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68 lines
2.0 KiB
68 lines
2.0 KiB
8 years ago
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#include "funding_tx.h"
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#include <assert.h>
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#include <bitcoin/script.h>
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#include <bitcoin/tx.h>
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#include <permute_tx.h>
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#ifndef SUPERVERBOSE
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#define SUPERVERBOSE(...)
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#endif
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struct bitcoin_tx *funding_tx(const tal_t *ctx,
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const struct sha256_double *input_txid,
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unsigned int input_txout,
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u64 input_satoshis,
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u64 funding_satoshis,
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const struct pubkey *local_fundingkey,
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const struct pubkey *remote_fundingkey,
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const struct pubkey *changekey,
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u64 feerate_per_kw,
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u64 dust_limit_satoshis)
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{
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struct bitcoin_tx *tx = bitcoin_tx(ctx, 1, 2);
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u8 *wscript;
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u64 fee, weight;
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tx->input[0].txid = *input_txid;
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tx->input[0].index = input_txout;
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tx->input[0].amount = tal_dup(tx, u64, &input_satoshis);
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tx->output[0].amount = funding_satoshis;
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wscript = bitcoin_redeem_2of2(tx, local_fundingkey, remote_fundingkey);
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SUPERVERBOSE("# funding witness script = %s\n",
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tal_hex(wscript, wscript));
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tx->output[0].script = scriptpubkey_p2wsh(tx, wscript);
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tal_free(wscript);
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assert(input_satoshis >= funding_satoshis);
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tx->output[1].script = scriptpubkey_p2wpkh(tx, changekey);
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/* Calculate what weight will be once we've signed. */
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weight = measure_tx_cost(tx) + 4 * (73 + 34);
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fee = weight * feerate_per_kw / 1000;
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/* Too small an output after fee? Drop it. */
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if (input_satoshis - funding_satoshis < dust_limit_satoshis + fee)
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tal_resize(&tx->output, 1);
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else {
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tx->output[1].amount = input_satoshis - funding_satoshis - fee;
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permute_outputs(tx->output, tal_count(tx->output), NULL);
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}
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return tx;
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}
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void sign_funding_tx(struct bitcoin_tx *funding,
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const struct pubkey *inputkey,
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const struct privkey *input_privkey)
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{
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secp256k1_ecdsa_signature sig;
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u8 *subscript = scriptpubkey_p2pkh(funding, inputkey);
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sign_tx_input(funding, 0, subscript, NULL, input_privkey, inputkey,
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&sig);
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tal_free(subscript);
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funding->input[0].script = bitcoin_redeem_p2pkh(funding, inputkey, &sig);
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}
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