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133 lines
3.6 KiB
Go
133 lines
3.6 KiB
Go
package dns
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import (
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"fmt"
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"strings"
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)
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// PrivateRdata is an interface used for implementing "Private Use" RR types, see
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// RFC 6895. This allows one to experiment with new RR types, without requesting an
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// official type code. Also see dns.PrivateHandle and dns.PrivateHandleRemove.
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type PrivateRdata interface {
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// String returns the text presentaton of the Rdata of the Private RR.
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String() string
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// Parse parses the Rdata of the private RR.
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Parse([]string) error
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// Pack is used when packing a private RR into a buffer.
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Pack([]byte) (int, error)
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// Unpack is used when unpacking a private RR from a buffer.
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// TODO(miek): diff. signature than Pack, see edns0.go for instance.
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Unpack([]byte) (int, error)
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// Copy copies the Rdata.
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Copy(PrivateRdata) error
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// Len returns the length in octets of the Rdata.
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Len() int
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}
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// PrivateRR represents an RR that uses a PrivateRdata user-defined type.
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// It mocks normal RRs and implements dns.RR interface.
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type PrivateRR struct {
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Hdr RR_Header
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Data PrivateRdata
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}
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func mkPrivateRR(rrtype uint16) *PrivateRR {
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// Panics if RR is not an instance of PrivateRR.
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rrfunc, ok := TypeToRR[rrtype]
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if !ok {
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panic(fmt.Sprintf("dns: invalid operation with Private RR type %d", rrtype))
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}
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anyrr := rrfunc()
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rr, ok := anyrr.(*PrivateRR)
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if !ok {
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panic(fmt.Sprintf("dns: RR is not a PrivateRR, TypeToRR[%d] generator returned %T", rrtype, anyrr))
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}
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return rr
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}
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// Header return the RR header of r.
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func (r *PrivateRR) Header() *RR_Header { return &r.Hdr }
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func (r *PrivateRR) String() string { return r.Hdr.String() + r.Data.String() }
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// Private len and copy parts to satisfy RR interface.
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func (r *PrivateRR) len(off int, compression map[string]struct{}) int {
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l := r.Hdr.len(off, compression)
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l += r.Data.Len()
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return l
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}
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func (r *PrivateRR) copy() RR {
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// make new RR like this:
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rr := mkPrivateRR(r.Hdr.Rrtype)
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rr.Hdr = r.Hdr
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err := r.Data.Copy(rr.Data)
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if err != nil {
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panic("dns: got value that could not be used to copy Private rdata")
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}
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return rr
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}
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func (r *PrivateRR) pack(msg []byte, off int, compression compressionMap, compress bool) (int, error) {
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n, err := r.Data.Pack(msg[off:])
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if err != nil {
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return len(msg), err
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}
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off += n
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return off, nil
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}
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func (r *PrivateRR) unpack(msg []byte, off int) (int, error) {
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off1, err := r.Data.Unpack(msg[off:])
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off += off1
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return off, err
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}
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func (r *PrivateRR) parse(c *zlexer, origin, file string) *ParseError {
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var l lex
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text := make([]string, 0, 2) // could be 0..N elements, median is probably 1
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Fetch:
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for {
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// TODO(miek): we could also be returning _QUOTE, this might or might not
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// be an issue (basically parsing TXT becomes hard)
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switch l, _ = c.Next(); l.value {
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case zNewline, zEOF:
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break Fetch
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case zString:
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text = append(text, l.token)
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}
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}
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err := r.Data.Parse(text)
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if err != nil {
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return &ParseError{file, err.Error(), l}
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}
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return nil
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}
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func (r1 *PrivateRR) isDuplicate(r2 RR) bool { return false }
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// PrivateHandle registers a private resource record type. It requires
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// string and numeric representation of private RR type and generator function as argument.
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func PrivateHandle(rtypestr string, rtype uint16, generator func() PrivateRdata) {
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rtypestr = strings.ToUpper(rtypestr)
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TypeToRR[rtype] = func() RR { return &PrivateRR{RR_Header{}, generator()} }
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TypeToString[rtype] = rtypestr
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StringToType[rtypestr] = rtype
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}
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// PrivateHandleRemove removes definitions required to support private RR type.
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func PrivateHandleRemove(rtype uint16) {
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rtypestr, ok := TypeToString[rtype]
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if ok {
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delete(TypeToRR, rtype)
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delete(TypeToString, rtype)
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delete(StringToType, rtypestr)
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}
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}
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