lite: add helper functions for initiating the light client (#4486)

* add new net client

* hijack example test

* lint fixes

* reorganised file structure

* renamed funcs and added documentation

* implemented suggested changes

* restored example tests

* edited comments

* Update lite2/setup.go

Co-Authored-By: Bot from GolangCI <42910462+golangcibot@users.noreply.github.com>

* Update lite2/client.go

* lite cmds use HTTP client

* better naming

* Delete go.sum

* Delete go.mod

* restore go mod

* restore go.sum

* fix double import

Co-authored-by: Anton Kaliaev <anton.kalyaev@gmail.com>
Co-authored-by: Bot from GolangCI <42910462+golangcibot@users.noreply.github.com>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

cmd/tendermint/commands/lite.go

@@ -9,14 +9,12 @@ import (
 	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
 
-	amino "github.com/tendermint/go-amino"
+	"github.com/tendermint/go-amino"
 	dbm "github.com/tendermint/tm-db"
 
 	"github.com/tendermint/tendermint/libs/log"
 	tmos "github.com/tendermint/tendermint/libs/os"
 	lite "github.com/tendermint/tendermint/lite2"
-	"github.com/tendermint/tendermint/lite2/provider"
-	httpp "github.com/tendermint/tendermint/lite2/provider/http"
 	lproxy "github.com/tendermint/tendermint/lite2/proxy"
 	lrpc "github.com/tendermint/tendermint/lite2/rpc"
 	dbs "github.com/tendermint/tendermint/lite2/store/db"
@@ -54,9 +52,9 @@ lite cosmoshub-3 -p 52.57.29.196:26657 -w public-seed-node.cosmoshub.certus.one:
 var (
 	listenAddr         string
 	primaryAddr        string
+	witnessAddrsJoined string
 	chainID            string
 	home               string
-	witnessesAddrs     string
 	maxOpenConnections int
 
 	trustingPeriod time.Duration
@@ -71,7 +69,7 @@ func init() {
 		"Serve the proxy on the given address")
 	LiteCmd.Flags().StringVarP(&primaryAddr, "primary", "p", "",
 		"Connect to a Tendermint node at this address")
-	LiteCmd.Flags().StringVarP(&witnessesAddrs, "witnesses", "w", "",
+	LiteCmd.Flags().StringVarP(&witnessAddrsJoined, "witnesses", "w", "",
 		"Tendermint nodes to cross-check the primary node, comma-separated")
 	LiteCmd.Flags().StringVar(&home, "home-dir", ".tendermint-lite", "Specify the home directory")
 	LiteCmd.Flags().IntVar(
@@ -98,26 +96,10 @@ func runProxy(cmd *cobra.Command, args []string) error {
 	logger = log.NewFilter(logger, option)
 
 	chainID = args[0]
-
-	logger.Info("Creating HTTP client for primary...", "addr", primaryAddr)
-	rpcClient, err := rpcclient.NewHTTP(primaryAddr, "/websocket")
-	if err != nil {
-		return errors.Wrapf(err, "http client for %s", primaryAddr)
-	}
-	primary := httpp.NewWithClient(chainID, rpcClient)
-
-	// TODO: use NewNetClient once we have it
-	addrs := strings.Split(witnessesAddrs, ",")
-	witnesses := make([]provider.Provider, len(addrs))
-	for i, addr := range addrs {
-		p, err := httpp.New(chainID, addr)
-		if err != nil {
-			return errors.Wrapf(err, "http provider for %s", addr)
-		}
-		witnesses[i] = p
-	}
-
 	logger.Info("Creating client...", "chainID", chainID)
+
+	witnessesAddrs := strings.Split(witnessAddrsJoined, ",")
+
 	db, err := dbm.NewGoLevelDB("lite-client-db", home)
 	if err != nil {
 		return err
@@ -125,24 +107,24 @@ func runProxy(cmd *cobra.Command, args []string) error {
 
 	var c *lite.Client
 	if trustedHeight > 0 && len(trustedHash) > 0 { // fresh installation
-		c, err = lite.NewClient(
+		c, err = lite.NewHTTPClient(
 			chainID,
 			lite.TrustOptions{
 				Period: trustingPeriod,
 				Height: trustedHeight,
 				Hash:   trustedHash,
 			},
-			primary,
-			witnesses,
+			primaryAddr,
+			witnessesAddrs,
 			dbs.New(db, chainID),
 			lite.Logger(logger),
 		)
 	} else { // continue from latest state
-		c, err = lite.NewClientFromTrustedStore(
+		c, err = lite.NewHTTPClientFromTrustedStore(
 			chainID,
 			trustingPeriod,
-			primary,
-			witnesses,
+			primaryAddr,
+			witnessesAddrs,
 			dbs.New(db, chainID),
 			lite.Logger(logger),
 		)
@@ -158,6 +140,10 @@ func runProxy(cmd *cobra.Command, args []string) error {
 	}
 	defer c.Stop()
 
+	rpcClient, err := rpcclient.NewHTTP(primaryAddr, "/websocket")
+	if err != nil {
+		return errors.Wrapf(err, "http client for %s", primaryAddr)
+	}
 	p := lproxy.Proxy{
 		Addr:   listenAddr,
 		Config: &rpcserver.Config{MaxOpenConnections: maxOpenConnections},

lite2/client.go

@@ -953,11 +953,8 @@ func (c *Client) autoUpdateRoutine() {
 	}
 }
 
-// Update attempts to advance the state making exponential steps (note:
-// when SequentialVerification is being used, the client will still be
-// downloading all intermediate headers).
-//
-// Exposed for testing.
+// Update attempts to advance the state by downloading the latest header and
+// comparing it with the existing one.
 func (c *Client) Update(now time.Time) error {
 	lastTrustedHeight, err := c.LastTrustedHeight()
 	if err != nil {

lite2/example_test.go

@@ -135,7 +135,7 @@ func ExampleClient_VerifyHeaderAtHeight() {
 			Hash:   header.Hash(),
 		},
 		primary,
-		[]provider.Provider{primary}, // TODO: primary should not be used here
+		[]provider.Provider{primary}, // NOTE: primary should not be used here
 		dbs.New(db, chainID),
 		UpdatePeriod(0),
 		// Logger(log.TestingLogger()),

lite2/setup.go

@@ -0,0 +1,77 @@
+package lite
+
+import (
+	"time"
+
+	"github.com/tendermint/tendermint/lite2/provider"
+	"github.com/tendermint/tendermint/lite2/provider/http"
+	"github.com/tendermint/tendermint/lite2/store"
+)
+
+// NewHTTPClient initiates an instance of a lite client using HTTP addresses
+// for both the primary provider and witnesses of the lite client. A trusted
+// header and hash must be passed to initialize the client.
+//
+// See all Option(s) for the additional configuration.
+// See NewClient.
+func NewHTTPClient(
+	chainID string,
+	trustOptions TrustOptions,
+	primaryAddress string,
+	witnessesAddresses []string,
+	trustedStore store.Store,
+	options ...Option) (*Client, error) {
+
+	providers, err := providersFromAddresses(append(witnessesAddresses, primaryAddress), chainID)
+	if err != nil {
+		return nil, err
+	}
+
+	return NewClient(
+		chainID,
+		trustOptions,
+		providers[len(providers)-1],
+		providers[:len(providers)-1],
+		trustedStore,
+		options...)
+}
+
+// NewHTTPClientFromTrustedStore initiates an instance of a lite client using
+// HTTP addresses for both the primary provider and witnesses and uses a
+// trusted store as the root of trust.
+//
+// See all Option(s) for the additional configuration.
+// See NewClientFromTrustedStore.
+func NewHTTPClientFromTrustedStore(
+	chainID string,
+	trustingPeriod time.Duration,
+	primaryAddress string,
+	witnessesAddresses []string,
+	trustedStore store.Store,
+	options ...Option) (*Client, error) {
+
+	providers, err := providersFromAddresses(append(witnessesAddresses, primaryAddress), chainID)
+	if err != nil {
+		return nil, err
+	}
+
+	return NewClientFromTrustedStore(
+		chainID,
+		trustingPeriod,
+		providers[len(providers)-1],
+		providers[:len(providers)-1],
+		trustedStore,
+		options...)
+}
+
+func providersFromAddresses(addrs []string, chainID string) ([]provider.Provider, error) {
+	providers := make([]provider.Provider, len(addrs))
+	for idx, address := range addrs {
+		p, err := http.New(chainID, address)
+		if err != nil {
+			return nil, err
+		}
+		providers[idx] = p
+	}
+	return providers, nil
+}