mirror of
https://github.com/caddyserver/caddy.git
synced 2024-12-23 22:27:38 -05:00
262 lines
8.2 KiB
Go
262 lines
8.2 KiB
Go
// Copyright 2015 Matthew Holt and The Caddy Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package caddyhttp
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import (
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"crypto/x509/pkix"
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"encoding/json"
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"fmt"
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"net/http"
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"reflect"
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"regexp"
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"strings"
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"time"
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"github.com/caddyserver/caddy/v2"
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"github.com/caddyserver/caddy/v2/caddyconfig/caddyfile"
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"github.com/google/cel-go/cel"
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"github.com/google/cel-go/checker/decls"
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"github.com/google/cel-go/common/types"
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"github.com/google/cel-go/common/types/ref"
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"github.com/google/cel-go/common/types/traits"
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"github.com/google/cel-go/ext"
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"github.com/google/cel-go/interpreter/functions"
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exprpb "google.golang.org/genproto/googleapis/api/expr/v1alpha1"
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"google.golang.org/protobuf/proto"
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timestamp "google.golang.org/protobuf/types/known/timestamppb"
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)
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func init() {
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caddy.RegisterModule(MatchExpression{})
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}
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// MatchExpression matches requests by evaluating a
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// [CEL](https://github.com/google/cel-spec) expression.
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// This enables complex logic to be expressed using a comfortable,
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// familiar syntax. Please refer to
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// [the standard definitions of CEL functions and operators](https://github.com/google/cel-spec/blob/master/doc/langdef.md#standard-definitions).
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//
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// This matcher's JSON interface is actually a string, not a struct.
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// The generated docs are not correct because this type has custom
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// marshaling logic.
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//
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// COMPATIBILITY NOTE: This module is still experimental and is not
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// subject to Caddy's compatibility guarantee.
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type MatchExpression struct {
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// The CEL expression to evaluate. Any Caddy placeholders
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// will be expanded and situated into proper CEL function
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// calls before evaluating.
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Expr string
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expandedExpr string
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prg cel.Program
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ta ref.TypeAdapter
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}
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// CaddyModule returns the Caddy module information.
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func (MatchExpression) CaddyModule() caddy.ModuleInfo {
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return caddy.ModuleInfo{
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ID: "http.matchers.expression",
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New: func() caddy.Module { return new(MatchExpression) },
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}
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}
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// MarshalJSON marshals m's expression.
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func (m MatchExpression) MarshalJSON() ([]byte, error) {
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return json.Marshal(m.Expr)
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}
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// UnmarshalJSON unmarshals m's expression.
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func (m *MatchExpression) UnmarshalJSON(data []byte) error {
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return json.Unmarshal(data, &m.Expr)
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}
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// Provision sets ups m.
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func (m *MatchExpression) Provision(_ caddy.Context) error {
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// replace placeholders with a function call - this is just some
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// light (and possibly naïve) syntactic sugar
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m.expandedExpr = placeholderRegexp.ReplaceAllString(m.Expr, placeholderExpansion)
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// our type adapter expands CEL's standard type support
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m.ta = celTypeAdapter{}
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// create the CEL environment
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env, err := cel.NewEnv(
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cel.Declarations(
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decls.NewVar("request", httpRequestObjectType),
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decls.NewFunction(placeholderFuncName,
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decls.NewOverload(placeholderFuncName+"_httpRequest_string",
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[]*exprpb.Type{httpRequestObjectType, decls.String},
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decls.Any)),
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),
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cel.CustomTypeAdapter(m.ta),
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ext.Strings(),
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)
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if err != nil {
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return fmt.Errorf("setting up CEL environment: %v", err)
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}
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// parse and type-check the expression
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checked, issues := env.Compile(m.expandedExpr)
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if issues != nil && issues.Err() != nil {
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return fmt.Errorf("compiling CEL program: %s", issues.Err())
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}
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// request matching is a boolean operation, so we don't really know
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// what to do if the expression returns a non-boolean type
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if !proto.Equal(checked.ResultType(), decls.Bool) {
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return fmt.Errorf("CEL request matcher expects return type of bool, not %s", checked.ResultType())
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}
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// compile the "program"
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m.prg, err = env.Program(checked,
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cel.Functions(
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&functions.Overload{
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Operator: placeholderFuncName,
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Binary: m.caddyPlaceholderFunc,
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},
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),
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)
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if err != nil {
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return fmt.Errorf("compiling CEL program: %s", err)
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}
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return nil
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}
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// Match returns true if r matches m.
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func (m MatchExpression) Match(r *http.Request) bool {
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out, _, _ := m.prg.Eval(map[string]interface{}{
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"request": celHTTPRequest{r},
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})
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if outBool, ok := out.Value().(bool); ok {
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return outBool
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}
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return false
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}
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// UnmarshalCaddyfile implements caddyfile.Unmarshaler.
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func (m *MatchExpression) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
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for d.Next() {
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m.Expr = strings.Join(d.RemainingArgs(), " ")
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}
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return nil
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}
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// caddyPlaceholderFunc implements the custom CEL function that accesses the
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// Replacer on a request and gets values from it.
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func (m MatchExpression) caddyPlaceholderFunc(lhs, rhs ref.Val) ref.Val {
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celReq, ok := lhs.(celHTTPRequest)
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if !ok {
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return types.NewErr(
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"invalid request of type '%v' to "+placeholderFuncName+"(request, placeholderVarName)",
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lhs.Type())
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}
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phStr, ok := rhs.(types.String)
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if !ok {
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return types.NewErr(
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"invalid placeholder variable name of type '%v' to "+placeholderFuncName+"(request, placeholderVarName)",
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rhs.Type())
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}
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repl := celReq.Context().Value(caddy.ReplacerCtxKey).(*caddy.Replacer)
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val, _ := repl.Get(string(phStr))
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return m.ta.NativeToValue(val)
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}
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// httpRequestCELType is the type representation of a native HTTP request.
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var httpRequestCELType = types.NewTypeValue("http.Request", traits.ReceiverType)
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// cellHTTPRequest wraps an http.Request with
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// methods to satisfy the ref.Val interface.
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type celHTTPRequest struct{ *http.Request }
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func (cr celHTTPRequest) ConvertToNative(typeDesc reflect.Type) (interface{}, error) {
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return cr.Request, nil
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}
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func (celHTTPRequest) ConvertToType(typeVal ref.Type) ref.Val {
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panic("not implemented")
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}
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func (cr celHTTPRequest) Equal(other ref.Val) ref.Val {
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if o, ok := other.Value().(celHTTPRequest); ok {
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return types.Bool(o.Request == cr.Request)
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}
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return types.ValOrErr(other, "%v is not comparable type", other)
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}
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func (celHTTPRequest) Type() ref.Type { return httpRequestCELType }
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func (cr celHTTPRequest) Value() interface{} { return cr }
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var pkixNameCELType = types.NewTypeValue("pkix.Name", traits.ReceiverType)
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// celPkixName wraps an pkix.Name with
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// methods to satisfy the ref.Val interface.
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type celPkixName struct{ *pkix.Name }
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func (pn celPkixName) ConvertToNative(typeDesc reflect.Type) (interface{}, error) {
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return pn.Name, nil
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}
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func (celPkixName) ConvertToType(typeVal ref.Type) ref.Val {
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panic("not implemented")
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}
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func (pn celPkixName) Equal(other ref.Val) ref.Val {
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if o, ok := other.Value().(string); ok {
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return types.Bool(pn.Name.String() == o)
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}
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return types.ValOrErr(other, "%v is not comparable type", other)
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}
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func (celPkixName) Type() ref.Type { return pkixNameCELType }
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func (pn celPkixName) Value() interface{} { return pn }
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// celTypeAdapter can adapt our custom types to a CEL value.
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type celTypeAdapter struct{}
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func (celTypeAdapter) NativeToValue(value interface{}) ref.Val {
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switch v := value.(type) {
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case celHTTPRequest:
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return v
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case pkix.Name:
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return celPkixName{&v}
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case time.Time:
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// TODO: eliminate direct protobuf dependency, sigh -- just wrap stdlib time.Time instead...
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return types.Timestamp{Timestamp: ×tamp.Timestamp{Seconds: v.Unix(), Nanos: int32(v.Nanosecond())}}
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case error:
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types.NewErr(v.Error())
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}
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return types.DefaultTypeAdapter.NativeToValue(value)
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}
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// Variables used for replacing Caddy placeholders in CEL
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// expressions with a proper CEL function call; this is
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// just for syntactic sugar.
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var (
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placeholderRegexp = regexp.MustCompile(`{([\w.-]+)}`)
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placeholderExpansion = `caddyPlaceholder(request, "${1}")`
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)
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var httpRequestObjectType = decls.NewObjectType("http.Request")
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// The name of the CEL function which accesses Replacer values.
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const placeholderFuncName = "caddyPlaceholder"
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// Interface guards
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var (
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_ caddy.Provisioner = (*MatchExpression)(nil)
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_ RequestMatcher = (*MatchExpression)(nil)
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_ caddyfile.Unmarshaler = (*MatchExpression)(nil)
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_ json.Marshaler = (*MatchExpression)(nil)
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_ json.Unmarshaler = (*MatchExpression)(nil)
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)
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