Skip to content

Fix interpretation of TTL as UINT32 with most significant bit unset #116

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
clue merged 1 commit into from
Nov 5, 2018
Merged

Fix interpretation of TTL as UINT32 with most significant bit unset #116

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
3 changes: 2 additions & 1 deletion src/Model/Record.php
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,8 @@ class Record
public $class;

/**
* @var int maximum TTL in seconds (UINT16)
* @var int maximum TTL in seconds (UINT32, most significant bit always unset)
* @link https://tools.ietf.org/html/rfc2181#section-8
*/
public $ttl;

Expand Down
10 changes: 9 additions & 1 deletion src/Protocol/Parser.php
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -154,6 +154,11 @@ public function parseAnswer(Message $message)
list($ttl) = array_values(unpack('N', substr($message->data, $consumed, 4)));
$consumed += 4;

// TTL is a UINT32 that must not have most significant bit set for BC reasons
if ($ttl < 0 || $ttl >= 1 << 31) {
$ttl = 0;
}

list($rdLength) = array_values(unpack('n', substr($message->data, $consumed, 2)));
$consumed += 2;

Expand Down Expand Up @@ -219,7 +224,6 @@ public function parseAnswer(Message $message)
$message->consumed = $consumed;

$name = implode('.', $labels);
$ttl = $this->signedLongToUnsignedLong($ttl);
$record = new Record($name, $type, $class, $ttl, $rdata);

$message->answers[] = $record;
Expand Down Expand Up @@ -291,6 +295,10 @@ public function getCompressedLabelOffset($data, $consumed)
return array($peek & $mask, $consumed + 2);
}

/**
* @deprecated unused, exists for BC only
* @codeCoverageIgnore
*/
public function signedLongToUnsignedLong($i)
{
return $i & 0x80000000 ? $i - 0xffffffff : $i;
Expand Down
75 changes: 75 additions & 0 deletions tests/Protocol/ParserTest.php
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -157,6 +157,81 @@ public function testParseAnswerWithInlineData()
$this->assertSame('178.79.169.131', $response->answers[0]->data);
}

public function testParseAnswerWithExcessiveTtlReturnsZeroTtl()
{
$data = "";
$data .= "04 69 67 6f 72 02 69 6f 00"; // answer: igor.io
$data .= "00 01 00 01"; // answer: type A, class IN
$data .= "ff ff ff ff"; // answer: ttl 2^32 - 1
$data .= "00 04"; // answer: rdlength 4
$data .= "b2 4f a9 83"; // answer: rdata 178.79.169.131

$data = $this->convertTcpDumpToBinary($data);

$response = new Message();
$response->header->set('anCount', 1);
$response->data = $data;

$this->parser->parseAnswer($response);

$this->assertCount(1, $response->answers);
$this->assertSame('igor.io', $response->answers[0]->name);
$this->assertSame(Message::TYPE_A, $response->answers[0]->type);
$this->assertSame(Message::CLASS_IN, $response->answers[0]->class);
$this->assertSame(0, $response->answers[0]->ttl);
$this->assertSame('178.79.169.131', $response->answers[0]->data);
}

public function testParseAnswerWithTtlExactlyBoundaryReturnsZeroTtl()
{
$data = "";
$data .= "04 69 67 6f 72 02 69 6f 00"; // answer: igor.io
$data .= "00 01 00 01"; // answer: type A, class IN
$data .= "80 00 00 00"; // answer: ttl 2^31
$data .= "00 04"; // answer: rdlength 4
$data .= "b2 4f a9 83"; // answer: rdata 178.79.169.131

$data = $this->convertTcpDumpToBinary($data);

$response = new Message();
$response->header->set('anCount', 1);
$response->data = $data;

$this->parser->parseAnswer($response);

$this->assertCount(1, $response->answers);
$this->assertSame('igor.io', $response->answers[0]->name);
$this->assertSame(Message::TYPE_A, $response->answers[0]->type);
$this->assertSame(Message::CLASS_IN, $response->answers[0]->class);
$this->assertSame(0, $response->answers[0]->ttl);
$this->assertSame('178.79.169.131', $response->answers[0]->data);
}

public function testParseAnswerWithMaximumTtlReturnsExactTtl()
{
$data = "";
$data .= "04 69 67 6f 72 02 69 6f 00"; // answer: igor.io
$data .= "00 01 00 01"; // answer: type A, class IN
$data .= "7f ff ff ff"; // answer: ttl 2^31 - 1
$data .= "00 04"; // answer: rdlength 4
$data .= "b2 4f a9 83"; // answer: rdata 178.79.169.131

$data = $this->convertTcpDumpToBinary($data);

$response = new Message();
$response->header->set('anCount', 1);
$response->data = $data;

$this->parser->parseAnswer($response);

$this->assertCount(1, $response->answers);
$this->assertSame('igor.io', $response->answers[0]->name);
$this->assertSame(Message::TYPE_A, $response->answers[0]->type);
$this->assertSame(Message::CLASS_IN, $response->answers[0]->class);
$this->assertSame(0x7fffffff, $response->answers[0]->ttl);
$this->assertSame('178.79.169.131', $response->answers[0]->data);
}

public function testParseAnswerWithUnknownType()
{
$data = "";
Expand Down