core/ngx_md5.c源文件分析
本节我们主要讲述一下nginx中md5的相关实现。
1. core/ngx_md5.c源文件
/*
* An internal implementation, based on Alexander Peslyak's
* public domain implementation:
* http://openwall.info/wiki/people/solar/software/public-domain-source-code/md5
* It is not expected to be optimal and is used only
* if no MD5 implementation was found in system.
*/
#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_md5.h>
#if !(NGX_HAVE_MD5)
static const u_char *ngx_md5_body(ngx_md5_t *ctx, const u_char *data,
size_t size);
void
ngx_md5_init(ngx_md5_t *ctx)
{
ctx->a = 0x67452301;
ctx->b = 0xefcdab89;
ctx->c = 0x98badcfe;
ctx->d = 0x10325476;
ctx->bytes = 0;
}
void
ngx_md5_update(ngx_md5_t *ctx, const void *data, size_t size)
{
size_t used, free;
used = (size_t) (ctx->bytes & 0x3f);
ctx->bytes += size;
if (used) {
free = 64 - used;
if (size < free) {
ngx_memcpy(&ctx->buffer[used], data, size);
return;
}
ngx_memcpy(&ctx->buffer[used], data, free);
data = (u_char *) data + free;
size -= free;
(void) ngx_md5_body(ctx, ctx->buffer, 64);
}
if (size >= 64) {
data = ngx_md5_body(ctx, data, size & ~(size_t) 0x3f);
size &= 0x3f;
}
ngx_memcpy(ctx->buffer, data, size);
}
void
ngx_md5_final(u_char result[16], ngx_md5_t *ctx)
{
size_t used, free;
used = (size_t) (ctx->bytes & 0x3f);
ctx->buffer[used++] = 0x80;
free = 64 - used;
if (free < 8) {
ngx_memzero(&ctx->buffer[used], free);
(void) ngx_md5_body(ctx, ctx->buffer, 64);
used = 0;
free = 64;
}
ngx_memzero(&ctx->buffer[used], free - 8);
ctx->bytes <<= 3;
ctx->buffer[56] = (u_char) ctx->bytes;
ctx->buffer[57] = (u_char) (ctx->bytes >> 8);
ctx->buffer[58] = (u_char) (ctx->bytes >> 16);
ctx->buffer[59] = (u_char) (ctx->bytes >> 24);
ctx->buffer[60] = (u_char) (ctx->bytes >> 32);
ctx->buffer[61] = (u_char) (ctx->bytes >> 40);
ctx->buffer[62] = (u_char) (ctx->bytes >> 48);
ctx->buffer[63] = (u_char) (ctx->bytes >> 56);
(void) ngx_md5_body(ctx, ctx->buffer, 64);
result[0] = (u_char) ctx->a;
result[1] = (u_char) (ctx->a >> 8);
result[2] = (u_char) (ctx->a >> 16);
result[3] = (u_char) (ctx->a >> 24);
result[4] = (u_char) ctx->b;
result[5] = (u_char) (ctx->b >> 8);
result[6] = (u_char) (ctx->b >> 16);
result[7] = (u_char) (ctx->b >> 24);
result[8] = (u_char) ctx->c;
result[9] = (u_char) (ctx->c >> 8);
result[10] = (u_char) (ctx->c >> 16);
result[11] = (u_char) (ctx->c >> 24);
result[12] = (u_char) ctx->d;
result[13] = (u_char) (ctx->d >> 8);
result[14] = (u_char) (ctx->d >> 16);
result[15] = (u_char) (ctx->d >> 24);
ngx_memzero(ctx, sizeof(*ctx));
}
/*
* The basic MD5 functions.
*
* F and G are optimized compared to their RFC 1321 definitions for
* architectures that lack an AND-NOT instruction, just like in
* Colin Plumb's implementation.
*/
#define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
#define G(x, y, z) ((y) ^ ((z) & ((x) ^ (y))))
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define I(x, y, z) ((y) ^ ((x) | ~(z)))
/*
* The MD5 transformation for all four rounds.
*/
#define STEP(f, a, b, c, d, x, t, s) \
(a) += f((b), (c), (d)) + (x) + (t); \
(a) = (((a) << (s)) | (((a) & 0xffffffff) >> (32 - (s)))); \
(a) += (b)
/*
* SET() reads 4 input bytes in little-endian byte order and stores them
* in a properly aligned word in host byte order.
*
* The check for little-endian architectures that tolerate unaligned
* memory accesses is just an optimization. Nothing will break if it
* does not work.
*/
#if (NGX_HAVE_LITTLE_ENDIAN && NGX_HAVE_NONALIGNED)
#define SET(n) (*(uint32_t *) &p[n * 4])
#define GET(n) (*(uint32_t *) &p[n * 4])
#else
#define SET(n) \
(block[n] = \
(uint32_t) p[n * 4] | \
((uint32_t) p[n * 4 + 1] << 8) | \
((uint32_t) p[n * 4 + 2] << 16) | \
((uint32_t) p[n * 4 + 3] << 24))
#define GET(n) block[n]
#endif
/*
* This processes one or more 64-byte data blocks, but does not update
* the bit counters. There are no alignment requirements.
*/
static const u_char *
ngx_md5_body(ngx_md5_t *ctx, const u_char *data, size_t size)
{
uint32_t a, b, c, d;
uint32_t saved_a, saved_b, saved_c, saved_d;
const u_char *p;
#if !(NGX_HAVE_LITTLE_ENDIAN && NGX_HAVE_NONALIGNED)
uint32_t block[16];
#endif
p = data;
a = ctx->a;
b = ctx->b;
c = ctx->c;
d = ctx->d;
do {
saved_a = a;
saved_b = b;
saved_c = c;
saved_d = d;
/* Round 1 */
STEP(F, a, b, c, d, SET(0), 0xd76aa478, 7);
STEP(F, d, a, b, c, SET(1), 0xe8c7b756, 12);
STEP(F, c, d, a, b, SET(2), 0x242070db, 17);
STEP(F, b, c, d, a, SET(3), 0xc1bdceee, 22);
STEP(F, a, b, c, d, SET(4), 0xf57c0faf, 7);
STEP(F, d, a, b, c, SET(5), 0x4787c62a, 12);
STEP(F, c, d, a, b, SET(6), 0xa8304613, 17);
STEP(F, b, c, d, a, SET(7), 0xfd469501, 22);
STEP(F, a, b, c, d, SET(8), 0x698098d8, 7);
STEP(F, d, a, b, c, SET(9), 0x8b44f7af, 12);
STEP(F, c, d, a, b, SET(10), 0xffff5bb1, 17);
STEP(F, b, c, d, a, SET(11), 0x895cd7be, 22);
STEP(F, a, b, c, d, SET(12), 0x6b901122, 7);
STEP(F, d, a, b, c, SET(13), 0xfd987193, 12);
STEP(F, c, d, a, b, SET(14), 0xa679438e, 17);
STEP(F, b, c, d, a, SET(15), 0x49b40821, 22);
/* Round 2 */
STEP(G, a, b, c, d, GET(1), 0xf61e2562, 5);
STEP(G, d, a, b, c, GET(6), 0xc040b340, 9);
STEP(G, c, d, a, b, GET(11), 0x265e5a51, 14);
STEP(G, b, c, d, a, GET(0), 0xe9b6c7aa, 20);
STEP(G, a, b, c, d, GET(5), 0xd62f105d, 5);
STEP(G, d, a, b, c, GET(10), 0x02441453, 9);
STEP(G, c, d, a, b, GET(15), 0xd8a1e681, 14);
STEP(G, b, c, d, a, GET(4), 0xe7d3fbc8, 20);
STEP(G, a, b, c, d, GET(9), 0x21e1cde6, 5);
STEP(G, d, a, b, c, GET(14), 0xc33707d6, 9);
STEP(G, c, d, a, b, GET(3), 0xf4d50d87, 14);
STEP(G, b, c, d, a, GET(8), 0x455a14ed, 20);
STEP(G, a, b, c, d, GET(13), 0xa9e3e905, 5);
STEP(G, d, a, b, c, GET(2), 0xfcefa3f8, 9);
STEP(G, c, d, a, b, GET(7), 0x676f02d9, 14);
STEP(G, b, c, d, a, GET(12), 0x8d2a4c8a, 20);
/* Round 3 */
STEP(H, a, b, c, d, GET(5), 0xfffa3942, 4);
STEP(H, d, a, b, c, GET(8), 0x8771f681, 11);
STEP(H, c, d, a, b, GET(11), 0x6d9d6122, 16);
STEP(H, b, c, d, a, GET(14), 0xfde5380c, 23);
STEP(H, a, b, c, d, GET(1), 0xa4beea44, 4);
STEP(H, d, a, b, c, GET(4), 0x4bdecfa9, 11);
STEP(H, c, d, a, b, GET(7), 0xf6bb4b60, 16);
STEP(H, b, c, d, a, GET(10), 0xbebfbc70, 23);
STEP(H, a, b, c, d, GET(13), 0x289b7ec6, 4);
STEP(H, d, a, b, c, GET(0), 0xeaa127fa, 11);
STEP(H, c, d, a, b, GET(3), 0xd4ef3085, 16);
STEP(H, b, c, d, a, GET(6), 0x04881d05, 23);
STEP(H, a, b, c, d, GET(9), 0xd9d4d039, 4);
STEP(H, d, a, b, c, GET(12), 0xe6db99e5, 11);
STEP(H, c, d, a, b, GET(15), 0x1fa27cf8, 16);
STEP(H, b, c, d, a, GET(2), 0xc4ac5665, 23);
/* Round 4 */
STEP(I, a, b, c, d, GET(0), 0xf4292244, 6);
STEP(I, d, a, b, c, GET(7), 0x432aff97, 10);
STEP(I, c, d, a, b, GET(14), 0xab9423a7, 15);
STEP(I, b, c, d, a, GET(5), 0xfc93a039, 21);
STEP(I, a, b, c, d, GET(12), 0x655b59c3, 6);
STEP(I, d, a, b, c, GET(3), 0x8f0ccc92, 10);
STEP(I, c, d, a, b, GET(10), 0xffeff47d, 15);
STEP(I, b, c, d, a, GET(1), 0x85845dd1, 21);
STEP(I, a, b, c, d, GET(8), 0x6fa87e4f, 6);
STEP(I, d, a, b, c, GET(15), 0xfe2ce6e0, 10);
STEP(I, c, d, a, b, GET(6), 0xa3014314, 15);
STEP(I, b, c, d, a, GET(13), 0x4e0811a1, 21);
STEP(I, a, b, c, d, GET(4), 0xf7537e82, 6);
STEP(I, d, a, b, c, GET(11), 0xbd3af235, 10);
STEP(I, c, d, a, b, GET(2), 0x2ad7d2bb, 15);
STEP(I, b, c, d, a, GET(9), 0xeb86d391, 21);
a += saved_a;
b += saved_b;
c += saved_c;
d += saved_d;
p += 64;
} while (size -= 64);
ctx->a = a;
ctx->b = b;
ctx->c = c;
ctx->d = d;
return p;
}
#endif这里暂时不详细介绍。
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