md5.c

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#include "config.h"
#include <stddef.h> // IWYU pragma: keep
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include "md5.h"
 
#ifdef WORDS_BIGENDIAN
#define SWAP(n)                                                                \
  (((n) << 24) | (((n) & 0xff00) << 8) | (((n) >> 8) & 0xff00) | ((n) >> 24))
#else
#define SWAP(n) (n)
#endif
 
static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ... */ };
 
/* These are the four functions used in the four steps of the MD5 algorithm
 * and defined in the RFC1321.  The first function is a little bit optimized
 * (as found in Colin Plumbs public domain implementation). */
#define FF(b, c, d) (d ^ (b & (c ^ d)))
#define FG(b, c, d) FF(d, b, c)
#define FH(b, c, d) (b ^ c ^ d)
#define FI(b, c, d) (c ^ (b | ~d))
 
static void mutt_md5_process_block(const void *buffer, size_t len, struct Md5Ctx *md5ctx)
{
  md5_uint32 correct_words[16];
  const md5_uint32 *words = buffer;
  size_t nwords = len / sizeof(md5_uint32);
  const md5_uint32 *endp = words + nwords;
  md5_uint32 A = md5ctx->A;
  md5_uint32 B = md5ctx->B;
  md5_uint32 C = md5ctx->C;
  md5_uint32 D = md5ctx->D;
 
  /* First increment the byte count.  RFC1321 specifies the possible length of
   * the file up to 2^64 bits.  Here we only compute the number of bytes.  Do a
   * double word increment. */
  md5ctx->total[0] += len;
  if (md5ctx->total[0] < len)
    md5ctx->total[1]++; // LCOV_EXCL_LINE
 
  /* Process all bytes in the buffer with 64 bytes in each round of the loop. */
  while (words < endp)
  {
    md5_uint32 *cwp = correct_words;
    md5_uint32 save_A = A;
    md5_uint32 save_B = B;
    md5_uint32 save_C = C;
    md5_uint32 save_D = D;
 
    /* First round: using the given function, the context and a constant the
     * next context is computed.  Because the algorithms processing unit is a
     * 32-bit word and it is determined to work on words in little endian byte
     * order we perhaps have to change the byte order before the computation.
     * To reduce the work for the next steps we store the swapped words in the
     * array CORRECT_WORDS. */
 
#define OP(a, b, c, d, s, T)                                                   \
  do                                                                           \
  {                                                                            \
    a += FF(b, c, d) + (*cwp++ = SWAP(*words)) + T;                            \
    words++;                                                                   \
    CYCLIC(a, s);                                                              \
    a += b;                                                                    \
  } while (false)
 
/* It is unfortunate that C does not provide an operator for
 * cyclic rotation.  Hope the C compiler is smart enough. */
#define CYCLIC(w, s) (w = (w << s) | (w >> (32 - s)))
 
    /* Before we start, one word to the strange constants.
     * They are defined in RFC1321 as
     * T[i] = (int) (4294967296.0 * fabs (sin (i))), i=1..64
     * Here is an equivalent invocation using Perl:
     * perl -e 'foreach(1..64){printf "0x%08x\n", int (4294967296 * abs (sin $_))}'
     */
 
    /* Round 1. */
    OP(A, B, C, D, 7, 0xd76aa478);
    OP(D, A, B, C, 12, 0xe8c7b756);
    OP(C, D, A, B, 17, 0x242070db);
    OP(B, C, D, A, 22, 0xc1bdceee);
    OP(A, B, C, D, 7, 0xf57c0faf);
    OP(D, A, B, C, 12, 0x4787c62a);
    OP(C, D, A, B, 17, 0xa8304613);
    OP(B, C, D, A, 22, 0xfd469501);
    OP(A, B, C, D, 7, 0x698098d8);
    OP(D, A, B, C, 12, 0x8b44f7af);
    OP(C, D, A, B, 17, 0xffff5bb1);
    OP(B, C, D, A, 22, 0x895cd7be);
    OP(A, B, C, D, 7, 0x6b901122);
    OP(D, A, B, C, 12, 0xfd987193);
    OP(C, D, A, B, 17, 0xa679438e);
    OP(B, C, D, A, 22, 0x49b40821);
 
/* For the second to fourth round we have the possibly swapped words
 * in CORRECT_WORDS.  Redefine the macro to take an additional first
 * argument specifying the function to use. */
#undef OP
#define OP(f, a, b, c, d, k, s, T)                                             \
  do                                                                           \
  {                                                                            \
    a += f(b, c, d) + correct_words[k] + T;                                    \
    CYCLIC(a, s);                                                              \
    a += b;                                                                    \
  } while (false)
 
    /* Round 2. */
    OP(FG, A, B, C, D, 1, 5, 0xf61e2562);
    OP(FG, D, A, B, C, 6, 9, 0xc040b340);
    OP(FG, C, D, A, B, 11, 14, 0x265e5a51);
    OP(FG, B, C, D, A, 0, 20, 0xe9b6c7aa);
    OP(FG, A, B, C, D, 5, 5, 0xd62f105d);
    OP(FG, D, A, B, C, 10, 9, 0x02441453);
    OP(FG, C, D, A, B, 15, 14, 0xd8a1e681);
    OP(FG, B, C, D, A, 4, 20, 0xe7d3fbc8);
    OP(FG, A, B, C, D, 9, 5, 0x21e1cde6);
    OP(FG, D, A, B, C, 14, 9, 0xc33707d6);
    OP(FG, C, D, A, B, 3, 14, 0xf4d50d87);
    OP(FG, B, C, D, A, 8, 20, 0x455a14ed);
    OP(FG, A, B, C, D, 13, 5, 0xa9e3e905);
    OP(FG, D, A, B, C, 2, 9, 0xfcefa3f8);
    OP(FG, C, D, A, B, 7, 14, 0x676f02d9);
    OP(FG, B, C, D, A, 12, 20, 0x8d2a4c8a);
 
    /* Round 3. */
    OP(FH, A, B, C, D, 5, 4, 0xfffa3942);
    OP(FH, D, A, B, C, 8, 11, 0x8771f681);
    OP(FH, C, D, A, B, 11, 16, 0x6d9d6122);
    OP(FH, B, C, D, A, 14, 23, 0xfde5380c);
    OP(FH, A, B, C, D, 1, 4, 0xa4beea44);
    OP(FH, D, A, B, C, 4, 11, 0x4bdecfa9);
    OP(FH, C, D, A, B, 7, 16, 0xf6bb4b60);
    OP(FH, B, C, D, A, 10, 23, 0xbebfbc70);
    OP(FH, A, B, C, D, 13, 4, 0x289b7ec6);
    OP(FH, D, A, B, C, 0, 11, 0xeaa127fa);
    OP(FH, C, D, A, B, 3, 16, 0xd4ef3085);
    OP(FH, B, C, D, A, 6, 23, 0x04881d05);
    OP(FH, A, B, C, D, 9, 4, 0xd9d4d039);
    OP(FH, D, A, B, C, 12, 11, 0xe6db99e5);
    OP(FH, C, D, A, B, 15, 16, 0x1fa27cf8);
    OP(FH, B, C, D, A, 2, 23, 0xc4ac5665);
 
    /* Round 4. */
    OP(FI, A, B, C, D, 0, 6, 0xf4292244);
    OP(FI, D, A, B, C, 7, 10, 0x432aff97);
    OP(FI, C, D, A, B, 14, 15, 0xab9423a7);
    OP(FI, B, C, D, A, 5, 21, 0xfc93a039);
    OP(FI, A, B, C, D, 12, 6, 0x655b59c3);
    OP(FI, D, A, B, C, 3, 10, 0x8f0ccc92);
    OP(FI, C, D, A, B, 10, 15, 0xffeff47d);
    OP(FI, B, C, D, A, 1, 21, 0x85845dd1);
    OP(FI, A, B, C, D, 8, 6, 0x6fa87e4f);
    OP(FI, D, A, B, C, 15, 10, 0xfe2ce6e0);
    OP(FI, C, D, A, B, 6, 15, 0xa3014314);
    OP(FI, B, C, D, A, 13, 21, 0x4e0811a1);
    OP(FI, A, B, C, D, 4, 6, 0xf7537e82);
    OP(FI, D, A, B, C, 11, 10, 0xbd3af235);
    OP(FI, C, D, A, B, 2, 15, 0x2ad7d2bb);
    OP(FI, B, C, D, A, 9, 21, 0xeb86d391);
 
    /* Add the starting values of the context. */
    A += save_A;
    B += save_B;
    C += save_C;
    D += save_D;
  }
 
  /* Put checksum in context given as argument. */
  md5ctx->A = A;
  md5ctx->B = B;
  md5ctx->C = C;
  md5ctx->D = D;
}
 
static inline void set_uint32(char *cp, md5_uint32 v)
{
  memcpy(cp, &v, sizeof(v));
}
 
static void *mutt_md5_read_ctx(const struct Md5Ctx *md5ctx, void *resbuf)
{
  if (!md5ctx || !resbuf)
    return NULL;
 
  char *r = resbuf;
 
  set_uint32(r + 0 * sizeof(md5ctx->A), SWAP(md5ctx->A));
  set_uint32(r + 1 * sizeof(md5ctx->B), SWAP(md5ctx->B));
  set_uint32(r + 2 * sizeof(md5ctx->C), SWAP(md5ctx->C));
  set_uint32(r + 3 * sizeof(md5ctx->D), SWAP(md5ctx->D));
 
  return resbuf;
}
 
void mutt_md5_init_ctx(struct Md5Ctx *md5ctx)
{
  if (!md5ctx)
    return;
 
  md5ctx->A = 0x67452301;
  md5ctx->B = 0xefcdab89;
  md5ctx->C = 0x98badcfe;
  md5ctx->D = 0x10325476;
 
  md5ctx->total[0] = 0;
  md5ctx->total[1] = 0;
  md5ctx->buflen = 0;
}
 
void *mutt_md5_finish_ctx(struct Md5Ctx *md5ctx, void *resbuf)
{
  if (!md5ctx)
    return NULL;
 
  /* Take yet unprocessed bytes into account. */
  md5_uint32 bytes = md5ctx->buflen;
  size_t size = (bytes < 56) ? 64 / 4 : 64 * 2 / 4;
 
  /* Now count remaining bytes. */
  md5ctx->total[0] += bytes;
  if (md5ctx->total[0] < bytes)
    md5ctx->total[1]++; // LCOV_EXCL_LINE
 
  /* Put the 64-bit file length in *bits* at the end of the buffer. */
  md5ctx->buffer[size - 2] = SWAP(md5ctx->total[0] << 3);
  md5ctx->buffer[size - 1] = SWAP((md5ctx->total[1] << 3) | (md5ctx->total[0] >> 29));
 
  memcpy(&((char *) md5ctx->buffer)[bytes], fillbuf, (size - 2) * 4 - bytes);
 
  /* Process last bytes. */
  mutt_md5_process_block(md5ctx->buffer, size * 4, md5ctx);
 
  return mutt_md5_read_ctx(md5ctx, resbuf);
}
 
void *mutt_md5(const char *str, void *buf)
{
  if (!str)
    return NULL;
 
  return mutt_md5_bytes(str, strlen(str), buf);
}
 
void *mutt_md5_bytes(const void *buffer, size_t len, void *resbuf)
{
  struct Md5Ctx md5ctx = { 0 };
 
  /* Initialize the computation context. */
  mutt_md5_init_ctx(&md5ctx);
 
  /* Process whole buffer but last len % 64 bytes. */
  mutt_md5_process_bytes(buffer, len, &md5ctx);
 
  /* Put result in desired memory area. */
  return mutt_md5_finish_ctx(&md5ctx, resbuf);
}
 
void mutt_md5_process(const char *str, struct Md5Ctx *md5ctx)
{
  if (!str)
    return;
 
  mutt_md5_process_bytes(str, strlen(str), md5ctx);
}
 
void mutt_md5_process_bytes(const void *buf, size_t buflen, struct Md5Ctx *md5ctx)
{
  if (!buf || !md5ctx)
    return;
 
  /* When we already have some bits in our internal buffer concatenate both
   * inputs first. */
  if (md5ctx->buflen != 0)
  {
    size_t left_over = md5ctx->buflen;
    size_t add = ((128 - left_over) > buflen) ? buflen : (128 - left_over);
 
    memcpy(&((char *) md5ctx->buffer)[left_over], buf, add);
    md5ctx->buflen += add;
 
    if (md5ctx->buflen > 64)
    {
      mutt_md5_process_block(md5ctx->buffer, md5ctx->buflen & ~63, md5ctx);
 
      md5ctx->buflen &= 63;
      /* The regions in the following copy operation can't overlap. */
      memcpy(md5ctx->buffer, &((char *) md5ctx->buffer)[(left_over + add) & ~63],
             md5ctx->buflen);
    }
 
    buf = (const char *) buf + add;
    buflen -= add;
  }
 
  /* Process available complete blocks. */
  if (buflen >= 64)
  {
#if !defined(_STRING_ARCH_unaligned)
#define alignof(type)                                                          \
  offsetof(                                                                    \
      struct {                                                                 \
        char c;                                                                \
        type x;                                                                \
      },                                                                       \
      x)
#define UNALIGNED_P(p) (((size_t) p) % alignof(md5_uint32) != 0)
    if (UNALIGNED_P(buf))
    {
      while (buflen > 64)
      {
        mutt_md5_process_block(memcpy(md5ctx->buffer, buf, 64), 64, md5ctx);
        buf = (const char *) buf + 64;
        buflen -= 64;
      }
    }
    else
#endif
    {
      mutt_md5_process_block(buf, buflen & ~63, md5ctx);
      buf = (const char *) buf + (buflen & ~63);
      buflen &= 63;
    }
  }
 
  /* Move remaining bytes in internal buffer. */
  if (buflen > 0)
  {
    size_t left_over = md5ctx->buflen;
 
    memcpy(&((char *) md5ctx->buffer)[left_over], buf, buflen);
    left_over += buflen;
    if (left_over >= 64)
    { // LCOV_EXCL_START
      mutt_md5_process_block(md5ctx->buffer, 64, md5ctx);
      left_over -= 64;
      memmove(md5ctx->buffer, &md5ctx->buffer[16], left_over);
    } // LCOV_EXCL_STOP
    md5ctx->buflen = left_over;
  }
}
 
void mutt_md5_toascii(const void *digest, char *resbuf)
{
  if (!digest || !resbuf)
    return;
 
  const unsigned char *c = digest;
  sprintf(resbuf, "%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x",
          c[0], c[1], c[2], c[3], c[4], c[5], c[6], c[7], c[8], c[9], c[10],
          c[11], c[12], c[13], c[14], c[15]);
}