DNS query sent out when the request with IPv6 address in authority

[yiyibaoguo]

Title: DNS query sent out when the request with IPv6 address in authority - with HTTP dynamic forward proxy

Description:

When the http request with IPv6 address in authority such as http://[fd00:bada:194:99::98]:8285/test, the address can be directly used but the DNS query

Repro steps:

Curl command:
curl -g -k --request POST -H "Content-Type:application/json" --header "Accept:application/json" --data '{"nrfConfigs":{"nrfConfig":[{"apiName":"nnrf-nfm","apiPrefix":null,"apiSpecificResourceUriPart":null,"apiVersion":"v2","authority":[{"addressType":"primary","host":"10.10.45.34","port":"8089"}],"nrfConfigId":"nrf2","responseTimeout":"90","scheme":"http"}]}}' --proxy http://chfed.sbc.svc.cluster.local:10007 -v http://[fd00:bada:194:99::88]:8285/test-management/test

Filter - key config:
"http_filters": [
{
"name": "envoy.filters.http.dynamic_forward_proxy",
"typed_config": {
"@type": "type.googleapis.com/envoy.extensions.filters.http.dynamic_forward_proxy.v3.FilterConfig",
"dns_cache_config": {
"name": "dynamic_forward_proxy_cache_config",
"host_ttl": "7200s",
"dns_lookup_family": "V4_PREFERRED"
}
}
},

Cluster -key config:
"typed_config": {
"@type": "type.googleapis.com/envoy.extensions.clusters.dynamic_forward_proxy.v3.ClusterConfig",
"dns_cache_config": {
"name": "dynamic_forward_proxy_cache_config",
"host_ttl": "7200s",
"dns_lookup_family": "V4_PREFERRED"
},

Note: The Envoy_collect tool
gathers a tarball with debug logs, config and the following admin
endpoints: /stats, /clusters and /server_info. Please note if there are
privacy concerns, sanitize the data prior to sharing the tarball/pasting.

Admin and Stats Output:

Include the admin output for the following endpoints: /stats,
/clusters, /routes, /server_info. For more information, refer to the
admin endpoint documentation.

Note: If there are privacy concerns, sanitize the data prior to
sharing.

Config:

Include the config used to configure Envoy.

Logs:

Include the access logs and the Envoy logs.

Reference to the code envoy/source/extensions/network/dns_resolver/cares/dns_impl.cc, it seems to be related with the below code logic.
DnsResolverImpl::AddrInfoPendingResolution::AddrInfoPendingResolution(
DnsResolverImpl& parent, ResolveCb callback, Event::Dispatcher& dispatcher,
ares_channel channel, const std::string& dns_name, DnsLookupFamily dns_lookup_family)
: PendingResolution(parent, callback, dispatcher, channel, dns_name),
dns_lookup_family_(dns_lookup_family), available_interfaces_(availableInterfaces()) {
if (dns_lookup_family == DnsLookupFamily::Auto ||
dns_lookup_family == DnsLookupFamily::V4Preferred) {
dual_resolution_ = true;
}

switch (dns_lookup_family_) {
case DnsLookupFamily::V4Only:
case DnsLookupFamily::V4Preferred:
family_ = AF_INET;
break;
case DnsLookupFamily::V6Only:
case DnsLookupFamily::Auto:
family_ = AF_INET6;
break;
case DnsLookupFamily::All:
family_ = AF_UNSPEC;
break;
}
}

Note: If there are privacy concerns, sanitize the data prior to
sharing.

Call Stack:

If the Envoy binary is crashing, a call stack is required.
Please refer to the Bazel Stack trace documentation.

[zuercher]

cc @alyssawilk @mattklein123