anubis/lib/challenge/proofofwork/proofofwork.go
Xe Iaso f2db43ad4b
feat: implement challenge registry (#607)
* feat: implement challenge method registry

This paves the way for implementing a no-js check method (#95) by making
the challenge providers more generic.

Signed-off-by: Xe Iaso <me@xeiaso.net>

* fix(lib/challenge): rename proof-of-work package to proofofwork

Signed-off-by: Xe Iaso <me@xeiaso.net>

* fix(lib): make validated challenges a CounterVec

Signed-off-by: Xe Iaso <me@xeiaso.net>

* fix(lib): annotate jwts with challenge method

Signed-off-by: Xe Iaso <me@xeiaso.net>

* test(lib/challenge/proofofwork): implement tests

Signed-off-by: Xe Iaso <me@xeiaso.net>

* test(lib): add smoke tests for known good and known bad config files

Signed-off-by: Xe Iaso <me@xeiaso.net>

* docs: update CHANGELOG

Signed-off-by: Xe Iaso <me@xeiaso.net>

* fix(lib): use challenge.Impl#Issue when issuing challenges

Signed-off-by: Xe Iaso <me@xeiaso.net>

---------

Signed-off-by: Xe Iaso <me@xeiaso.net>
2025-06-04 02:01:58 +00:00

84 lines
2.6 KiB
Go

package proofofwork
import (
"crypto/subtle"
"fmt"
"log/slog"
"net/http"
"strconv"
"strings"
"github.com/TecharoHQ/anubis/internal"
chall "github.com/TecharoHQ/anubis/lib/challenge"
"github.com/TecharoHQ/anubis/lib/policy"
"github.com/TecharoHQ/anubis/web"
"github.com/a-h/templ"
)
func init() {
chall.Register("fast", &Impl{Algorithm: "fast"})
chall.Register("slow", &Impl{Algorithm: "slow"})
}
type Impl struct {
Algorithm string
}
func (i *Impl) Fail(w http.ResponseWriter, r *http.Request) error {
return nil
}
func (i *Impl) Issue(r *http.Request, lg *slog.Logger, rule *policy.Bot, challenge string, ogTags map[string]string) (templ.Component, error) {
component, err := web.BaseWithChallengeAndOGTags("Making sure you're not a bot!", web.Index(), challenge, rule.Challenge, ogTags)
if err != nil {
return nil, fmt.Errorf("can't render page: %w", err)
}
return component, nil
}
func (i *Impl) Validate(r *http.Request, lg *slog.Logger, rule *policy.Bot, challenge string) error {
nonceStr := r.FormValue("nonce")
if nonceStr == "" {
return chall.NewError("validate", "invalid response", fmt.Errorf("%w nonce", chall.ErrMissingField))
}
nonce, err := strconv.Atoi(nonceStr)
if err != nil {
return chall.NewError("validate", "invalid response", fmt.Errorf("%w: nonce: %w", chall.ErrInvalidFormat, err))
}
elapsedTimeStr := r.FormValue("elapsedTime")
if elapsedTimeStr == "" {
return chall.NewError("validate", "invalid response", fmt.Errorf("%w elapsedTime", chall.ErrMissingField))
}
elapsedTime, err := strconv.ParseFloat(elapsedTimeStr, 64)
if err != nil {
return chall.NewError("validate", "invalid response", fmt.Errorf("%w: elapsedTime: %w", chall.ErrInvalidFormat, err))
}
response := r.FormValue("response")
if response == "" {
return chall.NewError("validate", "invalid response", fmt.Errorf("%w response", chall.ErrMissingField))
}
calcString := fmt.Sprintf("%s%d", challenge, nonce)
calculated := internal.SHA256sum(calcString)
if subtle.ConstantTimeCompare([]byte(response), []byte(calculated)) != 1 {
return chall.NewError("validate", "invalid response", fmt.Errorf("%w: wanted response %s but got %s", chall.ErrFailed, calculated, response))
}
// compare the leading zeroes
if !strings.HasPrefix(response, strings.Repeat("0", rule.Challenge.Difficulty)) {
return chall.NewError("validate", "invalid response", fmt.Errorf("%w: wanted %d leading zeros but got %s", chall.ErrFailed, rule.Challenge.Difficulty, response))
}
lg.Debug("challenge took", "elapsedTime", elapsedTime)
chall.TimeTaken.WithLabelValues(i.Algorithm).Observe(elapsedTime)
return nil
}