add metar request/response to protocol

protocol/metar_response.go

@@ -0,0 +1,39 @@
+package protocol
+
+import (
+	"fmt"
+	"strings"
+)
+
+type MetarResponsePDU struct {
+	From  string `validate:"required,alphanum,max=7"`
+	To    string `validate:"required,alphanum,max=7"`
+	Metar string `validate:"required,max=256"`
+}
+
+func (p *MetarResponsePDU) Serialize() string {
+	return fmt.Sprintf("$AR%s:%s:%s%s", p.From, p.To, p.Metar, PacketDelimeter)
+}
+
+func ParseMetarResponsePDU(rawPacket string) (*MetarResponsePDU, error) {
+	rawPacket = strings.TrimSuffix(rawPacket, PacketDelimeter)
+	rawPacket = strings.TrimPrefix(rawPacket, "$AR")
+	fields := strings.SplitN(rawPacket, Delimeter, 3)
+
+	if len(fields) != 3 {
+		return nil, NewGenericFSDError(SyntaxError)
+	}
+
+	pdu := MetarResponsePDU{
+		From:  fields[0],
+		To:    fields[1],
+		Metar: fields[2],
+	}
+
+	err := V.Struct(pdu)
+	if err != nil {
+		return nil, NewGenericFSDError(SyntaxError)
+	}
+
+	return &pdu, nil
+}