protocol: remove support for uncompressed pubkeys.

There's no good reason to support them, and this way every key is 33 bytes.

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

bitcoin/address.c

@@ -1,11 +1,12 @@
 #include "address.h"
 #include "pubkey.h"
+#include <ccan/mem/mem.h>
 #include <ccan/crypto/sha256/sha256.h>
 
 void bitcoin_address(const struct pubkey *key, struct bitcoin_address *addr)
 {
 	struct sha256 h;
 
-	sha256(&h, key->der, pubkey_derlen(key));
+	sha256(&h, memcheck(key->der, sizeof(key->der)), sizeof(key->der));
 	ripemd160(&addr->addr, h.u.u8, sizeof(h));
 }

bitcoin/pubkey.c

@@ -1,41 +1,19 @@
 #include "privkey.h"
 #include "pubkey.h"
 #include <assert.h>
+#include <ccan/mem/mem.h>
 #include <ccan/str/hex/hex.h>
 
-/* Must agree on key validity with bitcoin!  Stolen from bitcoin/src/pubkey.h's
- * GetLen:
- * // Copyright (c) 2009-2010 Satoshi Nakamoto
- * // Copyright (c) 2009-2014 The Bitcoin Core developers
- * // Distributed under the MIT software license, see the accompanying
- * // file COPYING or http://www.opensource.org/licenses/mit-license.php.
- */
-static unsigned int GetLen(unsigned char chHeader)
-{
-        if (chHeader == 2 || chHeader == 3)
-		return 33;
-        if (chHeader == 4 || chHeader == 6 || chHeader == 7)
-		return 65;
-        return 0;
-}
-
-size_t pubkey_derlen(const struct pubkey *key)
-{
-	size_t len = GetLen(key->der[0]);
-
-	assert(len);
-	return len;
-}
-
 bool pubkey_from_der(secp256k1_context *secpctx,
 		     const u8 *der, size_t len,
 		     struct pubkey *key)
 {
-	if (len > sizeof(key->der))
+	if (len != sizeof(key->der))
 		return false;
 
-	memcpy(key->der, der, len);
+	memcpy(key->der, memcheck(der, sizeof(key->der)), sizeof(key->der));
-	if (!secp256k1_ec_pubkey_parse(secpctx, &key->pubkey, key->der, len))
+	if (!secp256k1_ec_pubkey_parse(secpctx, &key->pubkey, key->der,
+				       sizeof(key->der)))
 		return false;
 
 	return true;
@@ -55,7 +33,7 @@ bool pubkey_from_privkey(secp256k1_context *secpctx,
 	if (!secp256k1_ec_pubkey_serialize(secpctx, key->der, &outlen,
 					   &key->pubkey, compressed_flags))
 		return false;
-	assert(outlen == pubkey_derlen(key));
+	assert(outlen == sizeof(key->der));
 	return true;
 }
 	
@@ -63,10 +41,10 @@ bool pubkey_from_hexstr(secp256k1_context *secpctx,
 			const char *derstr, size_t slen, struct pubkey *key)
 {
 	size_t dlen;
-	unsigned char der[65];
+	unsigned char der[sizeof(key->der)];
 
 	dlen = hex_data_size(slen);
-	if (dlen > sizeof(der))
+	if (dlen != sizeof(der))
 		return false;
 
 	if (!hex_decode(derstr, slen, der, dlen))
@@ -77,6 +55,5 @@ bool pubkey_from_hexstr(secp256k1_context *secpctx,
 
 bool pubkey_eq(const struct pubkey *a, const struct pubkey *b)
 {
-	return pubkey_derlen(a) == pubkey_derlen(b)
+	return memcmp(a->der, b->der, sizeof(a->der)) == 0;
-		&& memcmp(a->der, b->der, pubkey_derlen(a)) == 0;
 }

bitcoin/pubkey.h

@@ -9,7 +9,7 @@ struct privkey;
 
 struct pubkey {
 	/* DER-encoded key (as hashed by bitcoin, for addresses) */
-	u8 der[65];
+	u8 der[33];
 	/* Unpacked pubkey (as used by libsecp256k1 internally) */
 	secp256k1_pubkey pubkey;
 };
@@ -28,9 +28,6 @@ bool pubkey_from_privkey(secp256k1_context *secpctx,
 bool pubkey_from_der(secp256k1_context *secpctx,
 		     const u8 *der, size_t len, struct pubkey *key);
 
-/* How many bytes of key->der are valid. */
-size_t pubkey_derlen(const struct pubkey *key);
-
 /* Are these keys equal? */
 bool pubkey_eq(const struct pubkey *a, const struct pubkey *b);
 #endif /* LIGHTNING_PUBKEY_H */

bitcoin/script.c

@@ -102,7 +102,7 @@ static void add_number(u8 **script, u32 num)
 
 static void add_push_key(u8 **scriptp, const struct pubkey *key)
 {
-	add_push_bytes(scriptp, key->der, pubkey_derlen(key));
+	add_push_bytes(scriptp, key->der, sizeof(key->der));
 }
 
 static void add_push_sig(u8 **scriptp, const struct bitcoin_signature *sig)
@@ -129,11 +129,7 @@ static void add_push_sig(u8 **scriptp, const struct bitcoin_signature *sig)
 /* Is a < b? (If equal we don't care) */
 static bool key_less(const struct pubkey *a, const struct pubkey *b)
 {
-	/* Shorter one wins. */
+	return memcmp(a->der, b->der, sizeof(a->der)) < 0;
-	if (pubkey_derlen(a) != pubkey_derlen(b))
-		return pubkey_derlen(a) < pubkey_derlen(b);
-
-	return memcmp(a->der, b->der, pubkey_derlen(a)) < 0;
 }
 	
 /* tal_count() gives the length of the script. */

daemon/packets.c

@@ -35,7 +35,7 @@ static void dump_tx(const char *str, const struct bitcoin_tx *tx)
 
 static void dump_key(const char *str, const struct pubkey *key)
 {
-	printf("%s:%s\n", str, hex_of(NULL, key->der, pubkey_derlen(key)));
+	printf("%s:%s\n", str, hex_of(NULL, key->der, sizeof(key->der)));
 }
 
 /* Wrap (and own!) member inside Pkt */

daemon/peer.c

@@ -1363,7 +1363,7 @@ static void json_getpeers(struct command *cmd,
 		/* This is only valid after crypto setup. */
 		if (p->state != STATE_INIT)
 			json_add_hex(response, "peerid",
-				     p->id.der, pubkey_derlen(&p->id));
+				     p->id.der, sizeof(p->id.der));
 
 		if (p->cstate) {
 			json_object_start(response, "channel");

daemon/secrets.c

@@ -176,5 +176,5 @@ void secrets_init(struct lightningd_state *dstate)
 		fatal("Invalid privkey");
 
 	log_info(dstate->base_log, "ID: ");
-	log_add_hex(dstate->base_log, dstate->id.der, pubkey_derlen(&dstate->id));
+	log_add_hex(dstate->base_log, dstate->id.der, sizeof(dstate->id.der));
 }

lightning.pb-c.h

@@ -114,7 +114,7 @@ struct  _BitcoinPubkey
 {
   ProtobufCMessage base;
   /*
-   * Either 65 or 33 bytes.
+   * Must be 33 bytes.
    */
   ProtobufCBinaryData key;
 };

lightning.proto

@@ -35,7 +35,7 @@ message locktime {
 
 // Pubkey for commitment transaction input.
 message bitcoin_pubkey {
-  // Either 65 or 33 bytes.
+  // Must be 33 bytes.
   required bytes key = 1;
 }
 

protobuf_convert.c

@@ -71,7 +71,7 @@ BitcoinPubkey *pubkey_to_proto(const tal_t *ctx, const struct pubkey *key)
 	struct pubkey check;
 
 	bitcoin_pubkey__init(p);
-	p->key.len = pubkey_derlen(key);
+	p->key.len = sizeof(key->der);
 	p->key.data = tal_dup_arr(p, u8, key->der, p->key.len, 0);
 
 	{