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Change recursion checks to be rule based, better match the spec #443

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Aug 10, 2021
Merged

Change recursion checks to be rule based, better match the spec #443

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399065f
Change recursion checks to be rule based, better match the spec
TristonianJones Aug 6, 2021
0f342b2
Updates based on review feedback. Also, additional test for error rec…
TristonianJones Aug 9, 2021
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45 changes: 29 additions & 16 deletions parser/parser.go
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Original file line number Diff line number Diff line change
Expand Up @@ -46,7 +46,7 @@ func NewParser(opts ...Option) (*Parser, error) {
}
}
if p.maxRecursionDepth == 0 {
p.maxRecursionDepth = 250
p.maxRecursionDepth = 200
}
if p.maxRecursionDepth == -1 {
p.maxRecursionDepth = int((^uint(0)) >> 1)
Expand Down Expand Up @@ -158,29 +158,41 @@ func (re *recursionError) Error() string {
var _ error = &recursionError{}

type recursionListener struct {
maxDepth int
depth int
maxDepth int
ruleTypeDepth map[int]*int
}

func (rl *recursionListener) VisitTerminal(node antlr.TerminalNode) {}

func (rl *recursionListener) VisitErrorNode(node antlr.ErrorNode) {}

func (rl *recursionListener) EnterEveryRule(ctx antlr.ParserRuleContext) {
if ctx != nil && ctx.GetRuleIndex() == gen.CELParserRULE_expr {
if rl.depth >= rl.maxDepth {
rl.depth++
panic(&recursionError{
message: fmt.Sprintf("expression recursion limit exceeded: %d", rl.maxDepth),
})
}
rl.depth++
if ctx == nil {
return
}
ruleIndex := ctx.GetRuleIndex()
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Speed-wise, it might make more sense to use map[int]*int. That way you do not need to do do both a lookup and insert into a map each time.

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Done

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I think this is safe. I remember having to put the increment after the recursion check. But looking at ANTLR Go, it appears that if EnterEveryRule panics, ExitEveryRule should not be called. Might want to double-check, otherwise things could go negative.

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Done. Added a defensive check since I'm using a pointer now as well.

depth, found := rl.ruleTypeDepth[ruleIndex]
if !found {
var counter = 1
rl.ruleTypeDepth[ruleIndex] = &counter
depth = &counter
} else {
*depth++
}
if *depth >= rl.maxDepth {
panic(&recursionError{
message: fmt.Sprintf("expression recursion limit exceeded: %d", rl.maxDepth),
})
}
}

func (rl *recursionListener) ExitEveryRule(ctx antlr.ParserRuleContext) {
if ctx != nil && ctx.GetRuleIndex() == gen.CELParserRULE_expr {
rl.depth--
if ctx == nil {
return
}
ruleIndex := ctx.GetRuleIndex()
if depth, found := rl.ruleTypeDepth[ruleIndex]; found && *depth > 0 {
*depth--
}
}

Expand Down Expand Up @@ -214,7 +226,7 @@ func (rl *recoveryLimitErrorStrategy) RecoverInline(recognizer antlr.Parser) ant
}

func (rl *recoveryLimitErrorStrategy) checkAttempts(recognizer antlr.Parser) {
if rl.attempts >= rl.maxAttempts {
if rl.attempts == rl.maxAttempts {
rl.attempts++
msg := fmt.Sprintf("error recovery attempt limit exceeded: %d", rl.maxAttempts)
recognizer.NotifyErrorListeners(msg, nil, nil)
Expand Down Expand Up @@ -263,7 +275,8 @@ func (p *parser) parse(expr runes.Buffer, desc string) *exprpb.Expr {
// Unfortunately ANTLR Go runtime is missing (*antlr.BaseParser).RemoveParseListeners, so this is
// good enough until that is exported.
prsrListener := &recursionListener{
maxDepth: p.maxRecursionDepth,
maxDepth: p.maxRecursionDepth,
ruleTypeDepth: map[int]*int{},
}

defer func() {
Expand Down Expand Up @@ -295,7 +308,7 @@ func (p *parser) parse(expr runes.Buffer, desc string) *exprpb.Expr {
case *recursionError:
p.errors.ReportError(common.NoLocation, "%s", err.message)
case *recoveryLimitError:
p.errors.ReportError(common.NoLocation, "%s", err.message)
// do nothing, listeners already notified and error reported.
default:
panic(val)
}
Expand Down
75 changes: 67 additions & 8 deletions parser/parser_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1093,15 +1093,74 @@ ERROR: <input>:1:26: reserved identifier: var
| ?
| .^`,
},
{
I: `a ? b ((?))`,
E: `
ERROR: <input>:1:9: Syntax error: mismatched input '?' expecting {'[', '{', '(', '.', '-', '!', 'true', 'false', 'null', NUM_FLOAT, NUM_INT, NUM_UINT, STRING, BYTES, IDENTIFIER}
| a ? b ((?))
| ........^
ERROR: <input>:1:10: Syntax error: mismatched input ')' expecting {'[', '{', '(', '.', '-', '!', 'true', 'false', 'null', NUM_FLOAT, NUM_INT, NUM_UINT, STRING, BYTES, IDENTIFIER}
| a ? b ((?))
| .........^
ERROR: <input>:1:12: Syntax error: error recovery attempt limit exceeded: 4
| a ? b ((?))
| ...........^`,
},
{
I: `[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[
[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[
[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[
[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[['too many']]]]]]]]]]]]]]]]]]]]]]]]]]]]
]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]
]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]
]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]`,
E: "ERROR: <input>:-1:0: expression recursion limit exceeded: 250",
[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[['too many']]]]]]]]]]]]]]]]]]]]]]]]]]]]
]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]`,
E: "ERROR: <input>:-1:0: expression recursion limit exceeded: 32",
},
{
I: `-[-1--1--1--1---1--1--1--0--1--1--1--1--0--2--1--1--0--1--1--1--1--0--1--1--1
--3-[-1--1--1--1---1--1--1--0--1--1--1--1--0--3--1--1--0--1--1--1--1--0--1--1--1
--3-[-1--1--1--1---1--1--1--0-/1--1--1--1--0--2--1--1--0--1--1--1--1--0--1--1--1
--3-[-1--1--1--1---1--1--1--0--1--1--1--1--0--2--1--1--0--1--1--1--1--0--1--1--1
--3-[-1--1--1--1---1--1--1--0--1--1--1--1--0--2--1--1--0--1--1--1--1--0--1--1--1
--3-[-1--1--1--1---1--1--1--0--1--1--1--1--0--2--1--1--0--1--1--1--1--0--1--1--1
--3-[-1--1--1--1---1--1--1--0--1--1--1--1--0--3--1--1--0--1--1--1--1--0--1--1--1
--3-[-1--1--1--1---1--1--1--0-/1--1--1--1--0--2--1--1--0--1--1--1--1--0--1--1--1
--3-[-1--1--1--1---1-1--1--1--1--0--2--1--1--0--1--1--1--1--0--1--1--1--3-[-1--1
--1--1---1--1--1--0--1--1--1--1--0--2--1--1--0--1--1--1--1--0--1--1--1--3-[-1--1
--1--1---1--1-À1--0--1--1--1--1--0--2--1--1--0--1--1--1--1--0--1--1--1--3-[-1--1
--1--1---1--1--1--0--1--1--1--1--0--2--1--1--0--1--1--1--1--0--1--1--1--3-[-1--1
--1--1---1--1--1--0--1--1--1--1--0--3--1--1--0--1--1--1--1--0--1--1--1--3-[-1--1
--1--1---1--1--1--0-/1--1--1--1--0--2--1--1--0--1--1--1--1--0--1--1--1--3-[-1--1
--1--1---1--1--1--0--1--1--1--1--0--2--1--1--0--1--1--1--1--0--1--1--1--3-[-1--1
--1--1---1--1--1--0--1--1--1--1--0--2--1--1--0--1--1--1--1--0--1--1--1--3-[-1--1
--1--1---1--1--1--0--1--1--1--1--0--2--1--1--0--1--1--1--1--0--1--1--1--3-[-1--1
--1--1---1--1--1--0--1--1--1--1--0--3--1--1--0--1--1--1
--1--0--1--1--1--3-[-1--1--1--1---1--1--1--0-/1--1--1--1--0--2--1--1--0--1--1--1
--1--0--1--1--1--3-[-1--1--1--1---1--1--1--0--1--1--1--1--0--2--1--1--0--1--1--1
--1--0--1--1--1--3-[-1--1--1--1---1--1--1--0--1--1--1--1--0--2--1--1--0--1--1--1
--1--0--1--1--1--3-[-1--1--1--1---1--1--1--0--1--1--1--1--0--2--1--1--0--1--1--1
--1--0--1--1--1--3-[-1--1--1--1---1--1--1--0--1--1--1--1--0--3--1--1--0--1--1--1
--1--0--1--1--1--3-[-1--1--1--1---1--1--1--0-/1--1--1--1--0--2--1--1--0--1--1--1
--1--0--1--1--1--3-[-1--1--1--1---1--1--1--0--1--1--1--1--0--1--1--1--3-[-1--1--1
--1---1--1--1--0--1--1--1--1--0--2--1--1--0--1--1--1--1--0--1--1--1--3-[-1--1--1
--1---1--1--1--0--1--1--1--1--0--2--1--1--0--1--1--1--1--0--1--1--1--3-[-1--1--1
--1---1--1--1--0--1--1--1--1--0--2--1--1--0--1--1--1--1--0--1--1--1--3-[-1--1--1
--1---1--1--1--0--1--1--1--1--0--3--1--1--0--1--1--1--1--0--1--1--1--3-[-1--1--1
--1---1--1--1--0-/1--1--1--1--0--2--1--1--0--1--1--1--1--0--1--1--1--3-[-1--1--1
--1---1--1--1--0--1--1--1--1--0--2--1--1--0--1--1--1--1--0--1--1--1--3-[-1--1--1
--1---1--1--1--0--1--1--1--1--0--2--1--1--0--1--1--1--1--0--1--1--1--3-[-1--1--1
--1---1--1--1--0--1--1--1--1--0--2--1--1--0--1--1--1--1--0--1--1--1--3-[-1--1--1
--1---1--1--1--0--1--1--1--1--0--3--1--1--0--1`,
E: `
ERROR: <input>:-1:0: expression recursion limit exceeded: 32
ERROR: <input>:3:33: Syntax error: extraneous input '/' expecting {'[', '{', '(', '.', '-', '!', 'true', 'false', 'null', NUM_FLOAT, NUM_INT, NUM_UINT, STRING, BYTES, IDENTIFIER}
| --3-[-1--1--1--1---1--1--1--0-/1--1--1--1--0--2--1--1--0--1--1--1--1--0--1--1--1
| ................................^
ERROR: <input>:8:33: Syntax error: extraneous input '/' expecting {'[', '{', '(', '.', '-', '!', 'true', 'false', 'null', NUM_FLOAT, NUM_INT, NUM_UINT, STRING, BYTES, IDENTIFIER}
| --3-[-1--1--1--1---1--1--1--0-/1--1--1--1--0--2--1--1--0--1--1--1--1--0--1--1--1
| ................................^
ERROR: <input>:11:17: Syntax error: token recognition error at: 'À'
| --1--1---1--1-À1--0--1--1--1--1--0--2--1--1--0--1--1--1--1--0--1--1--1--3-[-1--1
| ................＾
ERROR: <input>:14:23: Syntax error: extraneous input '/' expecting {'[', '{', '(', '.', '-', '!', 'true', 'false', 'null', NUM_FLOAT, NUM_INT, NUM_UINT, STRING, BYTES, IDENTIFIER}
| --1--1---1--1--1--0-/1--1--1--1--0--2--1--1--0--1--1--1--1--0--1--1--1--3-[-1--1
| ......................^`,
},
}

Expand Down Expand Up @@ -1181,7 +1240,7 @@ func (l *locationAdorner) GetMetadata(elem interface{}) string {
}

func TestParse(t *testing.T) {
p, err := NewParser(Macros(AllMacros...))
p, err := NewParser(Macros(AllMacros...), MaxRecursionDepth(32), ErrorRecoveryLimit(4))
if err != nil {
t.Fatal(err)
}
Expand Down