6 files changed, 30 insertions, 1 deletions
diff --git a/src/libstore/legacy-ssh-store.cc b/src/libstore/legacy-ssh-store.cc
index 88d2574e8..26e185198 100644
--- a/src/libstore/legacy-ssh-store.cc
+++ b/src/libstore/legacy-ssh-store.cc
@@ -303,6 +303,12 @@ struct LegacySSHStore : public Store
     {
         auto conn(connections->get());
     }
+
+    unsigned int getProtocol() override
+    {
+        auto conn(connections->get());
+        return conn->remoteVersion;
+    }
 };
 
 static RegisterStoreImplementation regStore([](
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 197b9d789..216f3417c 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -1338,6 +1338,12 @@ void LocalStore::verifyPath(const Path & path, const PathSet & store,
 }
 
 
+unsigned int LocalStore::getProtocol()
+{
+    return PROTOCOL_VERSION;
+}
+
+
 #if defined(FS_IOC_SETFLAGS) && defined(FS_IOC_GETFLAGS) && defined(FS_IMMUTABLE_FL)
 
 static void makeMutable(const Path & path)
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index 746bdbeed..fce963433 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -209,6 +209,8 @@ public:
 
     void registerValidPaths(const ValidPathInfos & infos);
 
+    unsigned int getProtocol() override;
+
     void vacuumDB();
 
     /* Repair the contents of the given path by redownloading it using
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index ef8b0e53b..def140cfb 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -693,6 +693,13 @@ void RemoteStore::connect()
 }
 
 
+unsigned int RemoteStore::getProtocol()
+{
+    auto conn(connections->get());
+    return conn->daemonVersion;
+}
+
+
 void RemoteStore::flushBadConnections()
 {
     connections->flushBad();
diff --git a/src/libstore/remote-store.hh b/src/libstore/remote-store.hh
index 7f9d7d1f5..4f554b598 100644
--- a/src/libstore/remote-store.hh
+++ b/src/libstore/remote-store.hh
@@ -98,6 +98,8 @@ public:
 
     void connect() override;
 
+    unsigned int getProtocol() override;
+
     void flushBadConnections();
 
 protected:
@@ -127,7 +129,7 @@ protected:
 
     ConnectionHandle getConnection();
 
-    friend class ConnectionHandle;
+    friend struct ConnectionHandle;
 
 private:
 
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index 099818ed6..106b2be5e 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -599,6 +599,12 @@ public:
        a notion of connection. Otherwise this is a no-op. */
     virtual void connect() { };
 
+    /* Get the protocol version of this store or it's connection. */
+    virtual unsigned int getProtocol()
+    {
+        return 0;
+    };
+
     /* Get the priority of the store, used to order substituters. In
        particular, binary caches can specify a priority field in their
        "nix-cache-info" file. Lower value means higher priority. */