| 1 | package tinyclient |
| 2 | |
| 3 | import ( |
| 4 | "encoding/binary" |
| 5 | "encoding/hex" |
| 6 | "net/http" |
| 7 | "net/url" |
| 8 | "regexp" |
| 9 | "strconv" |
| 10 | "strings" |
| 11 | ) |
| 12 | |
| 13 | var hexID = regexp.MustCompile(`^[0-9a-f]{64}$` ) |
| 14 | |
| 15 | // openLink handles web+nostr links registered through the installed app. |
| 16 | // It decodes the NIP-19 target and redirects to the page that shows it. |
| 17 | func (a *App) openLink(writer http.ResponseWriter, request *http.Request) { |
| 18 | path, ok := nostrTargetPath(request.URL.Query().Get("target" )) |
| 19 | if !ok { |
| 20 | http.Error(writer, "unsupported nostr link" , http.StatusBadRequest) |
| 21 | return |
| 22 | } |
| 23 | http.Redirect(writer, request, requestPrefix(request)+path, http.StatusSeeOther) |
| 24 | } |
| 25 | |
| 26 | // nostrTargetPath maps a nostr: or web+nostr: target to a relay page. |
| 27 | func nostrTargetPath(target string) (string, bool) { |
| 28 | value := strings.TrimSpace(target) |
| 29 | for _, prefix := range []string{"web+nostr:" , "nostr:" } { |
| 30 | if strings.HasPrefix(strings.ToLower(value), prefix) { |
| 31 | value = value[len(prefix):] |
| 32 | break |
| 33 | } |
| 34 | } |
| 35 | value = strings.Trim(value, "/" ) |
| 36 | if hexID.MatchString(value) { |
| 37 | return "/e/" + value, true |
| 38 | } |
| 39 | hrp, data, ok := bech32Decode(strings.ToLower(value)) |
| 40 | if !ok { |
| 41 | return "" , false |
| 42 | } |
| 43 | switch hrp { |
| 44 | case "npub" : |
| 45 | if len(data) != 32 { |
| 46 | return "" , false |
| 47 | } |
| 48 | return "/search?author=" + hex.EncodeToString(data), true |
| 49 | case "note" : |
| 50 | if len(data) != 32 { |
| 51 | return "" , false |
| 52 | } |
| 53 | return "/e/" + hex.EncodeToString(data), true |
| 54 | case "nprofile" , "nevent" , "naddr" : |
| 55 | fields := tlvFields(data) |
| 56 | switch hrp { |
| 57 | case "nprofile" : |
| 58 | if len(fields[0]) != 32 { |
| 59 | return "" , false |
| 60 | } |
| 61 | return "/search?author=" + hex.EncodeToString(fields[0]), true |
| 62 | case "nevent" : |
| 63 | if len(fields[0]) != 32 { |
| 64 | return "" , false |
| 65 | } |
| 66 | return "/e/" + hex.EncodeToString(fields[0]), true |
| 67 | default: |
| 68 | if len(fields[2]) != 32 || len(fields[3]) != 4 { |
| 69 | return "" , false |
| 70 | } |
| 71 | kind := binary.BigEndian.Uint32(fields[3]) |
| 72 | return "/a/" + strconv.FormatUint(uint64(kind), 10) + ":" + hex.EncodeToString(fields[2]) + ":" + url.PathEscape(string(fields[0])), true |
| 73 | } |
| 74 | } |
| 75 | return "" , false |
| 76 | } |
| 77 | |
| 78 | // tlvFields returns the first value of each NIP-19 TLV type. |
| 79 | func tlvFields(data []byte) map[byte][]byte { |
| 80 | fields := map[byte][]byte{} |
| 81 | for len(data) >= 2 { |
| 82 | kind, length := data[0], int(data[1]) |
| 83 | if len(data) < 2+length { |
| 84 | break |
| 85 | } |
| 86 | if _, seen := fields[kind]; !seen { |
| 87 | fields[kind] = data[2 : 2+length] |
| 88 | } |
| 89 | data = data[2+length:] |
| 90 | } |
| 91 | return fields |
| 92 | } |
| 93 | |
| 94 | // bech32Decode verifies a bech32 string and returns its 8-bit payload. |
| 95 | func bech32Decode(value string) (string, []byte, bool) { |
| 96 | separator := strings.LastIndexByte(value, '1' ) |
| 97 | if separator < 1 || separator+7 > len(value) || len(value) > 5000 { |
| 98 | return "" , nil, false |
| 99 | } |
| 100 | hrp, encoded := value[:separator], value[separator+1:] |
| 101 | values := make([]byte, len(encoded)) |
| 102 | for i, char := range encoded { |
| 103 | position := strings.IndexRune(bech32Charset, char) |
| 104 | if position < 0 { |
| 105 | return "" , nil, false |
| 106 | } |
| 107 | values[i] = byte(position) |
| 108 | } |
| 109 | if bech32Polymod(append(bech32Expand(hrp), values...)) != 1 { |
| 110 | return "" , nil, false |
| 111 | } |
| 112 | data := values[:len(values)-6] |
| 113 | accumulator, bits := 0, 0 |
| 114 | var result []byte |
| 115 | for _, v := range data { |
| 116 | accumulator = accumulator<<5 | int(v) |
| 117 | bits += 5 |
| 118 | if bits >= 8 { |
| 119 | bits -= 8 |
| 120 | result = append(result, byte(accumulator>>bits&255)) |
| 121 | } |
| 122 | } |
| 123 | if bits >= 5 || accumulator<<(8-bits)&255 != 0 { |
| 124 | return "" , nil, false |
| 125 | } |
| 126 | return hrp, result, true |
| 127 | } |
| 128 | |
| 129 | func bech32Expand(hrp string) []byte { |
| 130 | expanded := make([]byte, 0, len(hrp)*2+1) |
| 131 | for _, c := range hrp { |
| 132 | expanded = append(expanded, byte(c)>>5) |
| 133 | } |
| 134 | expanded = append(expanded, 0) |
| 135 | for _, c := range hrp { |
| 136 | expanded = append(expanded, byte(c)&31) |
| 137 | } |
| 138 | return expanded |
| 139 | } |
