[commit] 1.4: be more tolerant of formally malformed response codes

[Oswald Buddenhagen via isync-devel]

commit 95a83c8220861185906df5b38eed589984847bfb
Author: Oswald Buddenhagen <o...@users.sf.net>
Date:   Sun Feb 14 23:37:39 2021 +0100

    be more tolerant of formally malformed response codes
    
    fastmail sends flags containing ']' in PERMANENTFLAGS, which is formally
    illegal. however, if we parse the embedded list before looking for the
    response code's closing ']', things work out fine.
    
    as a side effect we won't complain about similarly or completely
    malformed response codes we don't recognize at all, which may or may not
    be considered an improvement ...

 src/drv_imap.c | 29 +++++++++++++++++------------
 1 file changed, 17 insertions(+), 12 deletions(-)

diff --git a/src/drv_imap.c b/src/drv_imap.c
index 2ade80e..e6e4b26 100644
--- a/src/drv_imap.c
+++ b/src/drv_imap.c
@@ -1253,48 +1253,53 @@ parse_response_code( imap_store_t *ctx, imap_cmd_t 
*cmd, char *s )
        if (!s || *s != '[')
                return RESP_OK;         /* no response code */
        s++;
-       if (!(p = strchr( s, ']' ))) {
-         bad_resp:
+       if (!(arg = next_arg( &s ))) {
                error( "IMAP error: malformed response code\n" );
                return RESP_CANCEL;
        }
-       *p++ = 0;
-       if (!(arg = next_arg( &s )))
-               goto bad_resp;
        if (!strcmp( "UIDVALIDITY", arg )) {
                if (!(arg = next_arg( &s )) ||
-                   (ctx->uidvalidity = strtoul( arg, &earg, 10 ), *earg))
+                   (ctx->uidvalidity = strtoul( arg, &earg, 10 ), *earg != 
']'))
                {
                        error( "IMAP error: malformed UIDVALIDITY status\n" );
                        return RESP_CANCEL;
                }
        } else if (!strcmp( "UIDNEXT", arg )) {
                if (!(arg = next_arg( &s )) ||
-                   (ctx->uidnext = strtoul( arg, &earg, 10 ), *earg))
+                   (ctx->uidnext = strtoul( arg, &earg, 10 ), *earg != ']'))
                {
                        error( "IMAP error: malformed UIDNEXT status\n" );
                        return RESP_CANCEL;
                }
        } else if (!strcmp( "CAPABILITY", arg )) {
+               if (!(p = strchr( s, ']' ))) {
+                       error( "IMAP error: malformed CAPABILITY status\n" );
+                       return RESP_CANCEL;
+               }
+               *p = 0;
                parse_capability( ctx, s );
-       } else if (!strcmp( "ALERT", arg )) {
+       } else if (!strcmp( "ALERT]", arg )) {
                /* RFC2060 says that these messages MUST be displayed
                 * to the user
                 */
-               for (; isspace( (uchar)*p ); p++);
-               error( "*** IMAP ALERT *** %s\n", p );
+               if (!s) {
+                       error( "IMAP error: malformed ALERT status\n" );
+                       return RESP_CANCEL;
+               }
+               for (; isspace( (uchar)*s ); s++);
+               error( "*** IMAP ALERT *** %s\n", s );
        } else if (cmd && !strcmp( "APPENDUID", arg )) {
                if (!(arg = next_arg( &s )) ||
                    (ctx->uidvalidity = strtoul( arg, &earg, 10 ), *earg) ||
                    !(arg = next_arg( &s )) ||
-                   (((imap_cmd_out_uid_t *)cmd)->out_uid = strtoul( arg, 
&earg, 10 ), *earg))
+                   (((imap_cmd_out_uid_t *)cmd)->out_uid = strtoul( arg, 
&earg, 10 ), *earg != ']'))
                {
                        error( "IMAP error: malformed APPENDUID status\n" );
                        return RESP_CANCEL;
                }
        } else if (!strcmp( "PERMANENTFLAGS", arg )) {
                parse_list_init( &ctx->parse_list_sts );
-               if (parse_imap_list( NULL, &s, &ctx->parse_list_sts ) != 
LIST_OK) {
+               if (parse_imap_list( NULL, &s, &ctx->parse_list_sts ) != 
LIST_OK || *s != ']') {
                        error( "IMAP error: malformed PERMANENTFLAGS status\n" 
);
                        return RESP_CANCEL;
                }


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