#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include struct multiplier { const char letter; /* We can't represent p postfix to msat, so we multiply this by 10 */ u64 m10; }; /* BOLT #11: * * The following `multiplier` letters are defined: * * * `m` (milli): multiply by 0.001 * * `u` (micro): multiply by 0.000001 * * `n` (nano): multiply by 0.000000001 * * `p` (pico): multiply by 0.000000000001 */ static struct multiplier multipliers[] = { { 'm', 10 * MSAT_PER_BTC / 1000 }, { 'u', 10 * MSAT_PER_BTC / 1000000 }, { 'n', 10 * MSAT_PER_BTC / 1000000000 }, { 'p', 10 * MSAT_PER_BTC / 1000000000000ULL } }; /* If pad is false, we discard any bits which don't fit in the last byte. * Otherwise we add an extra byte */ static bool pull_bits(struct hash_u5 *hu5, u5 **data, size_t *data_len, void *dst, size_t nbits, bool pad) { size_t n5 = nbits / 5; size_t len = 0; if (nbits % 5) n5++; if (*data_len < n5) return false; if (!bech32_convert_bits(dst, &len, 8, *data, n5, 5, pad)) return false; if (hu5) hash_u5(hu5, *data, n5); *data += n5; *data_len -= n5; return true; } /* For pulling fields where we should have checked it will succeed already. */ #ifndef NDEBUG #define pull_bits_certain(hu5, data, data_len, dst, nbits, pad) \ assert(pull_bits((hu5), (data), (data_len), (dst), (nbits), (pad))) #else #define pull_bits_certain pull_bits #endif /* Helper for pulling a variable-length big-endian int. */ static bool pull_uint(struct hash_u5 *hu5, u5 **data, size_t *data_len, u64 *val, size_t databits) { be64 be_val; /* Too big. */ if (databits > sizeof(be_val) * CHAR_BIT) return false; if (!pull_bits(hu5, data, data_len, &be_val, databits, true)) return false; *val = be64_to_cpu(be_val) >> (sizeof(be_val) * CHAR_BIT - databits); return true; } static size_t num_u8(size_t num_u5) { return (num_u5 * 5 + 4) / 8; } /* Frees bolt11, returns NULL. */ static struct bolt11 *decode_fail(struct bolt11 *b11, char **fail, const char *fmt, ...) PRINTF_FMT(3,4); static struct bolt11 *decode_fail(struct bolt11 *b11, char **fail, const char *fmt, ...) { va_list ap; va_start(ap, fmt); *fail = tal_vfmt(tal_parent(b11), fmt, ap); va_end(ap); return tal_free(b11); } /* * These handle specific fields in the payment request; returning the problem * if any, or NULL. */ static char *unknown_field(struct bolt11 *b11, struct hash_u5 *hu5, u5 **data, size_t *data_len, u5 type, size_t length) { struct bolt11_field *extra = tal(b11, struct bolt11_field); u8 u8data[num_u8(length)]; extra->tag = type; extra->data = tal_dup_arr(extra, u5, *data, length, 0); list_add_tail(&b11->extra_fields, &extra->list); pull_bits_certain(hu5, data, data_len, u8data, length * 5, true); return NULL; } /* BOLT #11: * * `p` (1): `data_length` 52. 256-bit SHA256 payment_hash. Preimage of this * provides proof of payment */ static void decode_p(struct bolt11 *b11, struct hash_u5 *hu5, u5 **data, size_t *data_len, size_t data_length, bool *have_p) { /* BOLT #11: * * A payer... SHOULD use the first `p` field that it did NOT * skip as the payment hash. */ if (*have_p) { unknown_field(b11, hu5, data, data_len, 'p', data_length); return; } /* BOLT #11: * * A reader... MUST skip over unknown fields, OR an `f` field * with unknown `version`, OR `p`, `h`, `s` or `n` fields that do * NOT have `data_length`s of 52, 52, 52 or 53, respectively. */ if (data_length != 52) { unknown_field(b11, hu5, data, data_len, 'p', data_length); return; } pull_bits_certain(hu5, data, data_len, &b11->payment_hash, 256, false); *have_p = true; } /* BOLT #11: * * `d` (13): `data_length` variable. Short description of purpose of payment * (UTF-8), e.g. '1 cup of coffee' or 'ナンセンス 1杯' */ static char *decode_d(struct bolt11 *b11, struct hash_u5 *hu5, u5 **data, size_t *data_len, size_t data_length, bool *have_d) { u8 *desc; if (*have_d) return unknown_field(b11, hu5, data, data_len, 'd', data_length); desc = tal_arr(NULL, u8, data_length * 5 / 8); pull_bits_certain(hu5, data, data_len, desc, data_length*5, false); *have_d = true; b11->description = utf8_str(b11, take(desc), tal_bytelen(desc)); if (b11->description) return NULL; return tal_fmt(b11, "d: invalid utf8"); } /* BOLT #11: * * `h` (23): `data_length` 52. 256-bit description of purpose of payment * (SHA256). This is used to commit to an associated description that is over * 639 bytes, but the transport mechanism for the description in that case is * transport specific and not defined here. */ static void decode_h(struct bolt11 *b11, struct hash_u5 *hu5, u5 **data, size_t *data_len, size_t data_length, bool *have_h) { if (*have_h) { unknown_field(b11, hu5, data, data_len, 'h', data_length); return; } /* BOLT #11: * * A reader... MUST skip over unknown fields, OR an `f` field * with unknown `version`, OR `p`, `h`, `s` or `n` fields that do * NOT have `data_length`s of 52, 52, 52 or 53, respectively. */ if (data_length != 52) { unknown_field(b11, hu5, data, data_len, 'h', data_length); return; } b11->description_hash = tal(b11, struct sha256); pull_bits_certain(hu5, data, data_len, b11->description_hash, 256, false); *have_h = true; } /* BOLT #11: * * `x` (6): `data_length` variable. `expiry` time in seconds * (big-endian). Default is 3600 (1 hour) if not specified. */ #define DEFAULT_X 3600 static char *decode_x(struct bolt11 *b11, struct hash_u5 *hu5, u5 **data, size_t *data_len, size_t data_length, const bool *have_x) { if (*have_x) return unknown_field(b11, hu5, data, data_len, 'x', data_length); /* FIXME: Put upper limit in bolt 11 */ if (!pull_uint(hu5, data, data_len, &b11->expiry, data_length * 5)) return tal_fmt(b11, "x: length %zu chars is excessive", *data_len); return NULL; } /* BOLT #11: * * `c` (24): `data_length` variable. `min_final_cltv_expiry` to use for the * last HTLC in the route. Default is 18 if not specified. */ static char *decode_c(struct bolt11 *b11, struct hash_u5 *hu5, u5 **data, size_t *data_len, size_t data_length, const bool *have_c) { u64 c; if (*have_c) return unknown_field(b11, hu5, data, data_len, 'c', data_length); /* FIXME: Put upper limit in bolt 11 */ if (!pull_uint(hu5, data, data_len, &c, data_length * 5)) return tal_fmt(b11, "c: length %zu chars is excessive", *data_len); b11->min_final_cltv_expiry = c; /* Can overflow, since c is 64 bits but value must be < 32 bits */ if (b11->min_final_cltv_expiry != c) return tal_fmt(b11, "c: %"PRIu64" is too large", c); return NULL; } static char *decode_n(struct bolt11 *b11, struct hash_u5 *hu5, u5 **data, size_t *data_len, size_t data_length, bool *have_n) { if (*have_n) return unknown_field(b11, hu5, data, data_len, 'n', data_length); /* BOLT #11: * * A reader... MUST skip over unknown fields, OR an `f` field * with unknown `version`, OR `p`, `h`, `s` or `n` fields that do * NOT have `data_length`s of 52, 52, 52 or 53, respectively. */ if (data_length != 53) return unknown_field(b11, hu5, data, data_len, 'n', data_length); pull_bits_certain(hu5, data, data_len, &b11->receiver_id.k, data_length * 5, false); if (!node_id_valid(&b11->receiver_id)) return tal_fmt(b11, "n: invalid pubkey %s", node_id_to_hexstr(tmpctx, &b11->receiver_id)); *have_n = true; return NULL; } /* BOLT #11: * * * `s` (16): `data_length` 52. This 256-bit secret prevents * forwarding nodes from probing the payment recipient. */ static char *decode_s(struct bolt11 *b11, struct hash_u5 *hu5, u5 **data, size_t *data_len, size_t data_length, bool *have_s) { if (*have_s) return unknown_field(b11, hu5, data, data_len, 's', data_length); /* BOLT #11: * * A reader... MUST skip over unknown fields, OR an `f` field * with unknown `version`, OR `p`, `h`, `s` or `n` fields that do * NOT have `data_length`s of 52, 52, 52 or 53, respectively. */ if (data_length != 52) return unknown_field(b11, hu5, data, data_len, 's', data_length); b11->payment_secret = tal(b11, struct secret); pull_bits_certain(hu5, data, data_len, b11->payment_secret, 256, false); *have_s = true; return NULL; } /* BOLT #11: * * `f` (9): `data_length` variable, depending on version. Fallback * on-chain address: for Bitcoin, this starts with a 5-bit `version` * and contains a witness program or P2PKH or P2SH address. */ static char *decode_f(struct bolt11 *b11, struct hash_u5 *hu5, u5 **data, size_t *data_len, size_t data_length) { u64 version; u8 *fallback; if (!pull_uint(hu5, data, data_len, &version, 5)) return tal_fmt(b11, "f: data_length %zu short", data_length); data_length--; /* BOLT #11: * * for Bitcoin payments... MUST set an `f` field to a valid * witness version and program, OR to `17` followed by a * public key hash, OR to `18` followed by a script hash. */ if (version == 17) { /* Pay to pubkey hash (P2PKH) */ struct bitcoin_address pkhash; if (num_u8(data_length) != sizeof(pkhash)) return tal_fmt(b11, "f: pkhash length %zu", data_length); pull_bits_certain(hu5, data, data_len, &pkhash, data_length*5, false); fallback = scriptpubkey_p2pkh(b11, &pkhash); } else if (version == 18) { /* Pay to pubkey script hash (P2SH) */ struct ripemd160 shash; if (num_u8(data_length) != sizeof(shash)) return tal_fmt(b11, "f: p2sh length %zu", data_length); pull_bits_certain(hu5, data, data_len, &shash, data_length*5, false); fallback = scriptpubkey_p2sh_hash(b11, &shash); } else if (version < 17) { u8 *f = tal_arr(b11, u8, data_length * 5 / 8); if (version == 0) { if (tal_count(f) != 20 && tal_count(f) != 32) return tal_fmt(b11, "f: witness v0 bad length %zu", data_length); } pull_bits_certain(hu5, data, data_len, f, data_length * 5, false); fallback = scriptpubkey_witness_raw(b11, version, f, tal_count(f)); tal_free(f); } else { /* Restore version for unknown field! */ (*data)--; (*data_len)++; data_length++; return unknown_field(b11, hu5, data, data_len, 'f', data_length); } if (b11->fallbacks == NULL) b11->fallbacks = tal_arr(b11, const u8 *, 1); else tal_resize(&b11->fallbacks, tal_count(b11->fallbacks) + 1); b11->fallbacks[tal_count(b11->fallbacks)-1] = tal_steal(b11->fallbacks, fallback); return NULL; } static bool fromwire_route_info(const u8 **cursor, size_t *max, struct route_info *route_info) { fromwire_node_id(cursor, max, &route_info->pubkey); fromwire_short_channel_id(cursor, max, &route_info->short_channel_id); route_info->fee_base_msat = fromwire_u32(cursor, max); route_info->fee_proportional_millionths = fromwire_u32(cursor, max); route_info->cltv_expiry_delta = fromwire_u16(cursor, max); return *cursor != NULL; } static void towire_route_info(u8 **pptr, const struct route_info *route_info) { towire_node_id(pptr, &route_info->pubkey); towire_short_channel_id(pptr, &route_info->short_channel_id); towire_u32(pptr, route_info->fee_base_msat); towire_u32(pptr, route_info->fee_proportional_millionths); towire_u16(pptr, route_info->cltv_expiry_delta); } /* BOLT #11: * * `r` (3): `data_length` variable. One or more entries containing * extra routing information for a private route; there may be more * than one `r` field * * * `pubkey` (264 bits) * * `short_channel_id` (64 bits) * * `fee_base_msat` (32 bits, big-endian) * * `fee_proportional_millionths` (32 bits, big-endian) * * `cltv_expiry_delta` (16 bits, big-endian) */ static char *decode_r(struct bolt11 *b11, struct hash_u5 *hu5, u5 **data, size_t *data_len, size_t data_length) { size_t rlen = data_length * 5 / 8; u8 *r8 = tal_arr(tmpctx, u8, rlen); size_t n = 0; struct route_info *r = tal_arr(tmpctx, struct route_info, n); const u8 *cursor = r8; /* Route hops don't split in 5 bit boundaries, so convert whole thing */ pull_bits_certain(hu5, data, data_len, r8, data_length * 5, false); do { struct route_info ri; if (!fromwire_route_info(&cursor, &rlen, &ri)) { return tal_fmt(b11, "r: hop %zu truncated", n); } tal_arr_expand(&r, ri); } while (rlen); /* Append route */ tal_arr_expand(&b11->routes, tal_steal(b11, r)); return NULL; } static void shift_bitmap_down(u8 *bitmap, size_t bits) { u8 prev = 0; assert(bits < CHAR_BIT); for (size_t i = 0; i < tal_bytelen(bitmap); i++) { /* Save top bits for next one */ u8 v = bitmap[i]; bitmap[i] = (prev | (v >> bits)); prev = (v << (8 - bits)); } assert(prev == 0); } /* BOLT #11: * * `9` (5): `data_length` variable. One or more 5-bit values containing features * supported or required for receiving this payment. * See [Feature Bits](#feature-bits). */ static char *decode_9(struct bolt11 *b11, const struct feature_set *our_features, struct hash_u5 *hu5, u5 **data, size_t *data_len, size_t data_length) { size_t flen = (data_length * 5 + 7) / 8; int badf; b11->features = tal_arr(b11, u8, flen); pull_bits_certain(hu5, data, data_len, b11->features, data_length * 5, true); /* pull_bits pads with zero bits: we need to remove them. */ shift_bitmap_down(b11->features, flen * 8 - data_length * 5); /* BOLT #11: * * - if the `9` field contains unknown _odd_ bits that are non-zero: * - MUST ignore the bit. * - if the `9` field contains unknown _even_ bits that are non-zero: * - MUST fail the payment. */ /* We skip this check for the cli tool, which sets our_features to NULL */ if (our_features) { badf = features_unsupported(our_features, b11->features, BOLT11_FEATURE); if (badf != -1) return tal_fmt(b11, "9: unknown feature bit %i", badf); } return NULL; } struct bolt11 *new_bolt11(const tal_t *ctx, const struct amount_msat *msat TAKES) { struct bolt11 *b11 = tal(ctx, struct bolt11); list_head_init(&b11->extra_fields); b11->description = NULL; b11->description_hash = NULL; b11->fallbacks = NULL; b11->routes = NULL; b11->msat = NULL; b11->expiry = DEFAULT_X; b11->features = tal_arr(b11, u8, 0); /* BOLT #11: * - if the `c` field (`min_final_cltv_expiry`) is not provided: * - MUST use an expiry delta of at least 18 when making the payment */ b11->min_final_cltv_expiry = 18; b11->payment_secret = NULL; if (msat) b11->msat = tal_dup(b11, struct amount_msat, msat); return b11; } /* Extracts signature but does not check it. */ struct bolt11 *bolt11_decode_nosig(const tal_t *ctx, const char *str, const struct feature_set *our_features, const char *description, const struct chainparams *must_be_chain, struct sha256 *hash, u5 **sig, bool *have_n, char **fail) { char *hrp, *amountstr, *prefix; u5 *data; size_t data_len; struct bolt11 *b11 = new_bolt11(ctx, NULL); struct hash_u5 hu5; bool have_p = false, have_d = false, have_h = false, have_x = false, have_c = false, have_s = false; *have_n = false; b11->routes = tal_arr(b11, struct route_info *, 0); /* BOLT #11: * * If a URI scheme is desired, the current recommendation is to either * use 'lightning:' as a prefix before the BOLT-11 encoding */ if (strstarts(str, "lightning:") || strstarts(str, "LIGHTNING:")) str += strlen("lightning:"); if (strlen(str) < 8) return decode_fail(b11, fail, "Bad bech32 string"); hrp = tal_arr(tmpctx, char, strlen(str) - 6); data = tal_arr(tmpctx, u5, strlen(str) - 8); if (!bech32_decode(hrp, data, &data_len, str, (size_t)-1)) return decode_fail(b11, fail, "Bad bech32 string"); /* For signature checking at the end. */ hash_u5_init(&hu5, hrp); /* BOLT #11: * * The human-readable part of a Lightning invoice consists of two sections: * 1. `prefix`: `ln` + BIP-0173 currency prefix (e.g. `lnbc` for Bitcoin mainnet, * `lntb` for Bitcoin testnet, and `lnbcrt` for Bitcoin regtest) * 1. `amount`: optional number in that currency, followed by an optional * `multiplier` letter. The unit encoded here is the 'social' convention of a payment unit -- in the case of Bitcoin the unit is 'bitcoin' NOT satoshis. */ prefix = tal_strndup(tmpctx, hrp, strcspn(hrp, "0123456789")); /* BOLT #11: * * A reader...if it does NOT understand the `prefix`... MUST fail the payment. */ if (!strstarts(prefix, "ln")) return decode_fail(b11, fail, "Prefix '%s' does not start with ln", prefix); /* Signet chose to use prefix 'tb', just like testnet. So we tread * carefully here: */ if (must_be_chain) { if (streq(prefix + 2, must_be_chain->bip173_name)) b11->chain = must_be_chain; else return decode_fail(b11, fail, "Prefix %s is not for %s", prefix + 2, must_be_chain->network_name); } else { b11->chain = chainparams_by_bip173(prefix + 2); if (!b11->chain) return decode_fail(b11, fail, "Unknown chain %s", prefix + 2); } /* BOLT #11: * * - if the `amount` is empty: * */ amountstr = tal_strdup(tmpctx, hrp + strlen(prefix)); if (streq(amountstr, "")) { /* BOLT #11: * * - SHOULD indicate to the payer that amount is unspecified. */ b11->msat = NULL; } else { u64 m10 = 10 * MSAT_PER_BTC; /* Pico satoshis in a Bitcoin */ u64 amount; char *end; /* Gather and trim multiplier */ end = amountstr + strlen(amountstr)-1; for (size_t i = 0; i < ARRAY_SIZE(multipliers); i++) { if (*end == multipliers[i].letter) { m10 = multipliers[i].m10; *end = '\0'; break; } } /* BOLT #11: * * if `amount` contains a non-digit OR is followed by * anything except a `multiplier` (see table above)... MUST fail the * payment. **/ amount = strtoull(amountstr, &end, 10); if (amount == ULLONG_MAX && errno == ERANGE) return decode_fail(b11, fail, "Invalid amount '%s'", amountstr); if (!*amountstr || *end) return decode_fail(b11, fail, "Invalid amount postfix '%s'", end); /* BOLT #11: * * if the `multiplier` is present... MUST multiply * `amount` by the `multiplier` value to derive the * amount required for payment. */ b11->msat = tal(b11, struct amount_msat); /* BOLT #11: * * - if multiplier is `p` and the last decimal of `amount` is * not 0: * - MUST fail the payment. */ if (amount * m10 % 10 != 0) return decode_fail(b11, fail, "Invalid sub-millisatoshi amount" " '%sp'", amountstr); *b11->msat = amount_msat(amount * m10 / 10); } /* BOLT #11: * * The data part of a Lightning invoice consists of multiple sections: * * 1. `timestamp`: seconds-since-1970 (35 bits, big-endian) * 1. zero or more tagged parts * 1. `signature`: Bitcoin-style signature of above (520 bits) */ if (!pull_uint(&hu5, &data, &data_len, &b11->timestamp, 35)) return decode_fail(b11, fail, "Can't get 35-bit timestamp"); while (data_len > 520 / 5) { const char *problem = NULL; u64 type, data_length; /* BOLT #11: * * Each Tagged Field is of the form: * * 1. `type` (5 bits) * 1. `data_length` (10 bits, big-endian) * 1. `data` (`data_length` x 5 bits) */ if (!pull_uint(&hu5, &data, &data_len, &type, 5) || !pull_uint(&hu5, &data, &data_len, &data_length, 10)) return decode_fail(b11, fail, "Can't get tag and length"); /* Can't exceed total data remaining. */ if (data_length > data_len) return decode_fail(b11, fail, "%c: truncated", bech32_charset[type]); switch (bech32_charset[type]) { case 'p': decode_p(b11, &hu5, &data, &data_len, data_length, &have_p); break; case 'd': problem = decode_d(b11, &hu5, &data, &data_len, data_length, &have_d); break; case 'h': decode_h(b11, &hu5, &data, &data_len, data_length, &have_h); break; case 'n': problem = decode_n(b11, &hu5, &data, &data_len, data_length, have_n); break; case 'x': problem = decode_x(b11, &hu5, &data, &data_len, data_length, &have_x); break; case 'c': problem = decode_c(b11, &hu5, &data, &data_len, data_length, &have_c); break; case 'f': problem = decode_f(b11, &hu5, &data, &data_len, data_length); break; case 'r': problem = decode_r(b11, &hu5, &data, &data_len, data_length); break; case '9': problem = decode_9(b11, our_features, &hu5, &data, &data_len, data_length); break; case 's': problem = decode_s(b11, &hu5, &data, &data_len, data_length, &have_s); break; default: unknown_field(b11, &hu5, &data, &data_len, bech32_charset[type], data_length); } if (problem) return decode_fail(b11, fail, "%s", problem); } if (!have_p) return decode_fail(b11, fail, "No valid 'p' field found"); if (have_h && description) { struct sha256 sha; /* BOLT #11: * * A reader... MUST check that the SHA2 256-bit hash * in the `h` field exactly matches the hashed * description. */ sha256(&sha, description, strlen(description)); if (!sha256_eq(b11->description_hash, &sha)) return decode_fail(b11, fail, "h: does not match description"); } hash_u5_done(&hu5, hash); *sig = tal_dup_arr(ctx, u5, data, data_len, 0); return b11; } /* Decodes and checks signature; returns NULL on error. */ struct bolt11 *bolt11_decode(const tal_t *ctx, const char *str, const struct feature_set *our_features, const char *description, const struct chainparams *must_be_chain, char **fail) { u5 *sigdata; size_t data_len; u8 sig_and_recid[65]; secp256k1_ecdsa_recoverable_signature sig; struct bolt11 *b11; struct sha256 hash; bool have_n; b11 = bolt11_decode_nosig(ctx, str, our_features, description, must_be_chain, &hash, &sigdata, &have_n, fail); if (!b11) return NULL; /* BOLT #11: * * A writer...MUST set `signature` to a valid 512-bit * secp256k1 signature of the SHA2 256-bit hash of the * human-readable part, represented as UTF-8 bytes, * concatenated with the data part (excluding the signature) * with 0 bits appended to pad the data to the next byte * boundary, with a trailing byte containing the recovery ID * (0, 1, 2, or 3). */ data_len = tal_count(sigdata); if (!pull_bits(NULL, &sigdata, &data_len, sig_and_recid, 520, false)) return decode_fail(b11, fail, "signature truncated"); assert(data_len == 0); if (!secp256k1_ecdsa_recoverable_signature_parse_compact (secp256k1_ctx, &sig, sig_and_recid, sig_and_recid[64])) return decode_fail(b11, fail, "signature invalid"); secp256k1_ecdsa_recoverable_signature_convert(secp256k1_ctx, &b11->sig, &sig); /* BOLT #11: * * A reader... MUST check that the `signature` is valid (see * the `n` tagged field specified below). ... A reader... * MUST use the `n` field to validate the signature instead of * performing signature recovery. */ if (!have_n) { struct pubkey k; if (!secp256k1_ecdsa_recover(secp256k1_ctx, &k.pubkey, &sig, (const u8 *)&hash)) return decode_fail(b11, fail, "signature recovery failed"); node_id_from_pubkey(&b11->receiver_id, &k); } else { struct pubkey k; /* n parsing checked this! */ if (!pubkey_from_node_id(&k, &b11->receiver_id)) abort(); if (!secp256k1_ecdsa_verify(secp256k1_ctx, &b11->sig, (const u8 *)&hash, &k.pubkey)) return decode_fail(b11, fail, "invalid signature"); } return b11; } /* Helper for pushing a variable-length big-endian int. */ static void push_varlen_uint(u5 **data, u64 val, size_t nbits) { be64 be_val = cpu_to_be64(val << (64 - nbits)); bech32_push_bits(data, &be_val, nbits); } /* BOLT #11: * * Each Tagged Field is of the form: * * 1. `type` (5 bits) * 1. `data_length` (10 bits, big-endian) * 1. `data` (`data_length` x 5 bits) */ static void push_field_type_and_len(u5 **data, char type, size_t nbits) { assert(bech32_charset_rev[(unsigned char)type] >= 0); push_varlen_uint(data, bech32_charset_rev[(unsigned char)type], 5); push_varlen_uint(data, (nbits + 4) / 5, 10); } static void push_field(u5 **data, char type, const void *src, size_t nbits) { push_field_type_and_len(data, type, nbits); bech32_push_bits(data, src, nbits); } /* BOLT #11: * * - if `x` is included: * - SHOULD use the minimum `data_length` possible. * - MUST include one `c` field (`min_final_cltv_expiry`). *... * - SHOULD use the minimum `data_length` possible. */ static void push_varlen_field(u5 **data, char type, u64 val) { assert(bech32_charset_rev[(unsigned char)type] >= 0); push_varlen_uint(data, bech32_charset_rev[(unsigned char)type], 5); for (size_t nbits = 5; nbits < 65; nbits += 5) { if ((val >> nbits) == 0) { push_varlen_uint(data, nbits / 5, 10); push_varlen_uint(data, val, nbits); return; } } /* Can't be encoded in <= 60 bits. */ abort(); } /* BOLT #11: * * `f` (9): `data_length` variable, depending on version. Fallback * on-chain address: for Bitcoin, this starts with a 5-bit `version` * and contains a witness program or P2PKH or P2SH address. */ static void push_fallback_addr(u5 **data, u5 version, const void *addr, u16 addr_len) { push_varlen_uint(data, bech32_charset_rev[(unsigned char)'f'], 5); push_varlen_uint(data, ((5 + addr_len * CHAR_BIT) + 4) / 5, 10); push_varlen_uint(data, version, 5); bech32_push_bits(data, addr, addr_len * CHAR_BIT); } static void encode_p(u5 **data, const struct sha256 *hash) { push_field(data, 'p', hash, 256); } static void encode_d(u5 **data, const char *description) { push_field(data, 'd', description, strlen(description) * CHAR_BIT); } static void encode_h(u5 **data, const struct sha256 *hash) { push_field(data, 'h', hash, 256); } static void encode_n(u5 **data, const struct node_id *id) { assert(node_id_valid(id)); push_field(data, 'n', id->k, sizeof(id->k) * CHAR_BIT); } static void encode_x(u5 **data, u64 expiry) { push_varlen_field(data, 'x', expiry); } static void encode_c(u5 **data, u16 min_final_cltv_expiry) { push_varlen_field(data, 'c', min_final_cltv_expiry); } static void encode_s(u5 **data, const struct secret *payment_secret) { push_field(data, 's', payment_secret, 256); } static void encode_f(u5 **data, const u8 *fallback) { struct bitcoin_address pkh; struct ripemd160 sh; struct sha256 wsh; /* BOLT #11: * * for Bitcoin payments... MUST set an `f` field to a valid * witness version and program, OR to `17` followed by a * public key hash, OR to `18` followed by a script hash. */ if (is_p2pkh(fallback, &pkh)) { push_fallback_addr(data, 17, &pkh, sizeof(pkh)); } else if (is_p2sh(fallback, &sh)) { push_fallback_addr(data, 18, &sh, sizeof(sh)); } else if (is_p2wpkh(fallback, &pkh)) { push_fallback_addr(data, 0, &pkh, sizeof(pkh)); } else if (is_p2wsh(fallback, &wsh)) { push_fallback_addr(data, 0, &wsh, sizeof(wsh)); } else if (tal_count(fallback) && fallback[0] >= 0x50 && fallback[0] < (0x50+16)) { /* Other (future) witness versions: turn OP_N into N */ push_fallback_addr(data, fallback[0] - 0x50, fallback + 1, tal_count(fallback) - 1); } else { /* Copy raw. */ push_field(data, 'f', fallback, tal_count(fallback) * CHAR_BIT); } } static void encode_r(u5 **data, const struct route_info *r) { u8 *rinfo = tal_arr(NULL, u8, 0); for (size_t i = 0; i < tal_count(r); i++) towire_route_info(&rinfo, &r[i]); push_field(data, 'r', rinfo, tal_count(rinfo) * CHAR_BIT); tal_free(rinfo); } static void maybe_encode_9(u5 **data, const u8 *features) { u5 *f5 = tal_arr(NULL, u5, 0); for (size_t i = 0; i < tal_count(features) * CHAR_BIT; i++) { if (!feature_is_set(features, i)) continue; /* We expand it out so it makes a BE 5-bit/btye bitfield */ set_feature_bit(&f5, (i / 5) * 8 + (i % 5)); } /* BOLT #11: * * - if `9` contains non-zero bits: * - SHOULD use the minimum `data_length` possible. * - otherwise: * - MUST omit the `9` field altogether. */ if (tal_count(f5) != 0) { push_field_type_and_len(data, '9', tal_count(f5) * 5); tal_expand(data, f5, tal_count(f5)); } tal_free(f5); } static bool encode_extra(u5 **data, const struct bolt11_field *extra) { size_t len; /* Can't encode an invalid tag. */ if (bech32_charset_rev[(unsigned char)extra->tag] == -1) return false; push_varlen_uint(data, bech32_charset_rev[(unsigned char)extra->tag], 5); push_varlen_uint(data, tal_count(extra->data), 10); /* extra->data is already u5s, so do this raw. */ len = tal_count(*data); tal_resize(data, len + tal_count(extra->data)); memcpy(*data + len, extra->data, tal_count(extra->data)); return true; } /* Encodes, even if it's nonsense. */ char *bolt11_encode_(const tal_t *ctx, const struct bolt11 *b11, bool n_field, bool (*sign)(const u5 *u5bytes, const u8 *hrpu8, secp256k1_ecdsa_recoverable_signature *rsig, void *arg), void *arg) { u5 *data = tal_arr(tmpctx, u5, 0); char *hrp, *output; u64 amount; struct bolt11_field *extra; secp256k1_ecdsa_recoverable_signature rsig; u8 sig_and_recid[65]; u8 *hrpu8; int recid; /* BOLT #11: * * A writer: * - MUST encode `prefix` using the currency required for successful payment. * - if a specific minimum `amount` is required for successful payment: * - MUST include that `amount`. * - MUST encode `amount` as a positive decimal integer with no leading 0s. * - If the `p` multiplier is used the last decimal of `amount` MUST be `0`. * - SHOULD use the shortest representation possible, by using the largest multiplier or omitting the multiplier. */ if (b11->msat) { char postfix; u64 msat = b11->msat->millisatoshis; /* Raw: best-multiplier calc */ if (msat % MSAT_PER_BTC == 0) { postfix = '\0'; amount = msat / MSAT_PER_BTC; } else { size_t i; for (i = 0; i < ARRAY_SIZE(multipliers)-1; i++) { if (!(msat * 10 % multipliers[i].m10)) break; } postfix = multipliers[i].letter; amount = msat * 10 / multipliers[i].m10; } hrp = tal_fmt(tmpctx, "ln%s%"PRIu64"%c", b11->chain->bip173_name, amount, postfix); } else hrp = tal_fmt(tmpctx, "ln%s", b11->chain->bip173_name); /* BOLT #11: * * 1. `timestamp`: seconds-since-1970 (35 bits, big-endian) * 1. zero or more tagged parts * 1. `signature`: Bitcoin-style signature of above (520 bits) */ push_varlen_uint(&data, b11->timestamp, 35); /* BOLT #11: * * if a writer offers more than one of any field type, * it... MUST specify the most-preferred field first, followed * by less-preferred fields, in order. */ /* Thus we do built-in fields, then extras last. */ encode_p(&data, &b11->payment_hash); if (b11->description) encode_d(&data, b11->description); if (b11->description_hash) encode_h(&data, b11->description_hash); if (n_field) encode_n(&data, &b11->receiver_id); if (b11->expiry != DEFAULT_X) encode_x(&data, b11->expiry); /* BOLT #11: * - MUST include one `c` field (`min_final_cltv_expiry`). */ encode_c(&data, b11->min_final_cltv_expiry); if (b11->payment_secret) encode_s(&data, b11->payment_secret); for (size_t i = 0; i < tal_count(b11->fallbacks); i++) encode_f(&data, b11->fallbacks[i]); for (size_t i = 0; i < tal_count(b11->routes); i++) encode_r(&data, b11->routes[i]); maybe_encode_9(&data, b11->features); list_for_each(&b11->extra_fields, extra, list) if (!encode_extra(&data, extra)) return NULL; /* FIXME: towire_ should check this? */ if (tal_count(data) > 65535) return NULL; /* Need exact length here */ hrpu8 = tal_dup_arr(tmpctx, u8, (const u8 *)hrp, strlen(hrp), 0); if (!sign(data, hrpu8, &rsig, arg)) return NULL; secp256k1_ecdsa_recoverable_signature_serialize_compact( secp256k1_ctx, sig_and_recid, &recid, &rsig); sig_and_recid[64] = recid; bech32_push_bits(&data, sig_and_recid, sizeof(sig_and_recid) * CHAR_BIT); output = tal_arr(ctx, char, strlen(hrp) + tal_count(data) + 8); if (!bech32_encode(output, hrp, data, tal_count(data), (size_t)-1)) output = tal_free(output); return output; }