Re: [PATCH v3 1/2] sierra_net: Add support for IPv6 and Dual-Stack Link Sense Indications

From: Bjørn Mork <bjorn@mork.no>
Date: Wed, 08 Feb 2017 10:55:50 +0100

Stefan Brüns [off-list ref] writes:

quoted

If a context is configured as dualstack ("IPv4v6"), the modem indicates
the context activation with a slightly different indication message.
The dual-stack indication omits the link_type (IPv4/v6) and adds
additional address fields.

Great!

quoted

IPv6 LSIs are identical to IPv4 LSIs, but have a different link type.
+struct lsi_umts_dual {
+	struct lsi_umts lsi;
+	u8 pdp_addr4_len; /* NW-supplied PDP IPv4 address len */
+	u8 pdp_addr4[4];  /* NW-supplied PDP IPv4 address (bigendian)) */
+	u8 pdp_addr6_len; /* NW-supplied PDP IPv6 address len */
+	u8 pdp_addr6[16]; /* NW-supplied PDP IPv6 address (bigendian)) */

Maybe use "struct in_addr" and "struct in6_addr" for all the address
fields, making them a bit more accessible and avoiding having to define
endianness explicitly?

Can't do that, it will add padding to the structure and not match
what is really in the header.

The problem is that we get a "u8" length first which starts the
address on an odd byte.

And we don't want to use "__packed" to fix this either.