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phab/src/applications/diffusion/ssh/DiffusionMercurialWireClientSSHProtocolChannel.php
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DiffusionMercurialWireClientSSHProtocolChannel.php
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<?php
final class DiffusionMercurialWireClientSSHProtocolChannel
extends PhutilProtocolChannel {
private $buffer = '';
private $state = 'command';
private $expectArgumentCount;
private $argumentName;
private $expectBytes;
private $command;
private $arguments;
private $raw;
protected function encodeMessage($message) {
return $message;
}
private function initializeState($last_command = null) {
if ($last_command == 'unbundle') {
$this->command = '<raw-data>';
$this->state = 'data-length';
} else {
$this->state = 'command';
}
$this->expectArgumentCount = null;
$this->expectBytes = null;
$this->command = null;
$this->argumentName = null;
$this->arguments = array();
$this->raw = '';
}
private function readProtocolLine() {
$pos = strpos($this->buffer, "\n");
if ($pos === false) {
return null;
}
$line = substr($this->buffer, 0, $pos);
$this->raw .= $line."\n";
$this->buffer = substr($this->buffer, $pos + 1);
return $line;
}
private function readProtocolBytes() {
if (strlen($this->buffer) < $this->expectBytes) {
return null;
}
$bytes = substr($this->buffer, 0, $this->expectBytes);
$this->raw .= $bytes;
$this->buffer = substr($this->buffer, $this->expectBytes);
return $bytes;
}
private function newMessageAndResetState() {
$message = array(
'command' => $this->command,
'arguments' => $this->arguments,
'raw' => $this->raw,
);
$this->initializeState($this->command);
return $message;
}
private function newDataMessage($bytes) {
$message = array(
'command' => '<raw-data>',
'raw' => strlen($bytes)."\n".$bytes,
);
return $message;
}
protected function decodeStream($data) {
$this->buffer .= $data;
$out = array();
$messages = array();
while (true) {
if ($this->state == 'command') {
$this->initializeState();
// We're reading a command. It looks like:
//
// <command>
$line = $this->readProtocolLine();
if ($line === null) {
break;
}
$this->command = $line;
$this->state = 'arguments';
} else if ($this->state == 'arguments') {
// Check if we're still waiting for arguments.
$args = DiffusionMercurialWireProtocol::getCommandArgs($this->command);
$have = array_select_keys($this->arguments, $args);
if (count($have) == count($args)) {
// We have all the arguments. Emit a message and read the next
// command.
$messages[] = $this->newMessageAndResetState();
} else {
// We're still reading arguments. They can either look like:
//
// <name> <length(value)>
// <value>
// ...
//
// ...or like this:
//
// * <count>
// <name1> <length(value1)>
// <value1>
// ...
$line = $this->readProtocolLine();
if ($line === null) {
break;
}
list($arg, $size) = explode(' ', $line, 2);
$size = (int)$size;
if ($arg != '*') {
$this->expectBytes = $size;
$this->argumentName = $arg;
$this->state = 'value';
} else {
$this->arguments['*'] = array();
$this->expectArgumentCount = $size;
$this->state = 'argv';
}
}
} else if ($this->state == 'value' || $this->state == 'argv-value') {
// We're reading the value of an argument. We just need to wait for
// the right number of bytes to show up.
$bytes = $this->readProtocolBytes();
if ($bytes === null) {
break;
}
if ($this->state == 'argv-value') {
$this->arguments['*'][$this->argumentName] = $bytes;
$this->state = 'argv';
} else {
$this->arguments[$this->argumentName] = $bytes;
$this->state = 'arguments';
}
} else if ($this->state == 'argv') {
// We're reading a variable number of arguments. We need to wait for
// the arguments to arrive.
if ($this->expectArgumentCount) {
$line = $this->readProtocolLine();
if ($line === null) {
break;
}
list($arg, $size) = explode(' ', $line, 2);
$size = (int)$size;
$this->expectBytes = $size;
$this->argumentName = $arg;
$this->state = 'argv-value';
$this->expectArgumentCount--;
} else {
$this->state = 'arguments';
}
} else if ($this->state == 'data-length') {
// We're reading the length of a chunk of raw data. It looks like
// this:
//
// <length-in-bytes>\n
//
// The length is human-readable text (for example, "4096"), and
// may be 0.
$line = $this->readProtocolLine();
if ($line === null) {
break;
}
$this->expectBytes = (int)$line;
if (!$this->expectBytes) {
$messages[] = $this->newDataMessage('');
$this->initializeState();
} else {
$this->state = 'data-bytes';
}
} else if ($this->state == 'data-bytes') {
// We're reading some known, nonzero number of raw bytes of data.
// If we don't have any more bytes on the buffer yet, just bail:
// otherwise, we'll emit a pointless and possibly harmful 0-byte data
// frame. See T13036 for discussion.
if (!strlen($this->buffer)) {
break;
}
$bytes = substr($this->buffer, 0, $this->expectBytes);
$this->buffer = substr($this->buffer, strlen($bytes));
$this->expectBytes -= strlen($bytes);
// NOTE: We emit a data frame as soon as we read some data. This can
// cause us to repackage frames: for example, if we receive one large
// frame slowly, we may emit it as several smaller frames. In theory
// this is good; in practice, Mercurial never seems to select a frame
// size larger than 4096 bytes naturally and this may be more
// complexity and trouble than it is worth. See T13036.
$messages[] = $this->newDataMessage($bytes);
if (!$this->expectBytes) {
// We've finished reading this chunk, so go read the next chunk.
$this->state = 'data-length';
} else {
// We're waiting for more data, and have read everything available
// to us so far.
break;
}
} else {
throw new Exception(pht("Bad parser state '%s'!", $this->state));
}
}
return $messages;
}
}
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