bgpd: fix ecommunity parsing for AS4

The parser for extended communities was incorrectly disallowing an
operator from configuring "Route Origin" extended communities
(e.g. RD/RT/SoO) with a 4-byte value matching BGP_AS4_MAX (UINT32_MAX)
and allowed the user to overflow UINT32_MAX. This updates the parser to
read the value as a uint64_t so that we can do proper checks on the
upper bounds (> BGP_AS4_MAX || errno).

before:
```
TORC11(config-router-af)# neighbor uplink-1 soo 4294967296:65
TORC11(config-router-af)# do sh run | include soo
  neighbor uplink-1 soo 0:65
TORC11(config-router-af)# neighbor uplink-1 soo 4294967295:65
% Malformed SoO extended community
TORC11(config-router-af)#
```

after:
```
TORC11(config-router-af)# neighbor uplink-1 soo 4294967296:65
% Malformed SoO extended community
TORC11(config-router-af)# neighbor uplink-1 soo 4294967295:65
TORC11(config-router-af)# do sh run | include soo
  neighbor uplink-1 soo 4294967295:65
TORC11(config-router-af)#
```

Signed-off-by: Trey Aspelund <taspelund@nvidia.com>

0 files changed, 0 insertions, 0 deletions