1// Copyright (C) MongoDB, Inc. 2017-present. 2// 3// Licensed under the Apache License, Version 2.0 (the "License"); you may 4// not use this file except in compliance with the License. You may obtain 5// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 6 7package wiremessage 8 9import ( 10 "bytes" 11 "errors" 12 13 "go.mongodb.org/mongo-driver/bson" 14) 15 16func readInt32(b []byte, pos int32) int32 { 17 return (int32(b[pos+0])) | (int32(b[pos+1]) << 8) | (int32(b[pos+2]) << 16) | (int32(b[pos+3]) << 24) 18} 19 20func readCString(b []byte, pos int32) (string, error) { 21 null := bytes.IndexByte(b[pos:], 0x00) 22 if null == -1 { 23 return "", errors.New("invalid cstring") 24 } 25 return string(b[pos : int(pos)+null]), nil 26} 27 28func readInt64(b []byte, pos int32) int64 { 29 return (int64(b[pos+0])) | (int64(b[pos+1]) << 8) | (int64(b[pos+2]) << 16) | (int64(b[pos+3]) << 24) | (int64(b[pos+4]) << 32) | 30 (int64(b[pos+5]) << 40) | (int64(b[pos+6]) << 48) | (int64(b[pos+7]) << 56) 31 32} 33 34// readDocument will attempt to read a bson.Reader from the given slice of bytes 35// from the given position. 36func readDocument(b []byte, pos int32) (bson.Raw, int, Error) { 37 if int(pos)+4 > len(b) { 38 return nil, 0, Error{Message: "document too small to be valid"} 39 } 40 size := int(readInt32(b, int32(pos))) 41 if int(pos)+size > len(b) { 42 return nil, 0, Error{Message: "document size is larger than available bytes"} 43 } 44 if b[int(pos)+size-1] != 0x00 { 45 return nil, 0, Error{Message: "document invalid, last byte is not null"} 46 } 47 // TODO(GODRIVER-138): When we add 3.0 support, alter this so we either do one larger make or use a pool. 48 rdr := make(bson.Raw, size) 49 copy(rdr, b[pos:int(pos)+size]) 50 return rdr, size, Error{Type: ErrNil} 51} 52