Pull request 1840: 5752-unspec-ipv6

Merge in DNS/adguard-home from 5752-unspec-ipv6 to master

Closes #5752.

Squashed commit of the following:

commit 654b808d17c6d2374b6be919515113b361fc5ff7
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Fri Apr 21 18:11:34 2023 +0300

    home: imp docs

commit 28b4c36df790f1eaa05b11a1f0a7b986894d37dc
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Fri Apr 21 16:50:16 2023 +0300

    all: fix empty bind host

internal/home/config.go

@@ -414,6 +414,22 @@ func getLogSettings() logSettings {
 	return l
 }
 
+// validateBindHosts returns error if any of binding hosts from configuration is
+// not a valid IP address.
+func validateBindHosts(conf *configuration) (err error) {
+	if !conf.BindHost.IsValid() {
+		return errors.Error("bind_host is not a valid ip address")
+	}
+
+	for i, addr := range conf.DNS.BindHosts {
+		if !addr.IsValid() {
+			return fmt.Errorf("dns.bind_hosts at index %d is not a valid ip address", i)
+		}
+	}
+
+	return nil
+}
+
 // parseConfig loads configuration from the YAML file
 func parseConfig() (err error) {
 	var fileData []byte
@@ -425,6 +441,13 @@ func parseConfig() (err error) {
 	config.fileData = nil
 	err = yaml.Unmarshal(fileData, &config)
 	if err != nil {
+		// Don't wrap the error since it's informative enough as is.
+		return err
+	}
+
+	err = validateBindHosts(config)
+	if err != nil {
+		// Don't wrap the error since it's informative enough as is.
 		return err
 	}