peer from before this message and is refused by name.
+table PairBind {
+  nonce: [ubyte];
+  aux: bool;
+}
+
 // ---------------------------------------------------------------------------
 // Capabilities
 // ---------------------------------------------------------------------------
@@ -401,6 +414,7 @@ union CtrlMsg {
   LogFlush,
   DataBind,
   SurfaceProgress,
+  PairBind,
 }
 
 table CtrlEnvelope {

scripts/ci/protocol_revision_pins.json

@@ -1,5 +1,6 @@
 {
   "1": "7fc859f7fa756818401f4162e7d49a25d430b91e44d89c297321e3cb36c69638",
   "2": "b30928e6fc93ddc015fd86f634a6820f775a6f2f6de5a848d273981e706b2597",
-  "3": "da09f0acb48cf245703f28556ef5a38bc9e25241ebbf7b6baa9ab1765b7ddd50"
+  "3": "da09f0acb48cf245703f28556ef5a38bc9e25241ebbf7b6baa9ab1765b7ddd50",
+  "4": "6357c3a07ae258d2825dc42bfd610712b15a38a3beb7a96b5f56ea2988705e7f"
 }