| 1 | package geoip |
| 2 | |
| 3 | import ( |
| 4 | "math" |
| 5 | "net/http" |
| 6 | "regexp" |
| 7 | "strconv" |
| 8 | "strings" |
| 9 | |
| 10 | "github.com/carlosframework/platform/internal/geo" |
| 11 | ) |
| 12 | |
| 13 | const ( |
| 14 | HeaderCountry = "X-Carlos-Geo-Country" |
| 15 | HeaderSubdivision = "X-Carlos-Geo-Subdivision" |
| 16 | HeaderLat = "X-Carlos-Geo-Lat" |
| 17 | HeaderLon = "X-Carlos-Geo-Lon" |
| 18 | HeaderSource = "X-Carlos-Geo-Source" |
| 19 | // HeaderHop is edge-to-edge only (spec §8.1a): never written to a |
| 20 | // request an app receives. |
| 21 | HeaderHop = "X-Carlos-Hop-Geo" |
| 22 | ) |
| 23 | |
| 24 | var appHeaders = []string{HeaderCountry, HeaderSubdivision, HeaderLat, HeaderLon, HeaderSource} |
| 25 | |
| 26 | // State is what the ingress edge did: hit (a reader answered), miss (a |
| 27 | // reader was loaded and found nothing, or the address is not locatable), |
| 28 | // off (no lookup was attempted). |
| 29 | type State string |
| 30 | |
| 31 | const ( |
| 32 | StateHit State = "hit" |
| 33 | StateMiss State = "miss" |
| 34 | StateOff State = "off" |
| 35 | ) |
| 36 | |
| 37 | // Answer is one request's geo result, computed once at ingress or adopted |
| 38 | // from a trusted transport. Lat/Lon are already rounded to 2 places. |
| 39 | type Answer struct { |
| 40 | State State |
| 41 | Country string |
| 42 | Subdivision string |
| 43 | Source string |
| 44 | Lat, Lon float64 |
| 45 | HasPoint bool |
| 46 | } |
| 47 | |
| 48 | // Off is the answer for a request no lookup was attempted for. |
| 49 | func Off() Answer { return Answer{State: StateOff} } |
| 50 | |
| 51 | func round2(v float64) float64 { return math.Round(v*100) / 100 } |
| 52 | |
| 53 | // FromSnapshot turns one reader's answer into a request's answer. |
| 54 | func FromSnapshot(s geo.Snapshot) Answer { |
| 55 | switch { |
| 56 | case !s.Loaded: |
| 57 | return Off() |
| 58 | case !s.Found: |
| 59 | return Answer{State: StateMiss, Source: s.Source} |
| 60 | } |
| 61 | a := Answer{State: StateHit, Country: s.Result.Country, Subdivision: s.Result.Subdivision, Source: s.Source} |
| 62 | if s.Result.HasPoint { |
| 63 | a.Lat, a.Lon, a.HasPoint = round2(s.Result.Point.Lat), round2(s.Result.Point.Lon), true |
| 64 | } |
| 65 | return a |
| 66 | } |
| 67 | |
| 68 | // geoPrefix is the reserved namespace: spec §8.1 strips EVERY header in |
| 69 | // it, not just the five this version writes, so a client cannot hand an app |
| 70 | // an X-Carlos-Geo-City (or any later name) that looks platform-set. |
| 71 | const geoPrefix = "X-Carlos-Geo-" |
| 72 | |
| 73 | // StripAll deletes every X-Carlos-Geo-* header and X-Carlos-Hop-Geo, in |
| 74 | // any case and with underscores in place of hyphens: CGI and WSGI turn |
| 75 | // both into the same HTTP_X_CARLOS_GEO_* key, so X_Carlos_Geo_Country |
| 76 | // would otherwise reach a Python app as the platform's own header (code |
| 77 | // review R12-1). |
| 78 | func StripAll(h http.Header) { |
| 79 | for k := range h { |
| 80 | if reserved(k) { |
| 81 | delete(h, k) |
| 82 | } |
| 83 | } |
| 84 | } |
| 85 | |
| 86 | // reserved reports whether a header name falls in the platform's geo |
| 87 | // namespace once underscores are read as hyphens. |
| 88 | func reserved(k string) bool { |
| 89 | n := strings.ReplaceAll(k, "_", "-") |
| 90 | return len(n) >= len(geoPrefix) && strings.EqualFold(n[:len(geoPrefix)], geoPrefix) || strings.EqualFold(n, HeaderHop) |
| 91 | } |
| 92 | |
| 93 | // WriteApp deletes the app headers and writes this answer's. A miss and |
| 94 | // off write nothing at all; Source is written only beside another field. |
| 95 | func (a Answer) WriteApp(h http.Header) { |
| 96 | for _, k := range appHeaders { |
| 97 | h.Del(k) |
| 98 | } |
| 99 | if a.State != StateHit { |
| 100 | return |
| 101 | } |
| 102 | wrote := false |
| 103 | if a.Country != "" { |
| 104 | h.Set(HeaderCountry, a.Country) |
| 105 | wrote = true |
| 106 | if a.Subdivision != "" { |
| 107 | h.Set(HeaderSubdivision, a.Subdivision) |
| 108 | } |
| 109 | } |
| 110 | if a.HasPoint { |
| 111 | h.Set(HeaderLat, strconv.FormatFloat(a.Lat, 'f', 2, 64)) |
| 112 | h.Set(HeaderLon, strconv.FormatFloat(a.Lon, 'f', 2, 64)) |
| 113 | wrote = true |
| 114 | } |
| 115 | if wrote && a.Source != "" { |
| 116 | h.Set(HeaderSource, a.Source) |
| 117 | } |
| 118 | } |
| 119 | |
| 120 | // HopValue is X-Carlos-Hop-Geo for this answer. |
| 121 | func (a Answer) HopValue() string { |
| 122 | if a.State == StateOff || !sourceRE.MatchString(a.Source) { |
| 123 | return string(StateOff) |
| 124 | } |
| 125 | return string(a.State) + ";src=" + a.Source |
| 126 | } |
| 127 | |
| 128 | // Captured is what a request arrived carrying, before anyone trusts it. |
| 129 | type Captured struct { |
| 130 | Hop, Country, Subdivision, Lat, Lon, Source string |
| 131 | } |
| 132 | |
| 133 | // Capture copies the geo headers out of h and strips them all (spec §8.1 |
| 134 | // step 1). Nothing reads the copy until the transport is authenticated. |
| 135 | func Capture(h http.Header) Captured { |
| 136 | c := Captured{ |
| 137 | Hop: h.Get(HeaderHop), Country: h.Get(HeaderCountry), Subdivision: h.Get(HeaderSubdivision), |
| 138 | Lat: h.Get(HeaderLat), Lon: h.Get(HeaderLon), Source: h.Get(HeaderSource), |
| 139 | } |
| 140 | StripAll(h) |
| 141 | return c |
| 142 | } |
| 143 | |
| 144 | var ( |
| 145 | countryRE = regexp.MustCompile(`^[A-Z]{2}$`) |
| 146 | subdivisionRE = regexp.MustCompile(`^[A-Z]{2}-[A-Z0-9]{1,3}$`) |
| 147 | sourceRE = regexp.MustCompile(`^[A-Za-z0-9._-]{1,64}$`) |
| 148 | ) |
| 149 | |
| 150 | // Adopt validates what a TRUSTED transport carried (spec §8.4). Call it only |
| 151 | // for a verified hop or a TLS tunnel. Invalid fields are dropped one by one; |
| 152 | // a hit left with neither a country nor a coordinate pair, or a missing or |
| 153 | // malformed hop value, is off. |
| 154 | func (c Captured) Adopt() Answer { |
| 155 | state, src, ok := strings.Cut(c.Hop, ";src=") |
| 156 | switch { |
| 157 | case c.Hop == string(StateOff): |
| 158 | return Off() |
| 159 | case !ok || !sourceRE.MatchString(src): |
| 160 | return Off() |
| 161 | case State(state) == StateMiss: |
| 162 | return Answer{State: StateMiss, Source: src} |
| 163 | case State(state) != StateHit: |
| 164 | return Off() |
| 165 | } |
| 166 | a := Answer{State: StateHit, Source: src} |
| 167 | if countryRE.MatchString(c.Country) { |
| 168 | a.Country = c.Country |
| 169 | if subdivisionRE.MatchString(c.Subdivision) && strings.HasPrefix(c.Subdivision, c.Country+"-") { |
| 170 | a.Subdivision = c.Subdivision |
| 171 | } |
| 172 | } |
| 173 | if lat, lon, ok := parsePair(c.Lat, c.Lon); ok { |
| 174 | a.Lat, a.Lon, a.HasPoint = lat, lon, true |
| 175 | } |
| 176 | if a.Country == "" && !a.HasPoint { |
| 177 | return Off() |
| 178 | } |
| 179 | return a |
| 180 | } |
| 181 | |
| 182 | func parsePair(latS, lonS string) (float64, float64, bool) { |
| 183 | lat, err1 := strconv.ParseFloat(latS, 64) |
| 184 | lon, err2 := strconv.ParseFloat(lonS, 64) |
| 185 | if err1 != nil || err2 != nil || math.IsNaN(lat) || math.IsNaN(lon) || math.IsInf(lat, 0) || math.IsInf(lon, 0) || |
| 186 | lat < -90 || lat > 90 || lon < -180 || lon > 180 { |
| 187 | return 0, 0, false |
| 188 | } |
| 189 | return round2(lat), round2(lon), true |
| 190 | } |
| 191 | |
amadan