Geary.Imap: Update IMAP quirks based on server greeting rather type

Use server greeting to update IMAP quirks, so that if e.g. a GMail
account is configured as a generic account, it still gets the right
quirks.

src/engine/api/geary-engine.vala

@@ -284,10 +284,7 @@ public class Geary.Engine : BaseObject {
             (security, cx) => account.untrusted_host(service, security, cx)
         );
 
-        var client = new Imap.ClientSession(
-            endpoint,
-            Imap.ClientService.new_quirks_for_provider(account.service_provider)
-        );
+        var client = new Imap.ClientSession(endpoint, new Imap.Quirks());
         GLib.Error? imap_err = null;
         try {
             yield client.connect_async(

src/engine/imap/api/imap-client-service.vala

@@ -39,36 +39,6 @@ public class Geary.Imap.ClientService : Geary.ClientService {
     private const int CHECK_NOOP_THRESHOLD_SEC = 5;
 
 
-    public static Quirks new_quirks_for_provider(ServiceProvider provider) {
-        var quirks = new Quirks();
-        switch (provider) {
-        case GMAIL:
-            // As of 2020-05-02, GMail doesn't seem to quote flag
-            // atoms containing reserved characters, and at least one
-            // use of both `]` and ` ` have been found. This works
-            // around the former. See #746
-            quirks.flag_atom_exceptions = "]";
-            break;
-
-        case ServiceProvider.OUTLOOK:
-            // As of June 2016, outlook.com's IMAP servers have a bug
-            // where a large number (~50) of pipelined STATUS commands
-            // on mailboxes with many messages will eventually cause
-            // it to break command parsing and return a BAD response,
-            // causing us to drop the connection. Limit the number of
-            // pipelined commands per batch to work around this.  See
-            // b.g.o Bug 766552
-            quirks.max_pipeline_batch_size = 25;
-            break;
-
-        default:
-            // noop
-            break;
-        }
-        return quirks;
-    }
-
-
     /**
      * Set to zero or negative value if keepalives should be disabled when a connection has not
      * selected a mailbox.  (This is not recommended.)
@@ -131,7 +101,7 @@ public class Geary.Imap.ClientService : Geary.ClientService {
         get { return LOGGING_DOMAIN; }
     }
 
-    private Quirks quirks;
+    private Quirks quirks = new Quirks();
 
     private Nonblocking.Mutex sessions_mutex = new Nonblocking.Mutex();
     private Gee.Set<ClientSession> all_sessions =
@@ -147,7 +117,6 @@ public class Geary.Imap.ClientService : Geary.ClientService {
                          ServiceInformation configuration,
                          Endpoint remote) {
         base(account, configuration, remote);
-        this.quirks = new_quirks_for_provider(account.service_provider);
     }
 
     /**
@@ -403,6 +372,7 @@ public class Geary.Imap.ClientService : Geary.ClientService {
             // An error was thrown, so close the pool
             this.close_pool.begin(true);
         } else {
+            this.quirks.update_for_server(new_session);
             try {
                 yield this.sessions_mutex.execute_locked(() => {
                         this.all_sessions.add(new_session);

src/engine/imap/api/imap-quirks.vala

@@ -39,4 +39,46 @@ public class Geary.Imap.Quirks : BaseObject {
     public uint max_pipeline_batch_size { get; set; default = 0; }
 
 
+
+    public void update_for_server(ClientSession session) {
+        if (session.server_greeting != null) {
+            var greeting = session.server_greeting.get_text() ?? "";
+            if (greeting.has_prefix("Gimap")) {
+                update_for_gmail();
+            } else if (greeting.has_prefix("The Microsoft Exchange")) {
+                update_for_outlook();
+            }
+        }
+    }
+
+    /**
+     * Updates this quirks object with known quirks for GMail.
+     *
+     * As of 2020-05-02, GMail doesn't seem to quote flag
+     * atoms containing reserved characters, and at least one
+     * use of both `]` and ` ` have been found. This works
+     * around the former.
+     *
+     * See [[https://gitlab.gnome.org/GNOME/geary/-/issues/746]]
+     */
+    public void update_for_gmail() {
+        this.flag_atom_exceptions = "]";
+    }
+
+    /**
+     * Updates this quirks object with known quirks for Outlook.com.
+     *
+     * As of June 2016, outlook.com's IMAP servers have a bug where a
+     * large number (~50) of pipelined STATUS commands on mailboxes
+     * with many messages will eventually cause it to break command
+     * parsing and return a BAD response, causing us to drop the
+     * connection. Limit the number of pipelined commands per batch to
+     * work around this.
+     *
+     * See [[https://bugzilla.gnome.org/show_bug.cgi?id=766552]]
+     */
+    public void update_for_outlook() {
+        this.max_pipeline_batch_size = 25;
+    }
+
 }

test/engine/imap/transport/imap-deserializer-test.vala

@@ -202,7 +202,6 @@ class Geary.Imap.DeserializerTest : TestCase {
         string greeting = "* OK Gimap ready for requests from 115.187.245.46 c194mb399904375ivc";
         this.stream.add_data(greeting.data);
         this.stream.add_data(EOL.data);
-        this.deser.quirks = ClientService.new_quirks_for_provider(GMAIL);
 
         this.process.begin(Expect.MESSAGE, this.async_completion);
         RootParameters? message = this.process.end(async_result());
@@ -249,7 +248,8 @@ class Geary.Imap.DeserializerTest : TestCase {
         string flags = """* FLAGS (\Answered \Flagged \Draft \Deleted \Seen $NotPhishing $Phishing)""";
         this.stream.add_data(flags.data);
         this.stream.add_data(EOL.data);
-        this.deser.quirks = ClientService.new_quirks_for_provider(GMAIL);
+        this.deser.quirks = new Imap.Quirks();
+        this.deser.quirks.update_for_gmail();
 
         this.process.begin(Expect.MESSAGE, this.async_completion);
         RootParameters? message = this.process.end(async_result());
@@ -261,7 +261,8 @@ class Geary.Imap.DeserializerTest : TestCase {
         string flags = """* OK [PERMANENTFLAGS (\Answered \Flagged \Draft \Deleted \Seen $NotPhishing $Phishing \*)] Flags permitted.""";
         this.stream.add_data(flags.data);
         this.stream.add_data(EOL.data);
-        this.deser.quirks = ClientService.new_quirks_for_provider(GMAIL);
+        this.deser.quirks = new Imap.Quirks();
+        this.deser.quirks.update_for_gmail();
 
         this.process.begin(Expect.MESSAGE, this.async_completion);
         RootParameters? message = this.process.end(async_result());
@@ -275,7 +276,8 @@ class Geary.Imap.DeserializerTest : TestCase {
         string flags = """* FLAGS (\Answered \Flagged \Draft \Deleted \Seen $Forwarded $MDNSent $NotPhishing $Phishing Junk LoadRemoteImages NonJunk OIB-Seen-INBOX OIB-Seen-Unsubscribe OIB-Seen-[Gmail]/Important OIB-Seen-[Gmail]/Spam OIB-Seen-[Gmail]/Tous les messages)""";
         this.stream.add_data(flags.data);
         this.stream.add_data(EOL.data);
-        this.deser.quirks = ClientService.new_quirks_for_provider(GMAIL);
+        this.deser.quirks = new Imap.Quirks();
+        this.deser.quirks.update_for_gmail();
 
         this.process.begin(Expect.MESSAGE, this.async_completion);
         RootParameters? message = this.process.end(async_result());

test/integration/imap/client-session.vala

@@ -29,9 +29,7 @@ class Integration.Imap.ClientSession : TestCase {
     public override void set_up() {
         this.session = new Geary.Imap.ClientSession(
             this.config.target,
-            Geary.Imap.ClientService.new_quirks_for_provider(
-                this.config.provider
-            )
+            new Geary.Imap.Quirks()
         );
     }