// Copyright (c) 2019, Google Inc.
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

package main

import (
	"bufio"
	"bytes"
	"crypto/hmac"
	"crypto/sha256"
	"crypto/x509"
	"encoding/base64"
	"encoding/binary"
	"encoding/json"
	"encoding/pem"
	"errors"
	"flag"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	neturl "net/url"
	"os"
	"path/filepath"
	"strings"
	"time"

	"boringssl.googlesource.com/boringssl/util/fipstools/acvp/acvptool/acvp"
	"boringssl.googlesource.com/boringssl/util/fipstools/acvp/acvptool/subprocess"
)

var (
	configFilename = flag.String("config", "config.json", "Location of the configuration JSON file")
	runFlag        = flag.String("run", "", "Name of primitive to run tests for")
	wrapperPath    = flag.String("wrapper", "../../../../build/util/fipstools/acvp/modulewrapper/modulewrapper", "Path to the wrapper binary")
)

type Config struct {
	CertPEMFile        string
	PrivateKeyDERFile  string
	TOTPSecret         string
	ACVPServer         string
	SessionTokensCache string
	LogFile            string
}

func isCommentLine(line []byte) bool {
	var foundCommentStart bool
	for _, b := range line {
		if !foundCommentStart {
			if b == ' ' || b == '\t' {
				continue
			}
			if b != '/' {
				return false
			}
			foundCommentStart = true
		} else {
			return b == '/'
		}
	}
	return false
}

func jsonFromFile(out interface{}, filename string) error {
	in, err := os.Open(filename)
	if err != nil {
		return err
	}
	defer in.Close()

	scanner := bufio.NewScanner(in)
	var commentsRemoved bytes.Buffer
	for scanner.Scan() {
		if isCommentLine(scanner.Bytes()) {
			continue
		}
		commentsRemoved.Write(scanner.Bytes())
		commentsRemoved.WriteString("\n")
	}
	if err := scanner.Err(); err != nil {
		return err
	}

	decoder := json.NewDecoder(&commentsRemoved)
	decoder.DisallowUnknownFields()
	if err := decoder.Decode(out); err != nil {
		return err
	}
	if decoder.More() {
		return errors.New("trailing garbage found")
	}
	return nil
}

// TOTP implements the time-based one-time password algorithm with the suggested
// granularity of 30 seconds. See https://tools.ietf.org/html/rfc6238 and then
// https://tools.ietf.org/html/rfc4226#section-5.3
func TOTP(secret []byte) string {
	const timeStep = 30
	now := uint64(time.Now().Unix()) / 30
	var nowBuf [8]byte
	binary.BigEndian.PutUint64(nowBuf[:], now)
	mac := hmac.New(sha256.New, secret)
	mac.Write(nowBuf[:])
	digest := mac.Sum(nil)
	value := binary.BigEndian.Uint32(digest[digest[31]&15:])
	value &= 0x7fffffff
	value %= 100000000
	return fmt.Sprintf("%08d", value)
}

type Middle interface {
	Close()
	Config() ([]byte, error)
	Process(algorithm string, vectorSet []byte) ([]byte, error)
}

func loadCachedSessionTokens(server *acvp.Server, cachePath string) error {
	cacheDir, err := os.Open(cachePath)
	if err != nil {
		if os.IsNotExist(err) {
			if err := os.Mkdir(cachePath, 0700); err != nil {
				return fmt.Errorf("Failed to create session token cache directory %q: %s", cachePath, err)
			}
			return nil
		}
		return fmt.Errorf("Failed to open session token cache directory %q: %s", cachePath, err)
	}
	defer cacheDir.Close()
	names, err := cacheDir.Readdirnames(0)
	if err != nil {
		return fmt.Errorf("Failed to list session token cache directory %q: %s", cachePath, err)
	}

	loaded := 0
	for _, name := range names {
		if !strings.HasSuffix(name, ".token") {
			continue
		}
		path := filepath.Join(cachePath, name)
		contents, err := ioutil.ReadFile(path)
		if err != nil {
			return fmt.Errorf("Failed to read session token cache entry %q: %s", path, err)
		}
		urlPath, err := neturl.PathUnescape(name[:len(name)-6])
		if err != nil {
			return fmt.Errorf("Failed to unescape token filename %q: %s", name, err)
		}
		server.PrefixTokens[urlPath] = string(contents)
		loaded++
	}

	log.Printf("Loaded %d cached tokens", loaded)
	return nil
}

func trimLeadingSlash(s string) string {
	if strings.HasPrefix(s, "/") {
		return s[1:]
	}
	return s
}

func main() {
	flag.Parse()

	var config Config
	if err := jsonFromFile(&config, *configFilename); err != nil {
		log.Fatalf("Failed to load config file: %s", err)
	}

	if len(config.TOTPSecret) == 0 {
		log.Fatal("Config file missing TOTPSecret")
	}
	totpSecret, err := base64.StdEncoding.DecodeString(config.TOTPSecret)
	if err != nil {
		log.Fatalf("Failed to decode TOTP secret from config file: %s", err)
	}

	if len(config.CertPEMFile) == 0 {
		log.Fatal("Config file missing CertPEMFile")
	}
	certPEM, err := ioutil.ReadFile(config.CertPEMFile)
	if err != nil {
		log.Fatalf("failed to read certificate from %q: %s", config.CertPEMFile, err)
	}
	block, _ := pem.Decode(certPEM)
	certDER := block.Bytes

	if len(config.PrivateKeyDERFile) == 0 {
		log.Fatal("Config file missing PrivateKeyDERFile")
	}
	keyDER, err := ioutil.ReadFile(config.PrivateKeyDERFile)
	if err != nil {
		log.Fatalf("failed to read private key from %q: %s", config.PrivateKeyDERFile, err)
	}

	certKey, err := x509.ParsePKCS1PrivateKey(keyDER)
	if err != nil {
		log.Fatalf("failed to parse private key from %q: %s", config.PrivateKeyDERFile, err)
	}

	var middle Middle
	middle, err = subprocess.New(*wrapperPath)
	if err != nil {
		log.Fatalf("failed to initialise middle: %s", err)
	}
	defer middle.Close()

	configBytes, err := middle.Config()
	if err != nil {
		log.Fatalf("failed to get config from middle: %s", err)
	}

	var supportedAlgos []map[string]interface{}
	if err := json.Unmarshal(configBytes, &supportedAlgos); err != nil {
		log.Fatalf("failed to parse configuration from Middle: %s", err)
	}

	runAlgos := make(map[string]bool)
	if len(*runFlag) > 0 {
		for _, substr := range strings.Split(*runFlag, ",") {
			runAlgos[substr] = false
		}
	}

	var algorithms []map[string]interface{}
	for _, supportedAlgo := range supportedAlgos {
		algoInterface, ok := supportedAlgo["algorithm"]
		if !ok {
			continue
		}

		algo, ok := algoInterface.(string)
		if !ok {
			continue
		}

		if _, ok := runAlgos[algo]; ok {
			algorithms = append(algorithms, supportedAlgo)
			runAlgos[algo] = true
		}
	}

	for algo, recognised := range runAlgos {
		if !recognised {
			log.Fatalf("requested algorithm %q was not recognised", algo)
		}
	}

	if len(config.ACVPServer) == 0 {
		config.ACVPServer = "https://demo.acvts.nist.gov/"
	}
	server := acvp.NewServer(config.ACVPServer, config.LogFile, [][]byte{certDER}, certKey, func() string {
		return TOTP(totpSecret[:])
	})

	var sessionTokensCacheDir string
	if len(config.SessionTokensCache) > 0 {
		sessionTokensCacheDir = config.SessionTokensCache
		if strings.HasPrefix(sessionTokensCacheDir, "~/") {
			home := os.Getenv("HOME")
			if len(home) == 0 {
				log.Fatal("~ used in config file but $HOME not set")
			}
			sessionTokensCacheDir = filepath.Join(home, sessionTokensCacheDir[2:])
		}

		if err := loadCachedSessionTokens(server, sessionTokensCacheDir); err != nil {
			log.Fatal(err)
		}
	}

	if err := server.Login(); err != nil {
		log.Fatalf("failed to login: %s", err)
	}

	if len(*runFlag) == 0 {
		if interactiveModeSupported {
			runInteractive(server, config)
		} else {
			log.Fatalf("no arguments given but interactive mode not supported")
		}
		return
	}

	requestBytes, err := json.Marshal(acvp.TestSession{
		IsSample:    true,
		Publishable: false,
		Algorithms:  algorithms,
	})
	if err != nil {
		log.Fatalf("Failed to serialise JSON: %s", err)
	}

	var result acvp.TestSession
	if err := server.Post(&result, "acvp/v1/testSessions", requestBytes); err != nil {
		log.Fatalf("Request to create test session failed: %s", err)
	}

	url := trimLeadingSlash(result.URL)
	log.Printf("Created test session %q", url)
	if token := result.AccessToken; len(token) > 0 {
		server.PrefixTokens[url] = token
		if len(sessionTokensCacheDir) > 0 {
			ioutil.WriteFile(filepath.Join(sessionTokensCacheDir, neturl.PathEscape(url))+".token", []byte(token), 0600)
		}
	}

	log.Printf("Have vector sets %v", result.VectorSetURLs)

	for _, setURL := range result.VectorSetURLs {
		firstTime := true
		for {
			if firstTime {
				log.Printf("Fetching test vectors %q", setURL)
				firstTime = false
			}

			vectorsBytes, err := server.GetBytes(trimLeadingSlash(setURL))
			if err != nil {
				log.Fatalf("Failed to fetch vector set %q: %s", setURL, err)
			}

			var vectors acvp.Vectors
			if err := json.Unmarshal(vectorsBytes, &vectors); err != nil {
				log.Fatalf("Failed to parse vector set from %q: %s", setURL, err)
			}

			if retry := vectors.Retry; retry > 0 {
				log.Printf("Server requested %d seconds delay", retry)
				if retry > 10 {
					retry = 10
				}
				time.Sleep(time.Duration(retry) * time.Second)
				continue
			}

			replyGroups, err := middle.Process(vectors.Algo, vectorsBytes)
			if err != nil {
				log.Printf("Failed: %s", err)
				log.Printf("Deleting test set")
				server.Delete(url)
				os.Exit(1)
			}

			headerBytes, err := json.Marshal(acvp.Vectors{
				ID:   vectors.ID,
				Algo: vectors.Algo,
			})
			if err != nil {
				log.Printf("Failed to marshal result: %s", err)
				log.Printf("Deleting test set")
				server.Delete(url)
				os.Exit(1)
			}

			var resultBuf bytes.Buffer
			resultBuf.Write(headerBytes[:len(headerBytes)-1])
			resultBuf.WriteString(`,"testGroups":`)
			resultBuf.Write(replyGroups)
			resultBuf.WriteString("}")

			resultData := resultBuf.Bytes()
			resultSize := uint64(len(resultData)) + 32 /* for framing overhead */
			if server.SizeLimit > 0 && resultSize >= server.SizeLimit {
				// The NIST ACVP server no longer requires the large-upload process,
				// suggesting that it may no longer be needed.
				log.Printf("Result is %d bytes, too much given server limit of %d bytes. Using large-upload process.", resultSize, server.SizeLimit)
				largeRequestBytes, err := json.Marshal(acvp.LargeUploadRequest{
					Size: resultSize,
					URL:  setURL,
				})
				if err != nil {
					log.Printf("Failed to marshal large-upload request: %s", err)
					log.Printf("Deleting test set")
					server.Delete(url)
					os.Exit(1)
				}

				var largeResponse acvp.LargeUploadResponse
				if err := server.Post(&largeResponse, "/large", largeRequestBytes); err != nil {
					log.Fatalf("Failed to request large-upload endpoint: %s", err)
				}

				log.Printf("Directed to large-upload endpoint at %q", largeResponse.URL)
				client := &http.Client{}
				req, err := http.NewRequest("POST", largeResponse.URL, bytes.NewBuffer(resultData))
				if err != nil {
					log.Fatalf("Failed to create POST request: %s", err)
				}
				token := largeResponse.AccessToken
				if len(token) == 0 {
					token = server.AccessToken
				}
				req.Header.Add("Authorization", "Bearer "+token)
				req.Header.Add("Content-Type", "application/json")
				resp, err := client.Do(req)
				if err != nil {
					log.Fatalf("Failed writing large upload: %s", err)
				}
				resp.Body.Close()
				if resp.StatusCode != 200 {
					log.Fatalf("Large upload resulted in status code %d", resp.StatusCode)
				}
			} else {
				log.Printf("Result size %d bytes", resultSize)
				if err := server.Post(nil, trimLeadingSlash(setURL)+"/results", resultData); err != nil {
					log.Fatalf("Failed to upload results: %s\n", err)
				}
			}

			break
		}
	}

FetchResults:
	for {
		var results acvp.SessionResults
		if err := server.Get(&results, trimLeadingSlash(url)+"/results"); err != nil {
			log.Fatalf("Failed to fetch session results: %s", err)
		}

		if results.Passed {
			log.Print("Test passed")
			break
		}

		for _, result := range results.Results {
			if result.Status == "incomplete" {
				log.Print("Server hasn't finished processing results. Waiting 10 seconds.")
				time.Sleep(10 * time.Second)
				continue FetchResults
			}
		}

		log.Fatalf("Server did not accept results: %#v", results)
	}
}