The Tor Browser: media/webrtc/signaling/src/common/YuvStamper.cpp@ac0c01689b40 (annotated)

media/webrtc/signaling/src/common/YuvStamper.cpp@ac0c01689b40 (annotated)

media/webrtc/signaling/src/common/YuvStamper.cpp

Thu, 15 Jan 2015 15:59:08 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 15 Jan 2015 15:59:08 +0100
branch: TOR_BUG_9701
changeset 10: ac0c01689b40
permissions: -rw-r--r--

Implement a real Private Browsing Mode condition by changing the API/ABI;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 #ifdef HAVE_NETINET_IN_H
 #include <netinet/in.h>
 #elif defined XP_WIN
 #include <winsock2.h>
 #endif
 #include <string.h>
 #include "nspr.h"
 #include "YuvStamper.h"
 typedef uint32_t UINT4; //Needed for r_crc32() call
 extern "C" {
 #include "r_crc32.h"
 }
 namespace mozilla {
 #define ON_5 0x20
 #define ON_4 0x10
 #define ON_3 0x08
 #define ON_2 0x04
 #define ON_1 0x02
 #define ON_0 0x01
 /*
 , 0, 1, 1, 0, 0,
 , 1, 0, 0, 1, 0,
 , 0, 0, 0, 0, 1,
 , 0, 0, 0, 0, 1,
 , 0, 0, 0, 0, 1,
 , 1, 0, 0, 1, 0,
 , 0, 1, 1, 0, 0
 */
 static unsigned char DIGIT_0 [] =
   { ON_3 | ON_2,
     ON_4 | ON_1,
     ON_5 | ON_0,
     ON_5 | ON_0,
     ON_5 | ON_0,
     ON_4 | ON_1,
     ON_3 | ON_2
   };
 /*
 , 0, 0, 1, 0, 0,
 , 0, 0, 1, 0, 0,
 , 0, 0, 1, 0, 0,
 , 0, 0, 1, 0, 0,
 , 0, 0, 1, 0, 0,
 , 0, 0, 1, 0, 0,
 , 0, 0, 1, 0, 0,
 */
 static unsigned char DIGIT_1 [] =
   { ON_2,
     ON_2,
     ON_2,
     ON_2,
     ON_2,
     ON_2,
     ON_2
   };
 /*
 , 1, 1, 1, 1, 0,
 , 0, 0, 0, 0, 1,
 , 0, 0, 0, 0, 1,
 , 1, 1, 1, 1, 0,
 , 0, 0, 0, 0, 0,
 , 0, 0, 0, 0, 0,
 , 1, 1, 1, 1, 1,
 */
 static unsigned char DIGIT_2 [] =
   { ON_5 | ON_4 | ON_3 | ON_2 | ON_1,
     ON_0,
     ON_0,
     ON_4 | ON_3 | ON_2 | ON_1,
     ON_5,
     ON_5,
     ON_4 | ON_3 | ON_2 | ON_1 | ON_0,
   };
 /*
 , 1, 1, 1, 1, 0,
 , 0, 0, 0, 0, 1,
 , 0, 0, 0, 0, 1,
 , 1, 1, 1, 1, 1,
 , 0, 0, 0, 0, 1,
 , 0, 0, 0, 0, 1,
 , 1, 1, 1, 1, 0,
 */
 static unsigned char DIGIT_3 [] =
   { ON_5 | ON_4 | ON_3 | ON_2 | ON_1,
     ON_0,
     ON_0,
     ON_4 | ON_3 | ON_2 | ON_1 | ON_0,
     ON_0,
     ON_0,
     ON_5 | ON_4 | ON_3 | ON_2 | ON_1,
   };
 /*
 , 1, 0, 0, 0, 1,
 , 1, 0, 0, 0, 1,
 , 1, 0, 0, 0, 1,
 , 1, 1, 1, 1, 1,
 , 0, 0, 0, 0, 1,
 , 0, 0, 0, 0, 1,
 , 0, 0, 0, 0, 1
 */
 static unsigned char DIGIT_4 [] =
   { ON_4 | ON_0,
     ON_4 | ON_0,
     ON_4 | ON_0,
     ON_4 | ON_3 | ON_2 | ON_1 | ON_0,
     ON_0,
     ON_0,
     ON_0,
   };
 /*
 , 1, 1, 1, 1, 1,
 , 0, 0, 0, 0, 0,
 , 0, 0, 0, 0, 0,
 , 1, 1, 1, 1, 0,
 , 0, 0, 0, 0, 1,
 , 0, 0, 0, 0, 1,
 , 1, 1, 1, 1, 0,
 */
 static unsigned char DIGIT_5 [] =
   { ON_4 | ON_3 | ON_2 | ON_1 | ON_0,
     ON_5,
     ON_5,
     ON_4 | ON_3 | ON_2 | ON_1,
     ON_0,
     ON_0,
     ON_5 | ON_4 | ON_3 | ON_2 | ON_1,
   };
 /*
 , 1, 1, 1, 1, 1,
 , 0, 0, 0, 0, 0,
 , 0, 0, 0, 0, 0,
 , 1, 1, 1, 1, 0,
 , 0, 0, 0, 0, 1,
 , 0, 0, 0, 0, 1,
 , 1, 1, 1, 1, 0,
 */
 static unsigned char DIGIT_6 [] =
   { ON_4 | ON_3 | ON_2 | ON_1 | ON_0,
     ON_5,
     ON_5,
     ON_4 | ON_3 | ON_2 | ON_1,
     ON_5 | ON_0,
     ON_5 | ON_0,
     ON_4 | ON_3 | ON_2 | ON_1,
   };
 /*
 , 1, 1, 1, 1, 1,
 , 0, 0, 0, 0, 1,
 , 0, 0, 0, 1, 0,
 , 0, 0, 1, 0, 0,
 , 0, 1, 0, 0, 0,
 , 1, 0, 0, 0, 0,
 , 0, 0, 0, 0, 0
 */
 static unsigned char DIGIT_7 [] =
   { ON_5 | ON_4 | ON_3 | ON_2 | ON_1 | ON_0,
     ON_0,
     ON_1,
     ON_2,
     ON_3,
     ON_4,
     ON_5
   };
 /*
 , 1, 1, 1, 1, 1,
 , 0, 0, 0, 0, 1,
 , 0, 0, 0, 0, 1,
 , 1, 1, 1, 1, 0,
 , 0, 0, 0, 0, 1,
 , 0, 0, 0, 0, 1,
 , 1, 1, 1, 1, 0
 */
 static unsigned char DIGIT_8 [] =
   { ON_4 | ON_3 | ON_2 | ON_1,
     ON_5 | ON_0,
     ON_5 | ON_0,
     ON_4 | ON_3 | ON_2 | ON_1,
     ON_5 | ON_0,
     ON_5 | ON_0,
     ON_4 | ON_3 | ON_2 | ON_1,
   };
 /*
 , 1, 1, 1, 1, 1,
 , 0, 0, 0, 0, 1,
 , 0, 0, 0, 0, 1,
 , 1, 1, 1, 1, 1,
 , 0, 0, 0, 0, 1,
 , 0, 0, 0, 0, 1,
 , 1, 1, 1, 1, 0
 */
 static unsigned char DIGIT_9 [] =
   { ON_4 | ON_3 | ON_2 | ON_1 | ON_0,
     ON_5 | ON_0,
     ON_5 | ON_0,
     ON_4 | ON_3 | ON_2 | ON_1 | ON_0,
     ON_0,
     ON_0,
     ON_4 | ON_3 | ON_2 | ON_1,
   };
 static unsigned char *DIGITS[] = {
     DIGIT_0,
     DIGIT_1,
     DIGIT_2,
     DIGIT_3,
     DIGIT_4,
     DIGIT_5,
     DIGIT_6,
     DIGIT_7,
     DIGIT_8,
     DIGIT_9
 };
   YuvStamper::YuvStamper(unsigned char* pYData,
 			 uint32_t width,
 			 uint32_t height,
 			 uint32_t stride,
 			 uint32_t x,
 			 uint32_t y,
 			 unsigned char symbol_width,
 			 unsigned char symbol_height):
     pYData(pYData), mStride(stride),
     mWidth(width), mHeight(height),
     mSymbolWidth(symbol_width), mSymbolHeight(symbol_height),
     mCursor(x, y) {}
   bool YuvStamper::Encode(uint32_t width, uint32_t height, uint32_t stride,
 			  unsigned char* pYData, unsigned char* pMsg, size_t msg_len,
 			  uint32_t x, uint32_t y)
   {
     YuvStamper stamper(pYData, width, height, stride,
 		       x, y, sBitSize, sBitSize);
     // Reserve space for a checksum.
     if (stamper.Capacity() < 8 * (msg_len + sizeof(uint32_t)))
     {
       return false;
     }
     bool ok = false;
     uint32_t crc;
     unsigned char* pCrc = reinterpret_cast<unsigned char*>(&crc);
     r_crc32(reinterpret_cast<char*>(pMsg), (int)msg_len, &crc);
     crc = htonl(crc);
     while (msg_len-- > 0) {
       if (!stamper.Write8(*pMsg++)) {
 	return false;
       }
     }
     // Add checksum after the message.
     ok = stamper.Write8(*pCrc++) &&
          stamper.Write8(*pCrc++) &&
          stamper.Write8(*pCrc++) &&
          stamper.Write8(*pCrc++);
     return ok;
   }
   bool YuvStamper::Decode(uint32_t width, uint32_t height, uint32_t stride,
 			  unsigned char* pYData, unsigned char* pMsg, size_t msg_len,
 			  uint32_t x, uint32_t y)
   {
     YuvStamper stamper(pYData, width, height, stride,
 		       x, y, sBitSize, sBitSize);
     unsigned char* ptr = pMsg;
     size_t len = msg_len;
     uint32_t crc, msg_crc;
     unsigned char* pCrc = reinterpret_cast<unsigned char*>(&crc);
     // Account for space reserved for the checksum
     if (stamper.Capacity() < 8 * (len + sizeof(uint32_t))) {
       return false;
     }
     while (len-- > 0) {
       if(!stamper.Read8(*ptr++)) {
 	return false;
       }
     }
     if (!(stamper.Read8(*pCrc++) &&
           stamper.Read8(*pCrc++) &&
           stamper.Read8(*pCrc++) &&
           stamper.Read8(*pCrc++))) {
       return false;
     }
     r_crc32(reinterpret_cast<char*>(pMsg), (int)msg_len, &msg_crc);
     return crc == htonl(msg_crc);
   }
   inline uint32_t YuvStamper::Capacity()
   {
     // Enforce at least a symbol width and height offset from outer edges.
     if (mCursor.y + mSymbolHeight > mHeight) {
       return 0;
     }
     if (mCursor.x + mSymbolWidth > mWidth && !AdvanceCursor()) {
       return 0;
     }
     // Normalize frame integral to mSymbolWidth x mSymbolHeight
     uint32_t width = mWidth / mSymbolWidth;
     uint32_t height = mHeight / mSymbolHeight;
     uint32_t x = mCursor.x / mSymbolWidth;
     uint32_t y = mCursor.y / mSymbolHeight;
     return (width * height - width * y)- x;
   }
   bool YuvStamper::Write8(unsigned char value)
   {
     // Encode MSB to LSB.
     unsigned char mask = 0x80;
     while (mask) {
       if (!WriteBit(!!(value & mask))) {
 	return false;
       }
       mask >>= 1;
     }
     return true;
   }
   bool YuvStamper::WriteBit(bool one)
   {
     // A bit is mapped to a mSymbolWidth x mSymbolHeight square of luma data points.
     // Don't use ternary op.: https://bugzilla.mozilla.org/show_bug.cgi?id=1001708
     unsigned char value;
     if (one)
       value = sYOn;
     else
       value = sYOff;
     for (uint32_t y = 0; y < mSymbolHeight; y++) {
       for (uint32_t x = 0; x < mSymbolWidth; x++) {
 	*(pYData + (mCursor.x + x) + ((mCursor.y + y) * mStride)) = value;
       }
     }
     return AdvanceCursor();
   }
   bool YuvStamper::AdvanceCursor()
   {
     mCursor.x += mSymbolWidth;
     if (mCursor.x + mSymbolWidth > mWidth) {
       // move to the start of the next row if possible.
       mCursor.y += mSymbolHeight;
       if (mCursor.y + mSymbolHeight > mHeight) {
 	// end of frame, do not advance
 	mCursor.y -= mSymbolHeight;
 	mCursor.x -= mSymbolWidth;
 	return false;
       } else {
 	mCursor.x = 0;
       }
     }
     return true;
   }
   bool YuvStamper::Read8(unsigned char &value)
   {
     unsigned char octet = 0;
     unsigned char bit = 0;
     for (int i = 8; i > 0; --i) {
       if (!ReadBit(bit)) {
 	return false;
       }
       octet <<= 1;
       octet |= bit;
     }
     value = octet;
     return true;
   }
   bool YuvStamper::ReadBit(unsigned char &bit)
   {
     uint32_t sum = 0;
     for (uint32_t y = 0; y < mSymbolHeight; y++) {
       for (uint32_t x = 0; x < mSymbolWidth; x++) {
 	sum += *(pYData + mStride * (mCursor.y + y) + mCursor.x + x);
       }
     }
     // apply threshold to collected bit square
     bit = (sum > (sBitThreshold * mSymbolWidth * mSymbolHeight)) ? 1 : 0;
     return AdvanceCursor();
   }
   bool YuvStamper::WriteDigits(uint32_t value)
   {
     char buf[20];
     PR_snprintf(buf, sizeof(buf), "%.5u", value);
     size_t size = strlen(buf);
     if (Capacity() < size) {
       return false;
     }
     for (size_t i=0; i < size; ++i) {
       if (!WriteDigit(buf[i] - '0'))
 	return false;
       if (!AdvanceCursor()) {
 	return false;
       }
     }
     return true;
   }
   bool YuvStamper::WriteDigit(unsigned char digit) {
     if (digit > sizeof(DIGITS)/sizeof(DIGITS[0]))
       return false;
     unsigned char *dig = DIGITS[digit];
     for (uint32_t row = 0; row < sDigitHeight; ++row) {
       unsigned char mask = 0x01 << (sDigitWidth - 1);
       for (uint32_t col = 0; col < sDigitWidth; ++col, mask >>= 1) {
 	if (dig[row] & mask) {
 	  for (uint32_t xx=0; xx < sPixelSize; ++xx) {
 	    for (uint32_t yy=0; yy < sPixelSize; ++yy) {
 	      WritePixel(pYData,
 			 mCursor.x + (col * sPixelSize) + xx,
 			 mCursor.y + (row * sPixelSize) + yy);
 	    }
 	  }
 	}
       }
     }
     return true;
   }
   void YuvStamper::WritePixel(unsigned char *data, uint32_t x, uint32_t y) {
     unsigned char *ptr = &data[y * mStride + x];
     // Don't use ternary op.: https://bugzilla.mozilla.org/show_bug.cgi?id=1001708
     if (*ptr > sLumaThreshold)
       *ptr = sLumaMin;
     else
       *ptr = sLumaMax;
    }
 }  // Namespace mozilla.

The Tor Browser / annotate

media/webrtc/signaling/src/common/YuvStamper.cpp@ac0c01689b40 (annotated)

media/webrtc/signaling/src/common/YuvStamper.cpp