fix: extend forgejo_auth_token table

- Add a `purpose` column, this allows the `forgejo_auth_token` table to
be used by other parts of Forgejo, while still enjoying the
no-compromise architecture.
- Remove the 'roll your own crypto' time limited code functions and
migrate them to the `forgejo_auth_token` table. This migration ensures
generated codes can only be used for their purpose and ensure they are
invalidated after their usage by deleting it from the database, this
also should help making auditing of the security code easier, as we're
no longer trying to stuff a lot of data into a HMAC construction.
-Helper functions are rewritten to ensure a safe-by-design approach to
these tokens.
- Add the `forgejo_auth_token` to dbconsistency doctor and add it to the
`deleteUser` function.
- TODO: Add cron job to delete expired authorization tokens.
- Unit and integration tests added.

(cherry picked from commit 1ce33aa38d)

v9: Removed migration - XORM can handle this case automatically without
migration. Add `DEFAULT 'long_term_authorization'`.

modules/base/tool.go

@@ -4,26 +4,20 @@
 package base
 
 import (
-	"crypto/hmac"
-	"crypto/sha1"
 	"crypto/sha256"
-	"crypto/subtle"
 	"encoding/base64"
 	"encoding/hex"
 	"errors"
 	"fmt"
-	"hash"
 	"os"
 	"path/filepath"
 	"runtime"
 	"strconv"
 	"strings"
-	"time"
 	"unicode/utf8"
 
 	"code.gitea.io/gitea/modules/git"
 	"code.gitea.io/gitea/modules/log"
-	"code.gitea.io/gitea/modules/setting"
 
 	"github.com/dustin/go-humanize"
 )
@@ -54,66 +48,6 @@ func BasicAuthDecode(encoded string) (string, string, error) {
 	return "", "", errors.New("invalid basic authentication")
 }
 
-// VerifyTimeLimitCode verify time limit code
-func VerifyTimeLimitCode(now time.Time, data string, minutes int, code string) bool {
-	if len(code) <= 18 {
-		return false
-	}
-
-	startTimeStr := code[:12]
-	aliveTimeStr := code[12:18]
-	aliveTime, _ := strconv.Atoi(aliveTimeStr) // no need to check err, if anything wrong, the following code check will fail soon
-
-	// check code
-	retCode := CreateTimeLimitCode(data, aliveTime, startTimeStr, nil)
-	if subtle.ConstantTimeCompare([]byte(retCode), []byte(code)) != 1 {
-		retCode = CreateTimeLimitCode(data, aliveTime, startTimeStr, sha1.New()) // TODO: this is only for the support of legacy codes, remove this in/after 1.23
-		if subtle.ConstantTimeCompare([]byte(retCode), []byte(code)) != 1 {
-			return false
-		}
-	}
-
-	// check time is expired or not: startTime <= now && now < startTime + minutes
-	startTime, _ := time.ParseInLocation("200601021504", startTimeStr, time.Local)
-	return (startTime.Before(now) || startTime.Equal(now)) && now.Before(startTime.Add(time.Minute*time.Duration(minutes)))
-}
-
-// TimeLimitCodeLength default value for time limit code
-const TimeLimitCodeLength = 12 + 6 + 40
-
-// CreateTimeLimitCode create a time-limited code.
-// Format: 12 length date time string + 6 minutes string (not used) + 40 hash string, some other code depends on this fixed length
-// If h is nil, then use the default hmac hash.
-func CreateTimeLimitCode[T time.Time | string](data string, minutes int, startTimeGeneric T, h hash.Hash) string {
-	const format = "200601021504"
-
-	var start time.Time
-	var startTimeAny any = startTimeGeneric
-	if t, ok := startTimeAny.(time.Time); ok {
-		start = t
-	} else {
-		var err error
-		start, err = time.ParseInLocation(format, startTimeAny.(string), time.Local)
-		if err != nil {
-			return "" // return an invalid code because the "parse" failed
-		}
-	}
-	startStr := start.Format(format)
-	end := start.Add(time.Minute * time.Duration(minutes))
-
-	if h == nil {
-		h = hmac.New(sha1.New, setting.GetGeneralTokenSigningSecret())
-	}
-	_, _ = fmt.Fprintf(h, "%s%s%s%s%d", data, hex.EncodeToString(setting.GetGeneralTokenSigningSecret()), startStr, end.Format(format), minutes)
-	encoded := hex.EncodeToString(h.Sum(nil))
-
-	code := fmt.Sprintf("%s%06d%s", startStr, minutes, encoded)
-	if len(code) != TimeLimitCodeLength {
-		panic("there is a hard requirement for the length of time-limited code") // it shouldn't happen
-	}
-	return code
-}
-
 // FileSize calculates the file size and generate user-friendly string.
 func FileSize(s int64) string {
 	return humanize.IBytes(uint64(s))