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url_regex_filter.go
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url_regex_filter.go
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// Copyright 2015 Google Inc. All rights reserved.
//
// 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 martianurl
import (
"encoding/json"
"regexp"
"github.com/google/martian/filter"
"github.com/google/martian/parse"
)
func init() {
parse.Register("url.RegexFilter", regexFilterFromJSON)
}
// URLRegexFilter runs Modifier if the request URL matches the regex, and runs ElseModifier if not.
// This is not to be confused with url.Filter that does string matching on URL segments.
type URLRegexFilter struct {
*filter.Filter
}
type regexFilterJSON struct {
Regex string `json:"regex"`
Modifier json.RawMessage `json:"modifier"`
ElseModifier json.RawMessage `json:"else"`
Scope []parse.ModifierType `json:"scope"`
}
// NewRegexFilter constructs a filter that matches on regular expressions.
func NewRegexFilter(r *regexp.Regexp) *URLRegexFilter {
filter := filter.New()
matcher := NewRegexMatcher(r)
filter.SetRequestCondition(matcher)
filter.SetResponseCondition(matcher)
return &URLRegexFilter{filter}
}
// regexFilterFromJSON takes a JSON message as a byte slice and returns a
// parse.Result that contains a URLRegexFilter and a scope. The regex syntax is RE2
// as described at https://golang.org/s/re2syntax.
//
// Example JSON configuration message:
// {
// "scope": ["request", "response"],
// "regex": ".*www.example.com.*"
// }
func regexFilterFromJSON(b []byte) (*parse.Result, error) {
msg := ®exFilterJSON{}
if err := json.Unmarshal(b, msg); err != nil {
return nil, err
}
matcher, err := regexp.Compile(msg.Regex)
if err != nil {
return nil, err
}
filter := NewRegexFilter(matcher)
m, err := parse.FromJSON(msg.Modifier)
if err != nil {
return nil, err
}
filter.RequestWhenTrue(m.RequestModifier())
filter.ResponseWhenTrue(m.ResponseModifier())
if len(msg.ElseModifier) > 0 {
em, err := parse.FromJSON(msg.ElseModifier)
if err != nil {
return nil, err
}
if em != nil {
filter.RequestWhenFalse(em.RequestModifier())
filter.ResponseWhenFalse(em.ResponseModifier())
}
}
return parse.NewResult(filter, msg.Scope)
}