add http utils

pkg/http/main.go

@@ -0,0 +1,132 @@
+package http
+
+import (
+	"io/ioutil"
+	"net"
+	h "net/http"
+
+	"github.com/datahearth/ddnsclient/pkg/utils"
+	"github.com/sirupsen/logrus"
+	"github.com/spf13/viper"
+)
+
+// HTTP is the base interface to interact with websites
+type HTTP interface {
+	CheckIPAddr(addr string) (bool, error)
+	GetServerIP() (string, error)
+	GetSubdomainIP(addr string) (string, error)
+	RetrieveSubdomainIP(addr string) error
+	RetrieveServerIP() error
+}
+
+type http struct {
+	logger      logrus.FieldLogger
+	serverIP    string
+	subdomainIP string
+	webIP       string
+}
+
+// NewHTTP instanciate a new http implementation
+func NewHTTP(logger logrus.FieldLogger) (HTTP, error) {
+	if logger == nil {
+		return nil, utils.ErrNilLogger
+	}
+
+	logger = logger.WithField("package", "http")
+	webIP := viper.GetString("web-ip")
+
+	if webIP == "" {
+		logger.Infoln("web-ip field not set in config. Using default")
+		webIP = "http://dynamicdns.park-your-domain.com/getip"
+	}
+
+	return &http{
+		logger: logger,
+		webIP:  webIP,
+	}, nil
+}
+
+// RetrieveServerIP will use the defined web-ip service to get the server public address and save it to the struct
+func (http *http) RetrieveServerIP() error {
+	resp, err := h.Get(http.webIP)
+	if err != nil {
+		return err
+	}
+	if resp.StatusCode != 200 {
+		return utils.ErrWrongStatusCode
+	}
+	d, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return err
+	}
+
+	http.serverIP = string(d)
+
+	return nil
+}
+
+// GetServerIP will return the IP addr of the server.
+// If you haven't triggered the function before manually or with CheckIPAddr,
+// it'll trigger the RetrieveServerIP function and save it. Then, it'll return the IP
+func (http *http) GetServerIP() (string, error) {
+	if http.serverIP == "" {
+		if err := http.RetrieveServerIP(); err != nil {
+			return "", err
+		}
+	}
+
+	return http.serverIP, nil
+}
+
+// RetrieveSubdomainIP will retrieve the subdomain IP with a HEAD request then save it to the struct
+func (http *http) RetrieveSubdomainIP(addr string) error {
+	resp, err := h.Head(addr)
+	if err != nil {
+		return err
+	}
+	if resp.StatusCode != 200 {
+		return utils.ErrWrongStatusCode
+	}
+
+	h, _, err := net.SplitHostPort(resp.Request.RemoteAddr)
+	if err != nil {
+		return err
+	}
+
+	http.subdomainIP = h
+
+	return nil
+}
+
+// GetSubdomainIP will return the IP addr of the subdomain.
+// If you haven't triggered the function before manually or with CheckIPAddr,
+// it'll trigger the RetrieveSubdomainIP function and save it. Then, it'll return the IP
+func (http *http) GetSubdomainIP(addr string) (string, error) {
+	if http.subdomainIP == "" {
+		if err := http.RetrieveSubdomainIP(addr); err != nil {
+			return "", err
+		}
+	}
+
+	return http.subdomainIP, nil
+}
+
+// CheckIPAddr will get both ip addr (subdomain from addr and server) and compare it.
+// If one of them is missing, it'll retrieve it and then save it
+func (http *http) CheckIPAddr(addr string) (bool, error) {
+	srvIP, err := http.GetServerIP()
+	if err != nil {
+		return false, err
+	}
+
+	subIP, err := http.GetSubdomainIP(addr)
+	if err != nil {
+		return false, err
+	}
+
+	if srvIP != subIP {
+		return false, nil
+	}
+
+	return true, nil
+}