lightningd: move common "can I send HTLC" checks into send_htlc_out.

The pay.c ones were out of date, so unify.

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

lightningd/pay.c

@@ -163,6 +163,7 @@ static void json_sendpay(struct command *cmd,
 	u64 amount, lastamount;
 	struct onionpacket *packet;
 	struct secret *path_secrets;
+	enum onion_type failcode;
 
 	if (!json_get_params(buffer, params,
 			     "route", &routetok,
@@ -307,17 +308,6 @@ static void json_sendpay(struct command *cmd,
 		return;
 	}
 
-	if (!peer->scid) {
-		command_fail(cmd, "first peer channel not locked");
-		return;
-	}
-
-	if (!peer->owner || !streq(peer->owner->name, "lightningd_channel")) {
-		command_fail(cmd, "first peer in %s",
-			     peer->owner ? peer->owner->name : "limbo");
-		return;
-	}
-
 	randombytes_buf(&sessionkey, sizeof(sessionkey));
 
 	/* Onion will carry us from first peer onwards. */
@@ -341,11 +331,17 @@ static void json_sendpay(struct command *cmd,
 
 	log_info(ld->log, "Sending %"PRIu64" over %zu hops to deliver %"PRIu64,
 		 amount, n_hops, lastamount);
-	pc->out = send_htlc_out(peer, amount, first_hop_data.outgoing_cltv,
-				&rhash, onion, NULL, pc);
 
 	/* Wait until we get response. */
 	tal_add_destructor2(cmd, remove_cmd_from_pc, pc);
+
+	failcode = send_htlc_out(peer, amount, first_hop_data.outgoing_cltv,
+				 &rhash, onion, NULL, pc, &pc->out);
+	if (failcode) {
+		command_fail(cmd, "first peer not ready: %s",
+			     onion_type_name(failcode));
+		return;
+	}
 }
 
 static const struct json_command sendpay_command = {

lightningd/peer_htlcs.c

@@ -359,15 +359,28 @@ static bool rcvd_htlc_reply(struct subd *subd, const u8 *msg, const int *fds,
 	return true;
 }
 
-struct htlc_out *send_htlc_out(struct peer *out, u64 amount, u32 cltv,
+enum onion_type send_htlc_out(struct peer *out, u64 amount, u32 cltv,
-			       const struct sha256 *payment_hash,
+			      const struct sha256 *payment_hash,
-			       const u8 *onion_routing_packet,
+			      const u8 *onion_routing_packet,
-			       struct htlc_in *in,
+			      struct htlc_in *in,
-			       struct pay_command *pc)
+			      struct pay_command *pc,
+			      struct htlc_out **houtp)
 {
 	struct htlc_out *hout;
 	u8 *msg;
 
+	if (!peer_can_add_htlc(out)) {
+		log_info(out->log, "Attempt to send HTLC but not ready (%s)",
+			 peer_state_name(out->state));
+		return WIRE_UNKNOWN_NEXT_PEER;
+	}
+
+	if (!out->owner) {
+		log_info(out->log, "Attempt to send HTLC but unowned (%s)",
+			peer_state_name(out->state));
+		return WIRE_TEMPORARY_CHANNEL_FAILURE;
+	}
+
 	/* Make peer's daemon own it, catch if it dies. */
 	hout = new_htlc_out(out->owner, out, amount, cltv,
 			    payment_hash, onion_routing_packet, in, pc);
@@ -376,7 +389,10 @@ struct htlc_out *send_htlc_out(struct peer *out, u64 amount, u32 cltv,
 	msg = towire_channel_offer_htlc(out, amount, cltv, payment_hash,
 					onion_routing_packet);
 	subd_req(out->ld, out->owner, take(msg), -1, 0, rcvd_htlc_reply, hout);
-	return hout;
+
+	if (houtp)
+		*houtp = hout;
+	return 0;
 }
 
 static void forward_htlc(struct htlc_in *hin,
@@ -397,20 +413,6 @@ static void forward_htlc(struct htlc_in *hin,
 		goto fail;
 	}
 
-	if (!peer_can_add_htlc(next)) {
-		log_info(next->log, "Attempt to forward HTLC but not ready (%s)",
-			 peer_state_name(next->state));
-		failcode = WIRE_UNKNOWN_NEXT_PEER;
-		goto fail;
-	}
-
-	if (!next->owner) {
-		log_info(next->log, "Attempt to forward HTLC but unowned (%s)",
-			peer_state_name(next->state));
-		failcode = WIRE_TEMPORARY_CHANNEL_FAILURE;
-		goto fail;
-	}
-
 	/* BOLT #7:
 	 *
 	 * The node creating `channel_update` SHOULD accept HTLCs which pay a
@@ -456,10 +458,11 @@ static void forward_htlc(struct htlc_in *hin,
 		goto fail;
 	}
 
-	send_htlc_out(next, amt_to_forward,
+	failcode = send_htlc_out(next, amt_to_forward,
-		      outgoing_cltv_value, &hin->payment_hash,
+				 outgoing_cltv_value, &hin->payment_hash,
-		      next_onion, hin, NULL);
+				 next_onion, hin, NULL, NULL);
-	return;
+	if (!failcode)
+		return;
 
 fail:
 	fail_htlc(hin, failcode);

lightningd/peer_htlcs.h

@@ -31,9 +31,10 @@ int peer_sending_commitsig(struct peer *peer, const u8 *msg);
 int peer_got_commitsig(struct peer *peer, const u8 *msg);
 int peer_got_revoke(struct peer *peer, const u8 *msg);
 
-struct htlc_out *send_htlc_out(struct peer *out, u64 amount, u32 cltv,
+enum onion_type send_htlc_out(struct peer *out, u64 amount, u32 cltv,
-			       const struct sha256 *payment_hash,
+			      const struct sha256 *payment_hash,
-			       const u8 *onion_routing_packet,
+			      const u8 *onion_routing_packet,
-			       struct htlc_in *in,
+			      struct htlc_in *in,
-			       struct pay_command *pc);
+			      struct pay_command *pc,
+			      struct htlc_out **houtp);
 #endif /* LIGHTNING_LIGHTNINGD_PEER_HTLCS_H */