When creating a BGP peer the description field can be filled as well.
This can then be exported via API.

RFC7911 sec 4 allows multiple AFISAFIs in a single AddPath capability
entry, which also must be presented in a single capability message.
Without this patch the AddPath capability of a peer advertising multiple
AFISAFIs cannot be parsed and the connection will fail.

RFC2545 section 3 paragraph 2 allows for a next-hop field length of 32.
In this case two IPv6 addresses are being sent, first the global
address, then the link local address. For now we are just ignoring the
link local address and parsing only the first.

Without this patch Bio will not be able to talk to BGP spekaders using
this features. An UPDATE mesage containing such a next-hop field would
result in the following error:

Failed to decode BGP message: Failed to decode message: Unable to decode path attr: Failed to multi protocol reachable NLRI: Unable to decode MP_REACH_NLRI: Failed to decode next hop IP: byte slice has an invalid length. Expected either 4 (IPv4) or 16 (IPv6) bytes but got: 32

Co-authored-by: Daniel Czerwonk <czerwonk@users.noreply.github.com>

* Accept all RFC4486 bgp error subcodes

Bio-BGP used to only decode AdministrativeShut and AdministrativeReset
error subcodes when error code "Cease" was sent by a BGP peer. Other BGP
packets could not be decoded. With this commit Bio-BGP accepts and
decodes all error codes defined in RFC4486.

* Set OtherConfigChange to value defined in RFC4486

In the risserver every bmp server is identified by its address,
specified in the config, but the GetRouters() grpc only presents us with
the name acquired via the BMP session. To clarify the field usage the
router field is renamed to sys_name and an address field is added. The
address field is of type string to match the other grpc methods, which
require a router address to be specified as string.

Co-authored-by: takt <oliver.herms@exaring.de>

* Remove unused function

This unused function triggered go vet

github.com/bio-routing/bio-rd/syscallwrappers
[error]syscallwrappers/syscalls_linux.go:75:9: possible misuse of unsafe.Pointer

* Remove unreachable code

* Use keyed syntax for composite literals

* Remove copies of mutex locks

* Implement a GetRouters RPC to RIS

This RPC returns all configured routers and their VRF IDs. This can be
used by RIS clients to discovery the routers. The router and the VRF ID
is a required parameter for all other RPCs.

* Update grpc to v1.28.0 to support protoc-gen-go v1.21.0

* Fix test

Co-authored-by: Oliver Herms <oliver.peter.herms@gmail.com>