Merge pull request #19 from dlorenc/updatecmd

Add an update command to fetch and store the latest rootTreeHash/Size.

cmd/update.go

+/*
+Copyright © 2020 Luke Hinds <lhinds@redhat.com>
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+package cmd
+
+import (
+	"context"
+	"crypto"
+	"crypto/x509"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"os"
+	"path/filepath"
+	"time"
+
+	"github.com/mitchellh/go-homedir"
+
+	tcrypto "github.com/google/trillian/crypto"
+	"go.uber.org/zap"
+
+	tclient "github.com/google/trillian/client"
+
+	"github.com/google/trillian"
+	"github.com/google/trillian/merkle"
+	"github.com/google/trillian/merkle/rfc6962"
+	"github.com/projectrekor/rekor-cli/log"
+	"github.com/spf13/viper"
+
+	"github.com/spf13/cobra"
+)
+
+type latestResponse struct {
+	Proof *trillian.GetLatestSignedLogRootResponse
+	Key   []byte
+}
+
+type state struct {
+	Size int64
+	Hash []byte
+}
+
+func stateDir() (string, error) {
+	home, err := homedir.Dir()
+	if err != nil {
+		return "", err
+	}
+	rekorDir := filepath.Join(home, ".rekor")
+	if _, err := os.Stat(rekorDir); os.IsNotExist(err) {
+		if err := os.Mkdir(rekorDir, 0755); err != nil {
+			return "", err
+		}
+	}
+	return filepath.Join(home, ".rekor", "rekor.json"), nil
+}
+
+func getPreviousState(log *zap.SugaredLogger) *state {
+	p, err := stateDir()
+	if err != nil {
+		return nil
+	}
+	var oldState state
+	f, err := ioutil.ReadFile(p)
+	if err != nil {
+		log.Info(err)
+		return nil
+	}
+	if err := json.Unmarshal(f, &oldState); err != nil {
+		log.Info(err)
+		return nil
+	}
+	return &oldState
+}
+
+func setState(size int64, hash []byte) error {
+	// Update the file
+	newState := state{
+		Size: size,
+		Hash: hash,
+	}
+	b, err := json.Marshal(newState)
+	if err != nil {
+		return err
+	}
+	p, err := stateDir()
+	if err != nil {
+		return nil
+	}
+	if err := ioutil.WriteFile(p, b, 0644); err != nil {
+		return err
+	}
+	return nil
+}
+
+// updateCmd represents the get command
+var updateCmd = &cobra.Command{
+	Use:   "update",
+	Short: "Rekor update command",
+	Long:  `Performs a consistency proof against the tree between the last seen time and now`,
+	Run: func(cmd *cobra.Command, args []string) {
+		log := log.Logger
+		rekorServer := viper.GetString("rekor_server")
+		u := rekorServer + "/api/v1/latest"
+
+		oldState := getPreviousState(log)
+
+		// Set Context with Timeout for connects to thde log rpc server
+		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+		defer cancel()
+
+		request, err := http.NewRequestWithContext(ctx, "POST", u, nil)
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		if oldState != nil {
+			request.URL.RawQuery += fmt.Sprintf("lastSize=%d", oldState.Size)
+		}
+
+		client := &http.Client{}
+		response, err := client.Do(request)
+		if err != nil {
+			log.Fatal(err)
+		}
+		defer response.Body.Close()
+
+		content, err := ioutil.ReadAll(response.Body)
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		fmt.Println(string(content))
+
+		resp := latestResponse{}
+		if err := json.Unmarshal(content, &resp); err != nil {
+			log.Fatal(err)
+		}
+
+		pub, err := x509.ParsePKIXPublicKey(resp.Key)
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		verifier := tclient.NewLogVerifier(rfc6962.DefaultHasher, pub, crypto.SHA256)
+		root, err := tcrypto.VerifySignedLogRoot(verifier.PubKey, verifier.SigHash, resp.Proof.SignedLogRoot)
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		newSize := int64(root.TreeSize)
+		if oldState != nil && newSize <= oldState.Size {
+			log.Infof("Tree is unchanged at size %d", newSize)
+			return
+		}
+		// Only do the check if we sent an old one.
+		if oldState != nil {
+			v := merkle.NewLogVerifier(rfc6962.DefaultHasher)
+			if err := v.VerifyConsistencyProof(oldState.Size, newSize, oldState.Hash, root.RootHash, resp.Proof.Proof.Hashes); err != nil {
+				log.Fatal(err)
+			}
+			log.Infof("proof correct between sizes %d and %d", oldState.Size, newSize)
+		}
+		if err := setState(newSize, root.RootHash); err != nil {
+			log.Fatal(err)
+		}
+		log.Info("State updated")
+	},
+}
+
+func init() {
+	rootCmd.AddCommand(updateCmd)
+}