lightningd: remove secpctx

Use the global in the few remaining places.

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

daemon/cryptopkt.c

@@ -8,6 +8,7 @@
 #include "peer.h"
 #include "protobuf_convert.h"
 #include "secrets.h"
+#include "utils.h"
 #include <ccan/build_assert/build_assert.h>
 #include <ccan/crypto/sha256/sha256.h>
 #include <ccan/endian/endian.h>
@@ -507,7 +508,7 @@ static struct io_plan *keys_exchanged(struct io_conn *conn,
 	}
 
 	/* Derive shared secret. */
-	if (!secp256k1_ecdh(neg->dstate->secpctx, shared_secret,
+	if (!secp256k1_ecdh(secp256k1_ctx, shared_secret,
 			    &sessionkey.pubkey, neg->seckey)) {
 		log_unusual(neg->log, "Bad ECDH");
 		return io_close(conn);
@@ -590,13 +591,12 @@ static struct io_plan *session_key_len_receive(struct io_conn *conn,
 		       session_key_receive, neg);
 }
 
-static void gen_sessionkey(secp256k1_context *ctx,
-			   u8 seckey[32],
+static void gen_sessionkey(u8 seckey[32],
 			   secp256k1_pubkey *pubkey)
 {
 	do {
 		randombytes_buf(seckey, 32);
-	} while (!secp256k1_ec_pubkey_create(ctx, pubkey, seckey));
+	} while (!secp256k1_ec_pubkey_create(secp256k1_ctx, pubkey, seckey));
 }
 
 static struct io_plan *write_sessionkey(struct io_conn *conn,
@@ -638,10 +638,10 @@ struct io_plan *peer_crypto_setup_(struct io_conn *conn,
 	neg->expected_id = id;
 	neg->log = log;
 
-	gen_sessionkey(dstate->secpctx, neg->seckey, &sessionkey);
+	gen_sessionkey(neg->seckey, &sessionkey);
 
 	outputlen = sizeof(neg->our_sessionpubkey);
-	secp256k1_ec_pubkey_serialize(dstate->secpctx,
+	secp256k1_ec_pubkey_serialize(secp256k1_ctx,
 				      neg->our_sessionpubkey, &outputlen,
 				      &sessionkey,
 				      SECP256K1_EC_COMPRESSED);

daemon/lightningd.c

@@ -356,8 +356,6 @@ static struct lightningd_state *lightningd_state(void)
 	timers_init(&dstate->timers, time_mono());
 	txwatch_hash_init(&dstate->txwatches);
 	txowatch_hash_init(&dstate->txowatches);
-	secp256k1_ctx = dstate->secpctx = secp256k1_context_create(SECP256K1_CONTEXT_VERIFY
-						   | SECP256K1_CONTEXT_SIGN);
 	list_head_init(&dstate->bitcoin_req);
 	list_head_init(&dstate->wallet);
 	list_head_init(&dstate->unpaid);
@@ -483,6 +481,9 @@ int main(int argc, char *argv[])
 		errx(1, "Compiled against protobuf %s, but have %s",
 		     PROTOBUF_C_VERSION, protobuf_c_version());
 
+	secp256k1_ctx = secp256k1_context_create(SECP256K1_CONTEXT_VERIFY
+						 | SECP256K1_CONTEXT_SIGN);
+	
 	opt_register_noarg("--help|-h", opt_usage_and_exit,
 			   "\n"
 			   "A bitcoin lightning daemon.",

daemon/lightningd.h

@@ -107,9 +107,6 @@ struct lightningd_state {
 	/* Any outstanding "pay" commands. */
 	struct list_head pay_commands;
 
-	/* Crypto tables for global use. */
-	secp256k1_context *secpctx;
-
 	/* Our private key */
 	struct secret *secret;