core: do not accept contact request that was already accepted

src/Simplex/Chat/Library/Internal.hs

@@ -914,6 +914,10 @@ acceptContactRequest nm user@User {userId} UserContactRequest {agentInvitationId
             forM_ xContactId $ \xcId -> setContactAcceptedXContactId db ct xcId
             createAcceptedContactConn db user userContactLinkId_ contactId connId chatV cReqChatVRange pqSup' incognitoProfile subMode currentTs
           pure (ct {activeConn = Just conn} :: Contact, conn, incognitoProfile)
+        -- contact connection in any status other than prepared is created when the request is accepted
+        -- (see createAcceptedContactConn), so the request was already accepted -
+        -- accepting it again would fail in the agent, as the invitation is already used.
+        Just Connection {connStatus} | connStatus /= ConnPrepared -> throwCmdError "contact request already accepted"
         Just conn@Connection {customUserProfileId} -> do
           incognitoProfile <- forM customUserProfileId $ \pId -> withFastStore $ \db -> getProfileById db userId pId
           pure (ct, conn, ExistingIncognito <$> incognitoProfile)

tests/ChatTests/Profiles.hs

@@ -61,6 +61,7 @@ chatProfileTests = do
     it "supporter badge sent to contact connecting via address" testUserBadgeContactAddress
   describe "user contact link" $ do
     it "create and connect via contact link" testUserContactLink
+    it "accepting contact request twice fails" testAcceptContactRequestTwice
     it "create address on specified server" testCreateAddressOnServer
     it "retry connecting via contact link" testRetryConnectingViaContactLink
     it "add contact link to profile" testProfileLink
@@ -644,6 +645,24 @@ testUserContactLink =
       alice @@@ [("@cath", lastChatFeature), ("@bob", "hey")]
       alice <##> cath
 
+testAcceptContactRequestTwice :: HasCallStack => TestParams -> IO ()
+testAcceptContactRequestTwice =
+  testChat2 aliceProfile bobProfile $
+    \alice bob -> do
+      alice ##> "/ad"
+      cLink <- getContactLink alice True
+      bob ##> ("/c " <> cLink)
+      alice <#? bob
+      alice ##> "/ac bob"
+      alice <## "bob (Bob): accepting contact request, you can send messages to contact"
+      concurrently_
+        (bob <## "alice (Alice): contact is connected")
+        (alice <## "bob (Bob): contact is connected")
+      -- the request is not deleted when accepted, accepting it again fails without using the invitation
+      alice ##> "/_accept 1"
+      alice <## "bad chat command: contact request already accepted"
+      alice <##> bob
+
 testCreateAddressOnServer :: HasCallStack => TestParams -> IO ()
 testCreateAddressOnServer ps = testChat aliceProfile test ps
   where