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