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bolt11: remove unneeded fields.
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If we make unknown_field simply discard, we can remove decoders and
have them discard those fields.

Now we can cut down struct bolt11 to only the fields needed by
invoice.c, and also speed up parsing a little.

Signed-off-by: Rusty Russell <[email protected]>
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rustyrussell committed Aug 18, 2024
1 parent 4d783f1 commit c1bc205
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Showing 2 changed files with 3 additions and 189 deletions.
175 changes: 3 additions & 172 deletions src/bolt11/bolt11.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -28,10 +28,6 @@
#include <inttypes.h>
#include <assert.h>

struct secret {
u8 data[32];
};

#define MSAT_PER_SAT ((u64)1000)
#define SAT_PER_BTC ((u64)100000000)
#define MSAT_PER_BTC (MSAT_PER_SAT * SAT_PER_BTC)
Expand Down Expand Up @@ -151,15 +147,9 @@ static const char *unknown_field(struct bolt11 *b11,
const u5 **data, size_t *field_len,
u5 type)
{
struct bolt11_field *extra = tal(b11, struct bolt11_field);
const char *err;

extra->tag = type;
/* FIXME: record u8 data here, not u5! */
extra->data = tal_dup_arr(extra, u5, *data, *field_len, 0);
list_add_tail(&b11->extra_fields, &extra->list);

tal_free(pull_all(extra, hu5, data, field_len, true, &err));
tal_free(pull_all(NULL, hu5, data, field_len, true, &err));
return err;
}

Expand Down Expand Up @@ -192,6 +182,7 @@ static const char *decode_p(struct bolt11 *b11,
const u5 **data, size_t *field_len,
bool *have_p)
{
struct sha256 payment_hash;
/* BOLT #11:
*
* A payer... SHOULD use the first `p` field that it did NOT
Expand All @@ -206,7 +197,7 @@ static const char *decode_p(struct bolt11 *b11,
* NOT have `data_length`s of 52, 52, 52 or 53, respectively.
*/
return pull_expected_length(b11, hu5, data, field_len, 52, 'p',
have_p, &b11->payment_hash);
have_p, &payment_hash);
}

/* Check for valid UTF-8 */
Expand Down Expand Up @@ -327,170 +318,15 @@ static const char *decode_x(struct bolt11 *b11,
return NULL;
}

/* BOLT #11:
*
* `c` (24): `data_length` variable. `min_final_cltv_expiry_delta` to use for the
* last HTLC in the route. Default is 18 if not specified.
*/
static const char *decode_c(struct bolt11 *b11,
const struct feature_set *our_features,
struct hash_u5 *hu5,
const u5 **data, size_t *field_len,
bool *have_c)
{
u64 c;
const char *err;

assert(!*have_c);

/* FIXME: Put upper limit in bolt 11 */
err = pull_uint(hu5, data, field_len, &c, *field_len * 5);
if (err)
return tal_fmt(b11, "c: %s", err);
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 const char *decode_n(struct bolt11 *b11,
const struct feature_set *our_features,
struct hash_u5 *hu5,
const u5 **data, size_t *field_len,
bool *have_n)
{
const char *err;

assert(!*have_n);
/* 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. */
err = pull_expected_length(b11, hu5, data, field_len, 53, 'n', have_n,
&b11->receiver_id.k);

return err;
}

/* BOLT #11:
*
* * `s` (16): `data_length` 52. This 256-bit secret prevents
* forwarding nodes from probing the payment recipient.
*/
static const char *decode_s(struct bolt11 *b11,
const struct feature_set *our_features,
struct hash_u5 *hu5,
const u5 **data, size_t *field_len,
bool *have_s)
{
const char *err;
struct secret secret;

assert(!*have_s);

/* 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. */
err = pull_expected_length(b11, hu5, data, field_len, 52, 's',
have_s, &secret);
if (*have_s)
b11->payment_secret = tal_dup(b11, struct secret, &secret);
return err;
}

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 const char *decode_9(struct bolt11 *b11,
const struct feature_set *our_features,
struct hash_u5 *hu5,
const u5 **data, size_t *field_len,
bool *have_9)
{
size_t flen = (*field_len * 5 + 7) / 8;
size_t databits = *field_len * 5;
const char *err;

assert(!*have_9);

b11->features = pull_all(b11, hu5, data, field_len, true, &err);
if (!b11->features)
return err;

/* pull_bits pads with zero bits: we need to remove them. */
shift_bitmap_down(b11->features,
flen * 8 - databits);

*have_9 = 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 const char *decode_m(struct bolt11 *b11,
const struct feature_set *our_features,
struct hash_u5 *hu5,
const u5 **data, size_t *field_len,
bool *have_m)
{
const char *err;

assert(!*have_m);

b11->metadata = pull_all(b11, hu5, data, field_len, false, &err);
if (!b11->metadata)
return err;

*have_m = true;
return NULL;
}

static 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->msat = NULL;
b11->expiry = DEFAULT_X;
b11->features = tal_arr(b11, u8, 0);
/* BOLT #11:
* - if the `c` field (`min_final_cltv_expiry_delta`) 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);
Expand Down Expand Up @@ -522,11 +358,6 @@ static const struct decoder decoders[] = {
{ 'd', false, decode_d },
{ 'h', false, decode_h },
{ 'x', false, decode_x },
{ 'c', false, decode_c },
{ 'n', false, decode_n },
{ 's', false, decode_s },
{ '9', false, decode_9 },
{ 'm', false, decode_m },
};

static const struct decoder *find_decoder(char c)
Expand Down
17 changes: 0 additions & 17 deletions src/bolt11/bolt11.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,6 @@
#include "ccan/list/list.h"
#include "amount.h"
#include "node_id.h"
//#include <secp256k1_recovery.h>

/* We only have 10 bits for the field length, meaning < 640 bytes */
#define BOLT11_FIELD_BYTE_LIMIT ((1 << 10) * 5 / 8)
Expand All @@ -33,28 +32,12 @@ struct bolt11 {
u64 timestamp;
struct amount_msat *msat; /* NULL if not specified. */

struct sha256 payment_hash;
struct node_id receiver_id;

/* description_hash valid if and only if description is NULL. */
const char *description;
struct sha256 *description_hash;

/* How many seconds to pay from @timestamp above. */
u64 expiry;

/* How many blocks final hop requires. */
u32 min_final_cltv_expiry;

struct secret *payment_secret;

/* Features bitmap, if any. */
u8 *features;

/* Optional metadata to send with payment. */
u8 *metadata;

struct list_head extra_fields;
};

/* Does not check signature, nor extract node. */
Expand Down

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