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// Copyright 2016 Google Inc.
//
// 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 main
import (
"bufio"
"fmt"
"io"
"os"
"regexp"
"strings"
"sync"
)
// A Route maps a match on a domain name to a backend.
type Route struct {
match *regexp.Regexp
backend string
}
// Config stores the TLS routing configuration.
type Config struct {
mu sync.Mutex
routes []Route
}
func dnsRegex(s string) (*regexp.Regexp, error) {
if len(s) >= 2 && s[0] == '/' && s[len(s)-1] == '/' {
return regexp.Compile(s[1 : len(s)-1])
}
var b []string
for _, f := range strings.Split(s, ".") {
switch f {
case "*":
b = append(b, `[^.]+`)
case "":
return nil, fmt.Errorf("DNS name %q has empty label", s)
default:
b = append(b, regexp.QuoteMeta(f))
}
}
return regexp.Compile(strings.Join(b, `\.`))
}
// Match returns the backend for hostname.
func (c *Config) Match(hostname string) string {
c.mu.Lock()
defer c.mu.Unlock()
for _, r := range c.routes {
if r.match.MatchString(hostname) {
return r.backend
}
}
return ""
}
// Read replaces the current Config with one read from r.
func (c *Config) Read(r io.Reader) error {
var routes []Route
s := bufio.NewScanner(r)
for s.Scan() {
if strings.HasPrefix(strings.TrimSpace(s.Text()), "#") {
// Comment, ignore.
continue
}
fs := strings.Fields(s.Text())
switch len(fs) {
case 0:
continue
case 1:
return fmt.Errorf("invalid %q on a line by itself", s.Text())
case 2:
re, err := dnsRegex(fs[0])
if err != nil {
return err
}
routes = append(routes, Route{re, fs[1]})
default:
// TODO: multiple backends?
return fmt.Errorf("too many fields on line: %q", s.Text())
}
}
if err := s.Err(); err != nil {
return err
}
c.mu.Lock()
defer c.mu.Unlock()
c.routes = routes
return nil
}
// ReadFile replaces the current Config with one read from path.
func (c *Config) ReadFile(path string) error {
f, err := os.Open(path)
if err != nil {
return err
}
return c.Read(f)
}
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