add dns handler

pkg/handler/dns/metadata.go

@@ -0,0 +1,43 @@
+package dns
+
+import (
+	"time"
+
+	mdata "github.com/go-gost/gost/pkg/metadata"
+)
+
+type metadata struct {
+	readTimeout time.Duration
+	retryCount  int
+	ttl         time.Duration
+	timeout     time.Duration
+	prefer      string
+	clientIP    string
+	// nameservers
+	servers []string
+}
+
+func (h *dnsHandler) parseMetadata(md mdata.Metadata) (err error) {
+	const (
+		readTimeout = "readTimeout"
+		retryCount  = "retry"
+		ttl         = "ttl"
+		timeout     = "timeout"
+		prefer      = "prefer"
+		clientIP    = "clientIP"
+		servers     = "servers"
+	)
+
+	h.md.readTimeout = mdata.GetDuration(md, readTimeout)
+	h.md.retryCount = mdata.GetInt(md, retryCount)
+	h.md.ttl = mdata.GetDuration(md, ttl)
+	h.md.timeout = mdata.GetDuration(md, timeout)
+	if h.md.timeout <= 0 {
+		h.md.timeout = 5 * time.Second
+	}
+	h.md.prefer = mdata.GetString(md, prefer)
+	h.md.clientIP = mdata.GetString(md, clientIP)
+	h.md.servers = mdata.GetStrings(md, servers)
+
+	return
+}