channel: Along with the last_tx also remember its type

This takes the guesswork out of `drop_to_chain` and allows us to annotate the
last_tx consistently.

Signed-off-by: Christian Decker <decker.christian@gmail.com>

lightningd/channel.c

@@ -233,6 +233,7 @@ struct channel *new_channel(struct peer *peer, u64 dbid,
 	channel->msat_to_us_min = msat_to_us_min;
 	channel->msat_to_us_max = msat_to_us_max;
 	channel->last_tx = tal_steal(channel, last_tx);
+	channel->last_tx_type = TX_UNKNOWN;
 	channel->last_sig = *last_sig;
 	channel->last_htlc_sigs = tal_steal(channel, last_htlc_sigs);
 	channel->channel_info = *channel_info;
@@ -331,11 +332,13 @@ struct channel *channel_by_dbid(struct lightningd *ld, const u64 dbid)
 
 void channel_set_last_tx(struct channel *channel,
 			 struct bitcoin_tx *tx,
-			 const struct bitcoin_signature *sig)
+			 const struct bitcoin_signature *sig,
+			 txtypes txtypes)
 {
 	channel->last_sig = *sig;
 	tal_free(channel->last_tx);
 	channel->last_tx = tal_steal(channel, tx);
+	channel->last_tx_type = txtypes;
 }
 
 void channel_set_state(struct channel *channel,

lightningd/channel.h

@@ -76,6 +76,7 @@ struct channel {
 
 	/* Last tx they gave us. */
 	struct bitcoin_tx *last_tx;
+	txtypes last_tx_type;
 	struct bitcoin_signature last_sig;
 	secp256k1_ecdsa_signature *last_htlc_sigs;
 
@@ -201,7 +202,8 @@ struct channel *channel_by_dbid(struct lightningd *ld, const u64 dbid);
 
 void channel_set_last_tx(struct channel *channel,
 			 struct bitcoin_tx *tx,
-			 const struct bitcoin_signature *sig);
+			 const struct bitcoin_signature *sig,
+			 txtypes type);
 
 static inline bool channel_can_add_htlc(const struct channel *channel)
 {

lightningd/closing_control.c

@@ -95,8 +95,7 @@ static void peer_received_closing_signature(struct channel *channel,
 
 	/* FIXME: Make sure signature is correct! */
 	if (better_closing_fee(ld, channel, tx)) {
-		channel_set_last_tx(channel, tx, &sig);
-		/* TODO(cdecker) Selectively save updated fields to DB */
+		channel_set_last_tx(channel, tx, &sig, TX_CHANNEL_CLOSE);
 		wallet_channel_save(ld->wallet, channel);
 	}
 

lightningd/peer_htlcs.c

@@ -1240,7 +1240,7 @@ static bool peer_save_commitsig_received(struct channel *channel, u64 commitnum,
 	channel->next_index[LOCAL]++;
 
 	/* Update channel->last_sig and channel->last_tx before saving to db */
-	channel_set_last_tx(channel, tx, commit_sig);
+	channel_set_last_tx(channel, tx, commit_sig, TX_CHANNEL_UNILATERAL);
 
 	return true;
 }