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src: create helper for reading Uint32BE
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Fixes: #34827

Backport-PR-URL: #35701
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@juanarbol
juanarbol committed Oct 18, 2020
1 parent 81daf38 commit 02b9af1
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Showing 4 changed files with 108 additions and 87 deletions.
1 change: 1 addition & 0 deletions node.gyp
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Original file line number Diff line number Diff line change
Expand Up @@ -652,6 +652,7 @@
'src/base_object.h',
'src/base_object-inl.h',
'src/base64.h',
'src/base64-inl.h',
'src/callback_queue.h',
'src/callback_queue-inl.h',
'src/connect_wrap.h',
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98 changes: 98 additions & 0 deletions src/base64-inl.h
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Original file line number Diff line number Diff line change
@@ -0,0 +1,98 @@
#ifndef SRC_BASE64_INL_H_
#define SRC_BASE64_INL_H_

#if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS

#include "util.h"

namespace node {

extern const int8_t unbase64_table[256];


inline static int8_t unbase64(uint8_t x) {
return unbase64_table[x];
}


inline uint32_t ReadUint32BE(const unsigned char* p) {
return static_cast<uint32_t>(p[0] << 24U) |
static_cast<uint32_t>(p[1] << 16U) |
static_cast<uint32_t>(p[2] << 8U) |
static_cast<uint32_t>(p[3]);
}


template <typename TypeName>
bool base64_decode_group_slow(char* const dst, const size_t dstlen,
const TypeName* const src, const size_t srclen,
size_t* const i, size_t* const k) {
uint8_t hi;
uint8_t lo;
#define V(expr) \
for (;;) { \
const uint8_t c = src[*i]; \
lo = unbase64(c); \
*i += 1; \
if (lo < 64) \
break; /* Legal character. */ \
if (c == '=' || *i >= srclen) \
return false; /* Stop decoding. */ \
} \
expr; \
if (*i >= srclen) \
return false; \
if (*k >= dstlen) \
return false; \
hi = lo;
V(/* Nothing. */);
V(dst[(*k)++] = ((hi & 0x3F) << 2) | ((lo & 0x30) >> 4));
V(dst[(*k)++] = ((hi & 0x0F) << 4) | ((lo & 0x3C) >> 2));
V(dst[(*k)++] = ((hi & 0x03) << 6) | ((lo & 0x3F) >> 0));
#undef V
return true; // Continue decoding.
}


template <typename TypeName>
size_t base64_decode_fast(char* const dst, const size_t dstlen,
const TypeName* const src, const size_t srclen,
const size_t decoded_size) {
const size_t available = dstlen < decoded_size ? dstlen : decoded_size;
const size_t max_k = available / 3 * 3;
size_t max_i = srclen / 4 * 4;
size_t i = 0;
size_t k = 0;
while (i < max_i && k < max_k) {
const unsigned char txt[] = {
static_cast<unsigned char>(unbase64(src[i + 0])),
static_cast<unsigned char>(unbase64(src[i + 1])),
static_cast<unsigned char>(unbase64(src[i + 2])),
static_cast<unsigned char>(unbase64(src[i + 3])),
};

const uint32_t v = ReadUint32BE(txt);
// If MSB is set, input contains whitespace or is not valid base64.
if (v & 0x80808080) {
if (!base64_decode_group_slow(dst, dstlen, src, srclen, &i, &k))
return k;
max_i = i + (srclen - i) / 4 * 4; // Align max_i again.
} else {
dst[k + 0] = ((v >> 22) & 0xFC) | ((v >> 20) & 0x03);
dst[k + 1] = ((v >> 12) & 0xF0) | ((v >> 10) & 0x0F);
dst[k + 2] = ((v >> 2) & 0xC0) | ((v >> 0) & 0x3F);
i += 4;
k += 3;
}
}
if (i < srclen && k < dstlen) {
base64_decode_group_slow(dst, dstlen, src, srclen, &i, &k);
}
return k;
}

} // namespace node

#endif // defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS

#endif // SRC_BASE64_INL_H_
78 changes: 3 additions & 75 deletions src/base64.h
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Expand Up @@ -4,6 +4,7 @@
#if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS

#include "util.h"
#include "base64-inl.h"

#include <cstddef>
#include <cstdint>
Expand All @@ -20,6 +21,8 @@ static inline constexpr size_t base64_decoded_size_fast(size_t size) {
return size > 1 ? (size / 4) * 3 + (size % 4 + 1) / 2 : 0;
}

inline uint32_t ReadUint32BE(const unsigned char* p);

template <typename TypeName>
size_t base64_decoded_size(const TypeName* src, size_t size) {
// 1-byte input cannot be decoded
Expand All @@ -34,81 +37,6 @@ size_t base64_decoded_size(const TypeName* src, size_t size) {
return base64_decoded_size_fast(size);
}


extern const int8_t unbase64_table[256];


inline static int8_t unbase64(uint8_t x) {
return unbase64_table[x];
}


template <typename TypeName>
bool base64_decode_group_slow(char* const dst, const size_t dstlen,
const TypeName* const src, const size_t srclen,
size_t* const i, size_t* const k) {
uint8_t hi;
uint8_t lo;
#define V(expr) \
for (;;) { \
const uint8_t c = src[*i]; \
lo = unbase64(c); \
*i += 1; \
if (lo < 64) \
break; /* Legal character. */ \
if (c == '=' || *i >= srclen) \
return false; /* Stop decoding. */ \
} \
expr; \
if (*i >= srclen) \
return false; \
if (*k >= dstlen) \
return false; \
hi = lo;
V(/* Nothing. */);
V(dst[(*k)++] = ((hi & 0x3F) << 2) | ((lo & 0x30) >> 4));
V(dst[(*k)++] = ((hi & 0x0F) << 4) | ((lo & 0x3C) >> 2));
V(dst[(*k)++] = ((hi & 0x03) << 6) | ((lo & 0x3F) >> 0));
#undef V
return true; // Continue decoding.
}


template <typename TypeName>
size_t base64_decode_fast(char* const dst, const size_t dstlen,
const TypeName* const src, const size_t srclen,
const size_t decoded_size) {
const size_t available = dstlen < decoded_size ? dstlen : decoded_size;
const size_t max_k = available / 3 * 3;
size_t max_i = srclen / 4 * 4;
size_t i = 0;
size_t k = 0;
while (i < max_i && k < max_k) {
const uint32_t v =
unbase64(src[i + 0]) << 24 |
unbase64(src[i + 1]) << 16 |
unbase64(src[i + 2]) << 8 |
unbase64(src[i + 3]);
// If MSB is set, input contains whitespace or is not valid base64.
if (v & 0x80808080) {
if (!base64_decode_group_slow(dst, dstlen, src, srclen, &i, &k))
return k;
max_i = i + (srclen - i) / 4 * 4; // Align max_i again.
} else {
dst[k + 0] = ((v >> 22) & 0xFC) | ((v >> 20) & 0x03);
dst[k + 1] = ((v >> 12) & 0xF0) | ((v >> 10) & 0x0F);
dst[k + 2] = ((v >> 2) & 0xC0) | ((v >> 0) & 0x3F);
i += 4;
k += 3;
}
}
if (i < srclen && k < dstlen) {
base64_decode_group_slow(dst, dstlen, src, srclen, &i, &k);
}
return k;
}


template <typename TypeName>
size_t base64_decode(char* const dst, const size_t dstlen,
const TypeName* const src, const size_t srclen) {
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18 changes: 6 additions & 12 deletions src/cares_wrap.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@
#define CARES_STATICLIB
#include "ares.h"
#include "async_wrap-inl.h"
#include "base64-inl.h"
#include "env-inl.h"
#include "memory_tracker-inl.h"
#include "node.h"
Expand Down Expand Up @@ -79,13 +80,6 @@ inline uint16_t cares_get_16bit(const unsigned char* p) {
return static_cast<uint32_t>(p[0] << 8U) | (static_cast<uint32_t>(p[1]));
}

inline uint32_t cares_get_32bit(const unsigned char* p) {
return static_cast<uint32_t>(p[0] << 24U) |
static_cast<uint32_t>(p[1] << 16U) |
static_cast<uint32_t>(p[2] << 8U) |
static_cast<uint32_t>(p[3]);
}

const int ns_t_cname_or_a = -1;

#define DNS_ESETSRVPENDING -1000
Expand Down Expand Up @@ -1129,11 +1123,11 @@ int ParseSoaReply(Environment* env,
return ARES_EBADRESP;
}

const unsigned int serial = cares_get_32bit(ptr + 0 * 4);
const unsigned int refresh = cares_get_32bit(ptr + 1 * 4);
const unsigned int retry = cares_get_32bit(ptr + 2 * 4);
const unsigned int expire = cares_get_32bit(ptr + 3 * 4);
const unsigned int minttl = cares_get_32bit(ptr + 4 * 4);
const unsigned int serial = ReadUint32BE(ptr + 0 * 4);
const unsigned int refresh = ReadUint32BE(ptr + 1 * 4);
const unsigned int retry = ReadUint32BE(ptr + 2 * 4);
const unsigned int expire = ReadUint32BE(ptr + 3 * 4);
const unsigned int minttl = ReadUint32BE(ptr + 4 * 4);

Local<Object> soa_record = Object::New(env->isolate());
soa_record->Set(context,
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