commit 3b61cc8d82dc9cd01fc817fa6023297aa3d66125
Author: Yifu Yu <root@jackyyf.com>
Date:   Fri Oct 25 17:16:24 2019 +0800

    Initial version.

diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..7dd6c1e
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,5 @@
+module git.eve.moe/jackyyf/navigator
+
+go 1.13
+
+require github.com/ipipdotnet/ipdb-go v1.2.0
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..5a5932d
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,2 @@
+github.com/ipipdotnet/ipdb-go v1.2.0 h1:Afa0qx/SgRevzIK8Qg1TevuD5M28kFLWbzPvU+GQJ08=
+github.com/ipipdotnet/ipdb-go v1.2.0/go.mod h1:6SFLNyXDBF6q99FQvbOZJQCc2rdPrB1V5DSy4S83RSw=
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..d2462be
--- /dev/null
+++ b/main.go
@@ -0,0 +1,141 @@
+package main
+
+import (
+	"encoding/json"
+	"flag"
+	"fmt"
+	"log"
+	"net"
+	"net/http"
+	_ "net/http/pprof"
+	"strconv"
+	"strings"
+
+	"github.com/ipipdotnet/ipdb-go"
+)
+
+var (
+	requiredFields = []string{
+		"country_name",
+		"region_name",
+		"city_name",
+		"isp_domain",
+		"country_code",
+		"continent_code",
+	}
+)
+
+const (
+	errIPv4Only = "Navigator works for IPv4 only :)"
+)
+
+type errorMessage struct {
+	Error string `json:error`
+}
+
+func responseWithError(resp http.ResponseWriter, statusCode int, message string) {
+	resp.Header().Set("Content-Type", "text/plain")
+	resp.WriteHeader(statusCode)
+	resp.Write([]byte("error: " + message))
+}
+
+func responseWithJsonError(resp http.ResponseWriter, statusCode int, message string) {
+	resp.Header().Set("Content-Type", "application/json")
+	body, err := json.Marshal(&errorMessage{
+		Error: message,
+	})
+	resp.Header().Set("Content-Length", strconv.Itoa(len(body)))
+	if err != nil {
+		// This should never happen
+		panic("json marshal failed, check code")
+	}
+	resp.WriteHeader(statusCode)
+	resp.Write(body)
+}
+
+func buildLocation(info *ipdb.CityInfo) string {
+	ret := ""
+	if info.CountryName != "" {
+		ret += info.CountryName + " "
+	}
+	if info.RegionName != "" {
+		ret += info.RegionName + " "
+	}
+	if info.CityName != "" {
+		ret += info.CityName + " "
+	}
+	return strings.TrimSpace(ret)
+}
+
+func main() {
+	ipipdb := flag.String("ipdb-database", "ipip.db", "path to ipip database")
+	flag.Parse()
+
+	db, err := ipdb.NewCity(*ipipdb)
+	if err != nil {
+		log.Fatalln("Unable to open ipdb:", err.Error())
+	}
+	if !db.IsIPv4() {
+		log.Fatalln("This IPIP.net database has no IPv4 information!")
+	}
+	{
+		fields := db.Fields()
+		for _, requiredField := range requiredFields {
+			ok := false
+			for _, field := range fields {
+				if field == requiredField {
+					ok = true
+					break
+				}
+			}
+			if !ok {
+				log.Fatalln("This IPIP.net database has no required field", requiredField)
+			}
+		}
+	}
+
+	http.HandleFunc("/healthz", func(resp http.ResponseWriter, req *http.Request) {
+		resp.WriteHeader(200)
+		resp.Write([]byte("ok"))
+	})
+
+	http.HandleFunc("/info", func(resp http.ResponseWriter, req *http.Request) {
+		host, _, err := net.SplitHostPort(req.RemoteAddr)
+		if err != nil {
+			responseWithError(resp, http.StatusPreconditionFailed, errIPv4Only)
+			return
+		}
+		if net.ParseIP(host).To4() == nil {
+			responseWithError(resp, http.StatusPreconditionFailed, errIPv4Only)
+			return
+		}
+
+		info_cn, err := db.FindInfo(host, "CN")
+		if err != nil {
+			fmt.Fprintf(resp, "IP %s not found in the database.", host)
+			return
+		}
+		info_en, err := db.FindInfo(host, "EN")
+		if err != nil {
+			fmt.Fprintf(resp, "IP %s not found in the database.", host)
+			return
+		}
+		resp.Header().Set("Content-Type", "text/plain")
+		resp.WriteHeader(http.StatusOK)
+		fmt.Fprintln(resp, "您的IP:", host)
+		fmt.Fprintln(resp, "数据库中IP所属位置:", buildLocation(info_cn))
+		if info_cn.IspDomain != "" {
+			fmt.Fprintln(resp, "数据库中IP所属运营商:", info_cn.IspDomain)
+		}
+		// TODO(jackyyf): add mapping info here
+
+		fmt.Fprintln(resp, "Your IP:", host)
+		fmt.Fprintln(resp, "Location for your IP according our database:", buildLocation(info_en))
+		if info_en.IspDomain != "" {
+			fmt.Fprintln(resp, "ISP for your IP according our database:", info_en.IspDomain)
+		}
+		// TODO(jackyyf): add mapping info here
+
+	})
+	http.ListenAndServe("0.0.0.0:8086", nil)
+}