Split into two anchors.

This is a major change; instead of creating a mutual anchor (funding)
transaction, each side creates its own.  We use escape transactions in
case anything goes wrong; these will be revoked later.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

test-cli/open-anchor-id.c

@@ -0,0 +1,79 @@
+#include <ccan/crypto/shachain/shachain.h>
+#include <ccan/short_types/short_types.h>
+#include <ccan/tal/tal.h>
+#include <ccan/opt/opt.h>
+#include <ccan/str/hex/hex.h>
+#include <ccan/err/err.h>
+#include <ccan/read_write_all/read_write_all.h>
+#include "lightning.pb-c.h"
+#include "bitcoin/base58.h"
+#include "pkt.h"
+#include "bitcoin/script.h"
+#include "bitcoin/address.h"
+#include "bitcoin/tx.h"
+#include "bitcoin/pubkey.h"
+#include "bitcoin/privkey.h"
+#include "bitcoin/shadouble.h"
+#include "protobuf_convert.h"
+#include <unistd.h>
+#include <time.h>
+#include "opt_bits.h"
+
+int main(int argc, char *argv[])
+{
+	struct pkt *pkt;
+	const tal_t *ctx = tal_arr(NULL, char, 0);
+	struct bitcoin_tx *anchor;
+	struct sha256_double txid;
+	unsigned int i;
+
+	err_set_progname(argv[0]);
+
+	opt_register_noarg("--help|-h", opt_usage_and_exit,
+			   "<anchor-tx-file> <change-key>\n"
+			   "A test program to output open-anchor on stdout.",
+			   "Print this message.");
+
+ 	opt_parse(&argc, argv, opt_log_stderr_exit);
+
+	if (argc != 3)
+		opt_usage_exit_fail("Expected 1 argument");
+
+	anchor = bitcoin_tx_from_file(ctx, argv[1]);
+	bitcoin_txid(anchor, &txid);
+
+	/* Figure out which output is for the commit tx. */
+	if (anchor->output_count != 1) {
+		u8 *script;
+		struct pubkey change_key;
+		if (!pubkey_from_hexstr(argv[2], &change_key))
+			errx(1, "Invalid change key %s", argv[2]);
+
+		if (anchor->output_count != 2)
+			errx(1, "Expected 1 or 2 outputs on anchor");
+
+		script = scriptpubkey_p2sh(anchor,
+					   bitcoin_redeem_single(anchor,
+								 &change_key));
+		for (i = 0; i < anchor->output_count; i++) {
+			if (anchor->output[i].script_length != tal_count(script))
+				continue;
+			if (memcmp(anchor->output[i].script, script,
+				   tal_count(script)) == 0)
+				break;
+		}
+		if (i == anchor->output_count)
+			errx(1, "No output to change found");
+
+		/* We found change output, so we want the other one. */
+		i = !i;
+	} else
+		i = 0;
+
+	pkt = open_anchor_pkt(ctx, &txid, i);
+	if (!write_all(STDOUT_FILENO, pkt, pkt_totlen(pkt)))
+		err(1, "Writing out packet");
+
+	tal_free(ctx);
+	return 0;
+}