libstore: refuse to serialise ancient protocols

We don't want to deal with these at all, let's stop doing so.

(marking this one as the fix commit since its immediate predecessors
aren't the complete fix)
Fixes: lix-project/lix#325

Change-Id: Ieea1b0b8ac0f903d1e24e5b3e63cfe12eeec119d

src/libstore/daemon.cc

@@ -262,14 +262,8 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
     TrustedFlag trusted, RecursiveFlag recursive, WorkerProto::Version clientVersion,
     Source & from, BufferedSink & to, WorkerProto::Op op)
 {
-    WorkerProto::ReadConn rconn {
+    WorkerProto::ReadConn rconn{from, clientVersion};
-        .from = from,
+    WorkerProto::WriteConn wconn{to, clientVersion};
-        .version = clientVersion,
-    };
-    WorkerProto::WriteConn wconn {
-        .to = to,
-        .version = clientVersion,
-    };
 
     switch (op) {
 
@@ -1028,10 +1022,7 @@ void processConnection(
         auto temp = trusted
             ? store->isTrustedClient()
             : std::optional { NotTrusted };
-        WorkerProto::WriteConn wconn {
+        WorkerProto::WriteConn wconn {to, clientVersion};
-            .to = to,
-            .version = clientVersion,
-        };
         WorkerProto::write(*store, wconn, temp);
     }
 

src/libstore/remote-store-connection.hh

@@ -68,10 +68,7 @@ struct RemoteStore::Connection
      */
     operator WorkerProto::ReadConn ()
     {
-        return WorkerProto::ReadConn {
+        return WorkerProto::ReadConn {from, daemonVersion};
-            .from = from,
-            .version = daemonVersion,
-        };
     }
 
     /**
@@ -84,10 +81,7 @@ struct RemoteStore::Connection
      */
     operator WorkerProto::WriteConn ()
     {
-        return WorkerProto::WriteConn {
+        return WorkerProto::WriteConn {to, daemonVersion};
-            .to = to,
-            .version = daemonVersion,
-        };
     }
 
     virtual ~Connection();

src/libstore/remote-store.cc

@@ -466,7 +466,7 @@ void RemoteStore::addToStore(const ValidPathInfo & info, Source & source,
             sink
                 << exportMagic
                 << printStorePath(info.path);
-            WorkerProto::WriteConn nested { .to = sink, .version = conn->daemonVersion };
+            WorkerProto::WriteConn nested { sink, conn->daemonVersion };
             WorkerProto::write(*this, nested, info.references);
             sink
                 << (info.deriver ? printStorePath(*info.deriver) : "")
@@ -511,14 +511,13 @@ void RemoteStore::addMultipleToStore(
     RepairFlag repair,
     CheckSigsFlag checkSigs)
 {
+    auto remoteVersion = getProtocol();
+
     auto source = sinkToSource([&](Sink & sink) {
         sink << pathsToCopy.size();
         for (auto & [pathInfo, pathSource] : pathsToCopy) {
             WorkerProto::Serialise<ValidPathInfo>::write(*this,
-                 WorkerProto::WriteConn {
+                 WorkerProto::WriteConn {sink, remoteVersion},
-                     .to = sink,
-                     .version = 16,
-                 },
                  pathInfo);
             pathSource->drainInto(sink);
         }

src/libstore/store-api.cc

@@ -369,15 +369,14 @@ void Store::addMultipleToStore(
     RepairFlag repair,
     CheckSigsFlag checkSigs)
 {
+    auto remoteVersion = getProtocol();
+
     auto expected = readNum<uint64_t>(source);
     for (uint64_t i = 0; i < expected; ++i) {
-        // FIXME we should not be using the worker protocol here, let
+        // FIXME we should not be using the worker protocol here at all!
-        // alone the worker protocol with a hard-coded version!
         auto info = WorkerProto::Serialise<ValidPathInfo>::read(*this,
-            WorkerProto::ReadConn {
+            WorkerProto::ReadConn {source, remoteVersion}
-                .from = source,
+        );
-                .version = 16,
-            });
         info.ultimate = false;
         addToStore(info, source, repair, checkSigs);
     }

src/libstore/worker-protocol.hh

@@ -72,6 +72,10 @@ struct WorkerProto
     struct ReadConn {
         Source & from;
         Version version;
+
+        ReadConn(Source & from, Version version) : from(from), version(version) {
+            assert(version >= MIN_SUPPORTED_WORKER_PROTO_VERSION);
+        }
     };
 
     /**
@@ -81,6 +85,10 @@ struct WorkerProto
     struct WriteConn {
         Sink & to;
         Version version;
+
+        WriteConn(Sink & to, Version version) : to(to), version(version) {
+            assert(version >= MIN_SUPPORTED_WORKER_PROTO_VERSION);
+        }
     };
 
     /**

tests/unit/libstore/protocol.hh

@@ -39,10 +39,8 @@ public:
                 StringSource from { expected };
                 Proto::template Serialise<T>::read(
                     *LibStoreTest::store,
-                    typename Proto::ReadConn {
+                    typename Proto::ReadConn {from, version}
-                        .from = from,
+                );
-                        .version = version,
-                    });
             });
 
             ASSERT_EQ(got, value);
@@ -60,10 +58,7 @@ public:
         StringSink to;
         Proto::write(
             *LibStoreTest::store,
-            typename Proto::WriteConn {
+            typename Proto::WriteConn {to, version},
-                .to = to,
-                .version = version,
-            },
             value);
 
         if (testAccept())