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plugin: Implement the ability to receive keysend payments

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This still uses the experimental TLV-type, but once the type is standardized
we can add detection for the new type quite easily.

Changelog-Added: pay: The `keysend` plugin implements the ability to receive spontaneous payments (keysend)
This commit is contained in:
Christian Decker
2020-03-30 12:24:43 +02:00
committed by Rusty Russell
parent 5be59f4759
commit ef0f28cd50
2 changed files with 103 additions and 2 deletions
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2
plugins/Makefile
View File

@@ -59,7 +59,7 @@ plugins/fundchannel: common/addr.o $(PLUGIN_FUNDCHANNEL_OBJS) $(PLUGIN_LIB_OBJS)
plugins/bcli: bitcoin/chainparams.o $(PLUGIN_BCLI_OBJS) $(PLUGIN_LIB_OBJS) $(PLUGIN_COMMON_OBJS) $(JSMN_OBJS) $(CCAN_OBJS)
plugins/keysend: bitcoin/chainparams.o $(PLUGIN_KEYSEND_OBJS) $(PLUGIN_LIB_OBJS) $(PLUGIN_COMMON_OBJS) $(JSMN_OBJS) $(CCAN_OBJS)
plugins/keysend: bitcoin/chainparams.o wire/gen_onion_wire.o $(PLUGIN_KEYSEND_OBJS) $(PLUGIN_LIB_OBJS) $(PLUGIN_COMMON_OBJS) $(JSMN_OBJS) $(CCAN_OBJS)
$(PLUGIN_PAY_OBJS) $(PLUGIN_AUTOCLEAN_OBJS) $(PLUGIN_FUNDCHANNEL_OBJS) $(PLUGIN_BCLI_OBJS) $(PLUGIN_LIB_OBJS): $(PLUGIN_LIB_HEADER)

103
plugins/keysend.c
View File

@@ -1,5 +1,8 @@
#include <ccan/array_size/array_size.h>
#include <plugins/libplugin.h>
#include <wire/gen_onion_wire.h>
#define PREIMAGE_TLV_TYPE 5482373484
static void init(struct plugin *p, const char *buf UNUSED,
const jsmntok_t *config UNUSED)
@@ -9,10 +12,108 @@ static void init(struct plugin *p, const char *buf UNUSED,
static const struct plugin_command commands[] = {
};
static struct command_result *htlc_accepted_continue(struct command *cmd)
{
struct json_stream *response;
response = jsonrpc_stream_success(cmd);
json_add_string(response, "result", "continue");
return command_finished(cmd, response);
}
static struct command_result *htlc_accepted_resolve(struct command *cmd,
char *hexpreimage)
{
struct json_stream *response;
response = jsonrpc_stream_success(cmd);
json_add_string(response, "result", "resolve");
json_add_string(response, "payment_key", hexpreimage);
return command_finished(cmd, response);
}
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;
struct sha256 payment_hash;
bigsize_t s;
if (!payloadt)
return htlc_accepted_continue(cmd);
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);
}
fromwire_tlv_payload(&rawpayload, &max, payload);
/* Try looking for the field that contains the preimage */
for (int i=0; i<tal_count(payload->fields); i++) {
if (payload->fields[i].numtype == PREIMAGE_TLV_TYPE) {
preimage_field = &payload->fields[i];
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);
/* 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);
}
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(&payment_hash, preimage_field->value, preimage_field->length);
hexpaymenthash = tal_hexstr(cmd, &payment_hash, sizeof(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);
return htlc_accepted_continue(cmd);
}
/* 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.",
hexpaymenthash);
return htlc_accepted_resolve(cmd, hexpreimage);
}
static const struct plugin_hook hooks[] = {
{
"htlc_accepted",
htlc_accepted_call
},
};
int main(int argc, char *argv[])
{
setup_locale();
plugin_main(argv, init, PLUGIN_RESTARTABLE, commands, ARRAY_SIZE(commands),
NULL, 0, NULL, 0, NULL);
NULL, 0, hooks, ARRAY_SIZE(hooks), NULL);
}