diff options
Diffstat (limited to 'src/base/md5.c')
| -rw-r--r-- | src/base/md5.c | 57 |
1 files changed, 26 insertions, 31 deletions
diff --git a/src/base/md5.c b/src/base/md5.c index 52d96ac..b235e17 100644 --- a/src/base/md5.c +++ b/src/base/md5.c @@ -63,12 +63,19 @@ (a) += (b); /* - * SET reads 4 input bytes in little-endian byte order and stores them - * in a properly aligned word in host byte order. + * 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 - * doesn't work. + * The check for little-endian architectures that tolerate unaligned memory + * accesses is just an optimization. Nothing will break if it fails to detect + * a suitable architecture. + * + * Unfortunately, this optimization may be a C strict aliasing rules violation + * if the caller's data buffer has effective type that cannot be aliased by + * MD5_u32plus. In practice, this problem may occur if these MD5 routines are + * inlined into a calling function, or with future and dangerously advanced + * link-time optimizations. For the time being, keeping these MD5 routines in + * their own translation unit avoids the problem. */ #if defined(__i386__) || defined(__x86_64__) || defined(__vax__) #define SET(n) \ @@ -87,8 +94,8 @@ #endif /* - * This processes one or more 64-byte data blocks, but does NOT update - * the bit counters. There are no alignment requirements. + * This processes one or more 64-byte data blocks, but does NOT update the bit + * counters. There are no alignment requirements. */ static const void *body(MD5_CTX *ctx, const void *data, unsigned long size) { @@ -242,6 +249,12 @@ void MD5_Update(MD5_CTX *ctx, const void *data, unsigned long size) memcpy(ctx->buffer, data, size); } +#define OUT(dst, src) \ + (dst)[0] = (unsigned char)(src); \ + (dst)[1] = (unsigned char)((src) >> 8); \ + (dst)[2] = (unsigned char)((src) >> 16); \ + (dst)[3] = (unsigned char)((src) >> 24); + void MD5_Final(unsigned char *result, MD5_CTX *ctx) { unsigned long used, available; @@ -262,33 +275,15 @@ void MD5_Final(unsigned char *result, MD5_CTX *ctx) memset(&ctx->buffer[used], 0, available - 8); ctx->lo <<= 3; - ctx->buffer[56] = ctx->lo; - ctx->buffer[57] = ctx->lo >> 8; - ctx->buffer[58] = ctx->lo >> 16; - ctx->buffer[59] = ctx->lo >> 24; - ctx->buffer[60] = ctx->hi; - ctx->buffer[61] = ctx->hi >> 8; - ctx->buffer[62] = ctx->hi >> 16; - ctx->buffer[63] = ctx->hi >> 24; + OUT(&ctx->buffer[56], ctx->lo) + OUT(&ctx->buffer[60], ctx->hi) body(ctx, ctx->buffer, 64); - result[0] = ctx->a; - result[1] = ctx->a >> 8; - result[2] = ctx->a >> 16; - result[3] = ctx->a >> 24; - result[4] = ctx->b; - result[5] = ctx->b >> 8; - result[6] = ctx->b >> 16; - result[7] = ctx->b >> 24; - result[8] = ctx->c; - result[9] = ctx->c >> 8; - result[10] = ctx->c >> 16; - result[11] = ctx->c >> 24; - result[12] = ctx->d; - result[13] = ctx->d >> 8; - result[14] = ctx->d >> 16; - result[15] = ctx->d >> 24; + OUT(&result[0], ctx->a) + OUT(&result[4], ctx->b) + OUT(&result[8], ctx->c) + OUT(&result[12], ctx->d) memset(ctx, 0, sizeof(*ctx)); } |