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Fix for processing packets, where our EOM or EOP is split across buffer reads

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This commit is contained in:
Deon George 2023-12-07 20:19:48 +11:00
parent ddccc44261
commit e56ecaa999
1 changed files with 18 additions and 5 deletions
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23
app/Classes/FTN/Packet.php
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@ -250,29 +250,35 @@ class Packet extends FTNBase implements \Iterator, \Countable
->singleOrFail();
}
$buf_ptr = 0;
$message = '';
$readbuf = '';
$last = '';
$buf_ptr = 0; // Pointer to the end of the current message
$message = ''; // Current message we are building
$readbuf = ''; // What we are reading to determine the message contents
$last = ''; // If during buffer reads, the end of the last buffer had our NULL end of message marker
// We loop through reading from the buffer, to find our end of message tag
while ($buf_ptr || (! feof($f) && ($readbuf=fread($f,self::BLOCKSIZE)))) {
if (! $buf_ptr)
$read_ptr = ftell($f);
// Packed messages are Message::HEADER_LEN, prefixed with self::PACKED_MSG_LEAD
// If we havent got our header yet
if (strlen($message) < (Message::HEADER_LEN+strlen(self::PACKED_MSG_LEAD))) {
$addchars = (Message::HEADER_LEN+strlen(self::PACKED_MSG_LEAD))-strlen($message);
$message .= substr($readbuf,$buf_ptr,$addchars);
$buf_ptr += $addchars;
// If our buffer wasnt big enough...
// @todo can this be true?
if ($buf_ptr >= strlen($readbuf)) {
throw new \Exception('We found a situation that this is true');
$buf_ptr = 0;
continue;
}
}
// Take 2 chars from the buffer and check if we have our end packet signature
// $last is set, because we detected a NULL, so we'll add two more chars and see if we have our EOM
// signature. Some of those chars may belong to the next message, if $last has more than 1 NULL.
if ($last && ($buf_ptr === 0)) {
$last .= substr($readbuf,0,2);
@ -286,21 +292,27 @@ class Packet extends FTNBase implements \Iterator, \Countable
continue;
}
// We didnt have an EOM marker
$last = '';
}
// See if our EOM marker is in the read buffer
if (($end=strpos($readbuf,"\x00".self::PACKED_MSG_LEAD,$buf_ptr)) === FALSE) {
// Just in case our packet break is at the end of the buffer
$last = substr($readbuf,-2);
if ((str_contains($last,"\x00")) && ($size-$read_ptr > 2)) {
// We have an EOM or EOP marker here, so loop around to get the next read
if (str_contains($last,"\x00")) {
$message .= substr($readbuf,$buf_ptr);
$buf_ptr = 0;
continue;
}
// No EOM marker
$last = '';
// See if we have an EOP marker
$end = strpos($readbuf,"\x00\x00\x00",$buf_ptr);
}
@ -312,6 +324,7 @@ class Packet extends FTNBase implements \Iterator, \Countable
continue;
// No more to read, so the packet is bad
} else
throw new InvalidPacketException(sprintf('Cannot determine END of message/packet: %s|%s',get_class($o),hex_dump($message)));