FRR: Handle empty results and missing attributes properly #344
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In case a route is not present in the RIB, FRR returns an empty JSON
object:
```
$ vtysh -c "show bgp ipv4 unicast 1.2.3.4 json"
{}
```
Skip these empty objects to prevent the parser from failing.
Signed-off-by: Tan Siewert <[email protected]>
The metric and used fields might not be returned, causing the parser to
fail if they are not present. The absence was observed in FRR 10.4.1
with a multipath IPv6 route that has two next-hops (one GUA, one LL):
```
$ vtysh -c "show bgp ipv6 unicast 2003::/19 json" | jq '.paths[].nexthops'
[
{
"ip": "2a0d:2146:bdff:120::1",
"afi": "ipv6",
"scope": "global",
"linkLocalOnly": false,
"length": 32,
"metric": 0,
"accessible": true
},
{
"ip": "fe80::3e61:408:1e3e:cff0",
"afi": "ipv6",
"scope": "link-local",
"length": 32,
"accessible": true,
"used": true
}
]
[
{
"ip": "2a0d:2146:bdff:120::1",
"afi": "ipv6",
"scope": "global",
"linkLocalOnly": false,
"length": 32,
"metric": 0,
"accessible": true
},
{
"ip": "fe80::3e61:408:1e3e:cff0",
"afi": "ipv6",
"scope": "link-local",
"length": 32,
"accessible": true,
"used": true
}
]
```
Tested: Query a prefix with multiple next-hops where the metric or used
attributes are missing on one of them.
Signed-off-by: Tan Siewert <[email protected]>
Local prefixes usually do not have an AS_PATH:
```
vtysh -c "show bgp ipv4 unicast 10.10.10.10 json" | jq '.paths[].aspath'
{
"string": "Local",
"segments": [],
"length": 0
}
```
Set AS0 as a temporary solution when AS_PATH length is zero. This
avoids parser failures for local prefixes, though ideally we should
use the device's actual ASN (see TODO in code).
Signed-off-by: Tan Siewert <[email protected]>
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Description
This PR fixes three edge cases in the FRR parser that cause failures:
metricandused) on next-hops in multipath routesAS_PATHPlease see individual commit messages for detailed explanations and examples.
Related Issues
None that I could find.
Motivation and Context
When I set up hyperglass backed by an FRR instance I noticed that some edge cases cause the parser to fail (like a route that's not in the DFZ and so on).
Tests
Test Environment: Docker on Ubuntu 24.04, with FRR as device
Devices Tested: FRR 10.4.1 with bgpd enabled
Test Cases: