RESTBagOStuff.php

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<?php
 
use Psr\Log\LoggerInterface;
 
class RESTBagOStuff extends MediumSpecificBagOStuff {
    const DEFAULT_CONN_TIMEOUT = 1.2;
 
    const DEFAULT_REQ_TIMEOUT = 3.0;
 
    private $client;
 
    private $url;
 
    private $httpParams;
 
    private $serializationType;
 
    private $hmacKey;
 
    private $extendedErrorBodyFields;
 
    public function __construct( $params ) {
        $params['segmentationSize'] = $params['segmentationSize'] ?? INF;
        if ( empty( $params['url'] ) ) {
            throw new InvalidArgumentException( 'URL parameter is required' );
        }
 
        if ( empty( $params['client'] ) ) {
            // Pass through some params to the HTTP client.
            $clientParams = [
                'connTimeout' => $params['connTimeout'] ?? self::DEFAULT_CONN_TIMEOUT,
                'reqTimeout' => $params['reqTimeout'] ?? self::DEFAULT_REQ_TIMEOUT,
            ];
            foreach ( [ 'caBundlePath', 'proxy' ] as $key ) {
                if ( isset( $params[$key] ) ) {
                    $clientParams[$key] = $params[$key];
                }
            }
            $this->client = new MultiHttpClient( $clientParams );
        } else {
            $this->client = $params['client'];
        }
 
        $this->httpParams['writeMethod'] = $params['httpParams']['writeMethod'] ?? 'PUT';
        $this->httpParams['readHeaders'] = $params['httpParams']['readHeaders'] ?? [];
        $this->httpParams['writeHeaders'] = $params['httpParams']['writeHeaders'] ?? [];
        $this->httpParams['deleteHeaders'] = $params['httpParams']['deleteHeaders'] ?? [];
        $this->extendedErrorBodyFields = $params['extendedErrorBodyFields'] ?? [];
        $this->serializationType = $params['serialization_type'] ?? 'legacy';
        $this->hmacKey = $params['hmac_key'] ?? '';
 
        // The parent constructor calls setLogger() which sets the logger in $this->client
        parent::__construct( $params );
 
        // Make sure URL ends with /
        $this->url = rtrim( $params['url'], '/' ) . '/';
 
        // Default config, R+W > N; no locks on reads though; writes go straight to state-machine
        $this->attrMap[self::ATTR_SYNCWRITES] = self::QOS_SYNCWRITES_QC;
    }
 
    public function setLogger( LoggerInterface $logger ) {
        parent::setLogger( $logger );
        $this->client->setLogger( $logger );
    }
 
    protected function doGet( $key, $flags = 0, &$casToken = null ) {
        $casToken = null;
 
        $req = [
            'method' => 'GET',
            'url' => $this->url . rawurlencode( $key ),
            'headers' => $this->httpParams['readHeaders'],
        ];
 
        list( $rcode, $rdesc, $rhdrs, $rbody, $rerr ) = $this->client->run( $req );
        if ( $rcode === 200 ) {
            if ( is_string( $rbody ) ) {
                $value = $this->decodeBody( $rbody );
                $casToken = ( $value !== false ) ? $rbody : null;
 
                return $value;
            }
            return false;
        }
        if ( $rcode === 0 || ( $rcode >= 400 && $rcode != 404 ) ) {
            return $this->handleError( "Failed to fetch $key", $rcode, $rerr, $rhdrs, $rbody );
        }
        return false;
    }
 
    protected function doSet( $key, $value, $exptime = 0, $flags = 0 ) {
        // @TODO: respect WRITE_SYNC (e.g. EACH_QUORUM)
        // @TODO: respect $exptime
        $req = [
            'method' => $this->httpParams['writeMethod'],
            'url' => $this->url . rawurlencode( $key ),
            'body' => $this->encodeBody( $value ),
            'headers' => $this->httpParams['writeHeaders'],
        ];
 
        list( $rcode, $rdesc, $rhdrs, $rbody, $rerr ) = $this->client->run( $req );
        if ( $rcode === 200 || $rcode === 201 || $rcode === 204 ) {
            return true;
        }
        return $this->handleError( "Failed to store $key", $rcode, $rerr, $rhdrs, $rbody );
    }
 
    protected function doAdd( $key, $value, $exptime = 0, $flags = 0 ) {
        // @TODO: make this atomic
        if ( $this->get( $key ) === false ) {
            return $this->set( $key, $value, $exptime, $flags );
        }
 
        return false; // key already set
    }
 
    protected function doDelete( $key, $flags = 0 ) {
        // @TODO: respect WRITE_SYNC (e.g. EACH_QUORUM)
        $req = [
            'method' => 'DELETE',
            'url' => $this->url . rawurlencode( $key ),
            'headers' => $this->httpParams['deleteHeaders'],
        ];
 
        list( $rcode, $rdesc, $rhdrs, $rbody, $rerr ) = $this->client->run( $req );
        if ( in_array( $rcode, [ 200, 204, 205, 404, 410 ] ) ) {
            return true;
        }
        return $this->handleError( "Failed to delete $key", $rcode, $rerr, $rhdrs, $rbody );
    }
 
    public function incr( $key, $value = 1, $flags = 0 ) {
        // @TODO: make this atomic
        $n = $this->get( $key, self::READ_LATEST );
        if ( $this->isInteger( $n ) ) { // key exists?
            $n = max( $n + (int)$value, 0 );
            // @TODO: respect $exptime
            return $this->set( $key, $n ) ? $n : false;
        }
 
        return false;
    }
 
    public function decr( $key, $value = 1, $flags = 0 ) {
        return $this->incr( $key, -$value, $flags );
    }
 
    private function decodeBody( $body ) {
        if ( $this->serializationType === 'legacy' ) {
            $serialized = $body;
        } else {
            $pieces = explode( '.', $body, 3 );
            if ( count( $pieces ) !== 3 || $pieces[0] !== $this->serializationType ) {
                return false;
            }
            list( , $hmac, $serialized ) = $pieces;
            if ( $this->hmacKey !== '' ) {
                $checkHmac = hash_hmac( 'sha256', $serialized, $this->hmacKey, true );
                if ( !hash_equals( $checkHmac, base64_decode( $hmac ) ) ) {
                    return false;
                }
            }
        }
 
        switch ( $this->serializationType ) {
            case 'JSON':
                $value = json_decode( $serialized, true );
                return ( json_last_error() === JSON_ERROR_NONE ) ? $value : false;
 
            case 'PHP':
            case 'legacy':
                return unserialize( $serialized );
 
            default:
                throw new \DomainException(
                    "Unknown serialization type: $this->serializationType"
                );
        }
    }
 
    private function encodeBody( $body ) {
        switch ( $this->serializationType ) {
            case 'JSON':
                $value = json_encode( $body );
                if ( $value === false ) {
                    throw new InvalidArgumentException( __METHOD__ . ": body could not be encoded." );
                }
                break;
 
            case 'PHP':
            case "legacy":
                $value = serialize( $body );
                break;
 
            default:
                throw new \DomainException(
                    "Unknown serialization type: $this->serializationType"
                );
        }
 
        if ( $this->serializationType !== 'legacy' ) {
            if ( $this->hmacKey !== '' ) {
                $hmac = base64_encode(
                    hash_hmac( 'sha256', $value, $this->hmacKey, true )
                );
            } else {
                $hmac = '';
            }
            $value = $this->serializationType . '.' . $hmac . '.' . $value;
        }
 
        return $value;
    }
 
    protected function handleError( $msg, $rcode, $rerr, $rhdrs, $rbody ) {
        $message = "$msg : ({code}) {error}";
        $context = [
            'code' => $rcode,
            'error' => $rerr
        ];
 
        if ( $this->extendedErrorBodyFields !== [] ) {
            $body = $this->decodeBody( $rbody );
            if ( $body ) {
                $extraFields = '';
                foreach ( $this->extendedErrorBodyFields as $field ) {
                    if ( isset( $body[$field] ) ) {
                        $extraFields .= " : ({$field}) {$body[$field]}";
                    }
                }
                if ( $extraFields !== '' ) {
                    $message .= " {extra_fields}";
                    $context['extra_fields'] = $extraFields;
                }
            }
        }
 
        $this->logger->error( $message, $context );
        $this->setLastError( $rcode === 0 ? self::ERR_UNREACHABLE : self::ERR_UNEXPECTED );
        return false;
    }
}