sd-network: Rectify Advertise Message Processing by a Client

System Internals / systemd - Susant Sahani [vmware.com] - 29 May 2020 07:17 UTC

We need to fix RCC 2215 behaviour with rfc7550 errata and https://tools.ietf.org/html/rfc8415.

[RFC3315] specifies that a client must ignore an Advertise message if a server will not assign any addresses to a client, and [RFC3633] specifies that a client must ignore an Advertise message if a server returns the NoPrefixAvail status to a requesting router. Thus, a client requesting both IA_NA and IA_PD, with a server that only offers either addresses or delegated prefixes, is not supported by the current protocol specifications.

Solution: a client SHOULD accept Advertise messages, even when not all IA option types are being offered. And, in this case, the client SHOULD include the not offered IA option types in its Request. A client SHOULD only ignore an Advertise message when none of the requested IA options include offered addresses or delegated prefixes. Note that ignored messages MUST still be processed for SOL_MAX_RT and INF_MAX_RT options as specified in [RFC7083].

Replace Section 17.1.3 of RFC 3315: (existing errata)

The client MUST ignore any Advertise message that includes a Status Code option containing the value NoAddrsAvail, with the exception that the client MAY display the associated status message(s) to the user.

With the following text (which addresses the existing erratum [Err2471] and includes the changes made by [RFC7083]):

The client MUST ignore any Advertise message that contains no addresses (IAADDR options encapsulated in IA_NA or IA_TA options) and no delegated prefixes (IAPREFIX options encapsulated in IA_PD options; see RFC 3633) with the exception that the client:

- MUST process an included SOL_MAX_RT option (RFC 7083) and
- MUST process an included INF_MAX_RT option (RFC 7083).

A client can display any associated status message(s) to the user or activity log.

The client ignoring this Advertise message MUST NOT restart the Solicit retransmission timer.

5c95a9134a sd-network: Rectify Advertise Message Processing by a Client
src/libsystemd-network/dhcp6-internal.h | 2 +-
src/libsystemd-network/dhcp6-option.c | 19 ++++++++++-----
src/libsystemd-network/sd-dhcp6-client.c | 24 +++++++++++++++----
src/libsystemd-network/test-dhcp6-client.c | 38 +++++++++++++++---------------
4 files changed, 53 insertions(+), 30 deletions(-)

Upstream: github.com


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