gpg: Limit the nesting level of I/O filters.
* common/iobuf.c (MAX_NESTING_FILTER): New. (iobuf_push_filter2): Limit the nesting level. * g10/mainproc.c (mainproc_context): New field ANY. Change HAVE_DATA and ANY_SIG_SIGN to bit fields of ANY. Add bit field UNCOMPRESS_FAILED. (proc_compressed): Avoid printing multiple Bad Data messages. (check_nesting): Return GPG_ERR_BAD_DATA instead of UNEXPECTED_DATA.
This is a more general fix for the nested compression packet bug. In
particular this helps g10/import.c:read_block to stop pushing
compression filters onto an iobuf stream. This patch also reduces the
number of error messages for the non-import case.
- Signed-off-by: Werner Koch <wk@gnupg.org>