Better IMAP support.

svn path=/trunk/; revision=185

2 files changed, 30 insertions, 71 deletions

diff --git a/NEWS b/NEWS
index 566151f6..120f9434 100644
--- a/NEWS
+++ b/NEWS
@@ -3,8 +3,7 @@
 Test RPOP feature against a server that has it.
 
 Support IMAP4 extensions for secure challenge-response, once they're actually
-standardized.  Also, use the CAPABILITY command to detect when we're talking
-to a true IMAP4 server and use SEARCH UNSEEN.
+standardized.
 
 Inflict pain on the person(s) responsible for removing LAST from POP3.
 
@@ -18,6 +17,11 @@ fetchmail-1.3 (Sun Sep 29 01:22:21 EDT 1996):
 
 * Kill off -2 and -3 options, redundant popclient remnants.
 
+* IMAP code simplification and robustification.  Use FETCH FLAGS to find
+  seen messages.  Code should now work even if unseen messages are 
+  interspersed with seen ones, and even if messages are appended to the
+  mailbox during the run.
+
 fetchmail-1.2 (Sat Sep 28 15:40:50 EDT 1996):
 
 * The great option massacre.  Remove --stdout, --limit, --local, --mda.
diff --git a/imap.c b/imap.c
index 70e29150..cd7e4bdf 100644
--- a/imap.c
+++ b/imap.c
@@ -9,54 +9,11 @@
   programmer:   Eric S. Raymond
   description:  IMAP client code
 
-Chris Newman, one of the IMAP maintainers, criticized this as follows:
-------------------------------- CUT HERE -----------------------------------
-On Wed, 18 Sep 1996, Eric S. Raymond wrote:
-> 1. I do one one SELECT, at the beginning of the fetch.  
-> 
-> 2. I assume that I can pick an upper bound on message numbers from the EXISTS
->    reponse.
-
-Correct.
-
-> 3. If there is an UNSEEN nnn trailer on the OK response to SELECT, I assume
->    that the unseen messages have message numbers which are the nnn consecutive
->    integers up to and including the upper bound.
-> 
-> 4. Otherwise, if the response included RECENT nnn, I assume that the unseen
->    messages have message numbers which are the nnn consecutive integers up to
->    and including the upper bound.
-
-These will only work if your client is the only client that accesses the
-INBOX.  There is no requirement that the UNSEEN and RECENT messages are at
-the end of the folder in general.
-
-If you want to present all UNSEEN messages and flag all the messages you
-download as SEEN, you could do a SEARCH UNSEEN and just fetch those
-messages.
-
-However, the proper thing to do if you want to present the messages when
-disconnected from the server is to use UIDs.  To do this, you remember the
-highest UID you have (you can initialize to 0), and fetch everything with
-a higher UID.  Ideally, you shouldn't cause the SEEN flag to be set until
-the user has actually seen the message.  This requires STORE +FLAGS SEEN
-for those messages which have been seen since the last update.
-
-The key thing to remember is that in IMAP the server holds the
-authoratative list of messages and the client just holds a cache.  This is
-a very different model from POP.
-------------------------------- CUT HERE -----------------------------------
-
-A problem with this recommendation is that the UID commands don't exist
-in IMAP2bis.  Since we want to preserve IMAP2bis capability (so fetchmail
-will continue to work with the pre-IMAP4 imapd) and we've warned the user
-that multiple concurrent fetchmail runs are a Bad Idea, we'll stick with
-this logic for now.
-
  ***********************************************************************/
 
 #include  <config.h>
 #include  <stdio.h>
+#include  <string.h>
 #include  "socket.h"
 #include  "fetchmail.h"
 
@@ -66,8 +23,7 @@ this logic for now.
 
  *********************************************************************/
 
-static int count, first;
-static int exists, unseen, recent;
+static int count, seen;
 
 int imap_ok (argbuf,socket)
 /* parse command response */
@@ -79,6 +35,7 @@ int socket;
     char *bufp;
     int n;
 
+    seen = 0;
     do {
 	if (SockGets(socket, buf, sizeof(buf)) < 0)
 	    return(PS_SOCKET);
@@ -88,12 +45,9 @@ int socket;
 
 	/* interpret untagged status responses */
 	if (strstr(buf, "EXISTS"))
-	    exists = atoi(buf+2);
-	if (strstr(buf, "RECENT"))
-	    recent = atoi(buf+2);
-	if (sscanf(buf + 2, "OK [UNSEEN %d]", &n) == 1)
-	    unseen = n;
-
+	    count = atoi(buf+2);
+	if (strstr(buf, "FLAGS"))
+	    seen = (strstr(buf, "Seen") != (char *)NULL);
     } while
 	(tag[0] != '\0' && strncmp(buf, tag, strlen(tag)));
 
@@ -146,31 +100,32 @@ int *firstp;
     int ok;
 
     /* find out how many messages are waiting */
-    exists = unseen = recent = -1;
     ok = gen_transact(socket,
 		  "SELECT %s",
 		  queryctl->remotefolder[0] ? queryctl->remotefolder : "INBOX");
     if (ok != 0)
 	return(ok);
 
-    /* compute size of message run */
-    *countp = exists;
-    if (queryctl->fetchall)
-	*firstp = 1;
-    else {
-	if (exists > 0 && unseen == -1) {
-	    fprintf(stderr,
-		    "no UNSEEN response; assuming all %d RECENT messages are unseen\n",
-		    recent);
-	    *firstp = exists - recent + 1;
-	} else {
-	    *firstp = unseen;
-	}
-    }
+    *countp = count;
+    *firstp = 1;
 
     return(0);
 }
 
+static imap_is_old(socket, queryctl, num)
+int socket;
+struct hostrec *queryctl;
+int num;
+{
+    char buf [POPBUFSIZE+1];
+    int ok;
+
+    if ((ok = gen_transact(socket, "FETCH %d FLAGS", num)) != 0)
+	exit(PS_ERROR);
+
+    return(seen);
+}
+
 static int imap_fetch(socket, number, lenp)
 /* request nth message */
 int socket;
@@ -215,7 +170,7 @@ int socket;
 struct hostrec *queryctl;
 int number;
 {
-    return(socket, gen_transact("STORE %d +FLAGS (\\Deleted)", number));
+    return(gen_transact(socket, "STORE %d +FLAGS (\\Deleted)", number));
 }
 
 static struct method imap =
@@ -227,7 +182,7 @@ static struct method imap =
     imap_ok,		/* parse command response */
     imap_getauth,	/* get authorization */
     imap_getrange,	/* query range of messages */
-    NULL,		/* no UID check */
+    imap_is_old,	/* no UID check */
     imap_fetch,		/* request given message */
     imap_trail,		/* eat message trailer */
     imap_delete,	/* set IMAP delete flag */