tailscale/tka/chaintest_test.go

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// Copyright (c) 2022 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package tka
import (
"bytes"
"crypto/ed25519"
"fmt"
"strconv"
"strings"
"testing"
"text/scanner"
"github.com/google/go-cmp/cmp"
"github.com/google/go-cmp/cmp/cmpopts"
)
// chaintest_test.go implements test helpers for concisely describing
// chains of possibly signed AUMs, to assist in making tests shorter and
// easier to read.
// parsed representation of a named AUM in a test chain.
type testchainNode struct {
Name string
Parent string
Uses []scanner.Position
HashSeed int
Template string
SignedWith string
}
// testChain represents a constructed web of AUMs for testing purposes.
type testChain struct {
Nodes map[string]*testchainNode
AUMs map[string]AUM
AUMHashes map[string]AUMHash
// Configured by options to NewTestchain()
Template map[string]AUM
Key map[string]*Key
KeyPrivs map[string]ed25519.PrivateKey
SignAllKeys []string
}
// newTestchain constructs a web of AUMs based on the provided input and
// options.
//
// Input is expected to be a graph & tweaks, looking like this:
//
// G1 -> A -> B
// | -> C
//
// which defines AUMs G1, A, B, and C; with G1 having no parent, A having
// G1 as a parent, and both B & C having A as a parent.
//
// Tweaks are specified like this:
//
// <AUM>.<tweak> = <value>
//
// for example: G1.hashSeed = 2
//
// There are 3 available tweaks:
// - hashSeed: Set to an integer to tweak the AUM hash of that AUM.
// - template: Set to the name of a template provided via optTemplate().
// The template is copied and use as the content for that AUM.
// - signedWith: Set to the name of a key provided via optKey(). This
// key is used to sign that AUM.
func newTestchain(t *testing.T, input string, options ...testchainOpt) *testChain {
t.Helper()
var (
s scanner.Scanner
out = testChain{
Nodes: map[string]*testchainNode{},
Template: map[string]AUM{},
Key: map[string]*Key{},
KeyPrivs: map[string]ed25519.PrivateKey{},
}
)
// Process any options
for _, o := range options {
if o.Template != nil {
out.Template[o.Name] = *o.Template
}
if o.Key != nil {
out.Key[o.Name] = o.Key
out.KeyPrivs[o.Name] = o.Private
}
if o.SignAllWith {
out.SignAllKeys = append(out.SignAllKeys, o.Name)
}
}
s.Init(strings.NewReader(input))
s.Mode = scanner.ScanIdents | scanner.SkipComments | scanner.ScanComments | scanner.ScanChars | scanner.ScanInts
s.Whitespace ^= 1 << '\t' // clear tabs
var (
lastIdent string
lastWasChain bool // if the last token was '->'
)
for tok := s.Scan(); tok != scanner.EOF; tok = s.Scan() {
switch tok {
case '\t':
t.Fatalf("tabs disallowed, use spaces (seen at %v)", s.Pos())
case '.': // tweaks, like <ident>.hashSeed = <val>
s.Scan()
tweak := s.TokenText()
if tok := s.Scan(); tok == '=' {
s.Scan()
switch tweak {
case "hashSeed":
out.Nodes[lastIdent].HashSeed, _ = strconv.Atoi(s.TokenText())
case "template":
out.Nodes[lastIdent].Template = s.TokenText()
case "signedWith":
out.Nodes[lastIdent].SignedWith = s.TokenText()
}
}
case scanner.Ident:
out.recordPos(s.TokenText(), s.Pos())
// If the last token was '->', that means
// that the next identifier has a child relationship
// with the identifier preceeding '->'.
if lastWasChain {
out.recordParent(t, s.TokenText(), lastIdent)
}
lastIdent = s.TokenText()
case '-': // handle '->'
switch s.Peek() {
case '>':
s.Scan()
lastWasChain = true
continue
}
case '|': // handle '|'
line, col := s.Pos().Line, s.Pos().Column
nodeLoop:
for _, n := range out.Nodes {
for _, p := range n.Uses {
// Find the identifier used right here on the line above.
if p.Line == line-1 && col <= p.Column && col > p.Column-len(n.Name) {
lastIdent = n.Name
out.recordPos(n.Name, s.Pos())
break nodeLoop
}
}
}
}
lastWasChain = false
// t.Logf("tok = %v, %q", tok, s.TokenText())
}
out.buildChain()
return &out
}
// called from the parser to record the location of an
// identifier (a named AUM).
func (c *testChain) recordPos(ident string, pos scanner.Position) {
n := c.Nodes[ident]
if n == nil {
n = &testchainNode{Name: ident}
}
n.Uses = append(n.Uses, pos)
c.Nodes[ident] = n
}
// called from the parser to record a parent relationship between
// two AUMs.
func (c *testChain) recordParent(t *testing.T, child, parent string) {
if p := c.Nodes[child].Parent; p != "" && p != parent {
t.Fatalf("differing parent specified for %s: %q != %q", child, p, parent)
}
c.Nodes[child].Parent = parent
}
// called after parsing to build the web of AUM structures.
// This method populates c.AUMs and c.AUMHashes.
func (c *testChain) buildChain() {
pending := make(map[string]*testchainNode, len(c.Nodes))
for k, v := range c.Nodes {
pending[k] = v
}
// AUMs with a parent need to know their hash, so we
// only compute AUMs who's parents have been computed
// each iteration. Since at least the genesis AUM
// had no parent, theres always a path to completion
// in O(n+1) where n is the number of AUMs.
c.AUMs = make(map[string]AUM, len(c.Nodes))
c.AUMHashes = make(map[string]AUMHash, len(c.Nodes))
for i := 0; i < len(c.Nodes)+1; i++ {
if len(pending) == 0 {
return
}
next := make([]*testchainNode, 0, 10)
for _, v := range pending {
if _, parentPending := pending[v.Parent]; !parentPending {
next = append(next, v)
}
}
for _, v := range next {
aum := c.makeAUM(v)
h := aum.Hash()
c.AUMHashes[v.Name] = h
c.AUMs[v.Name] = aum
delete(pending, v.Name)
}
}
panic("unexpected: incomplete despite len(Nodes)+1 iterations")
}
func (c *testChain) makeAUM(v *testchainNode) AUM {
// By default, the AUM used is just a no-op AUM
// with a parent hash set (if any).
//
// If <AUM>.template is set to the same name as in
// a provided optTemplate(), the AUM is built
// from a copy of that instead.
//
// If <AUM>.hashSeed = <int> is set, the KeyID is
// tweaked to effect tweaking the hash. This is useful
// if you want one AUM to have a lower hash than another.
aum := AUM{MessageKind: AUMNoOp}
if template := v.Template; template != "" {
aum = c.Template[template]
}
if v.Parent != "" {
parentHash := c.AUMHashes[v.Parent]
aum.PrevAUMHash = parentHash[:]
}
if seed := v.HashSeed; seed != 0 {
aum.KeyID = []byte{byte(seed)}
}
if err := aum.StaticValidate(); err != nil {
// Usually caused by a test writer specifying a template
// AUM which is ultimately invalid.
panic(fmt.Sprintf("aum %+v failed static validation: %v", aum, err))
}
sigHash := aum.SigHash()
for _, key := range c.SignAllKeys {
aum.Signatures = append(aum.Signatures, Signature{
KeyID: c.Key[key].ID(),
Signature: ed25519.Sign(c.KeyPrivs[key], sigHash[:]),
})
}
// If the aum was specified as being signed by some key, then
// sign it using that key.
if key := v.SignedWith; key != "" {
aum.Signatures = append(aum.Signatures, Signature{
KeyID: c.Key[key].ID(),
Signature: ed25519.Sign(c.KeyPrivs[key], sigHash[:]),
})
}
return aum
}
// Chonk returns a tailchonk containing all AUMs.
func (c *testChain) Chonk() Chonk {
var out Mem
for _, update := range c.AUMs {
if err := out.CommitVerifiedAUMs([]AUM{update}); err != nil {
panic(err)
}
}
return &out
}
// ChonkWith returns a tailchonk containing the named AUMs.
func (c *testChain) ChonkWith(names ...string) Chonk {
var out Mem
for _, name := range names {
update := c.AUMs[name]
if err := out.CommitVerifiedAUMs([]AUM{update}); err != nil {
panic(err)
}
}
return &out
}
type testchainOpt struct {
Name string
Template *AUM
Key *Key
Private ed25519.PrivateKey
SignAllWith bool
}
func optTemplate(name string, template AUM) testchainOpt {
return testchainOpt{
Name: name,
Template: &template,
}
}
func optKey(name string, key Key, priv ed25519.PrivateKey) testchainOpt {
return testchainOpt{
Name: name,
Key: &key,
Private: priv,
}
}
func optSignAllUsing(keyName string) testchainOpt {
return testchainOpt{
Name: keyName,
SignAllWith: true,
}
}
func TestNewTestchain(t *testing.T) {
c := newTestchain(t, `
genesis -> B -> C
| -> D
| -> E -> F
E.hashSeed = 12 // tweak E to have the lowest hash so its chosen
F.template = test
`, optTemplate("test", AUM{MessageKind: AUMNoOp, KeyID: []byte{10}}))
want := map[string]*testchainNode{
"genesis": &testchainNode{Name: "genesis", Uses: []scanner.Position{{Line: 2, Column: 16}}},
"B": &testchainNode{
Name: "B",
Parent: "genesis",
Uses: []scanner.Position{{Line: 2, Column: 21}, {Line: 3, Column: 21}, {Line: 4, Column: 21}},
},
"C": &testchainNode{Name: "C", Parent: "B", Uses: []scanner.Position{{Line: 2, Column: 26}}},
"D": &testchainNode{Name: "D", Parent: "B", Uses: []scanner.Position{{Line: 3, Column: 26}}},
"E": &testchainNode{Name: "E", Parent: "B", HashSeed: 12, Uses: []scanner.Position{{Line: 4, Column: 26}, {Line: 6, Column: 10}}},
"F": &testchainNode{Name: "F", Parent: "E", Template: "test", Uses: []scanner.Position{{Line: 4, Column: 31}, {Line: 7, Column: 10}}},
}
if diff := cmp.Diff(want, c.Nodes, cmpopts.IgnoreFields(scanner.Position{}, "Offset")); diff != "" {
t.Errorf("decoded state differs (-want, +got):\n%s", diff)
}
if !bytes.Equal(c.AUMs["F"].KeyID, []byte{10}) {
t.Errorf("AUM 'F' missing KeyID from template: %v", c.AUMs["F"])
}
// chonk := c.Chonk()
// authority, err := Open(chonk)
// if err != nil {
// t.Errorf("failed to initialize from chonk: %v", err)
// }
// if authority.Head() != c.AUMHashes["F"] {
// t.Errorf("head = %X, want %X", authority.Head(), c.AUMHashes["F"])
// }
}