also handle PCOs that contain primary and secondary DNS in two separate IPCP containers
On GTP level in the CREATE PDP CONTEXT message, one finds a field Protocol Configuration Options. This field contains among other info the primary and secondary DNS server address inside an IPCP container. Usually primary and secondary DNS are packed into on IPCP container. However it seems also to be legal to have primary and secondary DNS server in two separate IPCP container. At the moment the parser can only handle one IPCP container so we will loose the secondary DNS in the two-container case. We now have to extend the parser so that it handles IPCP containers flexible.
Attached one finds an example packet where primary and secondary DNS are in two separate IPCP containers.
Proposed fix: https://gerrit.osmocom.org/#/c/osmo-ggsn/+/10061/
The test also needs small fixes: https://gerrit.osmocom.org/#/c/osmo-ttcn3-hacks/+/10060/