CRC32: Move checksum generation to a dedicated package

Signed-off-by: Michael Mayer <michael@photoprism.app>

internal/api/abort.go

@@ -47,7 +47,7 @@ var AbortNotFound = func(c *gin.Context) {
 		}
 
 		values := gin.H{
-			"signUp":   gin.H{"message": config.MsgSponsor, "url": config.SignUpURL},
+			"signUp":   config.SignUp,
 			"config":   conf.ClientPublic(),
 			"error":    i18n.Msg(i18n.ErrNotFound),
 			"code":     http.StatusNotFound,

internal/commands/places.go

@@ -7,7 +7,6 @@ import (
 	"github.com/manifoldco/promptui"
 	"github.com/urfave/cli"
 
-	"github.com/photoprism/photoprism/internal/config"
 	"github.com/photoprism/photoprism/internal/entity"
 	"github.com/photoprism/photoprism/internal/get"
 	"github.com/photoprism/photoprism/internal/query"
@@ -45,11 +44,13 @@ func placesUpdateAction(ctx *cli.Context) error {
 		return err
 	}
 
+	// Show info to non-members.
 	if !conf.Sponsor() && !conf.Test() {
-		log.Errorf(config.MsgSponsorCommand)
+		log.Errorf("Since running this command puts additional load on our infrastructure, we can unfortunately only offer it to members at this time.")
 		return nil
 	}
 
+	// Initialize database connection.
 	conf.InitDb()
 	defer conf.Shutdown()
 

internal/config/config.go

@@ -1,10 +1,32 @@
+/*
+Package config provides global options, command-line flags, and user settings.
+
+Copyright (c) 2018 - 2024 PhotoPrism UG. All rights reserved.
+
+	This program is free software: you can redistribute it and/or modify
+	it under Version 3 of the GNU Affero General Public License (the "AGPL"):
+	<https://docs.photoprism.app/license/agpl>
+
+	This program is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU Affero General Public License for more details.
+
+	The AGPL is supplemented by our Trademark and Brand Guidelines,
+	which describe how our Brand Assets may be used:
+	<https://www.photoprism.app/trademark>
+
+Feel free to send an email to hello@photoprism.app if you have questions,
+want to support our work, or just want to say hello.
+
+Additional information can be found in our Developer Guide:
+<https://docs.photoprism.app/developer-guide/>
+*/
 package config
 
 import (
 	"crypto/tls"
-	"encoding/hex"
 	"fmt"
-	"hash/crc32"
 	"net/http"
 	"net/url"
 	"os"
@@ -34,16 +56,14 @@ import (
 	"github.com/photoprism/photoprism/internal/mutex"
 	"github.com/photoprism/photoprism/internal/thumb"
 	"github.com/photoprism/photoprism/internal/ttl"
+	"github.com/photoprism/photoprism/pkg/checksum"
 	"github.com/photoprism/photoprism/pkg/clean"
 	"github.com/photoprism/photoprism/pkg/fs"
 	"github.com/photoprism/photoprism/pkg/rnd"
 )
 
+// log points to the global logger.
 var log = event.Log
-var once sync.Once
-var LowMem = false
-var TotalMem uint64
-var crc32Castagnoli = crc32.MakeTable(crc32.Castagnoli)
 
 // Config holds database, cache and all parameters of photoprism
 type Config struct {
@@ -357,15 +377,7 @@ func (c *Config) Serial() string {
 
 // SerialChecksum returns the CRC32 checksum of the storage serial.
 func (c *Config) SerialChecksum() string {
-	var result []byte
-
-	crc := crc32.New(crc32Castagnoli)
-
-	if _, err := crc.Write([]byte(c.Serial())); err != nil {
-		log.Warnf("config: %s", err)
-	}
-
-	return hex.EncodeToString(crc.Sum(result))
+	return checksum.Serial([]byte(c.Serial()))
 }
 
 // Name returns the app name.
@@ -402,7 +414,7 @@ func (c *Config) Version() string {
 
 // VersionChecksum returns the application version checksum.
 func (c *Config) VersionChecksum() uint32 {
-	return crc32.ChecksumIEEE([]byte(c.Version()))
+	return checksum.Crc32([]byte(c.Version()))
 }
 
 // UserAgent returns an HTTP user agent string based on the app config and version.

internal/config/config_test.go

@@ -590,11 +590,18 @@ func TestConfig_Serial(t *testing.T) {
 func TestConfig_SerialChecksum(t *testing.T) {
 	c := NewConfig(CliTestContext())
 
+	serial := "zr2g80wvjmm1zwzg"
+	expected := "c7dcdb1c"
+
+	c.serial = serial
+
 	result := c.SerialChecksum()
 
-	t.Logf("SerialChecksum: %s", result)
+	// t.Logf("Serial: %s", c.serial)
+	// t.Logf("SerialChecksum: %s", result)
 
 	assert.NotEmpty(t, result)
+	assert.Equal(t, expected, result)
 }
 
 func TestConfig_Public(t *testing.T) {

internal/config/messages.go

@@ -0,0 +1,8 @@
+package config
+
+var (
+	SignUpURL  = "https://www.photoprism.app/membership"
+	MsgSponsor = "Become a member today, support our mission and enjoy our member benefits! 💎"
+	MsgSignUp  = "Visit " + SignUpURL + " to learn more."
+	SignUp     = Values{"message": MsgSponsor, "url": SignUpURL}
+)

internal/config/var.go

@@ -0,0 +1,9 @@
+package config
+
+import (
+	"sync"
+)
+
+var once sync.Once
+var LowMem = false
+var TotalMem uint64

internal/server/routes_pwa.go

@@ -22,7 +22,7 @@ func registerPWARoutes(router *gin.Engine, conf *config.Config) {
 		}
 
 		values := gin.H{
-			"signUp": gin.H{"message": config.MsgSponsor, "url": config.SignUpURL},
+			"signUp": config.SignUp,
 			"config": conf.ClientPublic(),
 		}
 		c.HTML(http.StatusOK, conf.TemplateName(), values)

pkg/checksum/charset.go

@@ -0,0 +1,16 @@
+package checksum
+
+const (
+	CharsetBase36 = "abcdefghijklmnopqrstuvwxyz0123456789"
+	CharsetBase62 = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+)
+
+// Char returns a simple checksum byte based on Crc32 and the 62 characters specified in CharsetBase62.
+func Char(data []byte) byte {
+	return CharsetBase62[Crc32(data)%62]
+}
+
+// Base36 returns a simple checksum byte based on Crc32 and the 36 lower-case characters specified in CharsetBase36.
+func Base36(data []byte) byte {
+	return CharsetBase36[Crc32(data)%36]
+}

pkg/checksum/charset_test.go

@@ -0,0 +1,93 @@
+package checksum
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestChar(t *testing.T) {
+	t.Run("Empty", func(t *testing.T) {
+		data := ""
+		expected := "a"
+
+		result := string(Char([]byte(data)))
+
+		t.Logf("Char(%s): result %s, expected %s", data, result, expected)
+
+		assert.Equal(t, expected, result)
+	})
+	t.Run("One", func(t *testing.T) {
+		data := "1"
+		expected := "R"
+
+		result := string(Char([]byte(data)))
+
+		t.Logf("Char(%s): result %s, expected %s", data, result, expected)
+
+		assert.Equal(t, expected, result)
+	})
+	t.Run("Serial", func(t *testing.T) {
+		data := "zr2g80wvjmm1zwzg"
+		expected := "G"
+
+		result := string(Char([]byte(data)))
+
+		t.Logf("Char(%s): result %s, expected %s", data, result, expected)
+
+		assert.Equal(t, expected, result)
+	})
+	t.Run("HelloWorld", func(t *testing.T) {
+		data := "Hello World!"
+		expected := "X"
+
+		result := string(Char([]byte(data)))
+
+		t.Logf("Char(%s): result %s, expected %s", data, result, expected)
+
+		assert.Equal(t, expected, result)
+	})
+}
+
+func TestBase36(t *testing.T) {
+	t.Run("Empty", func(t *testing.T) {
+		data := ""
+		expected := "a"
+
+		result := string(Base36([]byte(data)))
+
+		t.Logf("Base36(%s): result %s, expected %s", data, result, expected)
+
+		assert.Equal(t, expected, result)
+	})
+	t.Run("One", func(t *testing.T) {
+		data := "1"
+		expected := "l"
+
+		result := string(Base36([]byte(data)))
+
+		t.Logf("Base36(%s): result %s, expected %s", data, result, expected)
+
+		assert.Equal(t, expected, result)
+	})
+	t.Run("Serial", func(t *testing.T) {
+		data := "zr2g80wvjmm1zwzg"
+		expected := "u"
+
+		result := string(Base36([]byte(data)))
+
+		t.Logf("Base36(%s): result %s, expected %s", data, result, expected)
+
+		assert.Equal(t, expected, result)
+	})
+	t.Run("HelloWorld", func(t *testing.T) {
+		data := "Hello World!"
+		expected := "x"
+
+		result := string(Base36([]byte(data)))
+
+		t.Logf("Base36(%s): result %s, expected %s", data, result, expected)
+
+		assert.Equal(t, expected, result)
+	})
+}

pkg/checksum/checksum.go

@@ -1,5 +1,5 @@
 /*
-Package config provides global options, command-line flags, and user settings.
+Package checksum provides functions and abstractions to generate data checksums.
 
 Copyright (c) 2018 - 2024 PhotoPrism UG. All rights reserved.
 
@@ -22,10 +22,4 @@ want to support our work, or just want to say hello.
 Additional information can be found in our Developer Guide:
 <https://docs.photoprism.app/developer-guide/>
 */
-package config
-
-var SignUpURL = "https://www.photoprism.app/membership"
-var MsgSponsor = "Become a member today, support our mission and enjoy our member benefits! 💎"
-var MsgSignUp = "Visit " + SignUpURL + " to learn more."
-var MsgSponsorCommand = "Since running this command puts additional load on our infrastructure," +
-	" we unfortunately can only offer it to members."
+package checksum

pkg/checksum/crc32.go

@@ -0,0 +1,19 @@
+package checksum
+
+import (
+	"fmt"
+	"hash/crc32"
+)
+
+var Crc32Castagnoli = crc32.MakeTable(crc32.Castagnoli)
+
+// Crc32 returns the CRC-32 checksum of data using the crc32.IEEE polynomial.
+func Crc32(data []byte) uint32 {
+	return crc32.ChecksumIEEE(data)
+}
+
+// Serial returns the CRC-32 checksum as a hexadecimal encoded string using the Castagnoli polynomial,
+// which has better error detection properties than crc32.IEEE.
+func Serial(data []byte) string {
+	return fmt.Sprintf("%08x", crc32.Checksum(data, Crc32Castagnoli))
+}

pkg/checksum/crc32_test.go

@@ -0,0 +1,98 @@
+package checksum
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestCrc32(t *testing.T) {
+	t.Run("Empty", func(t *testing.T) {
+		data := ""
+		expected := "00000000"
+
+		crc := Crc32([]byte(data))
+		result := fmt.Sprintf("%08x", crc)
+
+		t.Logf("Crc32(%s): result %s, expected %s", data, result, expected)
+
+		assert.Equal(t, expected, result)
+	})
+	t.Run("One", func(t *testing.T) {
+		data := "1"
+		expected := "83dcefb7"
+
+		crc := Crc32([]byte(data))
+		result := fmt.Sprintf("%08x", crc)
+
+		t.Logf("Crc32(%s): result %s, expected %s", data, result, expected)
+
+		assert.Equal(t, expected, result)
+	})
+	t.Run("Serial", func(t *testing.T) {
+		data := "zr2g80wvjmm1zwzg"
+		expected := "2db41d54"
+
+		crc := Crc32([]byte(data))
+		result := fmt.Sprintf("%08x", crc)
+
+		t.Logf("Crc32(%s): result %s, expected %s", data, result, expected)
+
+		assert.Equal(t, expected, result)
+	})
+	t.Run("HelloWorld", func(t *testing.T) {
+		data := "Hello World!"
+		expected := "1c291ca3"
+
+		crc := Crc32([]byte(data))
+		result := fmt.Sprintf("%08x", crc)
+
+		t.Logf("Crc32(%s): result %s, expected %s", data, result, expected)
+
+		assert.Equal(t, expected, result)
+	})
+}
+
+func TestSerial(t *testing.T) {
+	t.Run("Empty", func(t *testing.T) {
+		data := ""
+		expected := "00000000"
+
+		result := Serial([]byte(data))
+
+		t.Logf("Serial(%s): result %s, expected %s", data, result, expected)
+
+		assert.Equal(t, expected, result)
+	})
+	t.Run("One", func(t *testing.T) {
+		data := "1"
+		expected := "90f599e3"
+
+		result := Serial([]byte(data))
+
+		t.Logf("Serial(%s): result %s, expected %s", data, result, expected)
+
+		assert.Equal(t, expected, result)
+	})
+	t.Run("Serial", func(t *testing.T) {
+		data := "zr2g80wvjmm1zwzg"
+		expected := "c7dcdb1c"
+
+		result := Serial([]byte(data))
+
+		t.Logf("Serial(%s): result %s, expected %s", data, result, expected)
+
+		assert.Equal(t, expected, result)
+	})
+	t.Run("HelloWorld", func(t *testing.T) {
+		data := "Hello World!"
+		expected := "fe6cf1dc"
+
+		result := Serial([]byte(data))
+
+		t.Logf("Serial(%s): result %s, expected %s", data, result, expected)
+
+		assert.Equal(t, expected, result)
+	})
+}

pkg/checksum/digit.go

@@ -0,0 +1,6 @@
+package checksum
+
+// Digit returns a Crc32-based checksum number between 0 and 9.
+func Digit(data []byte) int {
+	return int(Crc32(data) % 10)
+}

pkg/checksum/digit_test.go

@@ -0,0 +1,70 @@
+package checksum
+
+import (
+	"crypto/rand"
+	"fmt"
+	"log"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestDigit(t *testing.T) {
+	t.Run("Empty", func(t *testing.T) {
+		data := ""
+		expected := "0"
+
+		result := Digit([]byte(data))
+
+		t.Logf("Digit(%s): result %d, expected %s", data, result, expected)
+
+		assert.Equal(t, expected, fmt.Sprintf("%d", result))
+	})
+	t.Run("One", func(t *testing.T) {
+		data := "1"
+		expected := "3"
+
+		result := Digit([]byte(data))
+
+		t.Logf("Digit(%s): result %d, expected %s", data, result, expected)
+
+		assert.Equal(t, expected, fmt.Sprintf("%d", result))
+	})
+	t.Run("Serial", func(t *testing.T) {
+		data := "zr2g80wvjmm1zwzg"
+		expected := "8"
+
+		result := Digit([]byte(data))
+
+		t.Logf("Digit(%s): result %d, expected %s", data, result, expected)
+
+		assert.Equal(t, expected, fmt.Sprintf("%d", result))
+	})
+	t.Run("HelloWorld", func(t *testing.T) {
+		data := "Hello World!"
+		expected := "5"
+
+		result := Digit([]byte(data))
+
+		t.Logf("Digit(%s): result %d, expected %s", data, result, expected)
+
+		assert.Equal(t, expected, fmt.Sprintf("%d", result))
+	})
+	t.Run("Rand", func(t *testing.T) {
+		for i := 0; i < 100; i++ {
+			b := make([]byte, 24)
+
+			if _, err := rand.Read(b); err != nil {
+				log.Fatal(err)
+			}
+
+			result := Digit(b)
+
+			if result < 0 {
+				t.Fatal("result < 0")
+			} else if result > 9 {
+				t.Fatal("result > 9")
+			}
+		}
+	})
+}

pkg/fs/hash.go

@@ -6,6 +6,8 @@ import (
 	"hash/crc32"
 	"io"
 	"os"
+
+	"github.com/photoprism/photoprism/pkg/checksum"
 )
 
 // Hash returns the SHA1 hash of a file as string.
@@ -41,7 +43,7 @@ func Checksum(fileName string) string {
 
 	defer file.Close()
 
-	hash := crc32.New(crc32.MakeTable(crc32.Castagnoli))
+	hash := crc32.New(checksum.Crc32Castagnoli)
 
 	if _, err := io.Copy(hash, file); err != nil {
 		return ""

pkg/rnd/auth.go

@@ -3,9 +3,10 @@ package rnd
 import (
 	"crypto/rand"
 	"fmt"
-	"hash/crc32"
 	"log"
 	"math/big"
+
+	"github.com/photoprism/photoprism/pkg/checksum"
 )
 
 const (
@@ -50,7 +51,7 @@ func AppPassword() string {
 		if (i+1)%7 == 0 {
 			b = append(b, AppPasswordSeparator)
 		} else if i == AppPasswordLength-1 {
-			b = append(b, CharsetBase62[crc32.ChecksumIEEE(b)%62])
+			b = append(b, checksum.Char(b))
 			return string(b)
 		} else if r, err := rand.Int(rand.Reader, m); err == nil {
 			b = append(b, CharsetBase62[r.Int64()])
@@ -85,7 +86,7 @@ func IsAppPassword(s string, verifyChecksum bool) bool {
 	}
 
 	// Verify token checksum.
-	return s[AppPasswordLength-1] == CharsetBase62[crc32.ChecksumIEEE([]byte(s[:AppPasswordLength-1]))%62]
+	return s[AppPasswordLength-1] == checksum.Char([]byte(s[:AppPasswordLength-1]))
 }
 
 // IsAuthAny checks if the string might be a valid auth token or app password.

pkg/rnd/crc.go

@@ -2,8 +2,9 @@ package rnd
 
 import (
 	"fmt"
-	"hash/crc32"
 	"strconv"
+
+	"github.com/photoprism/photoprism/pkg/checksum"
 )
 
 // CrcToken returns a string token with checksum.
@@ -14,9 +15,8 @@ func CrcToken() string {
 	token = append(token, '-')
 	token = append(token, []byte(Base36(4))...)
 
-	checksum := crc32.ChecksumIEEE(token)
-
-	sum := strconv.FormatInt(int64(checksum), 16)
+	crc := checksum.Crc32(token)
+	sum := strconv.FormatInt(int64(crc), 16)
 
 	return fmt.Sprintf("%s-%.4s", token, sum)
 }
@@ -29,9 +29,8 @@ func ValidateCrcToken(s string) bool {
 
 	token := []byte(s[:9])
 
-	checksum := crc32.ChecksumIEEE(token)
-
-	sum := strconv.FormatInt(int64(checksum), 16)
+	crc := checksum.Crc32(token)
+	sum := strconv.FormatInt(int64(crc), 16)
 
 	return s == fmt.Sprintf("%s-%.4s", token, sum)
 }

pkg/rnd/token.go

@@ -3,10 +3,12 @@ package rnd
 import (
 	"crypto/rand"
 	"math/big"
+
+	"github.com/photoprism/photoprism/pkg/checksum"
 )
 
-const CharsetBase36 = "abcdefghijklmnopqrstuvwxyz0123456789"
-const CharsetBase62 = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+const CharsetBase36 = checksum.CharsetBase36
+const CharsetBase62 = checksum.CharsetBase62
 
 // Base36 generates a random token containing lowercase letters and numbers.
 func Base36(length int) string {