Wolfgang Wander's patch for better UIDL-only support.

svn path=/trunk/; revision=1272

1 files changed, 114 insertions, 3 deletions

diff --git a/pop3.c b/pop3.c
index e5e26299..5b8f53b9 100644
--- a/pop3.c
+++ b/pop3.c
@@ -199,6 +199,113 @@ int pop3_getauth(int sock, struct query *ctl, char *greeting)
     return(0);
 }
 
+static int
+pop3_gettopid( int sock, int num , char *id)
+{
+    int ok;
+    int got_it;
+    char buf [POPBUFSIZE+1];
+    sprintf( buf, "TOP %d 1", num );
+    if( (ok = gen_transact(sock, buf ) ) != 0 )
+       return ok; 
+    got_it = 0;
+    while((ok = gen_recv(sock, buf, sizeof(buf))) == 0) {
+	if( buf[0] == '.' )
+	    break;
+	if( ! got_it && ! strncasecmp("Message-Id:", buf, 11 )) {
+	    got_it = 1;
+	    sscanf( buf+12, "%s", id);
+	}
+    }
+    return 0;
+}
+
+static int
+pop3_slowuidl( int sock,  struct query *ctl, int *countp, int *newp)
+{
+    /* This approach tries to get the message headers from the
+     * remote hosts and compares the message-id to the already known
+     * ones:
+     *  + if the first message containes a new id, all messages on
+     *    the server will be new
+     *  + if the first is known, try to estimate the last known message
+     *    on the server and check. If this works you know the total number
+     *    of messages to get.
+     *  + Otherwise run a binary search to determine the last known message
+     */
+    int ok, nolinear = 0;
+    int first_nr, list_len, try_id, try_nr, hop_id, add_id;
+    int num;
+    char id [IDLEN+1];
+    
+    if( (ok = pop3_gettopid( sock, 1, id )) != 0 )
+	return ok;
+    
+    if( ( first_nr = str_nr_in_list(&ctl->oldsaved, id) ) == -1 ) {
+	/* the first message is unknown -> all messages are new */
+	*newp = *countp;	
+	return 0;
+    }
+
+    /* check where we expect the latest known message */
+    list_len = count_list( &ctl->oldsaved );
+    try_id = list_len  - first_nr; /* -1 + 1 */
+    if( try_id > 1 ) {
+	if( try_id <= *countp ) {
+	    if( (ok = pop3_gettopid( sock, try_id, id )) != 0 )
+		return ok;
+    
+	    try_nr = str_nr_in_list(&ctl->oldsaved, id);
+	} else {
+	    try_id = *countp+1;
+	    try_nr = -1;
+	}
+	if( try_nr != list_len -1 ) {
+	    /* some messages inbetween have been deleted... */
+	    if( try_nr == -1 ) {
+		nolinear = 1;
+
+		for( add_id = 1<<30; add_id > try_id-1; add_id >>= 1 )
+		    ;
+		for( ; add_id; add_id >>= 1 ) {
+		    if( try_nr == -1 ) {
+			if( try_id - add_id <= 1 ) {
+			    continue;
+			}
+			try_id -= add_id;
+		    } else 
+			try_id += add_id;
+		    
+		    if( (ok = pop3_gettopid( sock, try_id, id )) != 0 )
+			return ok;
+		    try_nr = str_nr_in_list(&ctl->oldsaved, id);
+		}
+		if( try_nr == -1 ) {
+		    try_id--;
+		}
+	    } else {
+		error(0,0,"Messages inserted into list on server. "
+		      "Cannot handle this.");
+		return -1;
+	    }
+	} 
+    }
+    /* The first try_id messages are known -> copy them to
+       the newsaved list */
+    for( num = first_nr; num < list_len; num++ )
+	save_str(&ctl->newsaved, num-first_nr + 1,
+		 str_from_nr_list( &ctl->oldsaved, num ));
+
+    if( nolinear ) {
+	free_str_list(&ctl->oldsaved);
+	ctl->oldsaved = 0;
+	last = try_id;
+    }
+
+    *newp = *countp - try_id;
+    return 0;
+}
+
 static int pop3_getrange(int sock, 
 			 struct query *ctl,
 			 const char *folder,
@@ -243,9 +350,13 @@ static int pop3_getrange(int sock,
 	}
  	else
  	{
- 	    /* grab the mailbox's UID list */
- 	    if ((ok = gen_transact(sock, "UIDL")) != 0)
-		PROTOCOL_ERROR
+	    /* grab the mailbox's UID list */
+	    if ((ok = gen_transact(sock, "UIDL")) != 0)
+	    {
+		/* don't worry, yet! do it the slow way */
+		if((ok = pop3_slowuidl( sock, ctl, countp, newp))!=0)
+		    PROTOCOL_ERROR
+	    }
 	    else
 	    {
 		int	num;