diff options
Diffstat (limited to 'g10/armor.c')
| -rw-r--r-- | g10/armor.c | 67 |
1 files changed, 54 insertions, 13 deletions
diff --git a/g10/armor.c b/g10/armor.c index e34518e0b..98fb1056b 100644 --- a/g10/armor.c +++ b/g10/armor.c @@ -193,36 +193,77 @@ initialize(void) /**************** * Check whether this is an armored file or not See also - * parse-packet.c for details on this code For unknown historic - * reasons we use a string here but only the first byte will be used. + * parse-packet.c for details on this code. * Returns: True if it seems to be armored */ static int is_armored( const byte *buf ) { - int ctb, pkttype; + int ctb, pkttype; + int indeterminate_length_allowed; ctb = *buf; if( !(ctb & 0x80) ) - return 1; /* invalid packet: assume it is armored */ + /* The most significant bit of the CTB must be set. Since it is + cleared, this is not a binary OpenPGP message. Assume it is + armored. */ + return 1; + pkttype = ctb & 0x40 ? (ctb & 0x3f) : ((ctb>>2)&0xf); switch( pkttype ) { - case PKT_MARKER: + case PKT_PUBKEY_ENC: + case PKT_SIGNATURE: case PKT_SYMKEY_ENC: case PKT_ONEPASS_SIG: - case PKT_PUBLIC_KEY: case PKT_SECRET_KEY: - case PKT_PUBKEY_ENC: - case PKT_SIGNATURE: - case PKT_COMMENT: - case PKT_OLD_COMMENT: - case PKT_PLAINTEXT: + case PKT_PUBLIC_KEY: + case PKT_SECRET_SUBKEY: + case PKT_MARKER: + case PKT_RING_TRUST: + case PKT_USER_ID: + case PKT_PUBLIC_SUBKEY: + case PKT_ATTRIBUTE: + case PKT_MDC: + indeterminate_length_allowed = 0; + break; + case PKT_COMPRESSED: case PKT_ENCRYPTED: - return 0; /* seems to be a regular packet: not armored */ + case PKT_ENCRYPTED_MDC: + case PKT_PLAINTEXT: + case PKT_OLD_COMMENT: + case PKT_COMMENT: + case PKT_GPG_CONTROL: + indeterminate_length_allowed = 1; + break; + + default: + /* Invalid packet type. */ + return 1; } - return 1; + if (! indeterminate_length_allowed) + /* It is only legal to use an indeterminate length with a few + packet types. If a packet uses an indeterminate length, but + that is not allowed, then the data is not valid binary + OpenPGP data. */ + { + int new_format; + int indeterminate_length; + + new_format = !! (ctb & (1 << 6)); + if (new_format) + indeterminate_length = (buf[1] >= 224 && buf[1] < 255); + else + indeterminate_length = (ctb & 3) == 3; + + if (indeterminate_length) + return 1; + } + + /* The first CTB seems legit. It is probably not armored + data. */ + return 0; } |