net_imap: Increase buffer size for headers length to 32 KB.

Increase buffer used for all headers for FETCH response 4x from
8,192 to 32,768. This still isn't foolproof, but should work
better, short of using a dynamically resized buffer for this
operation. (At the very least, this buffer size is sufficient
to handle all of my 300,000+ archived messages.)

Author: InterLinked1

nets/net_imap/imap_server_fetch.c

@@ -262,7 +262,11 @@ static void adjust_send_offset(struct fetch_body_request *fbr, off_t *restrict o
 
 static int send_filtered_headers(struct imap_session *imap, struct fetch_body_request *fbr, const char *itemname, FILE **restrict fp, const char *fullname, const char *headerlist, int filter)
 {
-	char headersbuf[8192];
+	/* XXX FIXME This should probably be dynamically allocated/resized as needed.
+	 * No matter how large of a static buffer we use, it's always possible that the headers will be longer.
+	 * Downside of that would be efficiency, since that could be a lot of large allocations/deallocations
+	 * for a FETCH 1:* operation. */
+	char headersbuf[32768];
 	size_t headersbuflen = sizeof(headersbuf);
 	char *buf = headersbuf;
 	size_t len = headersbuflen;