Add DNS support to pcap (#100)

* begin adding dns pcap functionality

* improve question formatting

* work on capturing answers as well

* finalize DNS printing

* increase subfield limits

* add FlagContainer type

* prettier DNS printing

ipv4/icmpv4/icmpv4.go

@@ -6,6 +6,8 @@ import (
 	"github.com/soypat/lneto"
 )
 
+//go:generate stringer -type=Type,CodeDestinationUnreachable,CodeRedirect -linecomment -output stringers.go
+
 const (
 	sizeHeader = 8
 )
@@ -33,7 +35,7 @@ const (
 type CodeTimeExceeded uint8
 
 const (
-	CodeExceededInTransit  CodeTimeExceeded = iota // TTL exceeded in transit
+	CodeExceededInTransit  CodeTimeExceeded = iota // TTL exceeded
 	CodeFragmentReassembly                         // fragment reassembly time exceeded
 )
 

ipv4/icmpv4/stringers.go

@@ -0,0 +1,93 @@
+// Code generated by "stringer -type=Type,CodeDestinationUnreachable,CodeRedirect -linecomment -output stringers.go"; DO NOT EDIT.
+
+package icmpv4
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[TypeEchoReply-0]
+	_ = x[TypeEcho-8]
+	_ = x[TypeDestinationUnreachable-3]
+	_ = x[TypeSourceQuench-4]
+	_ = x[TypeRedirect-5]
+	_ = x[TypeTimeExceeded-11]
+	_ = x[TypeParameterProblem-12]
+	_ = x[TypeTimestamp-13]
+	_ = x[TypeTimestampReply-14]
+	_ = x[TypeInfoRequest-15]
+	_ = x[TypeInfoRequestReply-16]
+}
+
+const (
+	_Type_name_0 = "echo reply"
+	_Type_name_1 = "destination unreachablesource quenchredirect"
+	_Type_name_2 = "echo"
+	_Type_name_3 = "time exceededparameter problemtimestamptimestamp replyinformation requestinformation request reply"
+)
+
+var (
+	_Type_index_1 = [...]uint8{0, 23, 36, 44}
+	_Type_index_3 = [...]uint8{0, 13, 30, 39, 54, 73, 98}
+)
+
+func (i Type) String() string {
+	switch {
+	case i == 0:
+		return _Type_name_0
+	case 3 <= i && i <= 5:
+		i -= 3
+		return _Type_name_1[_Type_index_1[i]:_Type_index_1[i+1]]
+	case i == 8:
+		return _Type_name_2
+	case 11 <= i && i <= 16:
+		i -= 11
+		return _Type_name_3[_Type_index_3[i]:_Type_index_3[i+1]]
+	default:
+		return "Type(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+}
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[CodeNetUnreachable-0]
+	_ = x[CodeHostUnreachable-1]
+	_ = x[CodeProtoUnreachable-2]
+	_ = x[CodePortUnreachable-3]
+	_ = x[CodeFragNeededAndDFSet-4]
+	_ = x[CodeSourceRouteFailed-5]
+}
+
+const _CodeDestinationUnreachable_name = "net unreachablehost unreachableprotocol unreachableport unreachablefragmentation needed and DF setsource route failed"
+
+var _CodeDestinationUnreachable_index = [...]uint8{0, 15, 31, 51, 67, 98, 117}
+
+func (i CodeDestinationUnreachable) String() string {
+	if i >= CodeDestinationUnreachable(len(_CodeDestinationUnreachable_index)-1) {
+		return "CodeDestinationUnreachable(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _CodeDestinationUnreachable_name[_CodeDestinationUnreachable_index[i]:_CodeDestinationUnreachable_index[i+1]]
+}
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[CodeRedirectForNetwork-0]
+	_ = x[CodeRedirectForHost-1]
+	_ = x[CodeRedirectForToSAndNetwork-2]
+	_ = x[CodeRedirectToSAndHost-3]
+}
+
+const _CodeRedirect_name = "redirect for networkredirect for hostredirect for ToS+networkredirect for ToS+host"
+
+var _CodeRedirect_index = [...]uint8{0, 20, 37, 61, 82}
+
+func (i CodeRedirect) String() string {
+	if i >= CodeRedirect(len(_CodeRedirect_index)-1) {
+		return "CodeRedirect(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _CodeRedirect_name[_CodeRedirect_index[i]:_CodeRedirect_index[i+1]]
+}