imapc: Add imapc_features=no-msn-updates

This is a stricter version of fetch-msn-workarounds. The MSNs aren't trusted
at all. This means any new untagged EXISTS and EXPUNGE replies are ignored,
as well as untagged FETCH replies that don't include UID.

A potential downside with this feature is that UID FETCH/STORE commands
sent to expunged messages will likely fail without the IMAP client being
notified of the EXPUNGEs. New mails are also not noticed, so this should
be used only when it's known that the clients don't keep the connection
open for long.

diff --git a/src/lib-storage/index/imapc/imapc-mailbox.c b/src/lib-storage/index/imapc/imapc-mailbox.c
index 2045b1dd7527775ceca3bae8b2cbdae4e45c724a..7e5b134ec6e076ae1dd97da8d7d668eff30cb679 100644 (file)
--- a/src/lib-storage/index/imapc/imapc-mailbox.c
+++ b/src/lib-storage/index/imapc/imapc-mailbox.c
@@ -274,7 +274,7 @@ imapc_untagged_exists(const struct imapc_untagged_reply *reply,
        uint32_t exists_count = reply->num;
        const struct mail_index_header *hdr;
 
-       if (mbox == NULL)
+       if (mbox == NULL || IMAPC_BOX_HAS_FEATURE(mbox, IMAPC_FEATURE_NO_MSN_UPDATES))
                return;
 
        mbox->exists_count = exists_count;
@@ -352,7 +352,8 @@ imapc_mailbox_msgmap_update(struct imapc_mailbox *mbox,
        msgmap = imapc_client_mailbox_get_msgmap(mbox->client_box);
        msg_count = imapc_msgmap_count(msgmap);
        if (fetch_uid != 0 &&
-           IMAPC_BOX_HAS_FEATURE(mbox, IMAPC_FEATURE_FETCH_MSN_WORKAROUNDS)) {
+           (IMAPC_BOX_HAS_FEATURE(mbox, IMAPC_FEATURE_FETCH_MSN_WORKAROUNDS) ||
+            IMAPC_BOX_HAS_FEATURE(mbox, IMAPC_FEATURE_NO_MSN_UPDATES))) {
                /* if we know the UID, use own own generated rseq instead of
                   the potentially broken rseq that the server sent. */
                uint32_t fixed_rseq;
@@ -474,6 +475,11 @@ static void imapc_untagged_fetch(const struct imapc_untagged_reply *reply,
                        }
                }
        }
+       if (fetch_uid == 0 &&
+           IMAPC_BOX_HAS_FEATURE(mbox, IMAPC_FEATURE_NO_MSN_UPDATES)) {
+               /* UID missing and we're not tracking MSNs */
+               return;
+       }
 
        imapc_mailbox_init_delayed_trans(mbox);
        if (imapc_mailbox_msgmap_update(mbox, rseq, fetch_uid,
@@ -576,7 +582,8 @@ static void imapc_untagged_expunge(const struct imapc_untagged_reply *reply,
        struct imapc_msgmap *msgmap;
        uint32_t lseq, uid, rseq = reply->num;
        
-       if (mbox == NULL || rseq == 0)
+       if (mbox == NULL || rseq == 0 ||
+           IMAPC_BOX_HAS_FEATURE(mbox, IMAPC_FEATURE_NO_MSN_UPDATES))
                return;
 
        mbox->prev_skipped_rseq = 0;

diff --git a/src/lib-storage/index/imapc/imapc-settings.c b/src/lib-storage/index/imapc/imapc-settings.c
index d445ce8373a2cee41df01ad89b1b52c2b1481415..c62d03c4a2d03327c1e019048bea3fdf9607f8cc 100644 (file)
--- a/src/lib-storage/index/imapc/imapc-settings.c
+++ b/src/lib-storage/index/imapc/imapc-settings.c
@@ -104,6 +104,7 @@ static const struct imapc_feature_list imapc_feature_list[] = {
        { "fetch-bodystructure", IMAPC_FEATURE_FETCH_BODYSTRUCTURE },
        { "send-id", IMAPC_FEATURE_SEND_ID },
        { "fetch-empty-is-expunged", IMAPC_FEATURE_FETCH_EMPTY_IS_EXPUNGED },
+       { "no-msn-updates", IMAPC_FEATURE_NO_MSN_UPDATES },
        { NULL, 0 }
 };
 

diff --git a/src/lib-storage/index/imapc/imapc-settings.h b/src/lib-storage/index/imapc/imapc-settings.h
index 038bc4e3d1c0e5ce3f95b0dc8e7a6abeb44d37ab..8b92a3b6f55c2c3743cbab40cb524d4bf8bc2a3f 100644 (file)
--- a/src/lib-storage/index/imapc/imapc-settings.h
+++ b/src/lib-storage/index/imapc/imapc-settings.h
@@ -20,6 +20,7 @@ enum imapc_features {
        IMAPC_FEATURE_FETCH_BODYSTRUCTURE       = 0x1000,
        IMAPC_FEATURE_SEND_ID                   = 0x2000,
        IMAPC_FEATURE_FETCH_EMPTY_IS_EXPUNGED   = 0x4000,
+       IMAPC_FEATURE_NO_MSN_UPDATES            = 0x8000,
 };
 /* </settings checks> */