//
// bolt11.c
// damus
//
// Created by William Casarin on 2022-10-18.
//
#include "bolt11.h"
//#include "address.h"
//#include "script.h"
#include "bech32.h"
#include "utf8.h"
#include "compiler.h"
#include "endian.h"
#include "list.h"
#include "talstr.h"
#include "tal.h"
#include "node_id.h"
#include "bech32_util.h"
#include "bolt11.h"
#include "amount.h"
#include "array_size.h"
#include "structeq.h"
//#include "features.h"
#include <errno.h>
#include <inttypes.h>
#include <assert.h>
#define MSAT_PER_SAT ((u64)1000)
#define SAT_PER_BTC ((u64)100000000)
#define MSAT_PER_BTC (MSAT_PER_SAT * SAT_PER_BTC)
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;
}
static char *utf8_str(const tal_t *ctx, const u8 *buf TAKES, size_t buflen)
{
char *ret;
if (!utf8_check(buf, buflen)) {
if (taken(buf))
tal_free(buf);
return NULL;
}
/* Add one for nul term */
ret = tal_dup_arr(ctx, char, (const char *)buf, buflen, 1);
ret[buflen] = '\0';
return ret;
}
/* 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, 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);
*have_x = true;
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, 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);
*have_c = true;
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(b11, &b11->receiver_id));
*/
*have_n = true;
return NULL;
}
/* BOLT #11:
*
* `m` (27): `data_length` variable. Additional metadata to attach to
* the payment. Note that the size of this field is limited by the
* maximum hop payload size. Long metadata fields reduce the maximum
* route length.
*/
static char *decode_m(struct bolt11 *b11,
struct hash_u5 *hu5,
u5 **data, size_t *data_len,
size_t data_length,
bool *have_m)
{
size_t mlen = (data_length * 5) / 8;
if (*have_m)
return unknown_field(b11, hu5, data, data_len, 'm',
data_length);
b11->metadata = tal_arr(b11, u8, mlen);
pull_bits_certain(hu5, data, data_len, b11->metadata,
data_length * 5, false);
*have_m = true;
return NULL;
}
struct bolt11 *new_bolt11(const tal_t *ctx)
{
struct bolt11 *b11 = tal(ctx, struct bolt11);
list_head_init(&b11->extra_fields);
b11->description = NULL;
b11->description_hash = NULL;
b11->fallbacks = 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;
b11->metadata = NULL;
//if (msat)
//b11->msat = tal_dup(b11, struct amount_msat, msat);
return b11;
}
/* Define sha256_eq. */
//STRUCTEQ_DEF(sha256, 0, u);
/* Extracts signature but does not check it. */
struct bolt11 *bolt11_decode_nosig(const tal_t *ctx, const char *str, u5 **sig, char **fail)
{
char *hrp, *amountstr, *prefix;
u5 *data;
size_t data_len;
struct bolt11 *b11 = new_bolt11(ctx);
struct hash_u5 hu5;
bool have_p = false, have_d = false, have_h = false, have_n = false,
have_x = false, have_c = false, have_m = false;
/* 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(b11, char, strlen(str) - 6);
data = tal_arr(b11, u5, strlen(str) - 8);
if (bech32_decode(hrp, data, &data_len, str, (size_t)-1)
!= BECH32_ENCODING_BECH32)
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, `lntbs` for Bitcoin signet, 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(b11, 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);
/* BOLT #11:
*
* - if the `amount` is empty:
* */
amountstr = tal_strdup(b11, 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;
*/
case 'm':
problem = decode_m(b11, &hu5, &data, &data_len,
data_length, &have_m);
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");
*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, char **fail)
{
u5 *sigdata;
size_t data_len;
u8 sig_and_recid[65];
//secp256k1_ecdsa_recoverable_signature sig;
struct bolt11 *b11;
b11 = bolt11_decode_nosig(ctx, str, &sigdata, 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;
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;
}