1 files changed, 375 insertions, 0 deletions
diff --git a/vendor/github.com/authzed/cel-go/cel/validator.go b/vendor/github.com/authzed/cel-go/cel/validator.go
new file mode 100644
index 0000000..1664c13
--- /dev/null
+++ b/vendor/github.com/authzed/cel-go/cel/validator.go
@@ -0,0 +1,375 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cel
+
+import (
+	"fmt"
+	"reflect"
+	"regexp"
+
+	"github.com/authzed/cel-go/common/ast"
+	"github.com/authzed/cel-go/common/overloads"
+)
+
+const (
+	homogeneousValidatorName = "cel.lib.std.validate.types.homogeneous"
+
+	// HomogeneousAggregateLiteralExemptFunctions is the ValidatorConfig key used to configure
+	// the set of function names which are exempt from homogeneous type checks. The expected type
+	// is a string list of function names.
+	//
+	// As an example, the `<string>.format([args])` call expects the input arguments list to be
+	// comprised of a variety of types which correspond to the types expected by the format control
+	// clauses; however, all other uses of a mixed element type list, would be unexpected.
+	HomogeneousAggregateLiteralExemptFunctions = homogeneousValidatorName + ".exempt"
+)
+
+// ASTValidators configures a set of ASTValidator instances into the target environment.
+//
+// Validators are applied in the order in which the are specified and are treated as singletons.
+// The same ASTValidator with a given name will not be applied more than once.
+func ASTValidators(validators ...ASTValidator) EnvOption {
+	return func(e *Env) (*Env, error) {
+		for _, v := range validators {
+			if !e.HasValidator(v.Name()) {
+				e.validators = append(e.validators, v)
+			}
+		}
+		return e, nil
+	}
+}
+
+// ASTValidator defines a singleton interface for validating a type-checked Ast against an environment.
+//
+// Note: the Issues argument is mutable in the sense that it is intended to collect errors which will be
+// reported to the caller.
+type ASTValidator interface {
+	// Name returns the name of the validator. Names must be unique.
+	Name() string
+
+	// Validate validates a given Ast within an Environment and collects a set of potential issues.
+	//
+	// The ValidatorConfig is generated from the set of ASTValidatorConfigurer instances prior to
+	// the invocation of the Validate call. The expectation is that the validator configuration
+	// is created in sequence and immutable once provided to the Validate call.
+	//
+	// See individual validators for more information on their configuration keys and configuration
+	// properties.
+	Validate(*Env, ValidatorConfig, *ast.AST, *Issues)
+}
+
+// ValidatorConfig provides an accessor method for querying validator configuration state.
+type ValidatorConfig interface {
+	GetOrDefault(name string, value any) any
+}
+
+// MutableValidatorConfig provides mutation methods for querying and updating validator configuration
+// settings.
+type MutableValidatorConfig interface {
+	ValidatorConfig
+	Set(name string, value any) error
+}
+
+// ASTValidatorConfigurer indicates that this object, currently expected to be an ASTValidator,
+// participates in validator configuration settings.
+//
+// This interface may be split from the expectation of being an ASTValidator instance in the future.
+type ASTValidatorConfigurer interface {
+	Configure(MutableValidatorConfig) error
+}
+
+// validatorConfig implements the ValidatorConfig and MutableValidatorConfig interfaces.
+type validatorConfig struct {
+	data map[string]any
+}
+
+// newValidatorConfig initializes the validator config with default values for core CEL validators.
+func newValidatorConfig() *validatorConfig {
+	return &validatorConfig{
+		data: map[string]any{
+			HomogeneousAggregateLiteralExemptFunctions: []string{},
+		},
+	}
+}
+
+// GetOrDefault returns the configured value for the name, if present, else the input default value.
+//
+// Note, the type-agreement between the input default and configured value is not checked on read.
+func (config *validatorConfig) GetOrDefault(name string, value any) any {
+	v, found := config.data[name]
+	if !found {
+		return value
+	}
+	return v
+}
+
+// Set configures a validator option with the given name and value.
+//
+// If the value had previously been set, the new value must have the same reflection type as the old one,
+// or the call will error.
+func (config *validatorConfig) Set(name string, value any) error {
+	v, found := config.data[name]
+	if found && reflect.TypeOf(v) != reflect.TypeOf(value) {
+		return fmt.Errorf("incompatible configuration type for %s, got %T, wanted %T", name, value, v)
+	}
+	config.data[name] = value
+	return nil
+}
+
+// ExtendedValidations collects a set of common AST validations which reduce the likelihood of runtime errors.
+//
+// - Validate duration and timestamp literals
+// - Ensure regex strings are valid
+// - Disable mixed type list and map literals
+func ExtendedValidations() EnvOption {
+	return ASTValidators(
+		ValidateDurationLiterals(),
+		ValidateTimestampLiterals(),
+		ValidateRegexLiterals(),
+		ValidateHomogeneousAggregateLiterals(),
+	)
+}
+
+// ValidateDurationLiterals ensures that duration literal arguments are valid immediately after type-check.
+func ValidateDurationLiterals() ASTValidator {
+	return newFormatValidator(overloads.TypeConvertDuration, 0, evalCall)
+}
+
+// ValidateTimestampLiterals ensures that timestamp literal arguments are valid immediately after type-check.
+func ValidateTimestampLiterals() ASTValidator {
+	return newFormatValidator(overloads.TypeConvertTimestamp, 0, evalCall)
+}
+
+// ValidateRegexLiterals ensures that regex patterns are validated after type-check.
+func ValidateRegexLiterals() ASTValidator {
+	return newFormatValidator(overloads.Matches, 0, compileRegex)
+}
+
+// ValidateHomogeneousAggregateLiterals checks that all list and map literals entries have the same types, i.e.
+// no mixed list element types or mixed map key or map value types.
+//
+// Note: the string format call relies on a mixed element type list for ease of use, so this check skips all
+// literals which occur within string format calls.
+func ValidateHomogeneousAggregateLiterals() ASTValidator {
+	return homogeneousAggregateLiteralValidator{}
+}
+
+// ValidateComprehensionNestingLimit ensures that comprehension nesting does not exceed the specified limit.
+//
+// This validator can be useful for preventing arbitrarily nested comprehensions which can take high polynomial
+// time to complete.
+//
+// Note, this limit does not apply to comprehensions with an empty iteration range, as these comprehensions have
+// no actual looping cost. The cel.bind() utilizes the comprehension structure to perform local variable
+// assignments and supplies an empty iteration range, so they won't count against the nesting limit either.
+func ValidateComprehensionNestingLimit(limit int) ASTValidator {
+	return nestingLimitValidator{limit: limit}
+}
+
+type argChecker func(env *Env, call, arg ast.Expr) error
+
+func newFormatValidator(funcName string, argNum int, check argChecker) formatValidator {
+	return formatValidator{
+		funcName: funcName,
+		check:    check,
+		argNum:   argNum,
+	}
+}
+
+type formatValidator struct {
+	funcName string
+	argNum   int
+	check    argChecker
+}
+
+// Name returns the unique name of this function format validator.
+func (v formatValidator) Name() string {
+	return fmt.Sprintf("cel.lib.std.validate.functions.%s", v.funcName)
+}
+
+// Validate searches the AST for uses of a given function name with a constant argument and performs a check
+// on whether the argument is a valid literal value.
+func (v formatValidator) Validate(e *Env, _ ValidatorConfig, a *ast.AST, iss *Issues) {
+	root := ast.NavigateAST(a)
+	funcCalls := ast.MatchDescendants(root, ast.FunctionMatcher(v.funcName))
+	for _, call := range funcCalls {
+		callArgs := call.AsCall().Args()
+		if len(callArgs) <= v.argNum {
+			continue
+		}
+		litArg := callArgs[v.argNum]
+		if litArg.Kind() != ast.LiteralKind {
+			continue
+		}
+		if err := v.check(e, call, litArg); err != nil {
+			iss.ReportErrorAtID(litArg.ID(), "invalid %s argument", v.funcName)
+		}
+	}
+}
+
+func evalCall(env *Env, call, arg ast.Expr) error {
+	ast := &Ast{impl: ast.NewAST(call, ast.NewSourceInfo(nil))}
+	prg, err := env.Program(ast)
+	if err != nil {
+		return err
+	}
+	_, _, err = prg.Eval(NoVars())
+	return err
+}
+
+func compileRegex(_ *Env, _, arg ast.Expr) error {
+	pattern := arg.AsLiteral().Value().(string)
+	_, err := regexp.Compile(pattern)
+	return err
+}
+
+type homogeneousAggregateLiteralValidator struct{}
+
+// Name returns the unique name of the homogeneous type validator.
+func (homogeneousAggregateLiteralValidator) Name() string {
+	return homogeneousValidatorName
+}
+
+// Validate validates that all lists and map literals have homogeneous types, i.e. don't contain dyn types.
+//
+// This validator makes an exception for list and map literals which occur at any level of nesting within
+// string format calls.
+func (v homogeneousAggregateLiteralValidator) Validate(_ *Env, c ValidatorConfig, a *ast.AST, iss *Issues) {
+	var exemptedFunctions []string
+	exemptedFunctions = c.GetOrDefault(HomogeneousAggregateLiteralExemptFunctions, exemptedFunctions).([]string)
+	root := ast.NavigateAST(a)
+	listExprs := ast.MatchDescendants(root, ast.KindMatcher(ast.ListKind))
+	for _, listExpr := range listExprs {
+		if inExemptFunction(listExpr, exemptedFunctions) {
+			continue
+		}
+		l := listExpr.AsList()
+		elements := l.Elements()
+		optIndices := l.OptionalIndices()
+		var elemType *Type
+		for i, e := range elements {
+			et := a.GetType(e.ID())
+			if isOptionalIndex(i, optIndices) {
+				et = et.Parameters()[0]
+			}
+			if elemType == nil {
+				elemType = et
+				continue
+			}
+			if !elemType.IsEquivalentType(et) {
+				v.typeMismatch(iss, e.ID(), elemType, et)
+				break
+			}
+		}
+	}
+	mapExprs := ast.MatchDescendants(root, ast.KindMatcher(ast.MapKind))
+	for _, mapExpr := range mapExprs {
+		if inExemptFunction(mapExpr, exemptedFunctions) {
+			continue
+		}
+		m := mapExpr.AsMap()
+		entries := m.Entries()
+		var keyType, valType *Type
+		for _, e := range entries {
+			mapEntry := e.AsMapEntry()
+			key, val := mapEntry.Key(), mapEntry.Value()
+			kt, vt := a.GetType(key.ID()), a.GetType(val.ID())
+			if mapEntry.IsOptional() {
+				vt = vt.Parameters()[0]
+			}
+			if keyType == nil && valType == nil {
+				keyType, valType = kt, vt
+				continue
+			}
+			if !keyType.IsEquivalentType(kt) {
+				v.typeMismatch(iss, key.ID(), keyType, kt)
+			}
+			if !valType.IsEquivalentType(vt) {
+				v.typeMismatch(iss, val.ID(), valType, vt)
+			}
+		}
+	}
+}
+
+func inExemptFunction(e ast.NavigableExpr, exemptFunctions []string) bool {
+	parent, found := e.Parent()
+	for found {
+		if parent.Kind() == ast.CallKind {
+			fnName := parent.AsCall().FunctionName()
+			for _, exempt := range exemptFunctions {
+				if exempt == fnName {
+					return true
+				}
+			}
+		}
+		parent, found = parent.Parent()
+	}
+	return false
+}
+
+func isOptionalIndex(i int, optIndices []int32) bool {
+	for _, optInd := range optIndices {
+		if i == int(optInd) {
+			return true
+		}
+	}
+	return false
+}
+
+func (homogeneousAggregateLiteralValidator) typeMismatch(iss *Issues, id int64, expected, actual *Type) {
+	iss.ReportErrorAtID(id, "expected type '%s' but found '%s'", FormatCELType(expected), FormatCELType(actual))
+}
+
+type nestingLimitValidator struct {
+	limit int
+}
+
+func (v nestingLimitValidator) Name() string {
+	return "cel.lib.std.validate.comprehension_nesting_limit"
+}
+
+func (v nestingLimitValidator) Validate(e *Env, _ ValidatorConfig, a *ast.AST, iss *Issues) {
+	root := ast.NavigateAST(a)
+	comprehensions := ast.MatchDescendants(root, ast.KindMatcher(ast.ComprehensionKind))
+	if len(comprehensions) <= v.limit {
+		return
+	}
+	for _, comp := range comprehensions {
+		count := 0
+		e := comp
+		hasParent := true
+		for hasParent {
+			// When the expression is not a comprehension, continue to the next ancestor.
+			if e.Kind() != ast.ComprehensionKind {
+				e, hasParent = e.Parent()
+				continue
+			}
+			// When the comprehension has an empty range, continue to the next ancestor
+			// as this comprehension does not have any associated cost.
+			iterRange := e.AsComprehension().IterRange()
+			if iterRange.Kind() == ast.ListKind && iterRange.AsList().Size() == 0 {
+				e, hasParent = e.Parent()
+				continue
+			}
+			// Otherwise check the nesting limit.
+			count++
+			if count > v.limit {
+				iss.ReportErrorAtID(comp.ID(), "comprehension exceeds nesting limit")
+				break
+			}
+			e, hasParent = e.Parent()
+		}
+	}
+}