Protocol 28 (CAP-0084): muxed contract address support

common.mk

@@ -45,4 +45,8 @@ endif # ENABLE_NEXT_PROTOCOL_VERSION_UNSAFE_FOR_PRODUCTION
 
 if CAP_0083
 AM_CPPFLAGS += -DCAP_0083
-endif
+endif
+
+if CAP_0084
+AM_CPPFLAGS += -DCAP_0084
+endif

configure.ac

@@ -564,6 +564,9 @@ AM_CONDITIONAL(ENABLE_NEXT_PROTOCOL_VERSION_UNSAFE_FOR_PRODUCTION,
 AM_CONDITIONAL(CAP_0083,
     [test x$enable_next_protocol_version_unsafe_for_production = xyes])
 
+AM_CONDITIONAL(CAP_0084,
+    [test x$enable_next_protocol_version_unsafe_for_production = xyes])
+
 AC_PATH_PROG(CARGO, cargo)
 if test x"$CARGO" = x; then
   AC_MSG_ERROR([cannot find cargo, needed for rust code])

src/Makefile.am

@@ -100,6 +100,9 @@ XDR_FEATURE_FLAGS =
 if CAP_0083
 XDR_FEATURE_FLAGS += -DCAP_0083
 endif
+if CAP_0084
+XDR_FEATURE_FLAGS += -DCAP_0084
+endif
 
 SUFFIXES = .x .h .rs
 .x.h:

src/ledger/LedgerHashUtils.h

@@ -128,6 +128,12 @@ template <> class hash<stellar::SCAddress>
             stellar::hashMix(
                 res, std::hash<stellar::uint256>()(addr.liquidityPoolId()));
             break;
+#ifdef CAP_0084
+        case stellar::SC_ADDRESS_TYPE_MUXED_CONTRACT:
+            stellar::hashMix(
+                res, stellar::shortHash::xdrComputeHash(addr.muxedContract()));
+            break;
+#endif
         }
         return res;
     }

src/rust/src/dep-trees/p27-expect.txt

@@ -259,7 +259,7 @@ soroban-env-host v27.0.0 (src/rust/soroban/p27/soroban-env-host)
 │   │   │   ├── itoa v1.0.6
 │   │   │   ├── ryu v1.0.13
 │   │   │   └── serde v1.0.192 (*)
-│   │   ├── stellar-xdr v27.0.0
+│   │   ├── stellar-xdr v27.0.0 (https://github.com/sisuresh/rs-stellar-xdr?rev=bd30d420ce6f63ccd9360e371830384cb84d1c04#bd30d420)
 │   │   │   ├── escape-bytes v0.1.1
 │   │   │   ├── ethnum v1.5.3
 │   │   │   ├── hex v0.4.3
@@ -286,7 +286,7 @@ soroban-env-host v27.0.0 (src/rust/soroban/p27/soroban-env-host)
 │   │   └── wasmparser-nostd v0.100.2
 │   │       └── indexmap-nostd v0.4.0
 │   ├── static_assertions v1.1.0
-│   ├── stellar-xdr v27.0.0
+│   ├── stellar-xdr v27.0.0 (https://github.com/sisuresh/rs-stellar-xdr?rev=bd30d420ce6f63ccd9360e371830384cb84d1c04#bd30d420)
 │   │   ├── base64 v0.22.1
 │   │   ├── escape-bytes v0.1.1
 │   │   ├── ethnum v1.5.3
@@ -301,7 +301,10 @@ soroban-env-host v27.0.0 (src/rust/soroban/p27/soroban-env-host)
 │       │   └── hashbrown v0.14.1
 │       └── semver v1.0.17
 │   [build-dependencies]
-│   └── crate-git-revision v0.0.6 (*)
+│   └── crate-git-revision v0.0.9
+│       ├── serde v1.0.192 (*)
+│       ├── serde_derive v1.0.192 (proc-macro) (*)
+│       └── serde_json v1.0.108 (*)
 ├── soroban-wasmi v0.31.1-soroban.20.0.1 (https://github.com/stellar/wasmi?rev=0ed3f3dee30dc41ebe21972399e0a73a41944aa0#0ed3f3de) (*)
 ├── static_assertions v1.1.0
 ├── stellar-strkey v0.0.13 (*)

src/transactions/test/InvokeHostFunctionTests.cpp

@@ -600,7 +600,10 @@ TEST_CASE("Stellar asset contract transfer with CAP-67 address types",
     SorobanTest test(cfg);
     auto& root = test.getRoot();
 
-    auto a1 = root.create("a1", 1'000'000'000);
+    // a1 makes several native transfers within a single run (100M + 300M +
+    // 400M for the muxed-contract case), so it needs enough balance to stay
+    // above its account reserve after all of them.
+    auto a1 = root.create("a1", 2'000'000'000);
     auto a2 = root.create("a2", 1'000'000'000);
     Asset asset = makeAsset(root.getSecretKey(), "USDC");
     a1.changeTrust(asset, 2'000'000'000);
@@ -685,6 +688,25 @@ TEST_CASE("Stellar asset contract transfer with CAP-67 address types",
                 a1, makeClaimableBalanceAddress(ClaimableBalanceID()), 1));
             REQUIRE(client.lastEvent() == std::nullopt);
         }
+#ifdef CAP_0084
+        {
+            INFO("transfer to muxed contract (CAP-0084)");
+            // The destination is the SAC-transfer contract wrapped in a muxed
+            // contract address; the SAC de-muxes to the underlying contract for
+            // the balance and surfaces the id via the `to_muxed_id` event.
+            REQUIRE(client.transfer(
+                a1,
+                makeMuxedContractAddress(
+                    transferContract.getAddress().contractId(),
+                    987'654'321'987'654'321ULL),
+                400'000'000));
+            REQUIRE(*client.lastEvent() ==
+                    client.makeTransferEvent(a1Address,
+                                             transferContract.getAddress(),
+                                             400'000'000,
+                                             987'654'321'987'654'321ULL));
+        }
+#endif
     };
 
     SECTION("native asset")

src/transactions/test/SorobanTxTestUtils.cpp

@@ -66,6 +66,17 @@ makeMuxedAccountAddress(AccountID const& accountID, uint64_t id)
     return addr;
 }
 
+#ifdef CAP_0084
+SCAddress
+makeMuxedContractAddress(Hash const& contractId, uint64_t id)
+{
+    SCAddress addr(SC_ADDRESS_TYPE_MUXED_CONTRACT);
+    addr.muxedContract().contractId = contractId;
+    addr.muxedContract().id = id;
+    return addr;
+}
+#endif
+
 SCVal
 makeI32(int32_t i32)
 {
@@ -1729,18 +1740,29 @@ AssetContractTestClient::transferInvocation(TestAccount& fromAcc,
 
     SCVal toVal(SCV_ADDRESS);
     toAddr = maybeMuxedToAddr;
-    if (maybeMuxedToAddr.type() != SCAddressType::SC_ADDRESS_TYPE_MUXED_ACCOUNT)
-    {
-        toVal.address() = maybeMuxedToAddr;
-    }
-    else
+    if (maybeMuxedToAddr.type() == SCAddressType::SC_ADDRESS_TYPE_MUXED_ACCOUNT)
     {
         PublicKey pk;
         pk.ed25519() = maybeMuxedToAddr.muxedAccount().ed25519;
         toVal.address() =
             makeMuxedAccountAddress(pk, maybeMuxedToAddr.muxedAccount().id);
         toAddr = makeAccountAddress(pk);
     }
+#ifdef CAP_0084
+    else if (maybeMuxedToAddr.type() ==
+             SCAddressType::SC_ADDRESS_TYPE_MUXED_CONTRACT)
+    {
+        // The muxed contract address is passed to the SAC verbatim; balances
+        // are keyed on the underlying (de-muxed) contract.
+        toVal.address() = maybeMuxedToAddr;
+        toAddr =
+            makeContractAddress(maybeMuxedToAddr.muxedContract().contractId);
+    }
+#endif
+    else
+    {
+        toVal.address() = maybeMuxedToAddr;
+    }
 
     LedgerKey fromBalanceKey = makeBalanceKey(fromAcc.getPublicKey());
     LedgerKey toBalanceKey = makeBalanceKey(toAddr);

src/transactions/test/SorobanTxTestUtils.h

@@ -19,6 +19,9 @@ namespace txtest
 
 SCAddress makeContractAddress(Hash const& hash);
 SCAddress makeMuxedAccountAddress(AccountID const& accountID, uint64_t id);
+#ifdef CAP_0084
+SCAddress makeMuxedContractAddress(Hash const& contractId, uint64_t id);
+#endif
 SCVal makeI32(int32_t i32);
 SCVal makeI128(uint64_t u64);
 SCSymbol makeSymbol(std::string const& str);

src/util/XDRCereal.cpp

@@ -59,6 +59,19 @@ cereal_override(cereal::JSONOutputArchive& ar, stellar::SCAddress const& addr,
                 addr.liquidityPoolId().data(), addr.liquidityPoolId().size())),
             field);
         return;
+#ifdef CAP_0084
+    case stellar::SC_ADDRESS_TYPE_MUXED_CONTRACT:
+        ar.setNextName(field);
+        ar.startNode();
+        xdr::archive(ar, addr.muxedContract().id, "id");
+        xdr::archive(ar,
+                     stellar::strKey::toStrKey(stellar::strKey::STRKEY_CONTRACT,
+                                               addr.muxedContract().contractId)
+                         .value,
+                     "contractId");
+        ar.finishNode();
+        return;
+#endif
     default:
         // Unknown address type - serialize as "Unknown(type_id)"
         xdr::archive(ar,