mirror of
https://github.com/lnbits/lnbits-legend.git
synced 2025-02-25 15:10:41 +01:00
347 lines
9.5 KiB
JavaScript
347 lines
9.5 KiB
JavaScript
//TODO - A reader MUST check that the signature is valid (see the n tagged field)
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//TODO - Tagged part of type f: the fallback on-chain address should be decoded into an address format
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//TODO - A reader MUST check that the SHA-2 256 in the h field exactly matches the hashed description.
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//TODO - A reader MUST use the n field to validate the signature instead of performing signature recovery if a valid n field is provided.
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function decode(paymentRequest) {
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let input = paymentRequest.toLowerCase()
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let splitPosition = input.lastIndexOf('1')
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let humanReadablePart = input.substring(0, splitPosition)
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let data = input.substring(splitPosition + 1, input.length - 6)
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let checksum = input.substring(input.length - 6, input.length)
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if (
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!verify_checksum(humanReadablePart, bech32ToFiveBitArray(data + checksum))
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) {
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throw 'Malformed request: checksum is incorrect' // A reader MUST fail if the checksum is incorrect.
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}
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return {
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human_readable_part: decodeHumanReadablePart(humanReadablePart),
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data: decodeData(data, humanReadablePart),
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checksum: checksum
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}
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}
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function decodeHumanReadablePart(humanReadablePart) {
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let prefixes = ['lnbc', 'lntb', 'lnbcrt', 'lnsb']
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let prefix
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prefixes.forEach(value => {
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if (humanReadablePart.substring(0, value.length) === value) {
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prefix = value
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}
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})
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if (prefix == null) throw 'Malformed request: unknown prefix' // A reader MUST fail if it does not understand the prefix.
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let amount = decodeAmount(
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humanReadablePart.substring(prefix.length, humanReadablePart.length)
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)
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return {
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prefix: prefix,
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amount: amount
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}
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}
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function decodeData(data, humanReadablePart) {
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let date32 = data.substring(0, 7)
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let dateEpoch = bech32ToInt(date32)
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let signature = data.substring(data.length - 104, data.length)
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let tagData = data.substring(7, data.length - 104)
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let decodedTags = decodeTags(tagData)
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let value = bech32ToFiveBitArray(date32 + tagData)
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value = fiveBitArrayTo8BitArray(value, true)
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value = textToHexString(humanReadablePart).concat(byteArrayToHexString(value))
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return {
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time_stamp: dateEpoch,
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tags: decodedTags,
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signature: decodeSignature(signature),
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signing_data: value
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}
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}
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function decodeSignature(signature) {
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let data = fiveBitArrayTo8BitArray(bech32ToFiveBitArray(signature))
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let recoveryFlag = data[data.length - 1]
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let r = byteArrayToHexString(data.slice(0, 32))
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let s = byteArrayToHexString(data.slice(32, data.length - 1))
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return {
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r: r,
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s: s,
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recovery_flag: recoveryFlag
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}
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}
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function decodeAmount(str) {
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let multiplier = str.charAt(str.length - 1)
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let amount = str.substring(0, str.length - 1)
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if (amount.substring(0, 1) === '0') {
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throw 'Malformed request: amount cannot contain leading zeros'
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}
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amount = Number(amount)
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if (amount < 0 || !Number.isInteger(amount)) {
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throw 'Malformed request: amount must be a positive decimal integer' // A reader SHOULD fail if amount contains a non-digit
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}
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switch (multiplier) {
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case '':
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return 'Any amount' // A reader SHOULD indicate if amount is unspecified
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case 'p':
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return amount / 10
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case 'n':
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return amount * 100
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case 'u':
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return amount * 100000
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case 'm':
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return amount * 100000000
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default:
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// A reader SHOULD fail if amount is followed by anything except a defined multiplier.
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throw 'Malformed request: undefined amount multiplier'
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}
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}
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function decodeTags(tagData) {
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let tags = extractTags(tagData)
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let decodedTags = []
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tags.forEach(value =>
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decodedTags.push(decodeTag(value.type, value.length, value.data))
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)
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return decodedTags
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}
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function extractTags(str) {
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let tags = []
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while (str.length > 0) {
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let type = str.charAt(0)
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let dataLength = bech32ToInt(str.substring(1, 3))
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let data = str.substring(3, dataLength + 3)
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tags.push({
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type: type,
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length: dataLength,
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data: data
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})
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str = str.substring(3 + dataLength, str.length)
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}
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return tags
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}
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function decodeTag(type, length, data) {
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switch (type) {
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case 'p':
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if (length !== 52) break // A reader MUST skip over a 'p' field that does not have data_length 52
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return {
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type: type,
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length: length,
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description: 'payment_hash',
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value: byteArrayToHexString(
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fiveBitArrayTo8BitArray(bech32ToFiveBitArray(data))
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)
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}
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case 'd':
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return {
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type: type,
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length: length,
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description: 'description',
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value: bech32ToUTF8String(data)
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}
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case 'n':
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if (length !== 53) break // A reader MUST skip over a 'n' field that does not have data_length 53
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return {
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type: type,
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length: length,
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description: 'payee_public_key',
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value: byteArrayToHexString(
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fiveBitArrayTo8BitArray(bech32ToFiveBitArray(data))
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)
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}
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case 'h':
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if (length !== 52) break // A reader MUST skip over a 'h' field that does not have data_length 52
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return {
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type: type,
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length: length,
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description: 'description_hash',
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value: data
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}
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case 'x':
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return {
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type: type,
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length: length,
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description: 'expiry',
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value: bech32ToInt(data)
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}
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case 'c':
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return {
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type: type,
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length: length,
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description: 'min_final_cltv_expiry',
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value: bech32ToInt(data)
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}
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case 'f':
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let version = bech32ToFiveBitArray(data.charAt(0))[0]
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if (version < 0 || version > 18) break // a reader MUST skip over an f field with unknown version.
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data = data.substring(1, data.length)
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return {
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type: type,
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length: length,
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description: 'fallback_address',
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value: {
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version: version,
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fallback_address: data
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}
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}
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case 'r':
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data = fiveBitArrayTo8BitArray(bech32ToFiveBitArray(data))
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let pubkey = data.slice(0, 33)
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let shortChannelId = data.slice(33, 41)
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let feeBaseMsat = data.slice(41, 45)
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let feeProportionalMillionths = data.slice(45, 49)
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let cltvExpiryDelta = data.slice(49, 51)
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return {
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type: type,
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length: length,
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description: 'routing_information',
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value: {
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public_key: byteArrayToHexString(pubkey),
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short_channel_id: byteArrayToHexString(shortChannelId),
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fee_base_msat: byteArrayToInt(feeBaseMsat),
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fee_proportional_millionths: byteArrayToInt(
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feeProportionalMillionths
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),
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cltv_expiry_delta: byteArrayToInt(cltvExpiryDelta)
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}
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}
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default:
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// reader MUST skip over unknown fields
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}
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}
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function polymod(values) {
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let GEN = [0x3b6a57b2, 0x26508e6d, 0x1ea119fa, 0x3d4233dd, 0x2a1462b3]
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let chk = 1
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values.forEach(value => {
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let b = chk >> 25
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chk = ((chk & 0x1ffffff) << 5) ^ value
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for (let i = 0; i < 5; i++) {
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if (((b >> i) & 1) === 1) {
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chk ^= GEN[i]
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} else {
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chk ^= 0
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}
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}
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})
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return chk
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}
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function expand(str) {
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let array = []
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for (let i = 0; i < str.length; i++) {
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array.push(str.charCodeAt(i) >> 5)
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}
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array.push(0)
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for (let i = 0; i < str.length; i++) {
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array.push(str.charCodeAt(i) & 31)
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}
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return array
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}
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function verify_checksum(hrp, data) {
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hrp = expand(hrp)
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let all = hrp.concat(data)
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let bool = polymod(all)
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return bool === 1
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}
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const bech32CharValues = 'qpzry9x8gf2tvdw0s3jn54khce6mua7l'
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function byteArrayToInt(byteArray) {
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let value = 0
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for (let i = 0; i < byteArray.length; ++i) {
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value = (value << 8) + byteArray[i]
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}
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return value
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}
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function bech32ToInt(str) {
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let sum = 0
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for (let i = 0; i < str.length; i++) {
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sum = sum * 32
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sum = sum + bech32CharValues.indexOf(str.charAt(i))
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}
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return sum
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}
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function bech32ToFiveBitArray(str) {
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let array = []
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for (let i = 0; i < str.length; i++) {
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array.push(bech32CharValues.indexOf(str.charAt(i)))
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}
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return array
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}
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function fiveBitArrayTo8BitArray(int5Array, includeOverflow) {
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let count = 0
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let buffer = 0
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let byteArray = []
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int5Array.forEach(value => {
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buffer = (buffer << 5) + value
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count += 5
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if (count >= 8) {
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byteArray.push((buffer >> (count - 8)) & 255)
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count -= 8
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}
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})
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if (includeOverflow && count > 0) {
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byteArray.push((buffer << (8 - count)) & 255)
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}
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return byteArray
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}
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function bech32ToUTF8String(str) {
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let int5Array = bech32ToFiveBitArray(str)
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let byteArray = fiveBitArrayTo8BitArray(int5Array)
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let utf8String = ''
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for (let i = 0; i < byteArray.length; i++) {
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utf8String += '%' + ('0' + byteArray[i].toString(16)).slice(-2)
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}
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return decodeURIComponent(utf8String)
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}
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function byteArrayToHexString(byteArray) {
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return Array.prototype.map
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.call(byteArray, function (byte) {
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return ('0' + (byte & 0xff).toString(16)).slice(-2)
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})
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.join('')
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}
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function textToHexString(text) {
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let hexString = ''
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for (let i = 0; i < text.length; i++) {
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hexString += text.charCodeAt(i).toString(16)
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}
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return hexString
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}
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function epochToDate(int) {
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let date = new Date(int * 1000)
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return date.toUTCString()
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}
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function isEmptyOrSpaces(str) {
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return str === null || str.match(/^ *$/) !== null
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}
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function toFixed(x) {
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if (Math.abs(x) < 1.0) {
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var e = parseInt(x.toString().split('e-')[1])
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if (e) {
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x *= Math.pow(10, e - 1)
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x = '0.' + new Array(e).join('0') + x.toString().substring(2)
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}
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} else {
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var e = parseInt(x.toString().split('+')[1])
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if (e > 20) {
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e -= 20
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x /= Math.pow(10, e)
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x += new Array(e + 1).join('0')
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}
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}
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return x
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}
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