Enable CAA parsing

README.md

@@ -118,6 +118,7 @@ Example programs can be found in the `github.com/miekg/exdns` repository.
 * 6605 - ECDSA
 * 6725 - IANA Registry Update
 * 6742 - ILNP DNS
+* 6844 - CAA record
 * 6891 - EDNS0 update
 * 6895 - DNS IANA considerations
 * 6975 - Algorithm Understanding in DNSSEC
@@ -138,6 +139,5 @@ Example programs can be found in the `github.com/miekg/exdns` repository.
 * privatekey.Precompute() when signing?
 * Last remaining RRs: APL, ATMA, A6 and NXT and IPSECKEY;
 * Missing in parsing: ISDN, UNSPEC, ATMA;
-* CAA parsing is broken;
 * NSEC(3) cover/match/closest enclose;
 * Replies with TC bit are not parsed to the end;

dns_test.go

@@ -429,9 +429,6 @@ func TestToRFC3597(t *testing.T) {
 func TestNoRdataPack(t *testing.T) {
 	data := make([]byte, 1024)
 	for typ, fn := range typeToRR {
-		if typ == TypeCAA {
-			continue // TODO(miek): known omission
-		}
 		r := fn()
 		*r.Header() = RR_Header{Name: "miek.nl.", Rrtype: typ, Class: ClassINET, Ttl: 3600}
 		_, err := PackRR(r, data, 0, nil, false)

msg.go

@@ -100,7 +100,7 @@ var TypeToString = map[uint16]string{
 	TypeANY:        "ANY", // Meta RR
 	TypeATMA:       "ATMA",
 	TypeAXFR:       "AXFR", // Meta RR
-	TypeCAA:        "CAA",
+	TypeCAA:        "TYPE257",
 	TypeCDNSKEY:    "CDNSKEY",
 	TypeCDS:        "CDS",
 	TypeCERT:       "CERT",

types.go

@@ -1527,25 +1527,25 @@ func (rr *EUI64) copy() RR           { return &EUI64{*rr.Hdr.copyHeader(), rr.Ad
 func (rr *EUI64) String() string     { return rr.Hdr.String() + euiToString(rr.Address, 64) }
 func (rr *EUI64) len() int           { return rr.Hdr.len() + 8 }
 
-// Support in incomplete - just handle it as unknown record
-/*
 type CAA struct {
 	Hdr   RR_Header
 	Flag  uint8
 	Tag   string
-	Value string `dns:"octet"`
+	Value string `dns:"hex"`
 }
 
 func (rr *CAA) Header() *RR_Header { return &rr.Hdr }
 func (rr *CAA) copy() RR           { return &CAA{*rr.Hdr.copyHeader(), rr.Flag, rr.Tag, rr.Value} }
-func (rr *CAA) len() int           { return rr.Hdr.len() + 1 + len(rr.Tag) + 1 + len(rr.Value) }
+func (rr *CAA) len() int           { return rr.Hdr.len() + 1 + len(rr.Tag) + len(rr.Value)/2 }
 
 func (rr *CAA) String() string {
-	s := rr.Hdr.String() + strconv.FormatInt(int64(rr.Flag), 10) + " " + rr.Tag
-	s += strconv.QuoteToASCII(rr.Value)
+	s := rr.Hdr.String()
+
+	s += "\\# " + strconv.Itoa(2 + len(rr.Tag) + len(rr.Value)) + " "
+	s += fmt.Sprintf("%02X%02X%X%s", rr.Flag, len(rr.Tag), rr.Tag, strings.ToUpper(rr.Value))
 	return s
 }
-*/
+
 
 type UID struct {
 	Hdr RR_Header
@@ -1668,10 +1668,10 @@ func copyIP(ip net.IP) net.IP {
 
 // Map of constructors for each RR type.
 var typeToRR = map[uint16]func() RR{
-	TypeA:     func() RR { return new(A) },
-	TypeAAAA:  func() RR { return new(AAAA) },
-	TypeAFSDB: func() RR { return new(AFSDB) },
-	//	TypeCAA:        func() RR { return new(CAA) },
+	TypeA:          func() RR { return new(A) },
+	TypeAAAA:       func() RR { return new(AAAA) },
+	TypeAFSDB:      func() RR { return new(AFSDB) },
+	TypeCAA:        func() RR { return new(CAA) },
 	TypeCDS:        func() RR { return new(CDS) },
 	TypeCERT:       func() RR { return new(CERT) },
 	TypeCNAME:      func() RR { return new(CNAME) },

update_test.go

@@ -8,7 +8,7 @@ import (
 func TestDynamicUpdateParsing(t *testing.T) {
 	prefix := "example.com. IN "
 	for _, typ := range TypeToString {
-		if typ == "CAA" || typ == "OPT" || typ == "AXFR" || typ == "IXFR" || typ == "ANY" || typ == "TKEY" ||
+		if typ == "TYPE257" || typ == "OPT" || typ == "AXFR" || typ == "IXFR" || typ == "ANY" || typ == "TKEY" ||
 			typ == "TSIG" || typ == "ISDN" || typ == "UNSPEC" || typ == "NULL" || typ == "ATMA" {
 			continue
 		}

zscan_rr.go

@@ -2,6 +2,7 @@ package dns
 
 import (
 	"encoding/base64"
+	"encoding/hex"
 	"net"
 	"strconv"
 	"strings"
@@ -2170,10 +2171,57 @@ func setIPSECKEY(h RR_Header, c chan lex, o, f string) (RR, *ParseError, string)
 	return rr, nil, c1
 }
 
+func setCAA(h RR_Header, c chan lex, o, f string) (RR, *ParseError, string) {
+	rr := new(CAA)
+	rr.Hdr = h
+	l := <-c
+	if l.token != "\\#" {
+		return nil, &ParseError{f, "bad CAA Rdata", l}, ""
+	}
+	<-c // zBlank
+	l = <-c
+	rdlength, e := strconv.Atoi(l.token)
+	if e != nil {
+		return nil, &ParseError{f, "bad CAA Rdata", l}, ""
+	}
+	s, e1, c1 := endingToString(c, "bad CAA Rdata", f)
+	if e1 != nil {
+		return nil, e1, c1
+	}
+	if rdlength*2 != len(s) || rdlength*2 < 4 {
+		return nil, &ParseError{f, "bad CAA Rdata", l}, ""
+	}
+
+	flagbyte, e := hex.DecodeString(s[0:2])
+	if e != nil {
+		return nil, &ParseError{f, "bad CAA Flag", l}, ""
+	}
+	rr.Flag = uint8(flagbyte[0])
+
+	tagbyte, e := hex.DecodeString(s[2:4])
+	if e != nil {
+		return nil, &ParseError{f, "bad CAA Tag length", l}, ""
+	}
+	taglength := int(tagbyte[0])
+
+	if rdlength*2 < (4 + taglength) {
+		return nil, &ParseError{f, "bad CAA Tag length", l}, ""
+	}
+
+	tag, e := hex.DecodeString(s[4:4+taglength])
+	if e != nil {
+		return nil, &ParseError{f, "bad CAA Tag", l}, ""
+	}
+	rr.Tag = string(tag)
+
+	return rr, nil, c1
+}
+
 var typeToparserFunc = map[uint16]parserFunc{
 	TypeAAAA:       parserFunc{setAAAA, false},
 	TypeAFSDB:      parserFunc{setAFSDB, false},
 	TypeA:          parserFunc{setA, false},
+	TypeCAA:        parserFunc{setCAA, true},
 	TypeCDS:        parserFunc{setCDS, true},
 	TypeCDNSKEY:    parserFunc{setCDNSKEY, true},
 	TypeCERT:       parserFunc{setCERT, true},