pomerium/internal/mcp/token.go

package mcp

import (
	"fmt"

	"github.com/pomerium/pomerium/internal/oauth21"
)

func CheckPKCE(
	codeChallengeMethod string,
	codeChallenge string,
	codeVerifier string,
) error {
	if codeChallengeMethod == "" || codeChallengeMethod == "plain" {
		if !oauth21.VerifyPKCEPlain(codeVerifier, codeChallenge) {
			return fmt.Errorf("plain: code verifier does not match code challenge")
		}
	} else if codeChallengeMethod == "S256" {
		if !oauth21.VerifyPKCES256(codeVerifier, codeChallenge) {
			return fmt.Errorf("S256: code verifier does not match code challenge")
		}
	} else {
		return fmt.Errorf("unsupported code challenge method: %s", codeChallengeMethod)
	}

	return nil
}