100 lines
2.5 KiB
Go
100 lines
2.5 KiB
Go
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// Package location resolves the geographic position of this node via IP
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// geolocation and applies a privacy-preserving random offset proportional
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// to the chosen granularity level before publishing the result.
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package location
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import (
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"encoding/json"
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"fmt"
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"math/rand"
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"net/http"
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"time"
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peer "cloud.o-forge.io/core/oc-lib/models/peer"
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)
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// fuzzRadius returns the maximum random offset (in degrees) for each axis
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// given a granularity level.
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//
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// 0 → no location
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// 1 → continent ±15° lat / ±20° lng
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// 2 → country ±3° lat / ±4° lng (default)
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// 3 → region ±0.5° lat / ±0.7° lng
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// 4 → city ±0.05° lat / ±0.07° lng
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func fuzzRadius(granularity int) (latR, lngR float64) {
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switch granularity {
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case 1:
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return 15.0, 20.0
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case 2:
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return 3.0, 4.0
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case 3:
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return 0.5, 0.7
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case 4:
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return 0.05, 0.07
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default:
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return 3.0, 4.0
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}
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}
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// clamp keeps a value inside [min, max].
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func clamp(v, min, max float64) float64 {
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if v < min {
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return min
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}
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if v > max {
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return max
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}
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return v
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}
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// ipAPIResponse is the subset of fields returned by ip-api.com/json.
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type ipAPIResponse struct {
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Status string `json:"status"`
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Lat float64 `json:"lat"`
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Lon float64 `json:"lon"`
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Country string `json:"country"`
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Region string `json:"regionName"`
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City string `json:"city"`
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}
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// Geolocate resolves the current public IP location via ip-api.com (free,
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// no key required for non-commercial use), then fuzzes the result according
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// to granularity.
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//
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// Returns nil if granularity == 0 (opt-out) or if the lookup fails.
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func Geolocate(granularity int) *peer.PeerLocation {
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if granularity == 0 {
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return nil
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}
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client := &http.Client{Timeout: 5 * time.Second}
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resp, err := client.Get("http://ip-api.com/json?fields=status,lat,lon,country,regionName,city")
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if err != nil {
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return nil
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}
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defer resp.Body.Close()
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var result ipAPIResponse
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if err := json.NewDecoder(resp.Body).Decode(&result); err != nil || result.Status != "success" {
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return nil
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}
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latR, lngR := fuzzRadius(granularity)
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rng := rand.New(rand.NewSource(time.Now().UnixNano()))
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fuzzedLat := result.Lat + (rng.Float64()*2-1)*latR
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fuzzedLng := result.Lon + (rng.Float64()*2-1)*lngR
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fuzzedLat = clamp(fuzzedLat, -85.0, 85.0)
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fuzzedLng = clamp(fuzzedLng, -180.0, 180.0)
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fmt.Printf("[location] granularity=%d raw=(%.4f,%.4f) fuzzed=(%.4f,%.4f)\n",
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granularity, result.Lat, result.Lon, fuzzedLat, fuzzedLng)
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return &peer.PeerLocation{
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Latitude: fuzzedLat,
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Longitude: fuzzedLng,
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Granularity: granularity,
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}
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}
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