lnd: implement pendingchannels RPC

This commit implements the “pendingchannels” RPC within the rpcserver.
This RPC allows callers to receive details concerning the current
pending channels associated with the daemon. Pending channels are those
waiting for additional confirmations before they can be considered
opened/closed.

At the time of this commit, only open channels are shown. A future
commit will also add the confirmation updates, along with information
for close channels.

rpcserver.go

@@ -381,3 +381,40 @@ func (r *rpcServer) WalletBalance(ctx context.Context,
 
 	return &lnrpc.WalletBalanceResponse{balance}, nil
 }
+
+// PendingChannels returns a list of all the channels that are currently
+// considered "pending". A channel is pending if it has finished the funding
+// workflow and is waiting for confirmations for the funding txn, or is in the
+// process of closure, either initiated cooperatively or non-coopertively.
+func (r *rpcServer) PendingChannels(ctx context.Context,
+	in *lnrpc.PendingChannelRequest) (*lnrpc.PendingChannelResponse, error) {
+
+	both := in.Status == lnrpc.ChannelStatus_ALL
+	includeOpen := (in.Status == lnrpc.ChannelStatus_OPENING) || both
+	includeClose := (in.Status == lnrpc.ChannelStatus_CLOSING) || both
+	rpcsLog.Debugf("[pendingchannels] %v", in.Status)
+
+	var pendingChannels []*lnrpc.PendingChannelResponse_PendingChannel
+	if includeOpen {
+		pendingOpenChans := r.server.fundingMgr.PendingChannels()
+		for _, pendingOpen := range pendingOpenChans {
+			// TODO(roasbeef): add confirmation progress
+			pendingChan := &lnrpc.PendingChannelResponse_PendingChannel{
+				PeerId:        pendingOpen.peerId,
+				LightningId:   hex.EncodeToString(pendingOpen.lightningID[:]),
+				ChannelPoint:  pendingOpen.channelPoint.String(),
+				Capacity:      int64(pendingOpen.capacity),
+				LocalBalance:  int64(pendingOpen.localBalance),
+				RemoteBalance: int64(pendingOpen.remoteBalance),
+				Status:        lnrpc.ChannelStatus_OPENING,
+			}
+			pendingChannels = append(pendingChannels, pendingChan)
+		}
+	}
+	if includeClose {
+	}
+
+	return &lnrpc.PendingChannelResponse{
+		PendingChannels: pendingChannels,
+	}, nil
+}