// Copyright (c) 2025 Proton AG
//
// This file is part of Proton Mail Bridge.Bridge.
//
// Proton Mail Bridge is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Proton Mail Bridge 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.

//go:build !build_qa

package dialer

import (
	"crypto/tls"
	"errors"
	"net"
)

// CheckCertificate returns whether the connection presents a known TLS certificate.
func (p *TLSPinChecker) CheckCertificate(conn net.Conn) error {
	tlsConn, ok := conn.(*tls.Conn)
	if !ok {
		return errors.New("connection is not a TLS connection")
	}

	connState := tlsConn.ConnectionState()

	for _, peerCert := range connState.PeerCertificates {
		fingerprint := certFingerprint(peerCert)

		for _, pin := range p.trustedPins {
			if pin == fingerprint {
				return nil
			}
		}
	}

	return ErrTLSMismatch
}