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PhutilICSParser.php
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Tue, Jun 4, 21:17

PhutilICSParser.php
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<?php
final class PhutilICSParser extends Phobject {
private $stack;
private $node;
private $document;
public function parseICSData($data) {
$this->stack = array();
$this->node = null;
$this->document = null;
$lines = $this->unfoldICSLines($data);
foreach ($lines as $line) {
$matches = null;
if (preg_match('(^BEGIN:(.*)\z)', $line, $matches)) {
$this->beginParsingNode($matches[1]);
} else if (preg_match('(^END:(.*)\z)', $line, $matches)) {
$this->endParsingNode($matches[1]);
} else {
$this->parseICSProperty($line);
}
}
if (!$this->document) {
$this->raiseParseFailure(
pht(
'Expected ICS document to define a "VCALENDAR" section.'));
}
if ($this->stack) {
$this->raiseParseFailure(
pht(
'Expected all "BEGIN:" sections in ICS document to have '.
'corresponding "END:" sections.'));
}
$document = $this->document;
$this->document = null;
return $document;
}
private function getNode() {
return $this->node;
}
private function unfoldICSLines($data) {
$lines = phutil_split_lines($data, $retain_endings = false);
// ICS files are wrapped at 75 characters, with overlong lines continued
// on the following line with an initial space or tab. Unwrap all of the
// lines in the file.
$last = null;
foreach ($lines as $idx => $line) {
if (!preg_match('/^[ \t]/', $line)) {
$last = $idx;
continue;
}
if ($last === null) {
throw new Exception(
pht(
'First line of ICS file begins with a space or tab, but this '.
'marks a continuation line.'));
}
$lines[$last] = $lines[$last].substr($line, 1);
unset($lines[$idx]);
}
return $lines;
}
private function beginParsingNode($type) {
$node = $this->getNode();
$new_node = $this->newICSNode($type);
if ($node) {
if ($node instanceof PhutilCalendarContainerNode) {
$node->appendChild($new_node);
} else {
$this->raiseParseFailure(
pht(
'Found unexpected node "%s" inside node "%s".',
$new_node->getAttribute('ics.type'),
$node->getAttribute('ics.type')));
}
} else {
if ($new_node instanceof PhutilCalendarDocumentNode) {
if ($this->document) {
$this->raiseParseFailure(
pht(
'Found multiple "VCALENDAR" nodes in ICS document, '.
'expected only one.'));
} else {
$this->document = $new_node;
}
} else {
$this->raiseParseFailure(
pht(
'Expected ICS document to begin "BEGIN:VCALENDAR".'));
}
}
$this->stack[] = $new_node;
$this->node = $new_node;
return $this;
}
private function newICSNode($type) {
switch ($type) {
case 'VCALENDAR':
$node = new PhutilCalendarDocumentNode();
break;
case 'VEVENT':
$node = new PhutilCalendarEventNode();
break;
default:
$node = new PhutilCalendarRawNode();
break;
}
$node->setAttribute('ics.type', $type);
return $node;
}
private function endParsingNode($type) {
$node = $this->getNode();
if (!$node) {
$this->raiseParseFailure(
pht(
'Found unexpected "END" without a "BEGIN".'));
}
$old_type = $node->getAttribute('ics.type');
if ($old_type != $type) {
$this->raiseParseFailure(
pht(
'Found mismatched "BEGIN" ("%s") and "END" ("%s") sections.',
$old_type,
$type));
}
array_pop($this->stack);
if ($this->stack) {
$this->node = last($this->stack);
} else {
$this->node = null;
}
return $this;
}
private function parseICSProperty($line) {
$matches = null;
// Properties begin with an alphanumeric name with no escaping, followed
// by either a ";" (to begin a list of parameters) or a ":" (to begin
// the actual field body).
$ok = preg_match('(^([^;:]+)([;:])(.*)\z)', $line, $matches);
if (!$ok) {
$this->raiseParseFailure(
pht(
'Found malformed line in ICS document: %s',
$line));
}
$name = $matches[1];
$body = $matches[3];
$has_parameters = ($matches[2] == ';');
$parameters = array();
if ($has_parameters) {
// Parameters are a sensible name, a literal "=", a pile of magic,
// and then maybe a comma and another parameter.
while (true) {
// We're going to get the first couple of parts first.
$ok = preg_match('(^([^=]+)=)', $body, $matches);
if (!$ok) {
$this->raiseParseFailure(
pht(
'Found malformed property in ICS document: %s',
$body));
}
$param_name = $matches[1];
$body = substr($body, strlen($matches[0]));
// Now we're going to match zero or more values.
$param_values = array();
while (true) {
// The value can either be a double-quoted string or an unquoted
// string, with some characters forbidden.
if (strlen($body) && $body[0] == '"') {
$is_quoted = true;
$ok = preg_match(
'(^"([^\x00-\x08\x10-\x19"]*)")',
$body,
$matches);
if (!$ok) {
$this->raiseParseFailure(
pht(
'Found malformed double-quoted string in ICS document '.
'parameter value: %s',
$body));
}
} else {
$is_quoted = false;
$ok = preg_match(
'(^([^\x00-\x08\x10-\x19";:,]*))',
$body,
$matches);
if (!$ok) {
$this->raiseParseFailure(
pht(
'Found malformed unquoted string in ICS document '.
'parameter value: %s',
$body));
}
}
// NOTE: RFC5545 says "Property parameter values that are not in
// quoted-strings are case-insensitive." -- that is, the quoted and
// unquoted representations are not equivalent. Thus, preserve the
// original formatting in case we ever need to respect this.
$param_values[] = array(
'value' => $this->unescapeParameterValue($matches[1]),
'quoted' => $is_quoted,
);
$body = substr($body, strlen($matches[0]));
if (!strlen($body)) {
$this->raiseParseFailure(
pht(
'Expected ":" after parameters in ICS document property.'));
}
// If we have a comma now, we're going to read another value. Strip
// it off and keep going.
if ($body[0] == ',') {
$body = substr($body, 1);
continue;
}
// If we have a colon, this is the last value and also the last
// property. Break, then handle the colon below.
if ($body[0] == ':') {
break;
}
// We aren't expecting anything else.
$this->raiseParseFailure(
pht(
'Found unexpected text after reading parameter value: %s',
$body));
}
$parameters[] = array(
'name' => $param_name,
'values' => $param_values,
);
if ($body[0] == ':') {
$body = substr($body, 1);
break;
}
}
}
$value = $this->unescapeFieldValue($name, $parameters, $body);
$node = $this->getNode();
$raw = $node->getAttribute('ics.properties', array());
$raw[] = array(
'name' => $name,
'parameters' => $parameters,
'value' => $value,
);
$node->setAttribute('ics.properties', $raw);
}
private function unescapeParameterValue($data) {
// The parameter grammar is adjusted by RFC6868 to permit escaping with
// carets. Remove that escaping.
// This escaping is a bit weird because it's trying to be backwards
// compatible and the original spec didn't think about this and didn't
// provide much room to fix things.
$out = '';
$esc = false;
foreach (phutil_utf8v($data) as $c) {
if (!$esc) {
if ($c != '^') {
$out .= $c;
} else {
$esc = true;
}
} else {
switch ($c) {
case 'n':
$out .= "\n";
break;
case '^':
$out .= '^';
break;
case "'":
// NOTE: This is "<caret> <single quote>" being decoded into a
// double quote!
$out .= '"';
break;
default:
// NOTE: The caret is NOT an escape for any other characters.
// This is a "MUST" requirement of RFC6868.
$out .= '^'.$c;
break;
}
}
}
// NOTE: Because caret on its own just means "caret" for backward
// compatibility, we don't warn if we're still in escaped mode once we
// reach the end of the string.
return $out;
}
private function unescapeFieldValue($name, array $parameters, $data) {
// NOTE: The encoding of the field value data is dependent on the field
// name (which defines a default encoding) and the parameters (which may
// include "VALUE", specifying a type of the data.
$default_types = array(
'CALSCALE' => 'TEXT',
'METHOD' => 'TEXT',
'PRODID' => 'TEXT',
'VERSION' => 'TEXT',
'ATTACH' => 'URI',
'CATEGORIES' => 'TEXT',
'CLASS' => 'TEXT',
'COMMENT' => 'TEXT',
'DESCRIPTION' => 'TEXT',
// TODO: The spec appears to contradict itself: it says that the value
// type is FLOAT, but it also says that this property value is actually
// two semicolon-separated values, which is not what FLOAT is defined as.
'GEO' => 'TEXT',
'LOCATION' => 'TEXT',
'PERCENT-COMPLETE' => 'INTEGER',
'PRIORITY' => 'INTEGER',
'RESOURCES' => 'TEXT',
'STATUS' => 'TEXT',
'SUMMARY' => 'TEXT',
'COMPLETED' => 'DATE-TIME',
'DTEND' => 'DATE-TIME',
'DUE' => 'DATE-TIME',
'DTSTART' => 'DATE-TIME',
'DURATION' => 'DURATION',
'FREEBUSY' => 'PERIOD',
'TRANSP' => 'TEXT',
'TZID' => 'TEXT',
'TZNAME' => 'TEXT',
'TZOFFSETFROM' => 'UTC-OFFSET',
'TZOFFSETTO' => 'UTC-OFFSET',
'TZURL' => 'URI',
'ATTENDEE' => 'CAL-ADDRESS',
'CONTACT' => 'TEXT',
'ORGANIZER' => 'CAL-ADDRESS',
'RECURRENCE-ID' => 'DATE-TIME',
'RELATED-TO' => 'TEXT',
'URL' => 'URI',
'UID' => 'TEXT',
'EXDATE' => 'DATE-TIME',
'RDATE' => 'DATE-TIME',
'RRULE' => 'RECUR',
'ACTION' => 'TEXT',
'REPEAT' => 'INTEGER',
'TRIGGER' => 'DURATION',
'CREATED' => 'DATE-TIME',
'DTSTAMP' => 'DATE-TIME',
'LAST-MODIFIED' => 'DATE-TIME',
'SEQUENCE' => 'INTEGER',
'REQUEST-STATUS' => 'TEXT',
);
$value_type = idx($default_types, $name, 'TEXT');
foreach ($parameters as $parameter) {
if ($parameter['name'] == 'VALUE') {
$value_type = idx(head($parameter['values']), 'value');
}
}
switch ($value_type) {
case 'BINARY':
$result = base64_decode($data);
if ($result === false) {
$this->raiseParseFailure(
pht(
'Unable to decode base64 data: %s',
$data));
}
break;
case 'BOOLEAN':
$map = array(
'true' => true,
'false' => false,
);
$result = phutil_utf8_strtolower($data);
if (!isset($map[$result])) {
$this->raiseParseFailure(
pht(
'Unexpected BOOLEAN value "%s".',
$data));
}
$result = $map[$result];
break;
case 'CAL-ADDRESS':
$result = $data;
break;
case 'DATE':
// This is a comma-separated list of "YYYYMMDD" values.
$result = explode(',', $data);
break;
case 'DATE-TIME':
$result = explode(',', $data);
break;
case 'DURATION':
$result = explode(',', $data);
break;
case 'FLOAT':
$result = explode(',', $data);
foreach ($result as $k => $v) {
$result[$k] = (float)$v;
}
break;
case 'INTEGER':
$result = explode(',', $data);
foreach ($result as $k => $v) {
$result[$k] = (int)$v;
}
break;
case 'PERIOD':
$result = explode(',', $data);
break;
case 'RECUR':
$result = $data;
break;
case 'TEXT':
$result = $this->unescapeTextValue($data);
break;
case 'TIME':
$result = explode(',', $data);
break;
case 'URI':
$result = $data;
break;
case 'UTC-OFFSET':
$result = $data;
break;
default:
// RFC5545 says we MUST preserve the data for any types we don't
// recognize.
$result = $data;
break;
}
return array(
'type' => $value_type,
'value' => $result,
'raw' => $data,
);
}
private function unescapeTextValue($data) {
$result = array();
$buf = '';
$esc = false;
foreach (phutil_utf8v($data) as $c) {
if (!$esc) {
if ($c == '\\') {
$esc = true;
} else if ($c == ',') {
$result[] = $buf;
$buf = '';
} else {
$buf .= $c;
}
} else {
switch ($c) {
case 'n':
case 'N':
$buf .= "\n";
break;
default:
$buf .= $c;
break;
}
}
}
if ($esc) {
$this->raiseParsFailure(
pht(
'ICS document contains TEXT value ending with unescaped '.
'backslash.'));
}
$result[] = $buf;
return $result;
}
private function raiseParseFailure($message) {
throw new Exception($message);
}
}

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