// Copyright (c) Tailscale Inc & contributors
// SPDX-License-Identifier: BSD-3-Clause

// Package bakedroots contains WebPKI CA roots we bake into the tailscaled binary,
// lest the system's CA roots be missing them (or entirely empty).
package bakedroots

import (
	"crypto/x509"
	"fmt"
	"sync"

	"tailscale.com/util/testenv"
)

// Get returns the baked-in roots.
//
// As of 2026-07-20, this includes only the LetsEncrypt ISRG roots:
// the Generation X roots (X1 & X2) and the Generation Y roots (YE & YR).
func Get() *x509.CertPool {
	roots.once.Do(func() {
		roots.parsePEM([]byte(letsEncryptX1 + letsEncryptX2 + letsEncryptYE + letsEncryptYR))
	})
	return roots.p
}

// ResetForTest resets the cached roots for testing,
// optionally setting them to caPEM if non-nil.
func ResetForTest(tb testenv.TB, caPEM []byte) {
	if !testenv.InTest() {
		panic("not in test")
	}
	tb.Setenv("ASSERT_NOT_PARALLEL_TEST", "1") // panics if tb's Parallel was called

	roots = rootsOnce{}
	if caPEM != nil {
		roots.once.Do(func() { roots.parsePEM(caPEM) })
		tb.Cleanup(func() {
			// Reset the roots to real roots for any following test.
			roots = rootsOnce{}
		})
	}
}

var roots rootsOnce

type rootsOnce struct {
	once sync.Once
	p    *x509.CertPool
}

func (r *rootsOnce) parsePEM(caPEM []byte) {
	p := x509.NewCertPool()
	if !p.AppendCertsFromPEM(caPEM) {
		panic(fmt.Sprintf("bogus PEM: %q", caPEM))
	}
	r.p = p
}

/*
letsEncryptX1 is the LetsEncrypt X1 root:

Certificate:

	Data:
	    Version: 3 (0x2)
	    Serial Number:
	        82:10:cf:b0:d2:40:e3:59:44:63:e0:bb:63:82:8b:00
	    Signature Algorithm: sha256WithRSAEncryption
	    Issuer: C = US, O = Internet Security Research Group, CN = ISRG Root X1
	    Validity
	        Not Before: Jun  4 11:04:38 2015 GMT
	        Not After : Jun  4 11:04:38 2035 GMT
	    Subject: C = US, O = Internet Security Research Group, CN = ISRG Root X1
	    Subject Public Key Info:
	        Public Key Algorithm: rsaEncryption
	            RSA Public-Key: (4096 bit)

We bake it into the binary as a fallback verification root,
in case the system we're running on doesn't have it.
(Tailscale runs on some ancient devices.)

To test that this code is working on Debian/Ubuntu:

$ sudo mv /usr/share/ca-certificates/mozilla/ISRG_Root_X1.crt{,.old}
$ sudo update-ca-certificates

Then restart tailscaled. To also test dnsfallback's use of it, nuke
your /etc/resolv.conf and it should still start & run fine.
*/
const letsEncryptX1 = `
-----BEGIN CERTIFICATE-----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=
-----END CERTIFICATE-----
`

// letsEncryptX2 is the ISRG Root X2.
//
// Subject: O = Internet Security Research Group, CN = ISRG Root X2
// Key type: ECDSA P-384
// Validity: until 2035-09-04 (generated 2020-09-04)
const letsEncryptX2 = `
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
`

// letsEncryptYE is the ISRG Root YE, part of LetsEncrypt's
// "Generation Y" hierarchy announced 2025-11-24.
//
// Subject: C = US, O = ISRG, CN = Root YE
// Key type: ECDSA P-384
// Validity: 2025-09-03 to 2045-09-02
const letsEncryptYE = `
-----BEGIN CERTIFICATE-----
MIIB2TCCAWCgAwIBAgIRAKQCa6LvbHwg1AR+XmWmk4AwCgYIKoZIzj0EAwMwLjEL
MAkGA1UEBhMCVVMxDTALBgNVBAoTBElTUkcxEDAOBgNVBAMTB1Jvb3QgWUUwHhcN
MjUwOTAzMDAwMDAwWhcNNDUwOTAyMjM1OTU5WjAuMQswCQYDVQQGEwJVUzENMAsG
A1UEChMESVNSRzEQMA4GA1UEAxMHUm9vdCBZRTB2MBAGByqGSM49AgEGBSuBBAAi
A2IABDwS/6vhrcVqcbBo+wgdI3fwn9x7DNJJOY/lTOti0vkwuRN87RhEhTH17E7X
yFjWsPYhIPt/wzOqxTd2b+4ZJNy9ID04YywF9U5zasDVyGSNErVNtz8uSGh5izW8
7j77GaNCMEAwDgYDVR0PAQH/BAQDAgEGMA8GA1UdEwEB/wQFMAMBAf8wHQYDVR0O
BBYEFKPIJlqOoUzQNWP8myPIOq5W809WMAoGCCqGSM49BAMDA2cAMGQCMHhMr8N9
LdL1VQKs9BdV81r76eXRB6mtjuNjzk6/lBsPNToWLTDzGYgtQKO1jl63uAIwGV7m
onyF377c+MM1oqVNs17sgu7F9YKZwgLmVbeOMDbKAXHtKMDLbiGllCcs8f47
-----END CERTIFICATE-----
`

// letsEncryptYR is the ISRG Root YR, part of LetsEncrypt's
// "Generation Y" hierarchy announced 2025-11-24.
//
// Subject: C = US, O = ISRG, CN = Root YR
// Key type: RSA 4096
// Validity: 2025-09-03 to 2045-09-02
const letsEncryptYR = `
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
`