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#include <bitcoin/preimage.h>
#include <ccan/array_size/array_size.h>
#include <ccan/tal/str/str.h>
#include <plugins/libplugin-pay.h>
#include <plugins/libplugin.h>
#include <wire/onion_wire.h>
#define PREIMAGE_TLV_TYPE 5482373484
#define KEYSEND_FEATUREBIT 55
static unsigned int maxdelay_default;
static struct node_id my_id;
/*****************************************************************************
* Keysend modifier
* ================
*
* The keysend modifier adds the payment preimage to the TLV payload. This
* enables the recipient to accept the payment despite it not correspondin to
* an invoice that the recipient created. Keysend does not provide any proof
* or payment, but does not require an out-of-band communication round to get
* an invoice first.
*/
/* FIXME: If we have more than one plugin using keysend we can move this to
* libplugin-pay.c */
struct keysend_data {
struct preimage preimage;
};
REGISTER_PAYMENT_MODIFIER_HEADER(keysend, struct keysend_data);
static struct keysend_data *keysend_init(struct payment *p)
{
struct keysend_data *d;
struct sha256 payment_hash;
if (p->parent == NULL) {
/* If we are the root payment we generate a random preimage
* and populate the preimage field in the keysend_data and the
* payment_hash in the payment. */
d = tal(p, struct keysend_data);
randombytes_buf(&d->preimage, sizeof(d->preimage));
ccan_sha256(&payment_hash, &d->preimage, sizeof(d->preimage));
p->payment_hash = tal_dup(p, struct sha256, &payment_hash);
return d;
} else {
/* If we are a child payment (retry or split) we copy the
* parent's information, since the payment_hash needs to match
* in order to be collated at the recipient. */
return payment_mod_keysend_get_data(p->parent);
}
}
static void keysend_cb(struct keysend_data *d, struct payment *p) {
struct route_hop *last_hop;
struct createonion_hop *last_payload;
size_t hopcount;
if (p->step == PAYMENT_STEP_GOT_ROUTE) {
/* Force the last step to be a TLV, we might not have an
* announcement and it still supports it. Required later when
* we adjust the payload. */
last_hop = &p->route[tal_count(p->route) - 1];
last_hop->style = ROUTE_HOP_TLV;
}
if (p->step != PAYMENT_STEP_ONION_PAYLOAD)
return payment_continue(p);
hopcount = tal_count(p->createonion_request->hops);
last_payload = &p->createonion_request->hops[hopcount - 1];
tlvstream_set_raw(&last_payload->tlv_payload->fields, PREIMAGE_TLV_TYPE,
&d->preimage, sizeof(struct preimage));
return payment_continue(p);
}
REGISTER_PAYMENT_MODIFIER(keysend, struct keysend_data *, keysend_init,
keysend_cb);
/*
* End of keysend modifier
*****************************************************************************/
static void init(struct plugin *p, const char *buf UNUSED,
const jsmntok_t *config UNUSED)
{
const char *field;
field = rpc_delve(tmpctx, p, "getinfo",
take(json_out_obj(NULL, NULL, NULL)), ".id");
if (!node_id_from_hexstr(field, strlen(field), &my_id))
plugin_err(p, "getinfo didn't contain valid id: '%s'", field);
field =
rpc_delve(tmpctx, p, "listconfigs",
take(json_out_obj(NULL, "config", "max-locktime-blocks")),
".max-locktime-blocks");
maxdelay_default = atoi(field);
}
struct payment_modifier *pay_mods[8] = {
&keysend_pay_mod,
&local_channel_hints_pay_mod,
&directpay_pay_mod,
&shadowroute_pay_mod,
&exemptfee_pay_mod,
&waitblockheight_pay_mod,
&retry_pay_mod,
NULL,
};
static struct command_result *json_keysend(struct command *cmd, const char *buf,
const jsmntok_t *params)
{
struct payment *p;
const char *label;
struct amount_msat *exemptfee, *msat;
struct node_id *destination;
u64 *maxfee_pct_millionths;
u32 *maxdelay;
unsigned int *retryfor;
#if DEVELOPER
bool *use_shadow;
#endif
p = payment_new(NULL, cmd, NULL /* No parent */, pay_mods);
if (!param(cmd, buf, params,
p_req("destination", param_node_id, &destination),
p_req("msatoshi", param_msat, &msat),
p_opt("label", param_string, &label),
p_opt_def("maxfeepercent", param_millionths,
&maxfee_pct_millionths, 500000),
p_opt_def("retry_for", param_number, &retryfor, 60),
p_opt_def("maxdelay", param_number, &maxdelay,
maxdelay_default),
p_opt_def("exemptfee", param_msat, &exemptfee, AMOUNT_MSAT(5000)),
#if DEVELOPER
p_opt_def("use_shadow", param_bool, &use_shadow, true),
#endif
NULL))
return command_param_failed();
p->local_id = &my_id;
p->json_buffer = tal_steal(p, buf);
p->json_toks = params;
p->destination = tal_steal(p, destination);
p->payment_secret = NULL;
p->amount = *msat;
p->invoice = NULL;
p->bolt11 = NULL;
p->why = "Initial attempt";
p->constraints.cltv_budget = *maxdelay;
p->deadline = timeabs_add(time_now(), time_from_sec(*retryfor));
p->getroute->riskfactorppm = 10000000;
if (!amount_msat_fee(&p->constraints.fee_budget, p->amount, 0,
*maxfee_pct_millionths / 100)) {
tal_free(p);
return command_fail(
cmd, JSONRPC2_INVALID_PARAMS,
"Overflow when computing fee budget, fee rate too high.");
}
p->constraints.cltv_budget = *maxdelay;
payment_mod_exemptfee_get_data(p)->amount = *exemptfee;
#if DEVELOPER
payment_mod_shadowroute_get_data(p)->use_shadow = *use_shadow;
#endif
p->label = tal_steal(p, label);
payment_start(p);
return command_still_pending(cmd);
}
static const struct plugin_command commands[] = {
{
"keysend",
"payment",
"Send a payment without an invoice to a node",
"Send an unsolicited payment of {amount} to {destination}, by providing the recipient the necessary information to claim the payment",
json_keysend
},
};
static struct command_result *
htlc_accepted_continue(struct command *cmd, struct tlv_tlv_payload *payload)
{
struct json_stream *response;
response = jsonrpc_stream_success(cmd);
json_add_string(response, "result", "continue");
if (payload) {
u8 *binpayload = tal_arr(cmd, u8, 0);
towire_tlvstream_raw(&binpayload, payload->fields);
json_add_string(response, "payload", tal_hex(cmd, binpayload));
}
return command_finished(cmd, response);
}
/* Struct wrapping the information we extract from an incoming keysend
* payment */
struct keysend_in {
struct sha256 payment_hash;
struct preimage payment_preimage;
char *label;
struct tlv_tlv_payload *payload;
struct tlv_field *preimage_field;
};
static struct command_result *
htlc_accepted_invoice_created(struct command *cmd, const char *buf UNUSED,
const jsmntok_t *result UNUSED,
struct keysend_in *ki)
{
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);
/* Finally we can resolve the payment with the preimage. */
plugin_log(cmd->plugin, LOG_INFORM,
"Resolving incoming HTLC with preimage for payment_hash %s "
"provided in the onion payload.",
tal_hexstr(tmpctx, &ki->payment_hash, sizeof(struct sha256)));
return htlc_accepted_continue(cmd, ki->payload);
}
static struct command_result *htlc_accepted_call(struct command *cmd,
const char *buf,
const jsmntok_t *params)
{
const jsmntok_t *payloadt = json_delve(buf, params, ".onion.payload");
const jsmntok_t *payment_hash_tok = json_delve(buf, params, ".htlc.payment_hash");
const u8 *rawpayload;
size_t max;
struct tlv_tlv_payload *payload;
struct tlv_field *preimage_field = NULL;
char *hexpreimage, *hexpaymenthash;
bigsize_t s;
bool unknown_even_type = false;
struct tlv_field *field;
struct keysend_in *ki;
struct out_req *req;
struct timeabs now = time_now();
if (!payloadt)
return htlc_accepted_continue(cmd, NULL);
rawpayload = json_tok_bin_from_hex(cmd, buf, payloadt);
max = tal_bytelen(rawpayload);
payload = tlv_tlv_payload_new(cmd);
s = fromwire_varint(&rawpayload, &max);
if (s != max) {
return htlc_accepted_continue(cmd, NULL);
}
if (!fromwire_tlv_payload(&rawpayload, &max, payload)) {
plugin_log(
cmd->plugin, LOG_UNUSUAL, "Malformed TLV payload %.*s",
payloadt->end - payloadt->start, buf + payloadt->start);
return htlc_accepted_continue(cmd, NULL);
}
/* Try looking for the field that contains the preimage */
for (int i=0; i<tal_count(payload->fields); i++) {
field = &payload->fields[i];
if (field->numtype == PREIMAGE_TLV_TYPE) {
preimage_field = field;
break;
} else if (field->numtype % 2 == 0 && field->meta == NULL) {
unknown_even_type = true;
break;
}
}
/* If we don't have a preimage field then this is not a keysend, let
* someone else take care of it. */
if (preimage_field == NULL)
return htlc_accepted_continue(cmd, NULL);
if (unknown_even_type) {
plugin_log(cmd->plugin, LOG_UNUSUAL,
"Payload contains unknown even TLV-type %" PRIu64
", can't safely accept the keysend. Deferring to "
"other plugins.",
preimage_field->numtype);
return htlc_accepted_continue(cmd, NULL);
}
/* If the preimage is not 32 bytes long then we can't accept the
* payment. */
if (preimage_field->length != 32) {
plugin_log(cmd->plugin, LOG_UNUSUAL,
"Sender specified a preimage that is %zu bytes long, "
"we expected 32 bytes. Ignoring this HTLC.",
preimage_field->length);
return htlc_accepted_continue(cmd, NULL);
}
ki = tal(cmd, struct keysend_in);
memcpy(&ki->payment_preimage, preimage_field->value, 32);
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;
hexpreimage = tal_hex(cmd, preimage_field->value);
/* If the preimage doesn't hash to the payment_hash we must continue,
* maybe someone else knows how to handle these. */
sha256(&ki->payment_hash, preimage_field->value, preimage_field->length);
hexpaymenthash = tal_hexstr(cmd, &ki->payment_hash, sizeof(ki->payment_hash));
if (!json_tok_streq(buf, payment_hash_tok, hexpaymenthash)) {
plugin_log(
cmd->plugin, LOG_UNUSUAL,
"Preimage provided by the sender does not match the "
"payment_hash: SHA256(%s)=%s != %.*s. Ignoring keysend.",
hexpreimage, hexpaymenthash,
payment_hash_tok->end - payment_hash_tok->start,
buf + payment_hash_tok->start);
tal_free(ki);
return htlc_accepted_continue(cmd, NULL);
}
/* Now we can call `invoice` RPC to backfill an invoce matching this
* spontaneous payment, thus leaving us with an accounting
* trace. Creating the invoice is best effort: it may fail if the
* `payment_hash` is already attached to an existing invoice, and the
* label could collide (unlikely since we use the nanosecond time). If
* the call to `invoice` fails we will just continue, and `lightningd`
* will be nice and reject the payment. */
req = jsonrpc_request_start(cmd->plugin, cmd, "invoice",
&htlc_accepted_invoice_created,
&htlc_accepted_invoice_created,
ki);
plugin_log(cmd->plugin, LOG_INFORM, "Inserting a new invoice for keysend with payment_hash %s", hexpaymenthash);
json_add_string(req->js, "msatoshi", "any");
json_add_string(req->js, "label", ki->label);
json_add_string(req->js, "description", "Spontaneous incoming payment through keysend");
json_add_preimage(req->js, "preimage", &ki->payment_preimage);
return send_outreq(cmd->plugin, req);
}
static const struct plugin_hook hooks[] = {
{
"htlc_accepted",
htlc_accepted_call
},
};
int main(int argc, char *argv[])
{
struct feature_set features;
setup_locale();
for (int i=0; i<ARRAY_SIZE(features.bits); i++)
features.bits[i] = tal_arr(NULL, u8, 0);
set_feature_bit(&features.bits[NODE_ANNOUNCE_FEATURE], KEYSEND_FEATUREBIT);
plugin_main(argv, init, PLUGIN_STATIC, true, &features, commands,
ARRAY_SIZE(commands), NULL, 0, hooks, ARRAY_SIZE(hooks),
NULL);
}