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1 | /* | |
2 | * Copyright (C) 1996-2020 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 20 Storage Manager Swapfile Unpacker */ | |
10 | ||
11 | #include "squid.h" | |
12 | #include "base/TextException.h" | |
13 | #include "Debug.h" | |
14 | #include "defines.h" | |
15 | #include "StoreMeta.h" | |
16 | #include "StoreMetaUnpacker.h" | |
17 | ||
18 | int const StoreMetaUnpacker::MinimumBufferLength = sizeof(char) + sizeof(int); | |
19 | ||
20 | /// useful for meta stored in pre-initialized (with zeros) db files | |
21 | bool | |
22 | StoreMetaUnpacker::isBufferZero() | |
23 | { | |
24 | // We could memcmp the entire buffer, but it is probably safe enough | |
25 | // to test a few bytes because if we do not detect a corrupted entry | |
26 | // it is not a big deal. Empty entries are not isBufferSane anyway. | |
27 | const int depth = 10; | |
28 | if (buflen < depth) | |
29 | return false; // cannot be sure enough | |
30 | ||
31 | for (int i = 0; i < depth; ++i) { | |
32 | if (buf[i]) | |
33 | return false; | |
34 | } | |
35 | return true; | |
36 | } | |
37 | ||
38 | void | |
39 | StoreMetaUnpacker::checkBuffer() | |
40 | { | |
41 | assert(buf); // paranoid; already checked in the constructor | |
42 | if (buf[0] != static_cast<char>(STORE_META_OK)) | |
43 | throw TexcHere("store entry metadata is corrupted"); | |
44 | /* | |
45 | * sanity check on 'buflen' value. It should be at least big | |
46 | * enough to hold one type and one length. | |
47 | */ | |
48 | getBufferLength(); | |
49 | if (*hdr_len < MinimumBufferLength) | |
50 | throw TexcHere("store entry metadata is too small"); | |
51 | if (*hdr_len > buflen) | |
52 | throw TexcHere("store entry metadata is too big"); | |
53 | } | |
54 | ||
55 | void | |
56 | StoreMetaUnpacker::getBufferLength() | |
57 | { | |
58 | memcpy(hdr_len, &buf[1], sizeof(int)); | |
59 | } | |
60 | ||
61 | StoreMetaUnpacker::StoreMetaUnpacker(char const *aBuffer, ssize_t aLen, int *anInt) : | |
62 | buf(aBuffer), | |
63 | buflen(aLen), | |
64 | hdr_len(anInt), | |
65 | position(1 + sizeof(int)), | |
66 | type('\0'), | |
67 | length(0), | |
68 | tail(NULL) | |
69 | { | |
70 | assert(aBuffer != NULL); | |
71 | } | |
72 | ||
73 | void | |
74 | StoreMetaUnpacker::getType() | |
75 | { | |
76 | type = buf[position]; | |
77 | ++position; | |
78 | } | |
79 | ||
80 | void | |
81 | StoreMetaUnpacker::getLength() | |
82 | { | |
83 | memcpy(&length, &buf[position], sizeof(int)); | |
84 | position += sizeof(int); | |
85 | } | |
86 | ||
87 | bool | |
88 | StoreMetaUnpacker::doOneEntry() | |
89 | { | |
90 | getType(); | |
91 | getLength(); | |
92 | ||
93 | if (position + length > *hdr_len) { | |
94 | debugs(20, DBG_CRITICAL, "storeSwapMetaUnpack: overflow!"); | |
95 | debugs(20, DBG_CRITICAL, "\ttype=" << type << ", length=" << length << ", *hdr_len=" << *hdr_len << ", offset=" << position); | |
96 | return false; | |
97 | } | |
98 | ||
99 | StoreMeta *newNode = StoreMeta::Factory(type, length, &buf[position]); | |
100 | ||
101 | if (newNode) | |
102 | tail = StoreMeta::Add (tail, newNode); | |
103 | ||
104 | position += length; | |
105 | ||
106 | return true; | |
107 | } | |
108 | ||
109 | bool | |
110 | StoreMetaUnpacker::moreToProcess() const | |
111 | { | |
112 | return *hdr_len - position - MinimumBufferLength >= 0; | |
113 | } | |
114 | ||
115 | StoreMeta * | |
116 | StoreMetaUnpacker::createStoreMeta () | |
117 | { | |
118 | tlv *TLV = NULL; | |
119 | tail = &TLV; | |
120 | assert(hdr_len != NULL); | |
121 | ||
122 | checkBuffer(); | |
123 | ||
124 | getBufferLength(); | |
125 | ||
126 | assert (position == 1 + sizeof(int)); | |
127 | ||
128 | while (moreToProcess()) { | |
129 | if (!doOneEntry()) | |
130 | break; | |
131 | } | |
132 | ||
133 | if (!TLV) | |
134 | throw TexcHere("store entry metadata is empty"); | |
135 | ||
136 | assert(TLV); | |
137 | return TLV; | |
138 | } | |
139 |