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ping.go
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ping.go
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package main
import (
"flag"
"fmt"
"log"
"net/http"
"net/url"
"os"
"strconv"
"strings"
"time"
"github.com/jmoiron/sqlx"
"github.com/parkr/ping/analytics"
"github.com/parkr/ping/database"
)
var (
allowedHosts []string
whitelist = flag.String("hosts", "", "The hosts allowed to use this service. Comma-separated.")
)
const returnedJavaScript = "(function(){})();"
const lengthOfJavaScript = "17"
var db *sqlx.DB
func javascriptRespond(w http.ResponseWriter, code int, err string) {
w.WriteHeader(code)
var content string
if err == "" {
content = returnedJavaScript
} else if err == "not tracked" {
content = returnedJavaScript
w.Header().Set(DoNotTrackHeaderName, DoNotTrackHeaderValue)
} else {
content = fmt.Sprintf(`(function(){console.error("%s")})();`, err)
}
w.Header().Set("Content-Type", "application/javascript")
w.Header().Set("Content-Length", strconv.Itoa(len(content)))
fmt.Fprintf(w, content)
}
func allowedHost(host string) bool {
if whitelist == nil || *whitelist == "" {
return true
}
if len(allowedHosts) == 0 {
allowedHosts = strings.Split(*whitelist, ",")
}
for _, allowed := range allowedHosts {
if allowed == host {
return true
}
}
return false
}
func ping(w http.ResponseWriter, r *http.Request) {
if requestsDoNotTrack(r) {
log.Println("dnt requested")
javascriptRespond(w, http.StatusOK, "not tracked")
return
}
referrer := r.Referer()
if referrer == "" {
log.Println("empty referrer")
javascriptRespond(w, http.StatusBadRequest, "empty referrer")
return
}
url, err := url.Parse(referrer)
if err != nil {
log.Println("invalid referrer:", referrer)
javascriptRespond(w, 500, "Couldn't parse referrer: "+err.Error())
return
}
if !allowedHost(url.Host) {
log.Println("unauthorized host:", url.Host)
javascriptRespond(w, 403, "love the host, except noooope.")
return
}
var ip string
if res := r.Header.Get("X-Forwarded-For"); res != "" {
log.Println("Fetching IP from proxy:", res)
ip = res
} else {
ip = r.RemoteAddr
}
userAgent := r.Header.Get("User-Agent")
if userAgent == "" {
log.Println("empty user-agent")
javascriptRespond(w, http.StatusBadRequest, "empty user-agent")
return
}
visit := &database.Visit{
IP: ip,
Host: url.Host,
Path: url.Path,
UserAgent: userAgent,
CreatedAt: time.Now().UTC().Format(database.SQLDateTimeFormat),
}
log.Println("Logging visit:", visit.String())
err = visit.Save(db)
if err != nil {
log.Println("Error saving to db:", err)
javascriptRespond(w, 500, err.Error())
return
}
javascriptRespond(w, 201, "")
}
func counts(w http.ResponseWriter, r *http.Request) {
path := r.FormValue("path")
var err error
var views, visitors int
if path == "" {
http.Error(w, "Missing param", 400)
} else {
views, err = analytics.ViewsForPath(db, path)
if err != nil {
http.Error(w, err.Error(), 500)
return
}
visitors, err = analytics.VisitorsForPath(db, path)
if err != nil {
http.Error(w, err.Error(), 500)
return
}
writeJsonResponse(w, map[string]int{
"views": views,
"visitors": visitors,
})
}
}
func all(w http.ResponseWriter, r *http.Request) {
thing := r.FormValue("type")
if thing == "path" || thing == "host" {
entries, err := analytics.ListDistinctColumn(db, thing)
if err != nil {
http.Error(w, err.Error(), 500)
return
}
writeJsonResponse(w, map[string][]string{"entries": entries})
} else {
http.Error(w, "Missing param", 400)
return
}
}
func health(w http.ResponseWriter, r *http.Request) {
if db == nil {
http.Error(w, "error initializing db", http.StatusInternalServerError)
return
}
if err := db.Ping(); err != nil {
http.Error(w, "error pinging db: "+err.Error(), http.StatusInternalServerError)
return
}
fmt.Fprint(w, "healthy")
}
func main() {
defaultPort := os.Getenv("PORT")
if defaultPort == "" {
defaultPort = "8000"
}
var binding string
flag.StringVar(&binding, "http", ":"+defaultPort, "The IP/port to bind to.")
flag.Parse()
var err error
db, err = database.Initialize()
if err != nil {
log.Fatalf("unable to initialize db: %+v", err)
}
http.HandleFunc("/_health", health)
http.HandleFunc("/ping", ping)
http.HandleFunc("/ping.js", ping)
http.HandleFunc("/counts", counts)
http.HandleFunc("/all", all)
log.Println("Listening on", binding, "...")
log.Fatal(http.ListenAndServe(binding, nil))
}