Fix ability to specify backend server and default server

For electrum, the address must be HOST:tPORT or HOST:sPORT. If addr is
not specified, we default to the initial hardcoded node.

For btcd, the address must be HOST:PORT. If addr is not specifed, we
default to localhost:8334.

backend/btcd_backend.go

@@ -57,9 +57,9 @@ const (
 // BtcdBackend is meants to connect to a personal Btcd node (because public nodes don't expose the
 // API we need). There's no TLS support. If your node is not co-located with Beancounter, we
 // recommend wrapping your connection in a ssh or other secure tunnel.
-func NewBtcdBackend(hostPort, user, pass string, network utils.Network) (*BtcdBackend, error) {
+func NewBtcdBackend(host, port, user, pass string, network utils.Network) (*BtcdBackend, error) {
 	connCfg := &rpcclient.ConnConfig{
-		Host:         hostPort,
+		Host:         fmt.Sprintf("%s:%s", host, port),
 		User:         user,
 		Pass:         pass,
 		HTTPPostMode: true, // Bitcoin core only supports HTTP POST mode

backend/electrum/blockchain.go

@@ -139,6 +139,7 @@ func NewNode(addr, port string, network utils.Network) (*Node, error) {
 	}
 
 	if port[0] == 't' {
+		// TCP
 		var p string
 		if len(port) == 1 {
 			p = defaultTCP
@@ -147,13 +148,16 @@ func NewNode(addr, port string, network utils.Network) (*Node, error) {
 		}
 		t, err = NewTCPTransport(fmt.Sprintf("%s:%s", a, p))
 	} else if port[0] == 's' {
+		// TLS
 		var p string
 		if len(port) == 1 {
 			p = defaultSSL
 		} else {
 			p = port[1:]
 		}
 		t, err = NewSSLTransport(fmt.Sprintf("%s:%s", a, p))
+	} else {
+		panic(fmt.Sprintf("port (%s) must start with t or s", port))
 	}
 
 	if err != nil {

main.go

@@ -7,9 +7,7 @@ import (
 	"github.com/square/beancounter/blockfinder"
 	"log"
 	"math"
-	"net"
 	"os"
-	"strconv"
 	"strings"
 	"time"
 
@@ -37,7 +35,7 @@ var (
 	findBlock            = app.Command("find-block", "Finds the block height for a given date/time.")
 	findBlockTimestamp   = findBlock.Arg("timestamp", "Date/time to resolve. E.g. \"2006-01-02 15:04:05 MST\"").Required().String()
 	findBlockBackend     = findBlock.Flag("backend", "electrum | btcd | electrum-recorder | btcd-recorder | fixture").Default("electrum").Enum("electrum", "btcd", "electrum-recorder", "btcd-recorder", "fixture")
-	findBlockAddr        = findBlock.Flag("addr", "Backend to connect to initially. Defaults to a hardcoded node for Electrum and localhost for Btcd.").PlaceHolder("HOST:PORT").TCP()
+	findBlockAddr        = findBlock.Flag("addr", "Backend to connect to initially. Defaults to a hardcoded node for Electrum and localhost for Btcd.").PlaceHolder("HOST:PORT").String()
 	findBlockRpcUser     = findBlock.Flag("rpcuser", "RPC username").PlaceHolder("USER").String()
 	findBlockRpcPass     = findBlock.Flag("rpcpass", "RPC password").PlaceHolder("PASSWORD").String()
 	findBlockFixtureFile = findBlock.Flag("fixture-file", "Fixture file to use for recording or replaying data.").PlaceHolder("FILEPATH").String()
@@ -48,7 +46,7 @@ var (
 	computeBalanceM           = computeBalance.Flag("m", "number of signatures (quorum)").Short('m').Default("1").Int()
 	computeBalanceN           = computeBalance.Flag("n", "number of public keys").Short('n').Default("1").Int()
 	computeBalanceBackend     = computeBalance.Flag("backend", "electrum | btcd | electrum-recorder | btcd-recorder | fixture").Default("electrum").Enum("electrum", "btcd", "electrum-recorder", "btcd-recorder", "fixture")
-	computeBalanceAddr        = computeBalance.Flag("addr", "Backend to connect to initially. Defaults to a hardcoded node for Electrum and localhost for Btcd.").PlaceHolder("HOST:PORT").TCP()
+	computeBalanceAddr        = computeBalance.Flag("addr", "Backend to connect to initially. Defaults to a hardcoded node for Electrum and localhost for Btcd.").PlaceHolder("HOST:PORT").String()
 	computeBalanceRpcUser     = computeBalance.Flag("rpcuser", "RPC username").PlaceHolder("USER").String()
 	computeBalanceRpcPass     = computeBalance.Flag("rpcpass", "RPC password").PlaceHolder("PASSWORD").String()
 	computeBalanceFixtureFile = computeBalance.Flag("fixture-file", "Fixture file to use for recording or replaying data.").PlaceHolder("FILEPATH").String()
@@ -252,22 +250,22 @@ func findBlockBuildBackend(network Network) (backend.Backend, error) {
 	var err error
 	switch *findBlockBackend {
 	case "electrum":
-		addr, port := getServer(network, *findBlockAddr)
+		addr, port := GetDefaultServer(network, Electrum, *findBlockAddr)
 		b, err = backend.NewElectrumBackend(addr, port, network)
 		if err != nil {
 			return nil, err
 		}
 	case "btcd":
-		b, err = backend.NewBtcdBackend((**findBlockAddr).String(), *findBlockRpcUser,
-			*findBlockRpcPass, network)
+		addr, port := GetDefaultServer(network, Btcd, *findBlockAddr)
+		b, err = backend.NewBtcdBackend(addr, port, *findBlockRpcUser, *findBlockRpcPass, network)
 		if err != nil {
 			return nil, err
 		}
 	case "electrum-recorder":
 		if *findBlockFixtureFile == "" {
 			panic("electrum-recorder backend requires output --fixture-file.")
 		}
-		addr, port := getServer(network, *findBlockAddr)
+		addr, port := GetDefaultServer(network, Electrum, *findBlockAddr)
 		b, err = backend.NewElectrumBackend(addr, port, network)
 		if err != nil {
 			return nil, err
@@ -277,8 +275,8 @@ func findBlockBuildBackend(network Network) (backend.Backend, error) {
 		if *findBlockFixtureFile == "" {
 			panic("btcd-recorder backend requires output --fixture-file.")
 		}
-		b, err = backend.NewBtcdBackend((*findBlockAddr).String(), *findBlockRpcUser,
-			*findBlockRpcPass, network)
+		addr, port := GetDefaultServer(network, Btcd, *findBlockAddr)
+		b, err = backend.NewBtcdBackend(addr, port, *findBlockRpcUser, *findBlockRpcPass, network)
 		if err != nil {
 			return nil, err
 		}
@@ -303,22 +301,22 @@ func computeBalanceBuildBackend(network Network) (backend.Backend, error) {
 	var err error
 	switch *computeBalanceBackend {
 	case "electrum":
-		addr, port := getServer(network, *computeBalanceAddr)
+		addr, port := GetDefaultServer(network, Electrum, *computeBalanceAddr)
 		b, err = backend.NewElectrumBackend(addr, port, network)
 		if err != nil {
 			return nil, err
 		}
 	case "btcd":
-		b, err = backend.NewBtcdBackend((*computeBalanceAddr).String(), *computeBalanceRpcUser,
-			*computeBalanceRpcPass, network)
+		addr, port := GetDefaultServer(network, Btcd, *computeBalanceAddr)
+		b, err = backend.NewBtcdBackend(addr, port, *computeBalanceRpcUser, *computeBalanceRpcPass, network)
 		if err != nil {
 			return nil, err
 		}
 	case "electrum-recorder":
 		if *computeBalanceFixtureFile == "" {
 			panic("electrum-recorder backend requires output --fixture-file.")
 		}
-		addr, port := getServer(network, *computeBalanceAddr)
+		addr, port := GetDefaultServer(network, Electrum, *computeBalanceAddr)
 		b, err = backend.NewElectrumBackend(addr, port, network)
 		if err != nil {
 			return nil, err
@@ -328,8 +326,8 @@ func computeBalanceBuildBackend(network Network) (backend.Backend, error) {
 		if *computeBalanceFixtureFile == "" {
 			panic("btcd-recorder backend requires output --fixture-file.")
 		}
-		b, err = backend.NewBtcdBackend((*computeBalanceAddr).String(), *computeBalanceRpcUser,
-			*computeBalanceRpcPass, network)
+		addr, port := GetDefaultServer(network, Btcd, *computeBalanceAddr)
+		b, err = backend.NewBtcdBackend(addr, port, *computeBalanceRpcUser, *computeBalanceRpcPass, network)
 		if err != nil {
 			return nil, err
 		}
@@ -347,19 +345,3 @@ func computeBalanceBuildBackend(network Network) (backend.Backend, error) {
 	}
 	return b, err
 }
-
-// pick a default server for each network if none provided
-// TODO: default server should be localhost for Btcd backend.
-func getServer(network Network, addr *net.TCPAddr) (string, string) {
-	if addr != nil {
-		return addr.IP.String(), strconv.Itoa(addr.Port)
-	}
-	switch network {
-	case "mainnet":
-		return "electrum.petrkr.net", "s50002"
-	case "testnet":
-		return "electrum_testnet_unlimited.criptolayer.net", "s50102"
-	default:
-		panic("unreachable")
-	}
-}

utils/utils.go

@@ -2,6 +2,7 @@ package utils
 
 import (
 	"fmt"
+	"net"
 
 	"github.com/btcsuite/btcd/chaincfg"
 )
@@ -24,6 +25,14 @@ func Max(num uint32, nums ...uint32) uint32 {
 }
 
 type Network string
+type Backend string
+
+const (
+	Mainnet  Network = "mainnet"
+	Testnet  Network = "testnet"
+	Electrum Backend = "electrum"
+	Btcd     Backend = "btcd"
+)
 
 // ChainConfig returns a given chaincfg.Params for a given Network
 func (n Network) ChainConfig() *chaincfg.Params {
@@ -94,7 +103,34 @@ func VerifyMandN(m int, n int) error {
 	return nil
 }
 
-const (
-	Mainnet Network = "mainnet"
-	Testnet Network = "testnet"
-)
+// Picks a default server for electrum or localhost for btcd
+// Returns a pair of hostname:port (or pseudo-port for electrum)
+func GetDefaultServer(network Network, backend Backend, addr string) (string, string) {
+	if addr != "" {
+		host, port, err := net.SplitHostPort(addr)
+		PanicOnError(err)
+		return host, port
+	}
+	switch backend {
+	case Electrum:
+		switch network {
+		case "mainnet":
+			return "electrum.petrkr.net", "s50002"
+		case "testnet":
+			return "electrum_testnet_unlimited.criptolayer.net", "s50102"
+		default:
+			panic("unreachable")
+		}
+	case Btcd:
+		switch network {
+		case "mainnet":
+			return "localhost", "8334"
+		case "testnet":
+			return "localhost", "18334"
+		default:
+			panic("unreachable")
+		}
+	default:
+		panic("unreachable")
+	}
+}

utils/utils_test.go

@@ -76,3 +76,29 @@ func TestVerifyMandN(t *testing.T) {
 	assert.Nil(t, VerifyMandN(5, 20))
 	assert.Nil(t, VerifyMandN(20, 20))
 }
+
+func TestGetDefaultServer(t *testing.T) {
+	host, port := GetDefaultServer(Testnet, Electrum, "foobar:s1234")
+	assert.Equal(t, "foobar", host)
+	assert.Equal(t, "s1234", port)
+
+	host, port = GetDefaultServer(Testnet, Electrum, "192.0.2.5:s1234")
+	assert.Equal(t, "192.0.2.5", host)
+	assert.Equal(t, "s1234", port)
+
+	host, port = GetDefaultServer(Testnet, Electrum, "[2001:db8::1]:s1234")
+	assert.Equal(t, "2001:db8::1", host)
+	assert.Equal(t, "s1234", port)
+
+	host, port = GetDefaultServer(Testnet, Btcd, "foobar:1234")
+	assert.Equal(t, "foobar", host)
+	assert.Equal(t, "1234", port)
+
+	host, port = GetDefaultServer(Testnet, Electrum, "")
+	assert.NotEqual(t, "localhost", host)
+	assert.Equal(t, "s50102", port)
+
+	host, port = GetDefaultServer(Testnet, Btcd, "")
+	assert.Equal(t, "localhost", host)
+	assert.Equal(t, "18334", port)
+}