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core-lightning/common/bolt11.c
fiatjaf 17bb862cfe don't enforce description_hash checking
2019-11-25 18:15:35 +01:00

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#include <bitcoin/address.h>
#include <bitcoin/base58.h>
#include <bitcoin/chainparams.h>
#include <bitcoin/script.h>
#include <ccan/array_size/array_size.h>
#include <ccan/cast/cast.h>
#include <ccan/endian/endian.h>
#include <ccan/tal/str/str.h>
#include <common/bech32.h>
#include <common/bech32_util.h>
#include <common/bolt11.h>
#include <common/features.h>
#include <common/utils.h>
#include <errno.h>
#include <hsmd/gen_hsm_wire.h>
#include <inttypes.h>
#include <lightningd/hsm_control.h>
#include <lightningd/jsonrpc.h>
#include <lightningd/lightningd.h>
#include <lightningd/log.h>
#include <stdarg.h>
#include <stdio.h>
#include <wire/wire.h>
#include <wire/wire_sync.h>
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`, or `n` fields that do
* NOT have `data_length`s of 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 void decode_d(struct bolt11 *b11,
struct hash_u5 *hu5,
u5 **data, size_t *data_len,
size_t data_length, bool *have_d)
{
if (*have_d) {
unknown_field(b11, hu5, data, data_len, 'd', data_length);
return;
}
b11->description = tal_arrz(b11, char, num_u8(data_length) + 1);
pull_bits_certain(hu5, data, data_len, (u8 *)b11->description,
data_length*5, false);
*have_d = true;
}
/* 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`, or `n` fields that do
* NOT have `data_length`s of 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 9 if not specified.
*/
#define DEFAULT_C 9
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`, or `n` fields that do
* NOT have `data_length`s of 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",
type_to_string(tmpctx, struct node_id,
&b11->receiver_id));
*have_n = true;
return NULL;
}
/* BOLT-412c260b537be95b105ae2062463f1d992024ca7 #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-412c260b537be95b105ae2062463f1d992024ca7 #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
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,
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.
*/
/* BOLT #11:
* The field is big-endian. The least-significant bit is numbered 0,
* which is _even_, and the next most significant bit is numbered 1,
* which is _odd_. */
badf = features_unsupported(b11->features);
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);
b11->min_final_cltv_expiry = DEFAULT_C;
b11->payment_secret = NULL;
if (msat)
b11->msat = tal_dup(b11, struct amount_msat, msat);
return b11;
}
/* Decodes and checks signature; returns NULL on error. */
struct bolt11 *bolt11_decode(const tal_t *ctx, const char *str,
const char *description, char **fail)
{
char *hrp, *amountstr, *prefix;
u5 *data;
size_t data_len;
struct bolt11 *b11 = new_bolt11(ctx, NULL);
u8 sig_and_recid[65];
secp256k1_ecdsa_recoverable_signature sig;
struct hash_u5 hu5;
struct sha256 hash;
bool have_p = false, have_n = false, have_d = false, have_h = false,
have_x = false, have_c = false, have_s = 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);
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;
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);
b11->msat->millisatoshis = amount * m10 / 10; /* Raw: raw amount multiplier calculation */
}
/* 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':
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, &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);
/* 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).
*/
if (!pull_bits(NULL, &data, &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.
*...
* - if `c` is included:
* - 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.
* - 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);
if (b11->min_final_cltv_expiry != DEFAULT_C)
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;
}
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