a441f93e0c
* Finish the nodata stuff. See issue #9 * middleware/etc: add response to SOA queries * Remove and add a few TODOs
115 lines
3.1 KiB
Go
115 lines
3.1 KiB
Go
package middleware
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import (
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"strconv"
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"strings"
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"time"
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"github.com/miekg/dns"
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)
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// Replacer is a type which can replace placeholder
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// substrings in a string with actual values from a
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// dns.Msg and responseRecorder. Always use
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// NewReplacer to get one of these.
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type Replacer interface {
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Replace(string) string
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Set(key, value string)
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}
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type replacer struct {
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replacements map[string]string
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emptyValue string
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}
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// NewReplacer makes a new replacer based on r and rr.
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// Do not create a new replacer until r and rr have all
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// the needed values, because this function copies those
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// values into the replacer. rr may be nil if it is not
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// available. emptyValue should be the string that is used
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// in place of empty string (can still be empty string).
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func NewReplacer(r *dns.Msg, rr *ResponseRecorder, emptyValue string) Replacer {
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state := State{W: rr, Req: r}
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rep := replacer{
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replacements: map[string]string{
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"{type}": state.Type(),
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"{name}": state.Name(),
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"{class}": state.Class(),
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"{proto}": state.Proto(),
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"{when}": func() string {
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return time.Now().Format(timeFormat)
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}(),
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"{remote}": state.IP(),
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"{port}": func() string {
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p, _ := state.Port()
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return p
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}(),
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},
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emptyValue: emptyValue,
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}
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if rr != nil {
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rcode := dns.RcodeToString[rr.rcode]
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if rcode == "" {
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rcode = strconv.Itoa(rr.rcode)
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}
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rep.replacements["{rcode}"] = rcode
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rep.replacements["{size}"] = strconv.Itoa(rr.size)
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rep.replacements["{duration}"] = time.Since(rr.start).String()
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}
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// Header placeholders (case-insensitive)
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rep.replacements[headerReplacer+"id}"] = strconv.Itoa(int(r.Id))
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rep.replacements[headerReplacer+"opcode}"] = strconv.Itoa(int(r.Opcode))
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rep.replacements[headerReplacer+"do}"] = boolToString(state.Do())
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rep.replacements[headerReplacer+"bufsize}"] = strconv.Itoa(state.Size())
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return rep
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}
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// Replace performs a replacement of values on s and returns
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// the string with the replaced values.
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func (r replacer) Replace(s string) string {
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// Header replacements - these are case-insensitive, so we can't just use strings.Replace()
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for strings.Contains(s, headerReplacer) {
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idxStart := strings.Index(s, headerReplacer)
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endOffset := idxStart + len(headerReplacer)
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idxEnd := strings.Index(s[endOffset:], "}")
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if idxEnd > -1 {
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placeholder := strings.ToLower(s[idxStart : endOffset+idxEnd+1])
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replacement := r.replacements[placeholder]
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if replacement == "" {
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replacement = r.emptyValue
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}
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s = s[:idxStart] + replacement + s[endOffset+idxEnd+1:]
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} else {
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break
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}
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}
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// Regular replacements - these are easier because they're case-sensitive
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for placeholder, replacement := range r.replacements {
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if replacement == "" {
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replacement = r.emptyValue
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}
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s = strings.Replace(s, placeholder, replacement, -1)
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}
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return s
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}
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// Set sets key to value in the replacements map.
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func (r replacer) Set(key, value string) {
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r.replacements["{"+key+"}"] = value
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}
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func boolToString(b bool) string {
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if b {
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return "true"
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}
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return "false"
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}
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const (
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timeFormat = "02/Jan/2006:15:04:05 -0700"
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headerReplacer = "{>"
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)
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