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keysend: just strip even unknown fields. #5645

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Oct 4, 2022
Merged

keysend: just strip even unknown fields. #5645

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39 changes: 23 additions & 16 deletions plugins/keysend.c
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Original file line number Diff line number Diff line change
Expand Up @@ -248,7 +248,7 @@ struct keysend_in {
struct preimage payment_preimage;
char *label;
struct tlv_tlv_payload *payload;
struct tlv_field *preimage_field;
struct tlv_field *preimage_field, *desc_field;
};

static int tlvfield_cmp(const struct tlv_field *a,
Expand All @@ -267,11 +267,27 @@ htlc_accepted_invoice_created(struct command *cmd, const char *buf,
struct keysend_in *ki)
{
struct tlv_field field;
int preimage_field_idx = ki->preimage_field - ki->payload->fields;

/* Remove the preimage field so `lightningd` knows how to handle
* this. */
tal_arr_remove(&ki->payload->fields, preimage_field_idx);
/* Remove all unknown fields: complain about unused even ones!
* (Keysend is not a design, it's a kludge by people who
* didn't read the spec, and Just Made Something Work). */
Comment on lines +272 to +273
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for (size_t i = 0; i < tal_count(ki->payload->fields); i++) {
/* Odd fields are fine, leave them. */
if (ki->payload->fields[i].numtype % 2)
continue;
/* Same with known fields */
if (ki->payload->fields[i].meta)
continue;
/* Complain about it, at least. */
if (ki->preimage_field != &ki->payload->fields[i]) {
plugin_log(cmd->plugin, LOG_INFORM,
"Keysend payment uses illegal even field %"
PRIu64 ": stripping",
ki->payload->fields[i].numtype);
}
tal_arr_remove(&ki->payload->fields, i);
i--;
}

/* Now we can fill in the payment secret, from invoice. */
ki->payload->payment_data = tal(ki->payload,
Expand Down Expand Up @@ -331,7 +347,7 @@ static struct command_result *htlc_accepted_call(struct command *cmd,
struct sha256 payment_hash;
size_t max;
struct tlv_tlv_payload *payload;
struct tlv_field *preimage_field = NULL, *unknown_field = NULL, *desc_field = NULL;
struct tlv_field *preimage_field = NULL, *desc_field = NULL;
bigsize_t s;
struct keysend_in *ki;
struct out_req *req;
Expand Down Expand Up @@ -375,9 +391,6 @@ static struct command_result *htlc_accepted_call(struct command *cmd,
if (field->numtype == PREIMAGE_TLV_TYPE) {
preimage_field = field;
continue;
} else if (field->numtype % 2 == 0 && field->meta == NULL) {
/* This can only happen with FROMWIRE_TLV_ANY_TYPE! */
unknown_field = field;
}

/* Longest (unknown) text field wins. */
Expand All @@ -392,13 +405,6 @@ static struct command_result *htlc_accepted_call(struct command *cmd,
if (preimage_field == NULL)
return htlc_accepted_continue(cmd, NULL);

if (unknown_field != NULL) {
plugin_log(cmd->plugin, LOG_INFORM,
"Experimental: Accepting the keysend payment "
"despite having unknown even TLV type %" PRIu64 ".",
unknown_field->numtype);
}

/* If malformed (amt is compulsory), let lightningd handle it. */
if (!payload->amt_to_forward) {
plugin_log(cmd->plugin, LOG_UNUSUAL,
Expand All @@ -421,6 +427,7 @@ static struct command_result *htlc_accepted_call(struct command *cmd,
ki->label = tal_fmt(ki, "keysend-%lu.%09lu", (unsigned long)now.ts.tv_sec, now.ts.tv_nsec);
ki->payload = tal_steal(ki, payload);
ki->preimage_field = preimage_field;
ki->desc_field = desc_field;

/* If the preimage doesn't hash to the payment_hash we must continue,
* maybe someone else knows how to handle these. */
Expand Down
11 changes: 6 additions & 5 deletions tests/test_pay.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3580,8 +3580,8 @@ def test_keysend(node_factory):
l3.rpc.keysend(l4.info['id'], amt)


def test_keysend_extra_tlvs(node_factory):
"""Use the extratlvs option to deliver a message with sphinx' TLV type.
def test_keysend_strip_tlvs(node_factory):
"""Use the extratlvs option to deliver a message with sphinx' TLV type, which keysend strips.
"""
amt = 10000
l1, l2 = node_factory.line_graph(
Expand All @@ -3593,19 +3593,17 @@ def test_keysend_extra_tlvs(node_factory):
'accept-htlc-tlv-types': '133773310,99990',
},
{
'accept-htlc-tlv-types': '133773310',
"plugin": os.path.join(os.path.dirname(__file__), "plugins/sphinx-receiver.py"),
},
]
)

# Make sure listconfigs works here
assert l1.rpc.listconfigs()['accept-htlc-tlv-types'] == '133773310,99990'
assert l2.rpc.listconfigs()['accept-htlc-tlv-types'] == '133773310'

l1.rpc.keysend(l2.info['id'], amt, extratlvs={133773310: 'FEEDC0DE'})
inv = only_one(l2.rpc.listinvoices()['invoices'])
assert(l2.daemon.is_in_log(r'plugin-sphinx-receiver.py.*extratlvs.*133773310.*feedc0de'))
assert not l2.daemon.is_in_log(r'plugin-sphinx-receiver.py.*extratlvs.*133773310.*feedc0de')

assert(inv['amount_received_msat'] >= Millisatoshi(amt))
assert inv['description'] == 'keysend'
Expand All @@ -3615,13 +3613,15 @@ def test_keysend_extra_tlvs(node_factory):
l1.rpc.keysend(l2.info['id'], amt, extratlvs={133773310: b'hello there'.hex()})
inv = only_one(l2.rpc.listinvoices()['invoices'])
assert inv['description'] == 'keysend: hello there'
l2.daemon.wait_for_log('Keysend payment uses illegal even field 133773310: stripping')
l2.rpc.delinvoice(inv['label'], 'paid')

# We can (just!) fit a giant description in.
l1.rpc.keysend(l2.info['id'], amt, extratlvs={133773310: (b'a' * 1100).hex()})
inv = only_one(l2.rpc.listinvoices()['invoices'])
assert inv['description'] == 'keysend: ' + 'a' * 1100
l2.rpc.delinvoice(inv['label'], 'paid')
l2.daemon.wait_for_log('Keysend payment uses illegal even field 133773310: stripping')

# Now try with some special characters
ksinfo = """💕 ₿"'
Expand All @@ -3630,6 +3630,7 @@ def test_keysend_extra_tlvs(node_factory):
l1.rpc.keysend(l2.info['id'], amt, extratlvs={133773310: bytes(ksinfo, encoding='utf8').hex()})
inv = only_one(l2.rpc.listinvoices()['invoices'])
assert inv['description'] == 'keysend: ' + ksinfo
l2.daemon.wait_for_log('Keysend payment uses illegal even field 133773310: stripping')


def test_keysend_routehint(node_factory):
Expand Down