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- /* Copyright (C) 2002-2005 RealVNC Ltd. All Rights Reserved.
- * Copyright 2014-2020 Pierre Ossman for Cendio AB
- *
- * This is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This software is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this software; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
- * USA.
- */
-
- //
- // rdr::InStream marshalls data from a buffer stored in RDR (RFB Data
- // Representation).
- //
-
- #ifndef __RDR_INSTREAM_H__
- #define __RDR_INSTREAM_H__
-
- #include <rdr/types.h>
- #include <rdr/Exception.h>
- #include <string.h> // for memcpy
-
- // Check that callers are using InStream properly,
- // useful when writing new protocol handling
- #undef RFB_INSTREAM_CHECK
-
- namespace rdr {
-
- class InStream {
-
- public:
-
- virtual ~InStream() {}
-
- // avail() returns the number of bytes that are currenctly directly
- // available from the stream.
-
- inline size_t avail() {
- #ifdef RFB_INSTREAM_CHECK
- checkedBytes = end - ptr;
- #endif
-
- return end - ptr;
- }
-
- // hasData() ensures there is at least "length" bytes of buffer data,
- // possibly trying to fetch more data if there isn't enough right away
-
- inline bool hasData(size_t length) {
- #ifdef RFB_INSTREAM_CHECK
- checkedBytes = 0;
- #endif
-
- if (length > (size_t)(end - ptr)) {
- if (restorePoint != NULL) {
- bool ret;
- size_t restoreDiff;
-
- restoreDiff = ptr - restorePoint;
- ptr = restorePoint;
-
- ret = overrun(length + restoreDiff);
-
- restorePoint = ptr;
- ptr += restoreDiff;
-
- if (!ret)
- return false;
- } else {
- if (!overrun(length))
- return false;
- }
- }
-
- #ifdef RFB_INSTREAM_CHECK
- checkedBytes = length;
- #endif
-
- return true;
- }
-
- inline bool hasDataOrRestore(size_t length) {
- if (hasData(length))
- return true;
- gotoRestorePoint();
- return false;
- }
-
- inline void setRestorePoint() {
- #ifdef RFB_INSTREAM_CHECK
- if (restorePoint != NULL)
- throw Exception("Nested use of input stream restore point");
- #endif
- restorePoint = ptr;
- }
- inline void clearRestorePoint() {
- #ifdef RFB_INSTREAM_CHECK
- if (restorePoint == NULL)
- throw Exception("Incorrect clearing of input stream restore point");
- #endif
- restorePoint = NULL;
- }
- inline void gotoRestorePoint() {
- #ifdef RFB_INSTREAM_CHECK
- if (restorePoint == NULL)
- throw Exception("Incorrect activation of input stream restore point");
- #endif
- ptr = restorePoint;
- clearRestorePoint();
- }
-
- // readU/SN() methods read unsigned and signed N-bit integers.
-
- inline U8 readU8() { check(1); return *ptr++; }
- inline U16 readU16() { check(2); int b0 = *ptr++; int b1 = *ptr++;
- return b0 << 8 | b1; }
- inline U32 readU32() { check(4); int b0 = *ptr++; int b1 = *ptr++;
- int b2 = *ptr++; int b3 = *ptr++;
- return b0 << 24 | b1 << 16 | b2 << 8 | b3; }
-
- inline S8 readS8() { return (S8) readU8(); }
- inline S16 readS16() { return (S16)readU16(); }
- inline S32 readS32() { return (S32)readU32(); }
-
- // skip() ignores a number of bytes on the stream
-
- inline void skip(size_t bytes) {
- check(bytes);
- ptr += bytes;
- }
-
- // readBytes() reads an exact number of bytes.
-
- void readBytes(void* data, size_t length) {
- check(length);
- memcpy(data, ptr, length);
- ptr += length;
- }
-
- // readOpaqueN() reads a quantity without byte-swapping.
-
- inline U8 readOpaque8() { return readU8(); }
- inline U16 readOpaque16() { check(2); U16 r; ((U8*)&r)[0] = *ptr++;
- ((U8*)&r)[1] = *ptr++; return r; }
- inline U32 readOpaque32() { check(4); U32 r; ((U8*)&r)[0] = *ptr++;
- ((U8*)&r)[1] = *ptr++; ((U8*)&r)[2] = *ptr++;
- ((U8*)&r)[3] = *ptr++; return r; }
-
- // pos() returns the position in the stream.
-
- virtual size_t pos() = 0;
-
- // getptr() and setptr() are "dirty" methods which allow you direct access
- // to the buffer. This is useful for a stream which is a wrapper around an
- // some other stream API.
-
- inline const U8* getptr(size_t length) { check(length);
- #ifdef RFB_INSTREAM_CHECK
- checkedBytes += length;
- #endif
- return ptr; }
- inline void setptr(size_t length) { if (length > avail())
- throw Exception("Input stream overflow");
- skip(length); }
-
- private:
-
- const U8* restorePoint;
- #ifdef RFB_INSTREAM_CHECK
- size_t checkedBytes;
- #endif
-
- inline void check(size_t bytes) {
- #ifdef RFB_INSTREAM_CHECK
- if (bytes > checkedBytes)
- throw Exception("Input stream used without underrun check");
- checkedBytes -= bytes;
- #endif
- if (bytes > (size_t)(end - ptr))
- throw Exception("InStream buffer underrun");
- }
-
- // overrun() is implemented by a derived class to cope with buffer overrun.
- // It tries to ensure there are at least needed bytes of buffer data.
- // Returns true if it managed to satisfy the request, or false otherwise.
-
- virtual bool overrun(size_t needed) = 0;
-
- protected:
-
- InStream() : restorePoint(NULL)
- #ifdef RFB_INSTREAM_CHECK
- ,checkedBytes(0)
- #endif
- {}
- const U8* ptr;
- const U8* end;
- };
-
- }
-
- #endif
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