gpg: Make ASCII armor decoding more robust to encoding errors.

* g10/armor.c (radix64_read): If the = is followed by the string "3D",
check if the following four characters are valid radix 64 and are
followed by a new line.  If so, warn and ignore the '3D'.

--
Signed-off-by: Neal H. Walfield <[email protected]>
GnuPG-bug-id: 2250

1 files changed, 18 insertions, 0 deletions

diff --git a/g10/armor.c b/g10/armor.c
index 55ee5d328..e34518e0b 100644
--- a/g10/armor.c
+++ b/g10/armor.c
@@ -796,6 +796,24 @@ radix64_read( armor_filter_context_t *afx, IOBUF a, size_t *retn,
 		}
 	    }
 
+            /* Occasionally a bug MTA will leave the = escaped as
+               =3D.  If the 4 characters following that are valid
+               Radix64 characters and they are following by a new
+               line, assume that this is the case and skip the
+               3D.  */
+            if (afx->buffer_pos + 6 < afx->buffer_len
+                && afx->buffer[afx->buffer_pos + 0] == '3'
+                && afx->buffer[afx->buffer_pos + 1] == 'D'
+                && asctobin[afx->buffer[afx->buffer_pos + 2]] != 255
+                && asctobin[afx->buffer[afx->buffer_pos + 3]] != 255
+                && asctobin[afx->buffer[afx->buffer_pos + 4]] != 255
+                && asctobin[afx->buffer[afx->buffer_pos + 5]] != 255
+                && afx->buffer[afx->buffer_pos + 6] == '\n')
+              {
+                afx->buffer_pos += 2;
+                afx->qp_detected = 1;
+              }
+
 	    if (!n)
 	      onlypad = 1;