add sync function

.gitignore

@@ -23,3 +23,4 @@ go.work.sum
 
 # env file
 .env
+i2pkeys

sync.go

@@ -0,0 +1,88 @@
+package jumpserver
+
+import (
+	"io/ioutil"
+	"log"
+	"net/http"
+	"net/url"
+	"strings"
+	"time"
+
+	"github.com/go-i2p/i2pkeys"
+)
+
+func (j *JumpServer) SyncHostnames(u string) (host string, content string) {
+	uri, err := url.Parse(u)
+	if err != nil {
+		log.Printf("Failed to parse URL: %s\n", err)
+		return "", ""
+	}
+	if uri.Scheme == "" {
+		uri.Scheme = "http"
+	}
+	if uri.Host == "" {
+		log.Printf("Failed to parse URL: no host\n")
+		return "", ""
+	}
+	// Sync the hostnames of the jump server
+	// with the hostnames of the jump server
+	// at the given URL
+	req, err := http.NewRequest("GET", u, nil)
+	if err != nil {
+		log.Printf("Failed to create request: %s\n", err)
+		return "", ""
+	}
+	req.Header.Set("User-Agent", "go-jump-addr")
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		log.Printf("Failed to get response: %s\n", err)
+		return "", ""
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		log.Printf("Failed to get response: %s\n", resp.Status)
+		return "", ""
+	}
+	body, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		log.Printf("Failed to read response: %s\n", err)
+		return "", ""
+	}
+	// Extract the hostnames from the response
+	// and add them to the jump server
+	for _, host := range extractHostnames(body) {
+		vals := strings.Split(host, "=")
+		if len(vals) != 2 {
+			log.Printf("Failed to parse hostname: %s\n", host)
+			continue
+		}
+		hostname, dest := vals[0], vals[1]
+		addr, err := i2pkeys.NewI2PAddrFromString(dest)
+		if err != nil {
+			log.Printf("Failed to parse I2P address: %s\n", err)
+			continue
+		}
+		entry := &Hostname{
+			I2PAddr: &addr,
+			Time:    time.Now(),
+			Registrant: Registrant{
+				Type:        "service",
+				Name:        uri.Host,
+				Description: "",
+				Tags:        []string{uri.Host, uri.Scheme},
+			},
+			Hostname: hostname,
+		}
+		j.AddHostname(entry)
+	}
+	return uri.Host, string(body)
+}
+
+func extractHostnames(body []byte) []string {
+	// Extract hostnames from the response body
+	// and return them as a slice of strings
+	// This function is used by SyncHostnames
+	// to extract hostnames from the response
+	// of the jump server at the given URL
+	return strings.Split(string(body), "\n")
+}