commit 74ee02420a6c53ad9412fc6315183c123cda4d13
author Pau Espin Pedrol <pespin@sysmocom.de> Fri Jan 19 18:28:09 2024 +0100
committer Pau Espin Pedrol <pespin@sysmocom.de> Sat Jan 20 00:31:28 2024 +0100
tree 3527c3521107cecd25e2208c643d186e913d1c23
parent 68a04dfc889f69d9d062c465a5b057f5b19476e3

gsup: Convert PDP-Type IE to PDP-Address IE

The previous PDP-Type IE should have been a PDP-Address from the
start, since having only PDP-Type with no address is only a specific
case (dynamic addressing).
This becomes clear by looking at other similar protocols like:
* MAP: APN-Configuration IE has servedPartyIP-IP{v4,v6}-Address IEs
* Diameter S6b, 3GPP TS 29.272 7.3.35 APN-Configuration contains
  Served-Party-IP-Address AVPs
* Diameter SWx, 3GPP TS 29.273 APN-Configuration.
* GTPv1C Ts 29.060 7.7.29 PDP Context containing PDP Address.

Since PDP-Type on its own really makes no sense, being it a special case
of PDP-Address, let's keep the IE by renaming it (keeping old name too
for API backward compat) and extend it to support lengths > 2 bytes.

Old implementation of libosmogsm gsup actually ignored lengths > 2
bytes, so we are safe acting against older implementations here, both
on the sending and receiving side on the wire.

The big drawback of this commit is that it breaks ABI compatibility due
to adding "struct osmo_sockaddr pdp_address[2];" to struct
osmo_gsup_pdp_info, which in turn affects shift of fields in struct
osmo_gsup_message. Unfortunately, there's not much that can be done to
improve the situation when adding the missing field, due to existing API
having the same struct for all messages. Ideally we'd have 1 union with
structs per message type inside, this way the ABI break would be far
less pronounced.

The GSUP test output change is becaue we now accept some of the len>2
cases for PDP-Type/Address IE which were being rejected since a couple
commits ago.

libosmogsm gsup code is now disabled in EMBEDDED mode, since it nows
depends on core/socket.h (struct osmo_sockaddr) which is not available
in EMBEDDED, and hence fails during build:
"""
In file included from /build/include/osmocom/gsm/gsup.h:45,
                 from /build/src/gsm/gsup_sms.c:28:
/build/include/osmocom/core/socket.h:15:10: fatal error: arpa/inet.h: No such file or directory
   15 | #include <arpa/inet.h>
      |          ^~~~~~~~~~~~~
"""

Related: OS#6091
Change-Id: I775ff9c3be165d9f30d6ab55d03f99b6104eadd6