src/StoreSwapLogData.cc

   1 /*
   2  * Copyright (C) 1996-2018 The Squid Software Foundation and contributors
   3  *
   4  * Squid software is distributed under GPLv2+ license and includes
   5  * contributions from numerous individuals and organizations.
   6  * Please see the COPYING and CONTRIBUTORS files for details.
   7  */
   8
   9 /* DEBUG: section 47    Store Directory Routines */
  10
  11 #include "squid.h"
  12 #include "StoreSwapLogData.h"
  13 #include "swap_log_op.h"
  14
  15 #include <ostream>
  16
  17 // Based on Internet Checksum (RFC 1071) algorithm but takes three 32bit ints.
  18 // TODO: Consider Fletcher's checksum algorithm as a higher quality alternative
  19 void
  20 SwapChecksum24::set(uint32_t f1, uint32_t f2, uint32_t f3)
  21 {
  22     uint64_t sum = f1;
  23     sum += f2;
  24     sum += f3;
  25
  26     while (const uint64_t higherBits = sum >> 24)
  27         sum = (sum & 0xFFFFFF) + higherBits;
  28
  29     sum = ~sum;
  30
  31     raw[0] = static_cast<uint8_t>(sum);
  32     raw[1] = static_cast<uint8_t>(sum >> 8);
  33     raw[2] = static_cast<uint8_t>(sum >> 16);
  34 }
  35
  36 /// Same as 3-argument SwapChecksum24::set() but for int32_t and uint64_t
  37 void
  38 SwapChecksum24::set(int32_t f1, uint64_t f2)
  39 {
  40     // split the second 64bit word into two 32bit words
  41     set(static_cast<uint32_t>(f1),
  42         static_cast<uint32_t>(f2 >> 32),
  43         static_cast<uint32_t>(f2 & 0xFFFFFFFF));
  44 }
  45
  46 std::ostream &
  47 SwapChecksum24::print(std::ostream &os) const
  48 {
  49     return os << raw[0] << '-' << raw[1] << '-' << raw[2];
  50 }
  51
  52 StoreSwapLogData::StoreSwapLogData()
  53 {
  54     memset(this, 0, sizeof(*this));
  55 }
  56
  57 bool
  58 StoreSwapLogData::sane() const
  59 {
  60     SwapChecksum24 actualSum;
  61     actualSum.set(swap_filen, swap_file_sz);
  62     if (checksum != actualSum)
  63         return false;
  64
  65     const time_t minTime = -2; // -1 is common; expires sometimes uses -2
  66
  67     // Check what we safely can; for some fields any value might be valid
  68     return SWAP_LOG_NOP < op && op < SWAP_LOG_MAX &&
  69            swap_filen >= 0 &&
  70            timestamp >= minTime &&
  71            lastref >= minTime &&
  72            expires >= minTime &&
  73            lastmod >= minTime &&
  74            swap_file_sz > 0; // because swap headers ought to consume space
  75 }
  76
  77 void
  78 StoreSwapLogData::finalize()
  79 {
  80     checksum.set(swap_filen, swap_file_sz);
  81 }
  82
  83 StoreSwapLogHeader::StoreSwapLogHeader(): op(SWAP_LOG_VERSION), version(2),
  84     record_size(sizeof(StoreSwapLogData))
  85 {
  86     checksum.set(version, record_size, 0);
  87 }
  88
  89 bool
  90 StoreSwapLogHeader::sane() const
  91 {
  92     SwapChecksum24 actualSum;
  93     actualSum.set(version, record_size, 0);
  94     if (checksum != actualSum)
  95         return false;
  96
  97     return op == SWAP_LOG_VERSION && version >= 2 && record_size > 0;
  98 }
  99
 100 size_t
 101 StoreSwapLogHeader::gapSize() const
 102 {
 103     assert(record_size > 0);
 104     assert(static_cast<size_t>(record_size) > sizeof(*this));
 105     return static_cast<size_t>(record_size) - sizeof(*this);
 106 }
 107