[#446] Add support virtual-hosted-style

Signed-off-by: Roman Loginov <r.loginov@yadro.com>

cmd/s3-gw/app_settings.go

@@ -30,6 +30,8 @@ import (
 const (
 	destinationStdout   = "stdout"
 	destinationJournald = "journald"
+
+	wildcardPlaceholder = "<wildcard>"
 )
 
 const (
@@ -144,6 +146,9 @@ const ( // Settings.
 
 	cfgListenDomains = "listen_domains"
 
+	cfgVHSEnabled    = "vhs.enabled"
+	cfgVHSNamespaces = "vhs.namespaces"
+
 	// Peers.
 	cfgPeers = "peers"
 
@@ -668,6 +673,41 @@ func fetchServers(v *viper.Viper, log *zap.Logger) []ServerInfo {
 	return servers
 }
 
+func fetchDomains(v *viper.Viper, log *zap.Logger) []string {
+	domains := validateDomains(v.GetStringSlice(cfgListenDomains), log)
+
+	countParts := func(domain string) int {
+		return strings.Count(domain, ".")
+	}
+
+	sort.Slice(domains, func(i, j int) bool {
+		return countParts(domains[i]) > countParts(domains[j])
+	})
+
+	return domains
+}
+
+func fetchVHSNamespaces(v *viper.Viper, log *zap.Logger) map[string]bool {
+	vhsNamespacesEnabled := make(map[string]bool)
+	nsMap := v.GetStringMap(cfgVHSNamespaces)
+	for ns, val := range nsMap {
+		if _, ok := vhsNamespacesEnabled[ns]; ok {
+			log.Warn(logs.WarnDuplicateNamespaceVHS, zap.String("namespace", ns))
+			continue
+		}
+
+		enabledFlag, ok := val.(bool)
+		if !ok {
+			log.Warn(logs.WarnValueVHSEnabledFlagWrongType, zap.String("namespace", ns))
+			continue
+		}
+
+		vhsNamespacesEnabled[ns] = enabledFlag
+	}
+
+	return vhsNamespacesEnabled
+}
+
 func newSettings() *viper.Viper {
 	v := viper.New()
 
@@ -1029,3 +1069,19 @@ func getLogLevel(v *viper.Viper) (zapcore.Level, error) {
 	}
 	return lvl, nil
 }
+
+func validateDomains(domains []string, log *zap.Logger) []string {
+	validDomains := make([]string, 0, len(domains))
+LOOP:
+	for _, domain := range domains {
+		domainParts := strings.Split(domain, ".")
+		for _, part := range domainParts {
+			if strings.ContainsAny(part, "<>") && part != wildcardPlaceholder {
+				log.Warn(logs.WarnDomainContainsInvalidPlaceholder, zap.String("domain", domain))
+				continue LOOP
+			}
+		}
+		validDomains = append(validDomains, domain)
+	}
+	return validDomains
+}