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package dns
import (
"net"
"reflect"
"strconv"
)
// NumField returns the number of rdata fields r has.
func NumField(r RR) int {
return reflect.ValueOf(r).Elem().NumField() - 1 // Remove RR_Header
}
// Field returns the rdata field i as a string. Fields are indexed starting from 1.
// RR types that holds slice data, for instance the NSEC type bitmap will return a single
// string where the types are concatenated using a space.
// Accessing non existing fields will cause a panic.
func Field(r RR, i int) string {
if i == 0 {
return ""
}
d := reflect.ValueOf(r).Elem().Field(i)
switch d.Kind() {
case reflect.String:
return d.String()
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
return strconv.FormatInt(d.Int(), 10)
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
return strconv.FormatUint(d.Uint(), 10)
case reflect.Slice:
switch reflect.ValueOf(r).Elem().Type().Field(i).Tag {
case `dns:"a"`:
// TODO(miek): Hmm store this as 16 bytes
if d.Len() < net.IPv4len {
return ""
}
if d.Len() < net.IPv6len {
return net.IPv4(byte(d.Index(0).Uint()),
byte(d.Index(1).Uint()),
byte(d.Index(2).Uint()),
byte(d.Index(3).Uint())).String()
}
return net.IPv4(byte(d.Index(12).Uint()),
byte(d.Index(13).Uint()),
byte(d.Index(14).Uint()),
byte(d.Index(15).Uint())).String()
case `dns:"aaaa"`:
if d.Len() < net.IPv6len {
return ""
}
return net.IP{
byte(d.Index(0).Uint()),
byte(d.Index(1).Uint()),
byte(d.Index(2).Uint()),
byte(d.Index(3).Uint()),
byte(d.Index(4).Uint()),
byte(d.Index(5).Uint()),
byte(d.Index(6).Uint()),
byte(d.Index(7).Uint()),
byte(d.Index(8).Uint()),
byte(d.Index(9).Uint()),
byte(d.Index(10).Uint()),
byte(d.Index(11).Uint()),
byte(d.Index(12).Uint()),
byte(d.Index(13).Uint()),
byte(d.Index(14).Uint()),
byte(d.Index(15).Uint()),
}.String()
case `dns:"nsec"`:
if d.Len() == 0 {
return ""
}
s := Type(d.Index(0).Uint()).String()
for i := 1; i < d.Len(); i++ {
s += " " + Type(d.Index(i).Uint()).String()
}
return s
default:
// if it does not have a tag its a string slice
fallthrough
case `dns:"txt"`:
if d.Len() == 0 {
return ""
}
s := d.Index(0).String()
for i := 1; i < d.Len(); i++ {
s += " " + d.Index(i).String()
}
return s
}
}
return ""
}
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