pop3: Prevent clients from looping forever trying to fetch an expunged message.

--HG--
branch : HEAD

diff --git a/src/pop3/client.h b/src/pop3/client.h
index 4c21cece99e8e64a361db769f71a74e82092d91d..8e24c54a9a523a83ca3933cc9fb248dd3d7a1d7d 100644 (file)
--- a/src/pop3/client.h
+++ b/src/pop3/client.h
@@ -23,6 +23,7 @@ struct client {
 
        time_t last_input, last_output;
        unsigned int bad_counter;
+       unsigned int highest_expunged_fetch_msgnum;
 
        unsigned int uid_validity;
        unsigned int messages_count;

diff --git a/src/pop3/commands.c b/src/pop3/commands.c
index ce14ddba832ebde4f79f6bc2bca11dd00763f9f1..162e2ce92225360d70f79b396c312aefbf105763 100644 (file)
--- a/src/pop3/commands.c
+++ b/src/pop3/commands.c
@@ -373,10 +373,24 @@ static void fetch_callback(struct client *client)
        client->cmd = NULL;
 }
 
-static void fetch(struct client *client, unsigned int msgnum, uoff_t body_lines)
+static int client_reply_msg_expunged(struct client *client, unsigned int msgnum)
+{
+       client_send_line(client, "-ERR Message %u expunged.", msgnum + 1);
+       if (msgnum <= client->highest_expunged_fetch_msgnum) {
+               /* client tried to fetch an expunged message again.
+                  treat this as error so we'll eventually disconnect the
+                  client instead of letting it loop forever. */
+               return -1;
+       }
+       client->highest_expunged_fetch_msgnum = msgnum;
+       return 1;
+}
+
+static int fetch(struct client *client, unsigned int msgnum, uoff_t body_lines)
 {
         struct fetch_context *ctx;
        struct mail_search_args *search_args;
+       int ret;
 
        search_args = pop3_search_build(client, msgnum+1);
 
@@ -389,9 +403,9 @@ static void fetch(struct client *client, unsigned int msgnum, uoff_t body_lines)
 
        if (mailbox_search_next(ctx->search_ctx, ctx->mail) <= 0 ||
            mail_get_stream(ctx->mail, NULL, NULL, &ctx->stream) < 0) {
-               client_send_line(client, "-ERR Message not found.");
+               ret = client_reply_msg_expunged(client, msgnum);
                fetch_deinit(ctx);
-               return;
+               return ret;
        }
 
        if (body_lines == (uoff_t)-1 && !no_flag_updates) {
@@ -414,6 +428,7 @@ static void fetch(struct client *client, unsigned int msgnum, uoff_t body_lines)
        client->cmd = fetch_callback;
        client->cmd_context = ctx;
        fetch_callback(client);
+       return 1;
 }
 
 static int cmd_retr(struct client *client, const char *args)
@@ -430,8 +445,7 @@ static int cmd_retr(struct client *client, const char *args)
        client->byte_counter = &client->retr_bytes;
        client->byte_counter_offset = client->output->offset;
 
-       fetch(client, msgnum, (uoff_t)-1);
-       return 1;
+       return fetch(client, msgnum, (uoff_t)-1);
 }
 
 static int cmd_rset(struct client *client, const char *args ATTR_UNUSED)
@@ -495,8 +509,7 @@ static int cmd_top(struct client *client, const char *args)
        client->byte_counter = &client->top_bytes;
        client->byte_counter_offset = client->output->offset;
 
-       fetch(client, msgnum, max_lines);
-       return 1;
+       return fetch(client, msgnum, max_lines);
 }
 
 struct cmd_uidl_context {
@@ -653,7 +666,7 @@ static int cmd_uidl(struct client *client, const char *args)
 
                ctx = cmd_uidl_init(client, msgnum+1);
                if (!list_uids_iter(client, ctx))
-                       client_send_line(client, "-ERR Message not found.");
+                       return client_reply_msg_expunged(client, msgnum);
        }
 
        return 1;