/**
* This method checks the main HTTP preconditions.
*
* Currently these are:
* * If-Match
* * If-None-Match
* * If-Modified-Since
* * If-Unmodified-Since
*
* The method will return true if all preconditions are met
* The method will return false, or throw an exception if preconditions
* failed. If false is returned the operation should be aborted, and
* the appropriate HTTP response headers are already set.
*
* Normally this method will throw 412 Precondition Failed for failures
* related to If-None-Match, If-Match and If-Unmodified Since. It will
* set the status to 304 Not Modified for If-Modified_since.
*
* @param RequestInterface $request
* @param ResponseInterface $response
* @return bool
*/
function checkPreconditions(RequestInterface $request, ResponseInterface $response) {
$path = $request->getPath();
$node = null;
$lastMod = null;
$etag = null;
if ($ifMatch = $request->getHeader('If-Match')) {
// If-Match contains an entity tag. Only if the entity-tag
// matches we are allowed to make the request succeed.
// If the entity-tag is '*' we are only allowed to make the
// request succeed if a resource exists at that url.
try {
$node = $this->tree->getNodeForPath($path);
} catch (Exception\NotFound $e) {
throw new Exception\PreconditionFailed('An If-Match header was specified and the resource did not exist', 'If-Match');
}
// Only need to check entity tags if they are not *
if ($ifMatch !== '*') {
// There can be multiple ETags
$ifMatch = explode(',', $ifMatch);
$haveMatch = false;
foreach ($ifMatch as $ifMatchItem) {
// Stripping any extra spaces
$ifMatchItem = trim($ifMatchItem, ' ');
$etag = $node instanceof IFile ? $node->getETag() : null;
if ($etag === $ifMatchItem) {
$haveMatch = true;
} else {
// Evolution has a bug where it sometimes prepends the "
// with a \. This is our workaround.
if (str_replace('\\"', '"', $ifMatchItem) === $etag) {
$haveMatch = true;
}
}
}
if (!$haveMatch) {
if ($etag) $response->setHeader('ETag', $etag);
throw new Exception\PreconditionFailed('An If-Match header was specified, but none of the specified the ETags matched.', 'If-Match');
}
}
}
if ($ifNoneMatch = $request->getHeader('If-None-Match')) {
// The If-None-Match header contains an ETag.
// Only if the ETag does not match the current ETag, the request will succeed
// The header can also contain *, in which case the request
// will only succeed if the entity does not exist at all.
$nodeExists = true;
if (!$node) {
try {
$node = $this->tree->getNodeForPath($path);
} catch (Exception\NotFound $e) {
$nodeExists = false;
}
}
if ($nodeExists) {
$haveMatch = false;
if ($ifNoneMatch === '*') $haveMatch = true;
else {
// There might be multiple ETags
$ifNoneMatch = explode(',', $ifNoneMatch);
$etag = $node instanceof IFile ? $node->getETag() : null;
foreach ($ifNoneMatch as $ifNoneMatchItem) {
// Stripping any extra spaces
$ifNoneMatchItem = trim($ifNoneMatchItem, ' ');
if ($etag === $ifNoneMatchItem) $haveMatch = true;
}
}
if ($haveMatch) {
if ($etag) $response->setHeader('ETag', $etag);
if ($request->getMethod() === 'GET') {
$response->setStatus(304);
return false;
} else {
throw new Exception\PreconditionFailed('An If-None-Match header was specified, but the ETag matched (or * was specified).', 'If-None-Match');
}
}
}
}
if (!$ifNoneMatch && ($ifModifiedSince = $request->getHeader('If-Modified-Since'))) {
// The If-Modified-Since header contains a date. We
// will only return the entity if it has been changed since
// that date. If it hasn't been changed, we return a 304
// header
// Note that this header only has to be checked if there was no If-None-Match header
// as per the HTTP spec.
$date = HTTP\Util::parseHTTPDate($ifModifiedSince);
if ($date) {
if (is_null($node)) {
$node = $this->tree->getNodeForPath($path);
}
$lastMod = $node->getLastModified();
if ($lastMod) {
$lastMod = new \DateTime('@' . $lastMod);
if ($lastMod <= $date) {
$response->setStatus(304);
$response->setHeader('Last-Modified', HTTP\Util::toHTTPDate($lastMod));
return false;
}
}
}
}
if ($ifUnmodifiedSince = $request->getHeader('If-Unmodified-Since')) {
// The If-Unmodified-Since will allow allow the request if the
// entity has not changed since the specified date.
$date = HTTP\Util::parseHTTPDate($ifUnmodifiedSince);
// We must only check the date if it's valid
if ($date) {
if (is_null($node)) {
$node = $this->tree->getNodeForPath($path);
}
$lastMod = $node->getLastModified();
if ($lastMod) {
$lastMod = new \DateTime('@' . $lastMod);
if ($lastMod > $date) {
throw new Exception\PreconditionFailed('An If-Unmodified-Since header was specified, but the entity has been changed since the specified date.', 'If-Unmodified-Since');
}
}
}
}
// Now the hardest, the If: header. The If: header can contain multiple
// urls, ETags and so-called 'state tokens'.
//
// Examples of state tokens include lock-tokens (as defined in rfc4918)
// and sync-tokens (as defined in rfc6578).
//
// The only proper way to deal with these, is to emit events, that a
// Sync and Lock plugin can pick up.
$ifConditions = $this->getIfConditions($request);
foreach ($ifConditions as $kk => $ifCondition) {
foreach ($ifCondition['tokens'] as $ii => $token) {
$ifConditions[$kk]['tokens'][$ii]['validToken'] = false;
}
}
// Plugins are responsible for validating all the tokens.
// If a plugin deemed a token 'valid', it will set 'validToken' to
// true.
$this->emit('validateTokens', [ $request, &$ifConditions ]);
// Now we're going to analyze the result.
// Every ifCondition needs to validate to true, so we exit as soon as
// we have an invalid condition.
foreach ($ifConditions as $ifCondition) {
$uri = $ifCondition['uri'];
$tokens = $ifCondition['tokens'];
// We only need 1 valid token for the condition to succeed.
foreach ($tokens as $token) {
$tokenValid = $token['validToken'] || !$token['token'];
$etagValid = false;
if (!$token['etag']) {
$etagValid = true;
}
// Checking the ETag, only if the token was already deamed
// valid and there is one.
if ($token['etag'] && $tokenValid) {
// The token was valid, and there was an ETag. We must
// grab the current ETag and check it.
$node = $this->tree->getNodeForPath($uri);
$etagValid = $node instanceof IFile && $node->getETag() == $token['etag'];
}
if (($tokenValid && $etagValid) ^ $token['negate']) {
// Both were valid, so we can go to the next condition.
continue 2;
}
}
// If we ended here, it means there was no valid ETag + token
// combination found for the current condition. This means we fail!
throw new Exception\PreconditionFailed('Failed to find a valid token/etag combination for ' . $uri, 'If');
}
return true;
}
/**
* This method checks the main HTTP preconditions.
*
* Currently these are:
* * If-Match
* * If-None-Match
* * If-Modified-Since
* * If-Unmodified-Since
*
* The method will return true if all preconditions are met
* The method will return false, or throw an exception if preconditions
* failed. If false is returned the operation should be aborted, and
* the appropriate HTTP response headers are already set.
*
* Normally this method will throw 412 Precondition Failed for failures
* related to If-None-Match, If-Match and If-Unmodified Since. It will
* set the status to 304 Not Modified for If-Modified_since.
*
* If the $handleAsGET argument is set to true, it will also return 304
* Not Modified for failure of the If-None-Match precondition. This is the
* desired behaviour for HTTP GET and HTTP HEAD requests.
*
* @param bool $handleAsGET
* @return bool
*/
public function checkPreconditions($handleAsGET = false)
{
$uri = $this->getRequestUri();
$node = null;
$lastMod = null;
$etag = null;
if ($ifMatch = $this->httpRequest->getHeader('If-Match')) {
// If-Match contains an entity tag. Only if the entity-tag
// matches we are allowed to make the request succeed.
// If the entity-tag is '*' we are only allowed to make the
// request succeed if a resource exists at that url.
try {
$node = $this->tree->getNodeForPath($uri);
} catch (Exception\NotFound $e) {
throw new Exception\PreconditionFailed('An If-Match header was specified and the resource did not exist', 'If-Match');
}
// Only need to check entity tags if they are not *
if ($ifMatch !== '*') {
// There can be multiple etags
$ifMatch = explode(',', $ifMatch);
$haveMatch = false;
foreach ($ifMatch as $ifMatchItem) {
// Stripping any extra spaces
$ifMatchItem = trim($ifMatchItem, ' ');
$etag = $node->getETag();
if ($etag === $ifMatchItem) {
$haveMatch = true;
} else {
// Evolution has a bug where it sometimes prepends the "
// with a \. This is our workaround.
if (str_replace('\\"', '"', $ifMatchItem) === $etag) {
$haveMatch = true;
}
}
}
if (!$haveMatch) {
throw new Exception\PreconditionFailed('An If-Match header was specified, but none of the specified the ETags matched.', 'If-Match');
}
}
}
if ($ifNoneMatch = $this->httpRequest->getHeader('If-None-Match')) {
// The If-None-Match header contains an etag.
// Only if the ETag does not match the current ETag, the request will succeed
// The header can also contain *, in which case the request
// will only succeed if the entity does not exist at all.
$nodeExists = true;
if (!$node) {
try {
$node = $this->tree->getNodeForPath($uri);
} catch (Exception\NotFound $e) {
$nodeExists = false;
}
}
if ($nodeExists) {
$haveMatch = false;
if ($ifNoneMatch === '*') {
$haveMatch = true;
} else {
// There might be multiple etags
$ifNoneMatch = explode(',', $ifNoneMatch);
$etag = $node->getETag();
foreach ($ifNoneMatch as $ifNoneMatchItem) {
// Stripping any extra spaces
$ifNoneMatchItem = trim($ifNoneMatchItem, ' ');
if ($etag === $ifNoneMatchItem) {
$haveMatch = true;
}
}
}
if ($haveMatch) {
if ($handleAsGET) {
$this->httpResponse->sendStatus(304);
return false;
} else {
throw new Exception\PreconditionFailed('An If-None-Match header was specified, but the ETag matched (or * was specified).', 'If-None-Match');
}
}
}
}
if (!$ifNoneMatch && ($ifModifiedSince = $this->httpRequest->getHeader('If-Modified-Since'))) {
// The If-Modified-Since header contains a date. We
// will only return the entity if it has been changed since
// that date. If it hasn't been changed, we return a 304
// header
// Note that this header only has to be checked if there was no If-None-Match header
// as per the HTTP spec.
$date = HTTP\Util::parseHTTPDate($ifModifiedSince);
if ($date) {
if (is_null($node)) {
$node = $this->tree->getNodeForPath($uri);
}
$lastMod = $node->getLastModified();
if ($lastMod) {
$lastMod = new \DateTime('@' . $lastMod);
if ($lastMod <= $date) {
$this->httpResponse->sendStatus(304);
$this->httpResponse->setHeader('Last-Modified', HTTP\Util::toHTTPDate($lastMod));
return false;
}
}
}
}
if ($ifUnmodifiedSince = $this->httpRequest->getHeader('If-Unmodified-Since')) {
// The If-Unmodified-Since will allow allow the request if the
// entity has not changed since the specified date.
$date = HTTP\Util::parseHTTPDate($ifUnmodifiedSince);
// We must only check the date if it's valid
if ($date) {
if (is_null($node)) {
$node = $this->tree->getNodeForPath($uri);
}
$lastMod = $node->getLastModified();
if ($lastMod) {
$lastMod = new \DateTime('@' . $lastMod);
if ($lastMod > $date) {
throw new Exception\PreconditionFailed('An If-Unmodified-Since header was specified, but the entity has been changed since the specified date.', 'If-Unmodified-Since');
}
}
}
}
return true;
}