Move ISO88025 source routing information into sockaddr_dl's sdl_data

field.  This returns the sdl_data field to a variable-length field.  More
importantly, this prevents a easily-reproduceable data-corruption bug when
the interface name plus the hardware address exceed the sdl_data field's
original 12 byte limit.  However, token-ring interfaces may still overflow
the new sdl_data field's 46 byte limit if the interface name exceeds 6
characters (since 6 characters for interface name plus 6 for hardware
address plus 34 for source routing = the size of sdl_data).  Further
refinements could overcome this limitation but would break binary
compatibility; this commit only addresses fixing the bug for
commonly-occuring cases without breaking binary compatibility with the
intention that the functionality can be MFC'ed to -stable.

  See message ID's (both send to -arch):
	20020421013332.F87395-100000@gateway.posi.net
	20020430181359.G11009-300000@gateway.posi.net
  for a more thorough description of the bug addressed and how to
reproduce it.

Approved by:	silence on -arch and -net
Sponsored by:	NTT Multimedia Communications Labs
MFC after:	1 week

1 files changed, 9 insertions, 0 deletions

diff --git a/sys/net/iso88025.h b/sys/net/iso88025.h
index e30193e..aad8d54 100644
--- a/sys/net/iso88025.h
+++ b/sys/net/iso88025.h
@@ -109,6 +109,15 @@ struct iso88025_sockaddr_data {
 	u_char fc;
 };
 
+struct iso88025_sockaddr_dl_data {
+	u_short	 trld_rcf;
+	u_short	*trld_route[RIF_MAX_LEN];
+};
+
+#define SDL_ISO88025(s)		((struct iso88025_sockaddr_dl_data *)	\
+				 ((s)->sdl_data + min((s)->sdl_nlen +	\
+				  (s)->sdl_alen + (s)->sdl_slen, 12)))
+
 /*
  * Structure of a 48-bit iso 802.5 address.
  *  ( We could also add the 16 bit addresses as a union)