142 lines
3.1 KiB
Go
142 lines
3.1 KiB
Go
package main
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import (
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"encoding/json"
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"fmt"
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"io"
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"net/http"
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"strings"
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"time"
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)
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type Visit struct {
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RemoteAddr string
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Location string
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}
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type GeolocationResponse struct {
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Country string `json:"country"`
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City string `json:"city"`
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RegionName string `json:"regionName"`
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}
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type VisitHandler struct {
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geolocationApiBaseUrl string
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visitsCache map[string]int64
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pastRequests []int64
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rateLimitAmount int
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rateLimitDurationSeconds int
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cacheDurationSeconds int
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}
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func (v *VisitHandler) buildUrl(ipAddress string) string {
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return fmt.Sprintf("%s/json/%s?fields=country,regionName,city", v.geolocationApiBaseUrl, ipAddress)
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}
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func (v *VisitHandler) limitRate() bool {
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now := time.Now()
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idxToRemove := make([]int, 0)
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for idx, ts := range v.pastRequests {
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if now.Sub(time.Unix(ts, 0)).Seconds() >= float64(v.rateLimitDurationSeconds) {
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idxToRemove = append(idxToRemove, idx)
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}
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}
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for i := len(idxToRemove) - 1; i >= 0; i-- {
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idx := idxToRemove[i]
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v.pastRequests = append(v.pastRequests[:idx], v.pastRequests[idx+1:]...)
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}
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if len(v.pastRequests) == 0 {
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v.pastRequests = append(v.pastRequests, now.Unix())
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return true
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}
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retVal := false
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if len(v.pastRequests) < v.rateLimitAmount {
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v.pastRequests = append(v.pastRequests, now.Unix())
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retVal = true
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}
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return retVal
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}
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func (v *VisitHandler) getLocation(ipAddress string) *GeolocationResponse {
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if !v.limitRate() {
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return nil
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}
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resp, err := http.Get(v.buildUrl(ipAddress))
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if err != nil {
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return nil
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}
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body, err := io.ReadAll(resp.Body)
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if err != nil {
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return nil
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}
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var geoResponse GeolocationResponse
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err = json.Unmarshal(body, &geoResponse)
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return &geoResponse
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}
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func (v *VisitHandler) createVisit(ipAddress string) *Visit {
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loc := v.getLocation(ipAddress)
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if loc == nil {
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return nil
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}
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locationParts := []string{}
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if loc.City != "" {
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locationParts = append(locationParts, loc.City)
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}
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if loc.RegionName != "" {
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locationParts = append(locationParts, loc.RegionName)
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}
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if loc.Country != "" {
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locationParts = append(locationParts, loc.Country)
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}
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return &Visit{
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RemoteAddr: ipAddress,
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Location: strings.Join(locationParts, ", "),
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}
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}
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func (v *VisitHandler) HandleVisit(remoteAddr string) *Visit {
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if v.visitsCache == nil {
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v.visitsCache = make(map[string]int64)
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}
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if v.visitsCache[remoteAddr] == 0 || time.Since(time.Unix(v.visitsCache[remoteAddr], 0)).Seconds() > float64(v.cacheDurationSeconds) {
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visit := v.createVisit(remoteAddr)
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if visit == nil {
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return nil
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}
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v.visitsCache[visit.RemoteAddr] = time.Now().Unix()
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return visit
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}
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return nil
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}
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type VisitHandlerArgs struct {
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baseUrl string
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rateLimitAmount int
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rateLimitDurationSeconds int
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cacheDurationSeconds int
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}
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func SetupVisitHandler(args *VisitHandlerArgs) *VisitHandler {
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return &VisitHandler{
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geolocationApiBaseUrl: args.baseUrl,
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visitsCache: make(map[string]int64),
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pastRequests: make([]int64, 0),
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rateLimitAmount: args.rateLimitAmount,
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rateLimitDurationSeconds: args.rateLimitDurationSeconds,
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cacheDurationSeconds: args.cacheDurationSeconds,
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}
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}
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