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|
// Copyright 2015 Matthew Holt and The Caddy Authors
//
// 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 caddyhttp
import (
"crypto/x509/pkix"
"encoding/json"
"errors"
"fmt"
"net/http"
"reflect"
"regexp"
"strings"
"time"
"github.com/google/cel-go/cel"
"github.com/google/cel-go/common"
"github.com/google/cel-go/common/ast"
"github.com/google/cel-go/common/operators"
"github.com/google/cel-go/common/types"
"github.com/google/cel-go/common/types/ref"
"github.com/google/cel-go/common/types/traits"
"github.com/google/cel-go/ext"
"github.com/google/cel-go/interpreter"
"github.com/google/cel-go/interpreter/functions"
"github.com/google/cel-go/parser"
"go.uber.org/zap"
"github.com/caddyserver/caddy/v2"
"github.com/caddyserver/caddy/v2/caddyconfig/caddyfile"
)
func init() {
caddy.RegisterModule(MatchExpression{})
}
// MatchExpression matches requests by evaluating a
// [CEL](https://github.com/google/cel-spec) expression.
// This enables complex logic to be expressed using a comfortable,
// familiar syntax. Please refer to
// [the standard definitions of CEL functions and operators](https://github.com/google/cel-spec/blob/master/doc/langdef.md#standard-definitions).
//
// This matcher's JSON interface is actually a string, not a struct.
// The generated docs are not correct because this type has custom
// marshaling logic.
//
// COMPATIBILITY NOTE: This module is still experimental and is not
// subject to Caddy's compatibility guarantee.
type MatchExpression struct {
// The CEL expression to evaluate. Any Caddy placeholders
// will be expanded and situated into proper CEL function
// calls before evaluating.
Expr string `json:"expr,omitempty"`
// Name is an optional name for this matcher.
// This is used to populate the name for regexp
// matchers that appear in the expression.
Name string `json:"name,omitempty"`
expandedExpr string
prg cel.Program
ta types.Adapter
log *zap.Logger
}
// CaddyModule returns the Caddy module information.
func (MatchExpression) CaddyModule() caddy.ModuleInfo {
return caddy.ModuleInfo{
ID: "http.matchers.expression",
New: func() caddy.Module { return new(MatchExpression) },
}
}
// MarshalJSON marshals m's expression.
func (m MatchExpression) MarshalJSON() ([]byte, error) {
// if the name is empty, then we can marshal just the expression string
if m.Name == "" {
return json.Marshal(m.Expr)
}
// otherwise, we need to marshal the full object, using an
// anonymous struct to avoid infinite recursion
return json.Marshal(struct {
Expr string `json:"expr"`
Name string `json:"name"`
}{
Expr: m.Expr,
Name: m.Name,
})
}
// UnmarshalJSON unmarshals m's expression.
func (m *MatchExpression) UnmarshalJSON(data []byte) error {
// if the data is a string, then it's just the expression
if data[0] == '"' {
return json.Unmarshal(data, &m.Expr)
}
// otherwise, it's a full object, so unmarshal it,
// using an temp map to avoid infinite recursion
var tmpJson map[string]any
err := json.Unmarshal(data, &tmpJson)
*m = MatchExpression{
Expr: tmpJson["expr"].(string),
Name: tmpJson["name"].(string),
}
return err
}
// Provision sets ups m.
func (m *MatchExpression) Provision(ctx caddy.Context) error {
m.log = ctx.Logger()
// replace placeholders with a function call - this is just some
// light (and possibly naïve) syntactic sugar
m.expandedExpr = placeholderRegexp.ReplaceAllString(m.Expr, placeholderExpansion)
// as a second pass, we'll strip the escape character from an escaped
// placeholder, so that it can be used as an input to other CEL functions
m.expandedExpr = escapedPlaceholderRegexp.ReplaceAllString(m.expandedExpr, escapedPlaceholderExpansion)
// our type adapter expands CEL's standard type support
m.ta = celTypeAdapter{}
// initialize the CEL libraries from the Matcher implementations which
// have been configured to support CEL.
matcherLibProducers := []CELLibraryProducer{}
for _, info := range caddy.GetModules("http.matchers") {
p, ok := info.New().(CELLibraryProducer)
if ok {
matcherLibProducers = append(matcherLibProducers, p)
}
}
// add the matcher name to the context so that the matcher name
// can be used by regexp matchers being provisioned
ctx = ctx.WithValue(MatcherNameCtxKey, m.Name)
// Assemble the compilation and program options from the different library
// producers into a single cel.Library implementation.
matcherEnvOpts := []cel.EnvOption{}
matcherProgramOpts := []cel.ProgramOption{}
for _, producer := range matcherLibProducers {
l, err := producer.CELLibrary(ctx)
if err != nil {
return fmt.Errorf("error initializing CEL library for %T: %v", producer, err)
}
matcherEnvOpts = append(matcherEnvOpts, l.CompileOptions()...)
matcherProgramOpts = append(matcherProgramOpts, l.ProgramOptions()...)
}
matcherLib := cel.Lib(NewMatcherCELLibrary(matcherEnvOpts, matcherProgramOpts))
// create the CEL environment
env, err := cel.NewEnv(
cel.Function(CELPlaceholderFuncName, cel.SingletonBinaryBinding(m.caddyPlaceholderFunc), cel.Overload(
CELPlaceholderFuncName+"_httpRequest_string",
[]*cel.Type{httpRequestObjectType, cel.StringType},
cel.AnyType,
)),
cel.Variable(CELRequestVarName, httpRequestObjectType),
cel.CustomTypeAdapter(m.ta),
ext.Strings(),
ext.Bindings(),
ext.Lists(),
ext.Math(),
matcherLib,
)
if err != nil {
return fmt.Errorf("setting up CEL environment: %v", err)
}
// parse and type-check the expression
checked, issues := env.Compile(m.expandedExpr)
if issues.Err() != nil {
return fmt.Errorf("compiling CEL program: %s", issues.Err())
}
// request matching is a boolean operation, so we don't really know
// what to do if the expression returns a non-boolean type
if checked.OutputType() != cel.BoolType {
return fmt.Errorf("CEL request matcher expects return type of bool, not %s", checked.OutputType())
}
// compile the "program"
m.prg, err = env.Program(checked, cel.EvalOptions(cel.OptOptimize))
if err != nil {
return fmt.Errorf("compiling CEL program: %s", err)
}
return nil
}
// Match returns true if r matches m.
func (m MatchExpression) Match(r *http.Request) bool {
celReq := celHTTPRequest{r}
out, _, err := m.prg.Eval(celReq)
if err != nil {
m.log.Error("evaluating expression", zap.Error(err))
SetVar(r.Context(), MatcherErrorVarKey, err)
return false
}
if outBool, ok := out.Value().(bool); ok {
return outBool
}
return false
}
// UnmarshalCaddyfile implements caddyfile.Unmarshaler.
func (m *MatchExpression) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
d.Next() // consume matcher name
// if there's multiple args, then we need to keep the raw
// tokens because the user may have used quotes within their
// CEL expression (e.g. strings) and we should retain that
if d.CountRemainingArgs() > 1 {
m.Expr = strings.Join(d.RemainingArgsRaw(), " ")
return nil
}
// there should at least be one arg
if !d.NextArg() {
return d.ArgErr()
}
// if there's only one token, then we can safely grab the
// cleaned token (no quotes) and use that as the expression
// because there's no valid CEL expression that is only a
// quoted string; commonly quotes are used in Caddyfile to
// define the expression
m.Expr = d.Val()
// use the named matcher's name, to fill regexp
// matchers names by default
m.Name = d.GetContextString(caddyfile.MatcherNameCtxKey)
return nil
}
// caddyPlaceholderFunc implements the custom CEL function that accesses the
// Replacer on a request and gets values from it.
func (m MatchExpression) caddyPlaceholderFunc(lhs, rhs ref.Val) ref.Val {
celReq, ok := lhs.(celHTTPRequest)
if !ok {
return types.NewErr(
"invalid request of type '%v' to %s(request, placeholderVarName)",
lhs.Type(),
CELPlaceholderFuncName,
)
}
phStr, ok := rhs.(types.String)
if !ok {
return types.NewErr(
"invalid placeholder variable name of type '%v' to %s(request, placeholderVarName)",
rhs.Type(),
CELPlaceholderFuncName,
)
}
repl := celReq.Context().Value(caddy.ReplacerCtxKey).(*caddy.Replacer)
val, _ := repl.Get(string(phStr))
return m.ta.NativeToValue(val)
}
// httpRequestCELType is the type representation of a native HTTP request.
var httpRequestCELType = cel.ObjectType("http.Request", traits.ReceiverType)
// celHTTPRequest wraps an http.Request with ref.Val interface methods.
//
// This type also implements the interpreter.Activation interface which
// drops allocation costs for CEL expression evaluations by roughly half.
type celHTTPRequest struct{ *http.Request }
func (cr celHTTPRequest) ResolveName(name string) (any, bool) {
if name == CELRequestVarName {
return cr, true
}
return nil, false
}
func (cr celHTTPRequest) Parent() interpreter.Activation {
return nil
}
func (cr celHTTPRequest) ConvertToNative(typeDesc reflect.Type) (any, error) {
return cr.Request, nil
}
func (celHTTPRequest) ConvertToType(typeVal ref.Type) ref.Val {
panic("not implemented")
}
func (cr celHTTPRequest) Equal(other ref.Val) ref.Val {
if o, ok := other.Value().(celHTTPRequest); ok {
return types.Bool(o.Request == cr.Request)
}
return types.ValOrErr(other, "%v is not comparable type", other)
}
func (celHTTPRequest) Type() ref.Type { return httpRequestCELType }
func (cr celHTTPRequest) Value() any { return cr }
var pkixNameCELType = cel.ObjectType("pkix.Name", traits.ReceiverType)
// celPkixName wraps an pkix.Name with
// methods to satisfy the ref.Val interface.
type celPkixName struct{ *pkix.Name }
func (pn celPkixName) ConvertToNative(typeDesc reflect.Type) (any, error) {
return pn.Name, nil
}
func (pn celPkixName) ConvertToType(typeVal ref.Type) ref.Val {
if typeVal.TypeName() == "string" {
return types.String(pn.Name.String())
}
panic("not implemented")
}
func (pn celPkixName) Equal(other ref.Val) ref.Val {
if o, ok := other.Value().(string); ok {
return types.Bool(pn.Name.String() == o)
}
return types.ValOrErr(other, "%v is not comparable type", other)
}
func (celPkixName) Type() ref.Type { return pkixNameCELType }
func (pn celPkixName) Value() any { return pn }
// celTypeAdapter can adapt our custom types to a CEL value.
type celTypeAdapter struct{}
func (celTypeAdapter) NativeToValue(value any) ref.Val {
switch v := value.(type) {
case celHTTPRequest:
return v
case pkix.Name:
return celPkixName{&v}
case time.Time:
return types.Timestamp{Time: v}
case error:
return types.WrapErr(v)
}
return types.DefaultTypeAdapter.NativeToValue(value)
}
// CELLibraryProducer provide CEL libraries that expose a Matcher
// implementation as a first class function within the CEL expression
// matcher.
type CELLibraryProducer interface {
// CELLibrary creates a cel.Library which makes it possible to use the
// target object within CEL expression matchers.
CELLibrary(caddy.Context) (cel.Library, error)
}
// CELMatcherImpl creates a new cel.Library based on the following pieces of
// data:
//
// - macroName: the function name to be used within CEL. This will be a macro
// and not a function proper.
// - funcName: the function overload name generated by the CEL macro used to
// represent the matcher.
// - matcherDataTypes: the argument types to the macro.
// - fac: a matcherFactory implementation which converts from CEL constant
// values to a Matcher instance.
//
// Note, macro names and function names must not collide with other macros or
// functions exposed within CEL expressions, or an error will be produced
// during the expression matcher plan time.
//
// The existing CELMatcherImpl support methods are configured to support a
// limited set of function signatures. For strong type validation you may need
// to provide a custom macro which does a more detailed analysis of the CEL
// literal provided to the macro as an argument.
func CELMatcherImpl(macroName, funcName string, matcherDataTypes []*cel.Type, fac CELMatcherFactory) (cel.Library, error) {
requestType := cel.ObjectType("http.Request")
var macro parser.Macro
switch len(matcherDataTypes) {
case 1:
matcherDataType := matcherDataTypes[0]
switch matcherDataType.String() {
case "list(string)":
macro = parser.NewGlobalVarArgMacro(macroName, celMatcherStringListMacroExpander(funcName))
case cel.StringType.String():
macro = parser.NewGlobalMacro(macroName, 1, celMatcherStringMacroExpander(funcName))
case CELTypeJSON.String():
macro = parser.NewGlobalMacro(macroName, 1, celMatcherJSONMacroExpander(funcName))
default:
return nil, fmt.Errorf("unsupported matcher data type: %s", matcherDataType)
}
case 2:
if matcherDataTypes[0] == cel.StringType && matcherDataTypes[1] == cel.StringType {
macro = parser.NewGlobalMacro(macroName, 2, celMatcherStringListMacroExpander(funcName))
matcherDataTypes = []*cel.Type{cel.ListType(cel.StringType)}
} else {
return nil, fmt.Errorf("unsupported matcher data type: %s, %s", matcherDataTypes[0], matcherDataTypes[1])
}
case 3:
if matcherDataTypes[0] == cel.StringType && matcherDataTypes[1] == cel.StringType && matcherDataTypes[2] == cel.StringType {
macro = parser.NewGlobalMacro(macroName, 3, celMatcherStringListMacroExpander(funcName))
matcherDataTypes = []*cel.Type{cel.ListType(cel.StringType)}
} else {
return nil, fmt.Errorf("unsupported matcher data type: %s, %s, %s", matcherDataTypes[0], matcherDataTypes[1], matcherDataTypes[2])
}
}
envOptions := []cel.EnvOption{
cel.Macros(macro),
cel.Function(funcName,
cel.Overload(funcName, append([]*cel.Type{requestType}, matcherDataTypes...), cel.BoolType),
cel.SingletonBinaryBinding(CELMatcherRuntimeFunction(funcName, fac))),
}
programOptions := []cel.ProgramOption{
cel.CustomDecorator(CELMatcherDecorator(funcName, fac)),
}
return NewMatcherCELLibrary(envOptions, programOptions), nil
}
// CELMatcherFactory converts a constant CEL value into a RequestMatcher.
type CELMatcherFactory func(data ref.Val) (RequestMatcher, error)
// matcherCELLibrary is a simplistic configurable cel.Library implementation.
type matcherCELLibrary struct {
envOptions []cel.EnvOption
programOptions []cel.ProgramOption
}
// NewMatcherCELLibrary creates a matcherLibrary from option setes.
func NewMatcherCELLibrary(envOptions []cel.EnvOption, programOptions []cel.ProgramOption) cel.Library {
return &matcherCELLibrary{
envOptions: envOptions,
programOptions: programOptions,
}
}
func (lib *matcherCELLibrary) CompileOptions() []cel.EnvOption {
return lib.envOptions
}
func (lib *matcherCELLibrary) ProgramOptions() []cel.ProgramOption {
return lib.programOptions
}
// CELMatcherDecorator matches a call overload generated by a CEL macro
// that takes a single argument, and optimizes the implementation to precompile
// the matcher and return a function that references the precompiled and
// provisioned matcher.
func CELMatcherDecorator(funcName string, fac CELMatcherFactory) interpreter.InterpretableDecorator {
return func(i interpreter.Interpretable) (interpreter.Interpretable, error) {
call, ok := i.(interpreter.InterpretableCall)
if !ok {
return i, nil
}
if call.OverloadID() != funcName {
return i, nil
}
callArgs := call.Args()
reqAttr, ok := callArgs[0].(interpreter.InterpretableAttribute)
if !ok {
return nil, errors.New("missing 'req' argument")
}
nsAttr, ok := reqAttr.Attr().(interpreter.NamespacedAttribute)
if !ok {
return nil, errors.New("missing 'req' argument")
}
varNames := nsAttr.CandidateVariableNames()
if len(varNames) != 1 || len(varNames) == 1 && varNames[0] != CELRequestVarName {
return nil, errors.New("missing 'req' argument")
}
matcherData, ok := callArgs[1].(interpreter.InterpretableConst)
if !ok {
// If the matcher arguments are not constant, then this means
// they contain a Caddy placeholder reference and the evaluation
// and matcher provisioning should be handled at dynamically.
return i, nil
}
matcher, err := fac(matcherData.Value())
if err != nil {
return nil, err
}
return interpreter.NewCall(
i.ID(), funcName, funcName+"_opt",
[]interpreter.Interpretable{reqAttr},
func(args ...ref.Val) ref.Val {
// The request value, guaranteed to be of type celHTTPRequest
celReq := args[0]
// If needed this call could be changed to convert the value
// to a *http.Request using CEL's ConvertToNative method.
httpReq := celReq.Value().(celHTTPRequest)
return types.Bool(matcher.Match(httpReq.Request))
},
), nil
}
}
// CELMatcherRuntimeFunction creates a function binding for when the input to the matcher
// is dynamically resolved rather than a set of static constant values.
func CELMatcherRuntimeFunction(funcName string, fac CELMatcherFactory) functions.BinaryOp {
return func(celReq, matcherData ref.Val) ref.Val {
matcher, err := fac(matcherData)
if err != nil {
return types.WrapErr(err)
}
httpReq := celReq.Value().(celHTTPRequest)
return types.Bool(matcher.Match(httpReq.Request))
}
}
// celMatcherStringListMacroExpander validates that the macro is called
// with a variable number of string arguments (at least one).
//
// The arguments are collected into a single list argument the following
// function call returned: <funcName>(request, [args])
func celMatcherStringListMacroExpander(funcName string) cel.MacroFactory {
return func(eh cel.MacroExprFactory, target ast.Expr, args []ast.Expr) (ast.Expr, *common.Error) {
matchArgs := []ast.Expr{}
if len(args) == 0 {
return nil, eh.NewError(0, "matcher requires at least one argument")
}
for _, arg := range args {
if isCELStringExpr(arg) {
matchArgs = append(matchArgs, arg)
} else {
return nil, eh.NewError(arg.ID(), "matcher arguments must be string constants")
}
}
return eh.NewCall(funcName, eh.NewIdent(CELRequestVarName), eh.NewList(matchArgs...)), nil
}
}
// celMatcherStringMacroExpander validates that the macro is called a single
// string argument.
//
// The following function call is returned: <funcName>(request, arg)
func celMatcherStringMacroExpander(funcName string) parser.MacroExpander {
return func(eh cel.MacroExprFactory, target ast.Expr, args []ast.Expr) (ast.Expr, *common.Error) {
if len(args) != 1 {
return nil, eh.NewError(0, "matcher requires one argument")
}
if isCELStringExpr(args[0]) {
return eh.NewCall(funcName, eh.NewIdent(CELRequestVarName), args[0]), nil
}
return nil, eh.NewError(args[0].ID(), "matcher argument must be a string literal")
}
}
// celMatcherJSONMacroExpander validates that the macro is called a single
// map literal argument.
//
// The following function call is returned: <funcName>(request, arg)
func celMatcherJSONMacroExpander(funcName string) parser.MacroExpander {
return func(eh cel.MacroExprFactory, target ast.Expr, args []ast.Expr) (ast.Expr, *common.Error) {
if len(args) != 1 {
return nil, eh.NewError(0, "matcher requires a map literal argument")
}
arg := args[0]
switch arg.Kind() {
case ast.StructKind:
return nil, eh.NewError(arg.ID(),
fmt.Sprintf("matcher input must be a map literal, not a %s", arg.AsStruct().TypeName()))
case ast.MapKind:
mapExpr := arg.AsMap()
for _, entry := range mapExpr.Entries() {
isStringPlaceholder := isCELStringExpr(entry.AsMapEntry().Key())
if !isStringPlaceholder {
return nil, eh.NewError(entry.ID(), "matcher map keys must be string literals")
}
isStringListPlaceholder := isCELStringExpr(entry.AsMapEntry().Value()) ||
isCELStringListLiteral(entry.AsMapEntry().Value())
if !isStringListPlaceholder {
return nil, eh.NewError(entry.AsMapEntry().Value().ID(), "matcher map values must be string or list literals")
}
}
return eh.NewCall(funcName, eh.NewIdent(CELRequestVarName), arg), nil
case ast.UnspecifiedExprKind, ast.CallKind, ast.ComprehensionKind, ast.IdentKind, ast.ListKind, ast.LiteralKind, ast.SelectKind:
// appeasing the linter :)
}
return nil, eh.NewError(arg.ID(), "matcher requires a map literal argument")
}
}
// CELValueToMapStrList converts a CEL value to a map[string][]string
//
// Earlier validation stages should guarantee that the value has this type
// at compile time, and that the runtime value type is map[string]any.
// The reason for the slight difference in value type is that CEL allows for
// map literals containing heterogeneous values, in this case string and list
// of string.
func CELValueToMapStrList(data ref.Val) (map[string][]string, error) {
mapStrType := reflect.TypeOf(map[string]any{})
mapStrRaw, err := data.ConvertToNative(mapStrType)
if err != nil {
return nil, err
}
mapStrIface := mapStrRaw.(map[string]any)
mapStrListStr := make(map[string][]string, len(mapStrIface))
for k, v := range mapStrIface {
switch val := v.(type) {
case string:
mapStrListStr[k] = []string{val}
case types.String:
mapStrListStr[k] = []string{string(val)}
case []string:
mapStrListStr[k] = val
case []ref.Val:
convVals := make([]string, len(val))
for i, elem := range val {
strVal, ok := elem.(types.String)
if !ok {
return nil, fmt.Errorf("unsupported value type in header match: %T", val)
}
convVals[i] = string(strVal)
}
mapStrListStr[k] = convVals
default:
return nil, fmt.Errorf("unsupported value type in header match: %T", val)
}
}
return mapStrListStr, nil
}
// isCELStringExpr indicates whether the expression is a supported string expression
func isCELStringExpr(e ast.Expr) bool {
return isCELStringLiteral(e) || isCELCaddyPlaceholderCall(e) || isCELConcatCall(e)
}
// isCELStringLiteral returns whether the expression is a CEL string literal.
func isCELStringLiteral(e ast.Expr) bool {
switch e.Kind() {
case ast.LiteralKind:
constant := e.AsLiteral()
switch constant.Type() {
case types.StringType:
return true
}
case ast.UnspecifiedExprKind, ast.CallKind, ast.ComprehensionKind, ast.IdentKind, ast.ListKind, ast.MapKind, ast.SelectKind, ast.StructKind:
// appeasing the linter :)
}
return false
}
// isCELCaddyPlaceholderCall returns whether the expression is a caddy placeholder call.
func isCELCaddyPlaceholderCall(e ast.Expr) bool {
switch e.Kind() {
case ast.CallKind:
call := e.AsCall()
if call.FunctionName() == CELPlaceholderFuncName {
return true
}
case ast.UnspecifiedExprKind, ast.ComprehensionKind, ast.IdentKind, ast.ListKind, ast.LiteralKind, ast.MapKind, ast.SelectKind, ast.StructKind:
// appeasing the linter :)
}
return false
}
// isCELConcatCall tests whether the expression is a concat function (+) with string, placeholder, or
// other concat call arguments.
func isCELConcatCall(e ast.Expr) bool {
switch e.Kind() {
case ast.CallKind:
call := e.AsCall()
if call.Target().Kind() != ast.UnspecifiedExprKind {
return false
}
if call.FunctionName() != operators.Add {
return false
}
for _, arg := range call.Args() {
if !isCELStringExpr(arg) {
return false
}
}
return true
case ast.UnspecifiedExprKind, ast.ComprehensionKind, ast.IdentKind, ast.ListKind, ast.LiteralKind, ast.MapKind, ast.SelectKind, ast.StructKind:
// appeasing the linter :)
}
return false
}
// isCELStringListLiteral returns whether the expression resolves to a list literal
// containing only string constants or a placeholder call.
func isCELStringListLiteral(e ast.Expr) bool {
switch e.Kind() {
case ast.ListKind:
list := e.AsList()
for _, elem := range list.Elements() {
if !isCELStringExpr(elem) {
return false
}
}
return true
case ast.UnspecifiedExprKind, ast.CallKind, ast.ComprehensionKind, ast.IdentKind, ast.LiteralKind, ast.MapKind, ast.SelectKind, ast.StructKind:
// appeasing the linter :)
}
return false
}
// Variables used for replacing Caddy placeholders in CEL
// expressions with a proper CEL function call; this is
// just for syntactic sugar.
var (
// The placeholder may not be preceded by a backslash; the expansion
// will include the preceding character if it is not a backslash.
placeholderRegexp = regexp.MustCompile(`([^\\]|^){([a-zA-Z][\w.-]+)}`)
placeholderExpansion = `${1}ph(req, "${2}")`
// As a second pass, we need to strip the escape character in front of
// the placeholder, if it exists.
escapedPlaceholderRegexp = regexp.MustCompile(`\\{([a-zA-Z][\w.-]+)}`)
escapedPlaceholderExpansion = `{${1}}`
CELTypeJSON = cel.MapType(cel.StringType, cel.DynType)
)
var httpRequestObjectType = cel.ObjectType("http.Request")
// The name of the CEL function which accesses Replacer values.
const CELPlaceholderFuncName = "ph"
// The name of the CEL request variable.
const CELRequestVarName = "req"
const MatcherNameCtxKey = "matcher_name"
// Interface guards
var (
_ caddy.Provisioner = (*MatchExpression)(nil)
_ RequestMatcher = (*MatchExpression)(nil)
_ caddyfile.Unmarshaler = (*MatchExpression)(nil)
_ json.Marshaler = (*MatchExpression)(nil)
_ json.Unmarshaler = (*MatchExpression)(nil)
)
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