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fix bugs in GetLocationByMap #78

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fix bugs in GetLocationByMap #78

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81 changes: 46 additions & 35 deletions dnsrocks/db/rdbdriver.go
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@ package db

import (
"bytes"
"encoding/binary"
"fmt"
"net"
"time"
Expand Down Expand Up @@ -167,50 +168,32 @@ func isIPv4(addr net.IP) bool {
return addr != nil && (len(addr) == net.IPv4len || net.IP.Equal(addr[:12], firstIPv4[:12]))
}

// GetLocationByMap finds and returns location and mask. If the location is not found, returns nil and 0.
func (r *rdbdriver) GetLocationByMap(ipnet *net.IPNet, mapID []byte, context Context) (loc []byte, mlen uint8, err error) {
// Lookup the subnet in IP MAP: map ID, IP address -> LocID, mask
// Build key prefix: "\000\000\000!{MapID}"
// We prime the key byte array (fullKey) with the key prefix,
// followed by the original IP address in V6 format.
nmap := len(mapID)
fullKey := make([]byte, 4+nmap+net.IPv6len+1) // 4 bytes for prefix, n bytes for mapID, and the rest is IP and masklen
copy(fullKey, ipMapRangePointKeyElement) // prefix, 4 bytes
copy(fullKey[4:], mapID) // mapID, n bytes
copy(fullKey[4+nmap:], ipnet.IP.To16())
reqMaskLen, _ := ipnet.Mask.Size()
if isIPv4(ipnet.IP) {
reqMaskLen += 128 - 32
}
copy(fullKey[4+nmap+16:], []byte{uint8(reqMaskLen)})

ctx := context.(*rdb.Context)

// NOTE: Rearranger has merging on adjacent locations with same mask and locID,
// so findClosest() might return the key that will match some other IP. It is fine for our purposes.
// foundVal will consist of mask (1 byte) and LocID (2 bytes); if LocID is null, then there will be mask only.
foundKey, foundVal, err := r.db.FindClosest(fullKey, ctx)
if err != nil {
return nil, 0, err
func unpackLocation(foundKey, foundVal []byte) (loc []byte, mlen uint8, err error) {
if len(foundVal) < 4 {
if len(foundVal) == 0 {
return nil, 0, nil // consistent with the return at the end of cdbdriver.go:/GetLocationByMap
}
return nil, 0, fmt.Errorf("short value: length %d, value %v", len(foundVal), foundVal)
}
if len(foundVal) == 0 {
return nil, 0, nil // consistent with the return at the end of cdbdriver.go:/GetLocationByMap
if len(foundKey) == 0 {
return nil, 0, fmt.Errorf("empty key with non-empty value %v", foundVal)
}
if len(foundVal) < 4 {
err = fmt.Errorf("short value: length %d, value %v, map %v", len(foundVal), foundVal, mapID)
return nil, 0, err
// take the first value from the potential multi-value - see ../dnsdata/rdb/rdb_util.go
valLen := binary.LittleEndian.Uint32(foundVal[:4])
if len(foundVal) < int(valLen)+4 {
return nil, 0, fmt.Errorf("short value: length %d, length from header %d, value %v", len(foundVal), valLen, foundVal)
}
foundVal = foundVal[4:] // skip over the multi-value header - see ../dnsdata/rdb/rdb_util.go:/Put
foundVal = foundVal[4 : 4+valLen] // skip over the multi-value header
mlen = foundKey[len(foundKey)-1]
switch len(foundVal) {
switch valLen {
case 0:
// Rearranger will always add /0 mask, so if anything - the empty location will match
return nil, mlen, nil
case 2:
loc = foundVal
return loc, mlen, nil
default:
if len(foundVal) < 2 {
if valLen < 3 {
err = fmt.Errorf("Invalid location length %d, value %v", len(foundVal), foundVal)
return nil, 0, err
}
Expand All @@ -219,15 +202,43 @@ func (r *rdbdriver) GetLocationByMap(ipnet *net.IPNet, mapID []byte, context Con
return loc, mlen, nil
}
locLen, foundVal := foundVal[1], foundVal[2:]
if int(locLen) > len(foundVal) {
err = fmt.Errorf("invalid location length byte %d > %d", locLen, len(foundVal))
if int(locLen) > int(valLen) {
err = fmt.Errorf("invalid location length byte %d > %d", locLen, valLen)
return nil, 0, err
}
loc = foundVal[:locLen]
return loc, mlen, nil
}
}

// GetLocationByMap finds and returns location and mask. If the location is not found, returns nil and 0.
func (r *rdbdriver) GetLocationByMap(ipnet *net.IPNet, mapID []byte, context Context) (loc []byte, mlen uint8, err error) {
// Lookup the subnet in IP MAP: map ID, IP address -> LocID, mask
// Build key prefix: "\000\000\000!{MapID}"
// We prime the key byte array (fullKey) with the key prefix,
// followed by the original IP address in V6 format.
nmap := len(mapID)
fullKey := make([]byte, 4+nmap+net.IPv6len+1) // 4 bytes for prefix, n bytes for mapID, and the rest is IP and masklen
copy(fullKey, ipMapRangePointKeyElement) // prefix, 4 bytes
copy(fullKey[4:], mapID) // mapID, n bytes
copy(fullKey[4+nmap:], ipnet.IP.To16())
reqMaskLen, _ := ipnet.Mask.Size()
if isIPv4(ipnet.IP) {
reqMaskLen += 128 - 32
}
copy(fullKey[4+nmap+16:], []byte{uint8(reqMaskLen)}) //nolint:gosec

ctx := context.(*rdb.Context)

// NOTE: Rearranger has merging on adjacent locations with same mask and locID,
// so findClosest() might return the key that will match some other IP. It is fine for our purposes.
foundKey, foundVal, err := r.db.FindClosest(fullKey, ctx)
if err != nil {
return nil, 0, err
}
return unpackLocation(foundKey, foundVal)
}

func (r *rdbdriver) Close() error {
return r.db.Close()
}
Expand Down
130 changes: 130 additions & 0 deletions dnsrocks/db/rdbdriver_test.go
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Original file line number Diff line number Diff line change
@@ -0,0 +1,130 @@
/*
Copyright (c) Meta Platforms, Inc. and affiliates.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package db

import (
"testing"

"github.com/stretchr/testify/require"
)

func TestUnpackLocation(t *testing.T) {
testCases := []struct {
name string
key []byte
value []byte
wantLocation []byte
wantMask uint8
wantErr bool
}{
{
name: "empty key and value",
wantErr: false,
},
{
name: "empty key",
value: []byte{2, 0, 0, 0, 3, 4},
wantErr: true,
},
{
name: "empty location",
key: []byte{1, 2, 3},
wantErr: false, // empty location is valid
},
{
name: "short location",
key: []byte{1, 2, 3},
value: []byte{2, 0, 0}, // value should be at least 4 bytes (uint32 for length of multi-value field)
wantErr: true,
},
{
name: "not enough bytes for provided length",
key: []byte{1, 2, 3},
value: []byte{4, 0, 0, 0, 3, 2}, // 4 is the length of the first multi-value field
wantErr: true,
},
{
name: "not enough bytes for long location",
key: []byte{1, 2, 3},
value: []byte{6, 0, 0, 0, 255, 8, 3, 4, 5, 6}, // 4 is the length of the first multi-value, 255 is the marker, 8 is the length of the location
wantErr: true,
},
{
name: "zero length location",
key: []byte{1, 2, 3},
value: []byte{0, 0, 0, 0},
wantErr: false,
wantMask: 3,
},
{
name: "two-byte location",
key: []byte{1, 2, 3},
value: []byte{2, 0, 0, 0, 82, 10}, // 2 is the length of the first multi-value field, 82, 10 is the location
wantErr: false,
wantLocation: []byte{82, 10},
wantMask: 3,
},
{
name: "long location without marker",
key: []byte{1, 2, 3},
value: []byte{4, 0, 0, 0, 82, 10, 7, 8}, // 4 is the length of the first multi-value field, 82, 10, 7, 8 is the location
wantErr: false,
wantLocation: []byte{82, 10, 7, 8},
wantMask: 3,
},
{
name: "long location with marker",
key: []byte{1, 2, 3},
value: []byte{6, 0, 0, 0, 255, 4, 97, 108, 101, 120}, // 6 is the length of the first multi-value field, 255 is the marker, 4 is the length of the location, 'alex' is the location
wantErr: false,
wantLocation: []byte("alex"),
wantMask: 3,
},
{
name: "multi-value two-byte location",
key: []byte{1, 2, 3},
value: []byte{2, 0, 0, 0, 82, 10, 2, 0, 0, 0, 3, 4}, // 2 is the length of the first multi-value field, 82, 10 is the location, 2 is the length of the second multi-value field, 3, 4 is the location
wantErr: false,
wantLocation: []byte{82, 10},
wantMask: 3,
},
{
name: "multi-value empty location",
key: []byte{1, 2, 3},
value: []byte{0, 0, 0, 0, 2, 0, 0, 0, 3, 4}, // 0 is the length of the first multi-value field, 2 is the length of the second multi-value field, 3, 4 is the second location
wantErr: false,
wantMask: 3,
},
{
name: "multi-value long location",
key: []byte{1, 2, 3},
value: []byte{6, 0, 0, 0, 255, 4, 97, 108, 101, 120, 2, 0, 0, 0, 3, 4}, // 6 is the length of the first multi-value field, 255 is the marker, 4 is the length of the location, 'alex' is the location, 2 is the length of the second multi-value field, 3, 4 is the second location
wantErr: false,
wantLocation: []byte("alex"),
wantMask: 3,
},
}
for _, tc := range testCases {
t.Run(tc.name, func(t *testing.T) {
gotLocation, gotMask, err := unpackLocation(tc.key, tc.value)
if tc.wantErr {
require.Error(t, err)
return
}
require.NoError(t, err)
require.Equal(t, tc.wantLocation, gotLocation)
require.Equal(t, tc.wantMask, gotMask)
})
}
}
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