Add method to fetch device information

device.go

@@ -1,10 +1,46 @@
 package onvif
 
+import (
+	"encoding/json"
+)
+
 var deviceXMLNs = []string{
 	`xmlns:tds="http://www.onvif.org/ver10/device/wsdl"`,
 	`xmlns:tt="http://www.onvif.org/ver10/schema"`,
 }
 
+// GetDeviceInformation fetch information of ONVIF camera
+func (device Device) GetDeviceInformation() (DeviceInformation, error) {
+	// Create initial result
+	result := DeviceInformation{}
+
+	// Create SOAP
+	soap := SOAP{
+		Body:  "<tds:GetDeviceInformation/>",
+		XMLNs: deviceXMLNs,
+	}
+
+	// Send SOAP request
+	response, err := soap.SendRequest(device.XAddr)
+	if err != nil {
+		return result, err
+	}
+
+	// Parse response to interface
+	deviceInfo, err := response.ValueForPath("Envelope.Body.GetDeviceInformationResponse")
+	if err != nil {
+		return result, err
+	}
+
+	// Parse interface to struct
+	err = device.interfaceToStruct(&deviceInfo, &result)
+	if err != nil {
+		return result, err
+	}
+
+	return result, nil
+}
+
 // GetSystemDateAndTime fetch date and time from ONVIF camera
 func (device Device) GetSystemDateAndTime() (string, error) {
 	// Create SOAP
@@ -23,3 +59,17 @@ func (device Device) GetSystemDateAndTime() (string, error) {
 	dateTime, _ := response.ValueForPathString("Envelope.Body.GetSystemDateAndTimeResponse.SystemDateAndTime")
 	return dateTime, nil
 }
+
+func (device Device) interfaceToStruct(src, dst interface{}) error {
+	bt, err := json.Marshal(&src)
+	if err != nil {
+		return err
+	}
+
+	err = json.Unmarshal(bt, &dst)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}

model.go

@@ -8,3 +8,12 @@ type Device struct {
 	User     string
 	Password string
 }
+
+// DeviceInformation contains information of ONVIF camera
+type DeviceInformation struct {
+	FirmwareVersion string
+	HardwareID      string
+	Manufacturer    string
+	Model           string
+	SerialNumber    string
+}