core-lightning/common/amount.c

#include "config.h"
#include <assert.h>
#include <bitcoin/chainparams.h>
#include <ccan/mem/mem.h>
#include <ccan/tal/str/str.h>
#include <common/amount.h>
#include <common/overflows.h>
#include <common/utils.h>
#include <inttypes.h>
#include <wire/wire.h>

bool amount_sat_to_msat(struct amount_msat *msat,
			struct amount_sat sat)
{
	if (mul_overflows_u64(sat.satoshis, MSAT_PER_SAT))
		return false;
	msat->millisatoshis = sat.satoshis * MSAT_PER_SAT;
	return true;
}

bool amount_msat_to_sat(struct amount_sat *sat,
			struct amount_msat msat)
{
	if (msat.millisatoshis % MSAT_PER_SAT)
		return false;
	sat->satoshis = msat.millisatoshis / MSAT_PER_SAT;
	return true;
}


/* You can always truncate millisatoshis->satoshis. */
struct amount_sat amount_msat_to_sat_round_down(struct amount_msat msat)
{
	struct amount_sat sat;

	sat.satoshis = msat.millisatoshis / MSAT_PER_SAT;
	return sat;
}

struct amount_msat amount_msat_to_sat_remainder(struct amount_msat msat)
{
	struct amount_msat res;

	res.millisatoshis = msat.millisatoshis % MSAT_PER_SAT;
	return res;
}

/* Different formatting by amounts: btc, sat and msat */
const char *fmt_amount_msat_btc(const tal_t *ctx,
				struct amount_msat msat,
				bool append_unit)
{
	if (msat.millisatoshis == 0)
		return tal_fmt(ctx, append_unit ? "0btc" : "0");

	return tal_fmt(ctx, "%"PRIu64".%011"PRIu64"%s",
		       msat.millisatoshis / MSAT_PER_BTC,
		       msat.millisatoshis % MSAT_PER_BTC,
		       append_unit ? "btc" : "");
}

char *fmt_amount_msat(const tal_t *ctx, struct amount_msat msat)
{
	return tal_fmt(ctx, "%"PRIu64"msat", msat.millisatoshis);
}

const char *fmt_amount_sat_btc(const tal_t *ctx,
			       struct amount_sat sat,
			       bool append_unit)
{
	if (sat.satoshis == 0)
		return tal_fmt(ctx, append_unit ? "0btc" : "0");

	return tal_fmt(ctx, "%"PRIu64".%08"PRIu64"%s",
		       sat.satoshis / SAT_PER_BTC,
		       sat.satoshis % SAT_PER_BTC,
		       append_unit ? "btc" : "");
}

char *fmt_amount_sat(const tal_t *ctx, struct amount_sat sat)
{
	return tal_fmt(ctx, "%"PRIu64"sat", sat.satoshis);
}

static bool breakup(const char *str, size_t slen,
		    /* Length of first numeric part. */
		    size_t *whole_number_len,
		    /* Pointer to post-decimal part, or NULL */
		    const char **post_decimal_ptr,
		    size_t *post_decimal_len,
		    /* Pointer to suffix, or NULL */
		    const char **suffix_ptr,
		    size_t *suffix_len)
{
	size_t i;

	*whole_number_len = 0;
	*post_decimal_len = 0;
	*post_decimal_ptr = NULL;
	*suffix_ptr = NULL;
	*suffix_len = 0;

	for (i = 0;; i++) {
		/* The string may be null-terminated. */
		if (i >= slen || str[i] == '\0')
			return i != 0;
		if (cisdigit(str[i]))
			(*whole_number_len)++;
		else
			break;
	}

	if (str[i] == '.') {
		i++;
		*post_decimal_ptr = str + i;
		for (;; i++) {
			/* True if > 0 decimals. */
			if (i >= slen || str[i] == '\0')
				return str + i != *post_decimal_ptr;
			if (cisdigit(str[i]))
				(*post_decimal_len)++;
			else
				break;
		}
	}

	*suffix_ptr = str + i;
	*suffix_len = slen - i;
	return true;
}

static bool from_number(u64 *res, const char *s, size_t len, int tens_factor)
{
	if (len == 0)
		return false;

	*res = 0;
	for (size_t i = 0; i < len; i++) {
		if (mul_overflows_u64(*res, 10))
			return false;
		*res *= 10;
		assert(cisdigit(s[i]));
		if (add_overflows_u64(*res, s[i] - '0'))
			return false;
		*res += s[i] - '0';
	}
	while (tens_factor > 0) {
		if (mul_overflows_u64(*res, 10))
			return false;
		*res *= 10;
		tens_factor--;
	}
	return true;
}

static bool from_numbers(u64 *res,
			 const char *s1, size_t len1, int tens_factor,
			 const char *s2, size_t len2)
{
	u64 p1, p2;
	if (len2 > tens_factor)
		return false;

	if (!from_number(&p1, s1, len1, tens_factor)
	    || !from_number(&p2, s2, len2, tens_factor - len2))
		return false;

	if (add_overflows_u64(p1, p2))
		return false;

	*res = p1 + p2;
	return true;
}

/* Valid strings:
 *  [0-9]+ => millisatoshi.
 *  [0-9]+msat => millisatoshi.
 *  [0-9]+sat => *1000 -> millisatoshi.
 *  [0-9]+.[0-9]{1,11}btc => millisatoshi.
 */
bool parse_amount_msat(struct amount_msat *msat, const char *s, size_t slen)
{
	size_t whole_number_len, post_decimal_len, suffix_len;
	const char *post_decimal_ptr, *suffix_ptr;

	if (!breakup(s, slen, &whole_number_len,
		     &post_decimal_ptr, &post_decimal_len,
		     &suffix_ptr, &suffix_len))
		return false;

	if (!post_decimal_ptr && !suffix_ptr)
		return from_number(&msat->millisatoshis, s, whole_number_len, 0);
	if (!post_decimal_ptr && memstarts_str(suffix_ptr, suffix_len, "msat"))
		return from_number(&msat->millisatoshis, s, whole_number_len, 0);
	if (!post_decimal_ptr && memstarts_str(suffix_ptr, suffix_len, "sat"))
		return from_number(&msat->millisatoshis, s, whole_number_len, 3);
	if (memstarts_str(suffix_ptr, suffix_len, "btc")) {
		if (post_decimal_len > 0)
			return from_numbers(&msat->millisatoshis,
					    s, whole_number_len, 11,
					    post_decimal_ptr, post_decimal_len);
		return from_number(&msat->millisatoshis, s, whole_number_len, 11);
	}

	return false;
}

/* Valid strings:
 *  [0-9]+ => satoshi.
 *  [0-9]+sat => satoshi.
 *  [0-9]+000msat => satoshi.
 *  0msat => 0 satoshi
 *  [0-9]+.[0-9]{1,8}btc => satoshi.
 */
bool parse_amount_sat(struct amount_sat *sat, const char *s, size_t slen)
{
	size_t whole_number_len, post_decimal_len, suffix_len;
	const char *post_decimal_ptr, *suffix_ptr;

	if (!breakup(s, slen, &whole_number_len,
		     &post_decimal_ptr, &post_decimal_len,
		     &suffix_ptr, &suffix_len))
		return false;

	if (!post_decimal_ptr && !suffix_ptr)
		return from_number(&sat->satoshis, s, whole_number_len, 0);
	if (!post_decimal_ptr && memstarts_str(suffix_ptr, suffix_len, "sat"))
		return from_number(&sat->satoshis, s, whole_number_len, 0);
	if (!post_decimal_ptr && memstarts_str(suffix_ptr, suffix_len, "msat")) {
		if (!memends(s, whole_number_len, "000", strlen("000"))) {
			if (memstarts_str(s, whole_number_len, "0"))
				return from_number(&sat->satoshis, s,
						   whole_number_len, 0);
			return false;
		}
		return from_number(&sat->satoshis, s, whole_number_len - 3, 0);
	}
	if (memstarts_str(suffix_ptr, suffix_len, "btc")) {
		if (post_decimal_len > 0)
			return from_numbers(&sat->satoshis,
					    s, whole_number_len, 8,
					    post_decimal_ptr, post_decimal_len);
		return from_number(&sat->satoshis, s, whole_number_len, 8);
	}

	return false;
}

WARN_UNUSED_RESULT bool amount_msat_add(struct amount_msat *val,
					struct amount_msat a,
					struct amount_msat b)
{
	if (add_overflows_u64(a.millisatoshis, b.millisatoshis))
		return false;

	val->millisatoshis = a.millisatoshis + b.millisatoshis;
	return true;
}

WARN_UNUSED_RESULT bool amount_msat_accumulate(struct amount_msat *a,
					       struct amount_msat b)
{
	return amount_msat_add(a, *a, b);
}

WARN_UNUSED_RESULT bool amount_msat_sub(struct amount_msat *val,
					struct amount_msat a,
					struct amount_msat b)
{
	if (a.millisatoshis < b.millisatoshis)
		return false;

	val->millisatoshis = a.millisatoshis - b.millisatoshis;
	return true;
}

WARN_UNUSED_RESULT bool amount_sat_add(struct amount_sat *val,
				       struct amount_sat a,
				       struct amount_sat b)
{
	if (add_overflows_u64(a.satoshis, b.satoshis))
		return false;

	val->satoshis = a.satoshis + b.satoshis;
	return true;
}

WARN_UNUSED_RESULT bool amount_sat_sub(struct amount_sat *val,
				       struct amount_sat a,
				       struct amount_sat b)
{
	if (a.satoshis < b.satoshis)
		return false;

	val->satoshis = a.satoshis - b.satoshis;
	return true;
}

WARN_UNUSED_RESULT bool amount_msat_sub_sat(struct amount_msat *val,
					    struct amount_msat a,
					    struct amount_sat b)
{
	struct amount_msat msatb;

	if (!amount_sat_to_msat(&msatb, b))
		return false;

	return amount_msat_sub(val, a, msatb);
}

WARN_UNUSED_RESULT bool amount_sat_sub_msat(struct amount_msat *val,
					    struct amount_sat a,
					    struct amount_msat b)
{
	struct amount_msat msata;

	if (!amount_sat_to_msat(&msata, a))
		return false;

	return amount_msat_sub(val, msata, b);
}

WARN_UNUSED_RESULT bool amount_msat_add_sat(struct amount_msat *val,
					    struct amount_msat a,
					    struct amount_sat b)
{
	struct amount_msat msatb;

	if (!amount_sat_to_msat(&msatb, b))
		return false;

	return amount_msat_add(val, a, msatb);
}

WARN_UNUSED_RESULT bool amount_msat_scale(struct amount_msat *val,
					  struct amount_msat msat,
					  double scale)
{
	double scaled = msat.millisatoshis * scale;

	/* If mantissa is < 64 bits, a naive "if (scaled >
	 * UINT64_MAX)" doesn't work.  Stick to powers of 2. */
	if (scaled >= (double)((u64)1 << 63) * 2)
		return false;
	val->millisatoshis = scaled;
	return true;
}

WARN_UNUSED_RESULT bool amount_sat_scale(struct amount_sat *val,
					 struct amount_sat sat,
					 double scale)
{
	double scaled = sat.satoshis * scale;

	/* If mantissa is < 64 bits, a naive "if (scaled >
	 * UINT64_MAX)" doesn't work.  Stick to powers of 2. */
	if (scaled >= (double)((u64)1 << 63) * 2)
		return false;
	val->satoshis = scaled;
	return true;
}

WARN_UNUSED_RESULT bool amount_msat_add_sat_s64(struct amount_msat *val,
						struct amount_msat a,
						s64 b)
{
	if (b < 0)
		return amount_msat_sub_sat(val, a, amount_sat(-b));
	else
		return amount_msat_add_sat(val, a, amount_sat(b));
}


WARN_UNUSED_RESULT bool amount_sat_add_sat_s64(struct amount_sat *val,
					       struct amount_sat a,
					       s64 b)
{
	if (b < 0)
		return amount_sat_sub(val, a, amount_sat(-b));
	else
		return amount_sat_add(val, a, amount_sat(b));
}

bool amount_sat_eq(struct amount_sat a, struct amount_sat b)
{
	return a.satoshis == b.satoshis;
}

bool amount_sat_is_zero(struct amount_sat a)
{
	return a.satoshis == 0;
}

bool amount_msat_is_zero(struct amount_msat a)
{
	return a.millisatoshis == 0;
}

bool amount_msat_eq(struct amount_msat a, struct amount_msat b)
{
	return a.millisatoshis == b.millisatoshis;
}

bool amount_sat_greater(struct amount_sat a, struct amount_sat b)
{
	return a.satoshis > b.satoshis;
}

bool amount_msat_greater(struct amount_msat a, struct amount_msat b)
{
	return a.millisatoshis > b.millisatoshis;
}

bool amount_sat_greater_eq(struct amount_sat a, struct amount_sat b)
{
	return a.satoshis >= b.satoshis;
}

bool amount_msat_greater_eq(struct amount_msat a, struct amount_msat b)
{
	return a.millisatoshis >= b.millisatoshis;
}

bool amount_sat_less(struct amount_sat a, struct amount_sat b)
{
	return a.satoshis < b.satoshis;
}

bool amount_msat_less(struct amount_msat a, struct amount_msat b)
{
	return a.millisatoshis < b.millisatoshis;
}

bool amount_sat_less_eq(struct amount_sat a, struct amount_sat b)
{
	return a.satoshis <= b.satoshis;
}

bool amount_msat_less_eq(struct amount_msat a, struct amount_msat b)
{
	return a.millisatoshis <= b.millisatoshis;
}

bool amount_msat_greater_sat(struct amount_msat msat, struct amount_sat sat)
{
	struct amount_msat msat_from_sat;

	if (!amount_sat_to_msat(&msat_from_sat, sat))
		return false;
	return msat.millisatoshis > msat_from_sat.millisatoshis;
}

bool amount_msat_greater_eq_sat(struct amount_msat msat, struct amount_sat sat)
{
	struct amount_msat msat_from_sat;

	if (!amount_sat_to_msat(&msat_from_sat, sat))
		return false;
	return msat.millisatoshis >= msat_from_sat.millisatoshis;
}

bool amount_msat_less_sat(struct amount_msat msat, struct amount_sat sat)
{
	struct amount_msat msat_from_sat;

	if (!amount_sat_to_msat(&msat_from_sat, sat))
		return false;
	return msat.millisatoshis < msat_from_sat.millisatoshis;
}

bool amount_msat_less_eq_sat(struct amount_msat msat, struct amount_sat sat)
{
	struct amount_msat msat_from_sat;

	if (!amount_sat_to_msat(&msat_from_sat, sat))
		return false;
	return msat.millisatoshis <= msat_from_sat.millisatoshis;
}

bool amount_msat_eq_sat(struct amount_msat msat, struct amount_sat sat)
{
	struct amount_msat msat_from_sat;

	if (!amount_sat_to_msat(&msat_from_sat, sat))
		return false;

	return msat.millisatoshis == msat_from_sat.millisatoshis;
}

bool amount_msat_to_u32(struct amount_msat msat, u32 *millisatoshis)
{
	if (amount_msat_greater_eq(msat, AMOUNT_MSAT(0x100000000)))
		return false;
	*millisatoshis = msat.millisatoshis;
	return true;
}

struct amount_msat amount_msat(u64 millisatoshis)
{
	struct amount_msat msat;

	msat.millisatoshis = millisatoshis;
	return msat;
}

struct amount_sat amount_sat(u64 satoshis)
{
	struct amount_sat sat;

	sat.satoshis = satoshis;
	return sat;
}

double amount_msat_ratio(struct amount_msat a, struct amount_msat b)
{
	return (double)a.millisatoshis / b.millisatoshis;
}

struct amount_msat amount_msat_div(struct amount_msat msat, u64 div)
{
	msat.millisatoshis /= div;
	return msat;
}

struct amount_sat amount_sat_div(struct amount_sat sat, u64 div)
{
	sat.satoshis /= div;
	return sat;
}

bool amount_sat_mul(struct amount_sat *res, struct amount_sat sat, u64 mul)
{
	if (mul_overflows_u64(sat.satoshis, mul))
		return false;
	res->satoshis = sat.satoshis * mul;
	return true;
}

bool amount_msat_mul(struct amount_msat *res, struct amount_msat msat, u64 mul)
{
	if (mul_overflows_u64(msat.millisatoshis, mul))
		return false;
	res->millisatoshis = msat.millisatoshis * mul;
	return true;
}

bool amount_msat_fee(struct amount_msat *fee,
		     struct amount_msat amt,
		     u32 fee_base_msat,
		     u32 fee_proportional_millionths)
{
	struct amount_msat fee_base, fee_prop;

	/* BOLT #7:
	 *
	 *   - SHOULD accept HTLCs that pay a fee equal to or greater than:
	 *    - fee_base_msat + ( amount_to_forward * fee_proportional_millionths / 1000000 )
	 */
	fee_base.millisatoshis = fee_base_msat;

	if (mul_overflows_u64(amt.millisatoshis, fee_proportional_millionths))
		return false;
	fee_prop.millisatoshis = amt.millisatoshis * fee_proportional_millionths
		/ 1000000;

	return amount_msat_add(fee, fee_base, fee_prop);
}

/* Does this input give enough to provide fee for output? */
static bool within_fee(struct amount_msat in,
		       struct amount_msat out,
		       u32 fee_base_msat,
		       u32 fee_proportional_millionths)
{
	struct amount_msat with_fee = out;
	if (!amount_msat_add_fee(&with_fee,
				 fee_base_msat,
				 fee_proportional_millionths))
		return false;
	return amount_msat_less_eq(with_fee, in);
}

struct amount_msat amount_msat_sub_fee(struct amount_msat in,
				       u32 fee_base_msat,
				       u32 fee_proportional_millionths)
{
	struct amount_msat out, out_plus_one;

	/* out = in - base - (out * prop / 1000000)
	 * Thus: out * (1 + prop / 1000000) = in - base
	 *       out = (in - base) / (1 + prop / 1000000)
	 *       out = 1000000 * (in - base) / (1000000 + prop)
	 *
	 * Since we round the fee down, out can be a bit bigger than
	 * expected, so we iterate upwards.
	 */
	if (!amount_msat_sub(&out, in, amount_msat(fee_base_msat)))
		return AMOUNT_MSAT(0);
	if (!amount_msat_mul(&out, out, 1000000))
		return AMOUNT_MSAT(0);
	out = amount_msat_div(out, 1000000ULL + fee_proportional_millionths);

	/* If we calc reverse, it must work! */
	assert(within_fee(in, out, fee_base_msat, fee_proportional_millionths));

	/* We can be out-by-one */
	if (amount_msat_add(&out_plus_one, out, AMOUNT_MSAT(1))
	    && within_fee(in, out_plus_one, fee_base_msat, fee_proportional_millionths))
		return out_plus_one;
	return out;
}

bool amount_msat_add_fee(struct amount_msat *amt,
			 u32 fee_base_msat,
			 u32 fee_proportional_millionths)
{
	struct amount_msat fee;

	if (!amount_msat_fee(&fee, *amt,
			     fee_base_msat, fee_proportional_millionths))
		return false;
	return amount_msat_add(amt, *amt, fee);
}

struct amount_sat amount_tx_fee(u32 fee_per_kw, size_t weight)
{
	struct amount_sat fee;

	/* If this overflows, weight must be > 2^32, which is not a real tx */
	assert(!mul_overflows_u64(fee_per_kw, weight));
	fee.satoshis = (u64)fee_per_kw * weight / 1000;

	return fee;
}

bool amount_feerate(u32 *feerate, struct amount_sat fee, size_t weight)
{
	assert(weight);

	if (!amount_sat_mul(&fee, fee, 1000))
		return false;

	return assign_overflow_u32(feerate, fee.satoshis / weight);
}

bool amount_asset_is_main(struct amount_asset *amount)
{
	/* If we're not on elements, there is only one asset. */
	if (!chainparams->is_elements)
		return true;

	/* If we are on elements we better check against the chainparams. */
	return memeq(amount->asset, sizeof(amount->asset),
		     chainparams->fee_asset_tag, sizeof(amount->asset));
}

/* Convert from a generic asset to the fee-paying asset if possible. */
struct amount_sat amount_asset_to_sat(struct amount_asset *amount)
{
	struct amount_sat sats;
	assert(amount_asset_is_main(amount));
	sats.satoshis = amount->value;
	return sats;
}

struct amount_asset amount_sat_to_asset(struct amount_sat *sat, const u8 *asset) {
	struct amount_asset amt_asset;

	assert(33 == sizeof(amt_asset.asset));
	memcpy(amt_asset.asset, asset, sizeof(amt_asset.asset));
	amt_asset.value = sat->satoshis;
	return amt_asset;
}

u8 *amount_asset_extract_value(const tal_t *ctx, struct amount_asset *asset)
{
	u8 *val = tal_arr(ctx, u8, 9);

	/* FIXME: persist blinded values */
	if (asset->value == 0)
		return NULL;

	beint64_t be64 = cpu_to_be64(asset->value);
	val[0] = 0x01;
	memcpy(val + 1, &be64, sizeof(be64));
	return val;
}

struct amount_msat fromwire_amount_msat(const u8 **cursor, size_t *max)
{
	struct amount_msat msat;

	msat.millisatoshis = fromwire_u64(cursor, max);
	return msat;
}

struct amount_sat fromwire_amount_sat(const u8 **cursor, size_t *max)
{
	struct amount_sat sat;

	sat.satoshis = fromwire_u64(cursor, max);
	return sat;
}

void towire_amount_msat(u8 **pptr, const struct amount_msat msat)
{
	towire_u64(pptr, msat.millisatoshis);
}

void towire_amount_sat(u8 **pptr, const struct amount_sat sat)
{
	towire_u64(pptr, sat.satoshis);
}