According to our CODING_STYLE our library code should generally not log
beyond LOG_DEBUG. Let's hence get rid of log_radv_warning_errno() and
just use log_radv_errno() instead.
This part of the copyright blurb stems from the GPL use recommendations:
https://www.gnu.org/licenses/gpl-howto.en.html
The concept appears to originate in times where version control was per
file, instead of per tree, and was a way to glue the files together.
Ultimately, we nowadays don't live in that world anymore, and this
information is entirely useless anyway, as people are very welcome to
copy these files into any projects they like, and they shouldn't have to
change bits that are part of our copyright header for that.
hence, let's just get rid of this old cruft, and shorten our codebase a
bit.
Let's add "const" where we don't change structures passed.
Also, we generally use "unsigned char" for IP prefix length values, do
so here too. Previously different parts of the sd-radv.h API used
different types for this.
sd_radv_stop is called from two places. if sd_radv_stop is alrady
success then just don't try to close it .
```
systemd-networkd[604]: RADV: Stopping IPv6 Router Advertisement daemon
systemd-networkd[604]: RADV: Unable to send last Router Advertisement with router lifetime set to zero: Bad file descriptor <==================HERE
systemd-networkd[604]: RADV: Updated prefix 2a0a:*:*:fc::/64 preferred 1h valid 2h
systemd-networkd[604]: RADV: Started IPv6 Router Advertisement daemon
```
Closes one of the issue #8960
Files which are installed as-is (any .service and other unit files, .conf
files, .policy files, etc), are left as is. My assumption is that SPDX
identifiers are not yet that well known, so it's better to retain the
extended header to avoid any doubt.
I also kept any copyright lines. We can probably remove them, but it'd nice to
obtain explicit acks from all involved authors before doing that.
Both netinet/icmp6.h and linux/in6.h will define struct in6_addr, and in
user space we want to use the netinet/icmp6.h variant.
Fixes build problem:
In file included from src/libsystemd-network/sd-radv.c:23:0:
/home/hegtvedt/work/os/product/sunrise/root/_build/v2/include/linux/in6.h:30:8:
error: redefinition of 'struct in6_addr'
As DHCPv6 leases may expire at some point, the delegated prefixes
have to be removed. Add a prefix removal function to the Router
Advertisement handling code.
Add a boolean that indicates whether the prefixes will always exist
or if they will time out after the assigned valid lifetime. In the
latter case calculate the expiry times for both preferred and valid
lifetimes for the prefixes, and decrease the remaining lifetimes
each time when a Router Advertisement is sent.
Should the prefix be updated, re-calculate the prefix lifetime. When
updating, update the existing entry, if any, with the lifetimes of
the added entry as the existing entry has its lifetimes set
according to its previously calculated expiry times.
Add Router Advertisement DNS Search List option as specified
in RFC 8106. The search list option uses and identical option
header as the RDNSS option and therefore the option header
structure can be reused.
If systemd is compiled with IDNA support, internationalization
of the provided search domain is applied, after which the search
list is written in wire format into the DNSSL option.
Receive Router Solicitations and send a unicast Router Advertisment
in response. Refactor ICMPv6 packet handling code so that the common
ICMPv6 validation parts are reused between the existing router
discovery and the new functionality adding reception of Router
Solicitation messages.
Create and remove the ICMPv6 Router Advertisement socket file
descriptor and implement Router Advertisment sending. As not
all options are mandatory, use IO vectors to point to the included
options and the prefix information.
Router Advertisements are sent uniformly distributed between a
minimum and maximum time according to RFC 4861, Section 6.2.4.
Default values from RFC 4861 are for now used as minimum and
maximum Router Advertisement timeouts.
When stopping, a Router Advertisement with a router lifetime set
to zero is sent in order to inform any nodes that the interface
on this host no longer is a router.
Define Router Advertisement prefix structure. Add the Prefix
Information ICMPv6 option defined in RFC 4861 to the prefix
information structure, as it will simplify sending a Prefix
Information option later on. In order to handle endianness
correctly, the structure is redefined here instead of using
the one in netinet/icmp6.h.
Add functions to create and modify prefix information and set
default values as defined in RFC 4861, Section 6.2.1.
