feat(resolvers/HTTPS): add HTTP proxy support

pkg/resolvers/HTTPS.go

@@ -4,6 +4,7 @@ package resolvers
 
 import (
 	"bytes"
+	"crypto/tls"
 	"fmt"
 	"io"
 	"net/http"
@@ -26,6 +27,17 @@ func (resolver *HTTPSResolver) LookUp(msg *dns.Msg) (util.Response, error) {
 
 	httpR := &http.Client{
 		Timeout: resolver.opts.Request.Timeout,
+		Transport: &http.Transport{
+			MaxConnsPerHost:     1,
+			MaxIdleConns:        1,
+			MaxIdleConnsPerHost: 1,
+			Proxy:               http.ProxyFromEnvironment,
+			TLSClientConfig: &tls.Config{
+				//nolint:gosec // This is intentional if the user requests it
+				InsecureSkipVerify: resolver.opts.TLSNoVerify,
+				ServerName:         resolver.opts.TLSHost,
+			},
+		},
 	}
 
 	buf, err := msg.Pack()

pkg/resolvers/docs.go

@@ -0,0 +1,4 @@
+/*
+Package resolvers contain the various DNS resolvers to use.
+*/
+package resolvers