lib/dns: fix unpacking resource data on HTTPS record

Instead of passing the whole packet, pass the packet for unpacking
target name only and rdata for unpacking the SVCB HTTPS record.

5 files changed, 128 insertions, 16 deletions

diff --git a/lib/dns/message_test.go b/lib/dns/message_test.go
index 824ace68..8a1d47b2 100644
--- a/lib/dns/message_test.go
+++ b/lib/dns/message_test.go
@@ -2178,3 +2178,40 @@ func TestUnpackMessage_SVCB(t *testing.T) {
 		test.Assert(t, name, string(tdata.Output[name]), string(stream))
 	}
 }
+
+func TestUnpackMessage_HTTPS(t *testing.T) {
+	var (
+		logp  = `TestUnpackMessage_HTTPS`
+		tdata *test.Data
+		err   error
+	)
+
+	tdata, err = test.LoadData(`testdata/message/UnpackMessage_HTTPS_test.txt`)
+	if err != nil {
+		t.Fatal(logp, err)
+	}
+
+	var (
+		name   string
+		input  []byte
+		stream []byte
+		msg    *Message
+	)
+	for name, input = range tdata.Input {
+		stream, err = hexdump.Parse(input, true)
+		if err != nil {
+			t.Fatal(logp, err)
+		}
+
+		msg, err = UnpackMessage(stream)
+		if err != nil {
+			t.Fatal(logp, name, err)
+		}
+
+		stream, err = json.MarshalIndent(&msg, ``, `  `)
+		if err != nil {
+			t.Fatal(logp, err)
+		}
+		test.Assert(t, name, string(tdata.Output[name]), string(stream))
+	}
+}
diff --git a/lib/dns/rdata_svcb.go b/lib/dns/rdata_svcb.go
index 098e6b08..306b6f48 100644
--- a/lib/dns/rdata_svcb.go
+++ b/lib/dns/rdata_svcb.go
@@ -553,19 +553,19 @@ func (svcb *RDataSVCB) parseParams(zp *zoneParser) (err error) {
 	return nil
 }
 
-func (svcb *RDataSVCB) unpack(packet []byte) (err error) {
-	svcb.Priority = libbytes.ReadUint16(packet, 0)
-	packet = packet[2:]
-
-	var x uint
+func (svcb *RDataSVCB) unpack(packet, rdata []byte, start uint) (err error) {
+	svcb.Priority = libbytes.ReadUint16(rdata, 0)
+	rdata = rdata[2:]
+	start += 2
 
-	svcb.TargetName, x, err = unpackDomainName(packet, 0)
+	var end uint
+	svcb.TargetName, end, err = unpackDomainName(packet, start)
 	if err != nil {
 		return err
 	}
-	packet = packet[x:]
-
-	err = svcb.unpackParams(packet)
+	start = end - start
+	rdata = rdata[start:]
+	err = svcb.unpackParams(rdata)
 	if err != nil {
 		return err
 	}
diff --git a/lib/dns/resource_record.go b/lib/dns/resource_record.go
index ff8fe157..c0c04b23 100644
--- a/lib/dns/resource_record.go
+++ b/lib/dns/resource_record.go
@@ -539,11 +539,10 @@ func (rr *ResourceRecord) unpackSVCB(packet []byte, x uint) (err error) {
 		svcb = &RDataSVCB{
 			Params: map[int][]string{},
 		}
+		rdata = packet[x : x+uint(rr.rdlen)]
 	)
 
-	packet = packet[x:]
-
-	err = svcb.unpack(packet)
+	err = svcb.unpack(packet, rdata, x)
 	if err != nil {
 		return fmt.Errorf(`%s: %w`, logp, err)
 	}
@@ -561,11 +560,10 @@ func (rr *ResourceRecord) unpackHTTPS(packet []byte, x uint) (err error) {
 				Params: map[int][]string{},
 			},
 		}
+		rdata = packet[x : x+uint(rr.rdlen)]
 	)
 
-	packet = packet[x:]
-
-	err = https.RDataSVCB.unpack(packet)
+	err = https.RDataSVCB.unpack(packet, rdata, x)
 	if err != nil {
 		return fmt.Errorf(`%s: %w`, logp, err)
 	}
diff --git a/lib/dns/testdata/message/UnpackMessage_HTTPS_test.txt b/lib/dns/testdata/message/UnpackMessage_HTTPS_test.txt
new file mode 100644
index 00000000..80c1f58d
--- /dev/null
+++ b/lib/dns/testdata/message/UnpackMessage_HTTPS_test.txt
@@ -0,0 +1,77 @@
+
+>>> graph.facebook.com
+0000000 4a42 8180 0001 0003 0000 0000 0567 7261
+0000010 7068 0866 6163 6562 6f6f 6b03 636f 6d00
+0000020 0041 0001 c00c 0005 0001 0000 0bc3 000c
+0000030 0473 7461 7204 6331 3072 c012 c030 0041
+0000040 0001 0000 19d3 000d 0001 0000 0100 0602
+0000050 6832 0268 33c0 3000 4100 0100 0019 d300
+0000060 2d00 0204 7374 6172 0866 616c 6c62 6163
+0000070 6b04 6331 3072 0866 6163 6562 6f6f 6b03
+0000080 636f 6d00 0001 0006 0268 3202 6833
+
+<<< graph.facebook.com
+{
+  "Answer": [
+    {
+      "Value": "star.c10r.facebook.com",
+      "Name": "graph.facebook.com",
+      "Type": 5,
+      "Class": 1,
+      "TTL": 3011
+    },
+    {
+      "Value": {
+        "Params": {
+          "1": [
+            "h2",
+            "h3"
+          ]
+        },
+        "TargetName": "",
+        "Priority": 1
+      },
+      "Name": "star.c10r.facebook.com",
+      "Type": 65,
+      "Class": 1,
+      "TTL": 6611
+    },
+    {
+      "Value": {
+        "Params": {
+          "1": [
+            "h2",
+            "h3"
+          ]
+        },
+        "TargetName": "star.fallback.c10r.facebook.com",
+        "Priority": 2
+      },
+      "Name": "star.c10r.facebook.com",
+      "Type": 65,
+      "Class": 1,
+      "TTL": 6611
+    }
+  ],
+  "Authority": null,
+  "Additional": null,
+  "Question": {
+    "Name": "graph.facebook.com",
+    "Type": 65,
+    "Class": 1
+  },
+  "Header": {
+    "ID": 19010,
+    "IsQuery": false,
+    "Op": 0,
+    "IsAA": false,
+    "IsTC": false,
+    "IsRD": true,
+    "IsRA": true,
+    "RCode": 0,
+    "QDCount": 1,
+    "ANCount": 3,
+    "NSCount": 0,
+    "ARCount": 0
+  }
+}
diff --git a/lib/dns/testdata/message/UnpackMessage_SVCB_test.txt b/lib/dns/testdata/message/UnpackMessage_SVCB_test.txt
index 8454905f..1162c6fb 100644
--- a/lib/dns/testdata/message/UnpackMessage_SVCB_test.txt
+++ b/lib/dns/testdata/message/UnpackMessage_SVCB_test.txt
@@ -4,7 +4,7 @@ The test input taken from output of parsing SVCB record from zone file.
 >>> AliasMode
 0000000 0000 8400 0001 0001 0000 0000 0765 7861
 0000010 6d70 6c65 0363 6f6d 0000 4100 01c0 0c00
-0000020 4100 0100 0000 3c00 1100 0003 666f 6f07
+0000020 4100 0100 0000 3c00 1300 0003 666f 6f07
 0000030 6578 616d 706c 6503 636f 6d00
 
 <<< AliasMode