src: create helper for reading Uint32BE

Fixes: https://github.com/nodejs/node/issues/34827

PR-URL: https://github.com/nodejs/node/pull/34944
Reviewed-By: Anna Henningsen <anna@addaleax.net>

1 files changed, 3 insertions, 75 deletions

diff --git a/src/base64.h b/src/base64.h
index 1cb90bdeba7..24fc57e1d60 100644
--- a/src/base64.h
+++ b/src/base64.h
@@ -4,6 +4,7 @@
 #if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
 
 #include "util.h"
+#include "base64-inl.h"
 
 #include <cstddef>
 #include <cstdint>
@@ -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
@@ -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) {