Update deps

vendor/github.com/miekg/dns/msg.go

@@ -691,18 +691,20 @@ func (dns *Msg) Pack() (msg []byte, err error) {
 	return dns.PackBuffer(nil)
 }
 
-// PackBuffer packs a Msg, using the given buffer buf. If buf is too small
-// a new buffer is allocated.
+// PackBuffer packs a Msg, using the given buffer buf. If buf is too small a new buffer is allocated.
 func (dns *Msg) PackBuffer(buf []byte) (msg []byte, err error) {
-	// We use a similar function in tsig.go's stripTsig.
-	var (
-		dh          Header
-		compression map[string]int
-	)
-
+	var compression map[string]int
 	if dns.Compress {
-		compression = make(map[string]int) // Compression pointer mappings
+		compression = make(map[string]int) // Compression pointer mappings.
 	}
+	return dns.packBufferWithCompressionMap(buf, compression)
+}
+
+// packBufferWithCompressionMap packs a Msg, using the given buffer buf.
+func (dns *Msg) packBufferWithCompressionMap(buf []byte, compression map[string]int) (msg []byte, err error) {
+	// We use a similar function in tsig.go's stripTsig.
+
+	var dh Header
 
 	if dns.Rcode < 0 || dns.Rcode > 0xFFF {
 		return nil, ErrRcode
@@ -714,12 +716,11 @@ func (dns *Msg) PackBuffer(buf []byte) (msg []byte, err error) {
 			return nil, ErrExtendedRcode
 		}
 		opt.SetExtendedRcode(uint8(dns.Rcode >> 4))
-		dns.Rcode &= 0xF
 	}
 
 	// Convert convenient Msg into wire-like Header.
 	dh.Id = dns.Id
-	dh.Bits = uint16(dns.Opcode)<<11 | uint16(dns.Rcode)
+	dh.Bits = uint16(dns.Opcode)<<11 | uint16(dns.Rcode&0xF)
 	if dns.Response {
 		dh.Bits |= _QR
 	}
@@ -922,23 +923,27 @@ func (dns *Msg) String() string {
 // than packing it, measuring the size and discarding the buffer.
 func (dns *Msg) Len() int { return compressedLen(dns, dns.Compress) }
 
+func compressedLenWithCompressionMap(dns *Msg, compression map[string]int) int {
+	l := 12 // Message header is always 12 bytes
+	for _, r := range dns.Question {
+		compressionLenHelper(compression, r.Name, l)
+		l += r.len()
+	}
+	l += compressionLenSlice(l, compression, dns.Answer)
+	l += compressionLenSlice(l, compression, dns.Ns)
+	l += compressionLenSlice(l, compression, dns.Extra)
+	return l
+}
+
 // compressedLen returns the message length when in compressed wire format
 // when compress is true, otherwise the uncompressed length is returned.
 func compressedLen(dns *Msg, compress bool) int {
 	// We always return one more than needed.
-	l := 12 // Message header is always 12 bytes
 	if compress {
 		compression := map[string]int{}
-		for _, r := range dns.Question {
-			l += r.len()
-			compressionLenHelper(compression, r.Name)
-		}
-		l += compressionLenSlice(l, compression, dns.Answer)
-		l += compressionLenSlice(l, compression, dns.Ns)
-		l += compressionLenSlice(l, compression, dns.Extra)
-
-		return l
+		return compressedLenWithCompressionMap(dns, compression)
 	}
+	l := 12 // Message header is always 12 bytes
 
 	for _, r := range dns.Question {
 		l += r.len()
@@ -962,70 +967,94 @@ func compressedLen(dns *Msg, compress bool) int {
 	return l
 }
 
-func compressionLenSlice(len int, c map[string]int, rs []RR) int {
-	var l int
+func compressionLenSlice(lenp int, c map[string]int, rs []RR) int {
+	initLen := lenp
 	for _, r := range rs {
 		if r == nil {
 			continue
 		}
-		// track this length, and the global length in len, while taking compression into account for both.
+		// TmpLen is to track len of record at 14bits boudaries
+		tmpLen := lenp
+
 		x := r.len()
-		l += x
-		len += x
-
-		k, ok := compressionLenSearch(c, r.Header().Name)
+		// track this length, and the global length in len, while taking compression into account for both.
+		k, ok, _ := compressionLenSearch(c, r.Header().Name)
 		if ok {
-			l += 1 - k
-			len += 1 - k
+			// Size of x is reduced by k, but we add 1 since k includes the '.' and label descriptor take 2 bytes
+			// so, basically x:= x - k - 1 + 2
+			x += 1 - k
 		}
 
-		if len < maxCompressionOffset {
-			compressionLenHelper(c, r.Header().Name)
-		}
-
-		k, ok = compressionLenSearchType(c, r)
+		tmpLen += compressionLenHelper(c, r.Header().Name, tmpLen)
+		k, ok, _ = compressionLenSearchType(c, r)
 		if ok {
-			l += 1 - k
-			len += 1 - k
+			x += 1 - k
 		}
+		lenp += x
+		tmpLen = lenp
+		tmpLen += compressionLenHelperType(c, r, tmpLen)
 
-		if len < maxCompressionOffset {
-			compressionLenHelperType(c, r)
-		}
 	}
-	return l
+	return lenp - initLen
 }
 
-// Put the parts of the name in the compression map.
-func compressionLenHelper(c map[string]int, s string) {
+// Put the parts of the name in the compression map, return the size in bytes added in payload
+func compressionLenHelper(c map[string]int, s string, currentLen int) int {
+	if currentLen > maxCompressionOffset {
+		// We won't be able to add any label that could be re-used later anyway
+		return 0
+	}
+	if _, ok := c[s]; ok {
+		return 0
+	}
+	initLen := currentLen
 	pref := ""
+	prev := s
 	lbs := Split(s)
-	for j := len(lbs) - 1; j >= 0; j-- {
+	for j := 0; j < len(lbs); j++ {
 		pref = s[lbs[j]:]
+		currentLen += len(prev) - len(pref)
+		prev = pref
 		if _, ok := c[pref]; !ok {
-			c[pref] = len(pref)
+			// If first byte label is within the first 14bits, it might be re-used later
+			if currentLen < maxCompressionOffset {
+				c[pref] = currentLen
+			}
+		} else {
+			added := currentLen - initLen
+			if j > 0 {
+				// We added a new PTR
+				added += 2
+			}
+			return added
 		}
 	}
+	return currentLen - initLen
 }
 
 // Look for each part in the compression map and returns its length,
 // keep on searching so we get the longest match.
-func compressionLenSearch(c map[string]int, s string) (int, bool) {
+// Will return the size of compression found, whether a match has been
+// found and the size of record if added in payload
+func compressionLenSearch(c map[string]int, s string) (int, bool, int) {
 	off := 0
 	end := false
 	if s == "" { // don't bork on bogus data
-		return 0, false
+		return 0, false, 0
 	}
+	fullSize := 0
 	for {
 		if _, ok := c[s[off:]]; ok {
-			return len(s[off:]), true
+			return len(s[off:]), true, fullSize + off
 		}
 		if end {
 			break
 		}
+		// Each label descriptor takes 2 bytes, add it
+		fullSize += 2
 		off, end = NextLabel(s, off)
 	}
-	return 0, false
+	return 0, false, fullSize + len(s)
 }
 
 // Copy returns a new RR which is a deep-copy of r.