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PhutilICSParser.php
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Sun, Nov 24, 11:21

PhutilICSParser.php
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<?php
final class PhutilICSParser extends Phobject {
private $stack;
private $node;
private $document;
private $lines;
private $cursor;
private $warnings;
const PARSE_MISSING_END = 'missing-end';
const PARSE_INITIAL_UNFOLD = 'initial-unfold';
const PARSE_UNEXPECTED_CHILD = 'unexpected-child';
const PARSE_EXTRA_END = 'extra-end';
const PARSE_MISMATCHED_SECTIONS = 'mismatched-sections';
const PARSE_ROOT_PROPERTY = 'root-property';
const PARSE_BAD_BASE64 = 'bad-base64';
const PARSE_BAD_BOOLEAN = 'bad-boolean';
const PARSE_UNEXPECTED_TEXT = 'unexpected-text';
const PARSE_MALFORMED_DOUBLE_QUOTE = 'malformed-double-quote';
const PARSE_MALFORMED_PARAMETER_NAME = 'malformed-parameter';
const PARSE_MALFORMED_PROPERTY = 'malformed-property';
const PARSE_MISSING_VALUE = 'missing-value';
const PARSE_UNESCAPED_BACKSLASH = 'unescaped-backslash';
const PARSE_MULTIPLE_PARAMETERS = 'multiple-parameters';
const PARSE_EMPTY_DATETIME = 'empty-datetime';
const PARSE_MANY_DATETIME = 'many-datetime';
const PARSE_BAD_DATETIME = 'bad-datetime';
const PARSE_EMPTY_DURATION = 'empty-duration';
const PARSE_MANY_DURATION = 'many-duration';
const PARSE_BAD_DURATION = 'bad-duration';
const WARN_TZID_UTC = 'warn-tzid-utc';
const WARN_TZID_GUESS = 'warn-tzid-guess';
const WARN_TZID_IGNORED = 'warn-tzid-ignored';
public function parseICSData($data) {
$this->stack = array();
$this->node = null;
$this->cursor = null;
$this->warnings = array();
$lines = $this->unfoldICSLines($data);
$this->lines = $lines;
$root = $this->newICSNode('<ROOT>');
$this->stack[] = $root;
$this->node = $root;
foreach ($lines as $key => $line) {
$this->cursor = $key;
$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 {
if (count($this->stack) < 2) {
$this->raiseParseFailure(
self::PARSE_ROOT_PROPERTY,
pht(
'Found unexpected property at ICS document root.'));
}
$this->parseICSProperty($line);
}
}
if (count($this->stack) > 1) {
$this->raiseParseFailure(
self::PARSE_MISSING_END,
pht(
'Expected all "BEGIN:" sections in ICS document to have '.
'corresponding "END:" sections.'));
}
$this->node = null;
$this->lines = null;
$this->cursor = null;
return $root;
}
private function getNode() {
return $this->node;
}
private function unfoldICSLines($data) {
$lines = phutil_split_lines($data, $retain_endings = false);
$this->lines = $lines;
// 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.
// This unwrapping is specifically byte-oriented, not character oriented,
// and RFC5545 anticipates that simple implementations may even split UTF8
// characters in the middle.
$last = null;
foreach ($lines as $idx => $line) {
$this->cursor = $idx;
if (!preg_match('/^[ \t]/', $line)) {
$last = $idx;
continue;
}
if ($last === null) {
$this->raiseParseFailure(
self::PARSE_INITIAL_UNFOLD,
pht(
'First line of ICS file begins with a space or tab, but this '.
'marks a line which should be unfolded.'));
}
$lines[$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 instanceof PhutilCalendarContainerNode) {
$node->appendChild($new_node);
} else {
$this->raiseParseFailure(
self::PARSE_UNEXPECTED_CHILD,
pht(
'Found unexpected node "%s" inside node "%s".',
$new_node->getAttribute('ics.type'),
$node->getAttribute('ics.type')));
}
$this->stack[] = $new_node;
$this->node = $new_node;
return $this;
}
private function newICSNode($type) {
switch ($type) {
case '<ROOT>':
$node = new PhutilCalendarRootNode();
break;
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 instanceof PhutilCalendarRootNode) {
$this->raiseParseFailure(
self::PARSE_EXTRA_END,
pht(
'Found unexpected "END" without a "BEGIN".'));
}
$old_type = $node->getAttribute('ics.type');
if ($old_type != $type) {
$this->raiseParseFailure(
self::PARSE_MISMATCHED_SECTIONS,
pht(
'Found mismatched "BEGIN" ("%s") and "END" ("%s") sections.',
$old_type,
$type));
}
array_pop($this->stack);
$this->node = last($this->stack);
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('(^([A-Za-z0-9-]+)([;:])(.*)\z)', $line, $matches);
if (!$ok) {
$this->raiseParseFailure(
self::PARSE_MALFORMED_PROPERTY,
pht(
'Found malformed property in ICS document.'));
}
$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(
self::PARSE_MALFORMED_PARAMETER_NAME,
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(
self::PARSE_MALFORMED_DOUBLE_QUOTE,
pht(
'Found malformed double-quoted string in ICS document '.
'parameter value.'));
}
} else {
$is_quoted = false;
// It's impossible for this not to match since it can match
// nothing, and it's valid for it to match nothing.
preg_match('(^([^\x00-\x08\x10-\x19";:,]*))', $body, $matches);
}
// 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)) {
$this->raiseParseFailure(
self::PARSE_MISSING_VALUE,
pht(
'Expected ":" after parameters in ICS document property.'));
}
// If we have a comma now, we're going to read another value. Strip
// it off and keep going.
if ($body[0] == ',') {
$body = substr($body, 1);
continue;
}
// If we have a semicolon, we're going to read another parameter.
if ($body[0] == ';') {
break;
}
// If we have a colon, this is the last value and also the last
// property. Break, then handle the colon below.
if ($body[0] == ':') {
break;
}
$short_body = id(new PhutilUTF8StringTruncator())
->setMaximumGlyphs(32)
->truncateString($body);
// We aren't expecting anything else.
$this->raiseParseFailure(
self::PARSE_UNEXPECTED_TEXT,
pht(
'Found unexpected text ("%s") after reading parameter value.',
$short_body));
}
$parameters[] = array(
'name' => $param_name,
'values' => $param_values,
);
if ($body[0] == ';') {
$body = substr($body, 1);
continue;
}
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', $raw);
switch ($node->getAttribute('ics.type')) {
case 'VEVENT':
$this->didParseEventProperty($node, $name, $parameters, $value);
break;
}
}
private function unescapeParameterValue($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, true);
if ($result === false) {
$this->raiseParseFailure(
self::PARSE_BAD_BASE64,
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(
self::PARSE_BAD_BOOLEAN,
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(',', $data);
break;
case 'DATE-TIME':
if (!strlen($data)) {
$result = array();
} else {
$result = explode(',', $data);
}
break;
case 'DURATION':
if (!strlen($data)) {
$result = array();
} else {
$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;
}
$esc = false;
}
}
if ($esc) {
$this->raiseParseFailure(
self::PARSE_UNESCAPED_BACKSLASH,
pht(
'ICS document contains TEXT value ending with unescaped '.
'backslash.'));
}
$result[] = $buf;
return $result;
}
private function raiseParseFailure($code, $message) {
if ($this->lines && isset($this->lines[$this->cursor])) {
$message = pht(
"ICS Parse Error near line %s:\n\n>>> %s\n\n%s",
$this->cursor + 1,
$this->lines[$this->cursor],
$message);
} else {
$message = pht(
'ICS Parse Error: %s',
$message);
}
throw id(new PhutilICSParserException($message))
->setParserFailureCode($code);
}
private function raiseWarning($code, $message) {
$this->warnings[] = array(
'code' => $code,
'line' => $this->cursor,
'text' => $this->lines[$this->cursor],
'message' => $message,
);
return $this;
}
public function getWarnings() {
return $this->warnings;
}
private function didParseEventProperty(
PhutilCalendarEventNode $node,
$name,
array $parameters,
array $value) {
switch ($name) {
case 'UID':
$text = $this->newTextFromProperty($parameters, $value);
$node->setUID($text);
break;
case 'CREATED':
$datetime = $this->newDateTimeFromProperty($parameters, $value);
$node->setCreatedDateTime($datetime);
break;
case 'DTSTAMP':
$datetime = $this->newDateTimeFromProperty($parameters, $value);
$node->setModifiedDateTime($datetime);
break;
case 'SUMMARY':
$text = $this->newTextFromProperty($parameters, $value);
$node->setName($text);
break;
case 'DESCRIPTION':
$text = $this->newTextFromProperty($parameters, $value);
$node->setDescription($text);
break;
case 'DTSTART':
$datetime = $this->newDateTimeFromProperty($parameters, $value);
$node->setStartDateTime($datetime);
break;
case 'DTEND':
$datetime = $this->newDateTimeFromProperty($parameters, $value);
$node->setEndDateTime($datetime);
break;
case 'DURATION':
$duration = $this->newDurationFromProperty($parameters, $value);
$node->setDuration($duration);
break;
case 'RRULE':
$rrule = $this->newRecurrenceRuleFromProperty($parameters, $value);
$node->setRecurrenceRule($rrule);
break;
case 'RECURRENCE-ID':
$text = $this->newTextFromProperty($parameters, $value);
$node->setRecurrenceID($text);
break;
case 'ATTENDEE':
$attendee = $this->newAttendeeFromProperty($parameters, $value);
$node->addAttendee($attendee);
break;
}
}
private function newTextFromProperty(array $parameters, array $value) {
$value = $value['value'];
return implode("\n\n", $value);
}
private function newAttendeeFromProperty(array $parameters, array $value) {
$uri = $value['value'];
switch (idx($parameters, 'PARTSTAT')) {
case 'ACCEPTED':
$status = PhutilCalendarUserNode::STATUS_ACCEPTED;
break;
case 'DECLINED':
$status = PhutilCalendarUserNode::STATUS_DECLINED;
break;
case 'NEEDS-ACTION':
default:
$status = PhutilCalendarUserNode::STATUS_INVITED;
break;
}
$name = $this->getScalarParameterValue($parameters, 'CN');
return id(new PhutilCalendarUserNode())
->setURI($uri)
->setName($name)
->setStatus($status);
}
private function newDateTimeFromProperty(array $parameters, array $value) {
$value = $value['value'];
if (!$value) {
$this->raiseParseFailure(
self::PARSE_EMPTY_DATETIME,
pht(
'Expected DATE-TIME to have exactly one value, found none.'));
}
if (count($value) > 1) {
$this->raiseParseFailure(
self::PARSE_MANY_DATETIME,
pht(
'Expected DATE-TIME to have exactly one value, found more than '.
'one.'));
}
$value = head($value);
$tzid = $this->getScalarParameterValue($parameters, 'TZID');
if (preg_match('/Z\z/', $value)) {
if ($tzid) {
$this->raiseWarning(
self::WARN_TZID_UTC,
pht(
'DATE-TIME "%s" uses "Z" to specify UTC, but also has a TZID '.
'parameter with value "%s". This violates RFC5545. The TZID '.
'will be ignored, and the value will be interpreted as UTC.',
$value,
$tzid));
}
$tzid = 'UTC';
} else if ($tzid !== null) {
$tzid = $this->guessTimezone($tzid);
}
try {
$datetime = PhutilCalendarAbsoluteDateTime::newFromISO8601(
$value,
$tzid);
} catch (Exception $ex) {
$this->raiseParseFailure(
self::PARSE_BAD_DATETIME,
pht(
'Error parsing DATE-TIME: %s',
$ex->getMessage()));
}
return $datetime;
}
private function newDurationFromProperty(array $parameters, array $value) {
$value = $value['value'];
if (!$value) {
$this->raiseParseFailure(
self::PARSE_EMPTY_DURATION,
pht(
'Expected DURATION to have exactly one value, found none.'));
}
if (count($value) > 1) {
$this->raiseParseFailure(
self::PARSE_MANY_DURATION,
pht(
'Expected DURATION to have exactly one value, found more than '.
'one.'));
}
$value = head($value);
try {
$duration = PhutilCalendarDuration::newFromISO8601($value);
} catch (Exception $ex) {
$this->raiseParseFailure(
self::PARSE_BAD_DURATION,
pht(
'Invalid DURATION: %s',
$ex->getMessage()));
}
return $duration;
}
private function newRecurrenceRuleFromProperty(array $parameters, $value) {
return PhutilCalendarRecurrenceRule::newFromRRULE($value['value']);
}
private function getScalarParameterValue(
array $parameters,
$name,
$default = null) {
$match = null;
foreach ($parameters as $parameter) {
if ($parameter['name'] == $name) {
$match = $parameter;
}
}
if ($match === null) {
return $default;
}
$value = $match['values'];
if (!$value) {
// Parameter is specified, but with no value, like "KEY=". Just return
// the default, as though the parameter was not specified.
return $default;
}
if (count($value) > 1) {
$this->raiseParseFailure(
self::PARSE_MULTIPLE_PARAMETERS,
pht(
'Expected parameter "%s" to have at most one value, but found '.
'more than one.',
$name));
}
return idx(head($value), 'value');
}
private function guessTimezone($tzid) {
$map = DateTimeZone::listIdentifiers();
$map = array_fuse($map);
if (isset($map[$tzid])) {
// This is a real timezone we recognize, so just use it as provided.
return $tzid;
}
// These are alternate names for timezones.
static $aliases;
if ($aliases === null) {
$aliases = array(
'Etc/GMT' => 'UTC',
);
// Load the map of Windows timezones.
$root_path = dirname(phutil_get_library_root('phutil'));
$windows_path = $root_path.'/resources/timezones/windows_timezones.json';
$windows_data = Filesystem::readFile($windows_path);
$windows_zones = phutil_json_decode($windows_data);
$aliases = $aliases + $windows_zones;
}
if (isset($aliases[$tzid])) {
return $aliases[$tzid];
}
// Look for something that looks like "UTC+3" or "GMT -05.00". If we find
// anything, pick a timezone with that offset.
$offset_pattern =
'/'.
'(?:UTC|GMT)'.
'\s*'.
'(?P<sign>[+-])'.
'\s*'.
'(?P<h>\d+)'.
'(?:'.
'[:.](?P<m>\d+)'.
')?'.
'/i';
$matches = null;
if (preg_match($offset_pattern, $tzid, $matches)) {
$hours = (int)$matches['h'];
$minutes = (int)idx($matches, 'm');
$offset = ($hours * 60 * 60) + ($minutes * 60);
if (idx($matches, 'sign') == '-') {
$offset = -$offset;
}
// NOTE: We could possibly do better than this, by using the event start
// time to guess a timezone. However, that won't work for recurring
// events and would require us to do this work after finishing initial
// parsing. Since these unusual offset-based timezones appear to be rare,
// the benefit may not be worth the complexity.
$now = new DateTime('@'.time());
foreach ($map as $identifier) {
$zone = new DateTimeZone($identifier);
if ($zone->getOffset($now) == $offset) {
$this->raiseWarning(
self::WARN_TZID_GUESS,
pht(
'TZID "%s" is unknown, guessing "%s" based on pattern "%s".',
$tzid,
$identifier,
$matches[0]));
return $identifier;
}
}
}
$this->raiseWarning(
self::WARN_TZID_IGNORED,
pht(
'TZID "%s" is unknown, using UTC instead.',
$tzid));
return 'UTC';
}
}

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