IMO it is not a good idea to replicate library functions. Dependency
on libraries isn't necessarily a bad thing. These functions are in
libraries for a reason and that is reuse. If there are differences
across the distros, it should be solved with the check scripts (as it
is done everywhere).
This might be a trivial example to pick (just an md5 function), but still.
-dulloor
On Fri, Jun 4, 2010 at 7:22 AM, Stefano Stabellini
<stefano.stabellini@xxxxxxxxxxxxx> wrote:
> Hi all,
> I am adding a public domain implementation of md5 to blktap2, so that it
> doesn't need ssl or gcrypt to work anymore.
>
>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
>
> ---
>
> diff -r 4ab68bf4c37e tools/blktap2/drivers/Makefile
> --- a/tools/blktap2/drivers/Makefile Thu Jun 03 07:30:54 2010 +0100
> +++ b/tools/blktap2/drivers/Makefile Fri Jun 04 15:22:04 2010 +0100
> @@ -26,18 +26,6 @@
>
> LIBS += -lrt -lz
>
> -ifeq ($(CONFIG_Linux),y)
> -ifeq ($(shell . ./check_gcrypt $(CC)),yes)
> -CFLAGS += -DUSE_GCRYPT
> -CRYPT_LIB += -lgcrypt
> -else
> -CRYPT_LIB += -lcrypto
> -$(warning === libgcrypt not installed: falling back to libcrypto ===)
> -endif
> -else
> -CRYPT_LIB += -lcrypto
> -endif
> -
> LDFLAGS_img := $(LDFLAGS_libxenctrl) $(CRYPT_LIB) -lpthread -lz -lm
>
> LIBS += -L$(LIBVHDDIR) -lvhd
> @@ -97,6 +85,7 @@
> BLK-OBJS-y += block-log.o
> BLK-OBJS-y += block-qcow.o
> BLK-OBJS-y += aes.o
> +BLK-OBJS-y += md5.o
> BLK-OBJS-y += $(PORTABLE-OBJS-y)
> BLK-OBJS-y += $(REMUS-OBJS)
>
> diff -r 4ab68bf4c37e tools/blktap2/drivers/block-qcow.c
> --- a/tools/blktap2/drivers/block-qcow.c Thu Jun 03 07:30:54 2010 +0100
> +++ b/tools/blktap2/drivers/block-qcow.c Fri Jun 04 15:22:04 2010 +0100
> @@ -33,10 +33,10 @@
> #include <zlib.h>
> #include <inttypes.h>
> #include <libaio.h>
> -#include <openssl/md5.h>
> #include <limits.h>
> #include "bswap.h"
> #include "aes.h"
> +#include "md5.h"
>
> #include "tapdisk.h"
> #include "tapdisk-driver.h"
> @@ -80,47 +80,17 @@
>
> static int decompress_cluster(struct tdqcow_state *s, uint64_t
> cluster_offset);
>
> -#ifdef USE_GCRYPT
> -
> -#include <gcrypt.h>
> -
> uint32_t gen_cksum(char *ptr, int len)
> {
> int i;
> uint32_t md[4];
>
> /* Generate checksum */
> - gcry_md_hash_buffer(GCRY_MD_MD5, md, ptr, len);
> + md5_sum((const uint8_t*)ptr, len, (uint8_t*)md);
>
> return md[0];
> }
>
> -#else /* use libcrypto */
> -
> -#include <openssl/md5.h>
> -
> -uint32_t gen_cksum(char *ptr, int len)
> -{
> - int i;
> - unsigned char *md;
> - uint32_t ret;
> -
> - md = malloc(MD5_DIGEST_LENGTH);
> - if(!md) return 0;
> -
> - /* Generate checksum */
> - if (MD5((unsigned char *)ptr, len, md) != md)
> - ret = 0;
> - else
> - memcpy(&ret, md, sizeof(uint32_t));
> -
> - free(md);
> - return ret;
> -}
> -
> -#endif
> -
> -
> static void free_aio_state(struct tdqcow_state* s)
> {
> free(s->aio_requests);
> diff -r 4ab68bf4c37e tools/blktap2/drivers/img2qcow.c
> --- a/tools/blktap2/drivers/img2qcow.c Thu Jun 03 07:30:54 2010 +0100
> +++ b/tools/blktap2/drivers/img2qcow.c Fri Jun 04 15:22:04 2010 +0100
> @@ -41,7 +41,6 @@
> #include <zlib.h>
> #include <inttypes.h>
> #include <libaio.h>
> -#include <openssl/md5.h>
>
> #include "bswap.h"
> #include "aes.h"
> diff -r 4ab68bf4c37e tools/blktap2/drivers/md5.c
> --- /dev/null Thu Jan 01 00:00:00 1970 +0000
> +++ b/tools/blktap2/drivers/md5.c Fri Jun 04 15:22:04 2010 +0100
> @@ -0,0 +1,278 @@
> +/* start - public domain MD5 implementation */
> +/*
> + * This code implements the MD5 message-digest algorithm.
> + * The algorithm is due to Ron Rivest. This code was
> + * written by Colin Plumb in 1993, no copyright is claimed.
> + * This code is in the public domain; do with it what you wish.
> + *
> + * Equivalent code is available from RSA Data Security, Inc.
> + * This code has been tested against that, and is equivalent,
> + * except that you don't need to include two pages of legalese
> + * with every copy.
> + *
> + * To compute the message digest of a chunk of bytes, declare an
> + * MD5Context structure, pass it to MD5Init, call MD5Update as
> + * needed on buffers full of bytes, and then call MD5Final, which
> + * will fill a supplied 16-byte array with the digest.
> + */
> +
> +#include <string.h>
> +#include <stdint.h>
> +
> +struct MD5Context {
> + uint32_t buf[4];
> + uint32_t bits[2];
> + uint8_t in[64];
> +};
> +
> +static void MD5Init(struct MD5Context *context);
> +static void MD5Update(struct MD5Context *context, unsigned char const *buf,
> + unsigned len);
> +static void MD5Final(unsigned char digest[16], struct MD5Context *context);
> +static void MD5Transform(uint32_t buf[4], uint32_t const in[16]);
> +
> +
> +typedef struct MD5Context MD5_CTX;
> +
> +
> +/**
> + * md5_sum - MD5 hash for a data block
> + * @addr: Pointers to the data area
> + * @len: Lengths of the data block
> + * @mac: Buffer for the hash
> + */
> +void md5_sum(const uint8_t *addr, const size_t len, uint8_t *mac)
> +{
> + MD5_CTX ctx;
> +
> + MD5Init(&ctx);
> + MD5Update(&ctx, addr, len);
> + MD5Final(mac, &ctx);
> +}
> +
> +
> +#ifndef WORDS_BIGENDIAN
> +#define byteReverse(buf, len) /* Nothing */
> +#else
> +/*
> + * Note: this code is harmless on little-endian machines.
> + */
> +static void byteReverse(unsigned char *buf, unsigned longs)
> +{
> + uint32_t t;
> + do {
> + t = (uint32_t) ((unsigned) buf[3] << 8 | buf[2]) << 16 |
> + ((unsigned) buf[1] << 8 | buf[0]);
> + *(uint32_t *) buf = t;
> + buf += 4;
> + } while (--longs);
> +}
> +#endif
> +
> +/*
> + * Start MD5 accumulation. Set bit count to 0 and buffer to mysterious
> + * initialization constants.
> + */
> +void MD5Init(struct MD5Context *ctx)
> +{
> + ctx->buf[0] = 0x67452301;
> + ctx->buf[1] = 0xefcdab89;
> + ctx->buf[2] = 0x98badcfe;
> + ctx->buf[3] = 0x10325476;
> +
> + ctx->bits[0] = 0;
> + ctx->bits[1] = 0;
> +}
> +
> +/*
> + * Update context to reflect the concatenation of another buffer full
> + * of bytes.
> + */
> +void MD5Update(struct MD5Context *ctx, unsigned char const *buf, unsigned
> len)
> +{
> + uint32_t t;
> +
> + /* Update bitcount */
> +
> + t = ctx->bits[0];
> + if ((ctx->bits[0] = t + ((uint32_t) len << 3)) < t)
> + ctx->bits[1]++; /* Carry from low to high */
> + ctx->bits[1] += len >> 29;
> +
> + t = (t >> 3) & 0x3f; /* Bytes already in shsInfo->data */
> +
> + /* Handle any leading odd-sized chunks */
> +
> + if (t) {
> + unsigned char *p = (unsigned char *) ctx->in + t;
> +
> + t = 64 - t;
> + if (len < t) {
> + memcpy(p, buf, len);
> + return;
> + }
> + memcpy(p, buf, t);
> + byteReverse(ctx->in, 16);
> + MD5Transform(ctx->buf, (uint32_t *) ctx->in);
> + buf += t;
> + len -= t;
> + }
> + /* Process data in 64-byte chunks */
> +
> + while (len >= 64) {
> + memcpy(ctx->in, buf, 64);
> + byteReverse(ctx->in, 16);
> + MD5Transform(ctx->buf, (uint32_t *) ctx->in);
> + buf += 64;
> + len -= 64;
> + }
> +
> + /* Handle any remaining bytes of data. */
> +
> + memcpy(ctx->in, buf, len);
> +}
> +
> +/*
> + * Final wrapup - pad to 64-byte boundary with the bit pattern
> + * 1 0* (64-bit count of bits processed, MSB-first)
> + */
> +void MD5Final(unsigned char digest[16], struct MD5Context *ctx)
> +{
> + unsigned count;
> + unsigned char *p;
> +
> + /* Compute number of bytes mod 64 */
> + count = (ctx->bits[0] >> 3) & 0x3F;
> +
> + /* Set the first char of padding to 0x80. This is safe since there is
> + always at least one byte free */
> + p = ctx->in + count;
> + *p++ = 0x80;
> +
> + /* Bytes of padding needed to make 64 bytes */
> + count = 64 - 1 - count;
> +
> + /* Pad out to 56 mod 64 */
> + if (count < 8) {
> + /* Two lots of padding: Pad the first block to 64 bytes */
> + memset(p, 0, count);
> + byteReverse(ctx->in, 16);
> + MD5Transform(ctx->buf, (uint32_t *) ctx->in);
> +
> + /* Now fill the next block with 56 bytes */
> + memset(ctx->in, 0, 56);
> + } else {
> + /* Pad block to 56 bytes */
> + memset(p, 0, count - 8);
> + }
> + byteReverse(ctx->in, 14);
> +
> + /* Append length in bits and transform */
> + ((uint32_t *) ctx->in)[14] = ctx->bits[0];
> + ((uint32_t *) ctx->in)[15] = ctx->bits[1];
> +
> + MD5Transform(ctx->buf, (uint32_t *) ctx->in);
> + byteReverse((unsigned char *) ctx->buf, 4);
> + memcpy(digest, ctx->buf, 16);
> + memset(ctx, 0, sizeof(ctx)); /* In case it's sensitive */
> +}
> +
> +/* The four core functions - F1 is optimized somewhat */
> +
> +/* #define F1(x, y, z) (x & y | ~x & z) */
> +#define F1(x, y, z) (z ^ (x & (y ^ z)))
> +#define F2(x, y, z) F1(z, x, y)
> +#define F3(x, y, z) (x ^ y ^ z)
> +#define F4(x, y, z) (y ^ (x | ~z))
> +
> +/* This is the central step in the MD5 algorithm. */
> +#define MD5STEP(f, w, x, y, z, data, s) \
> + ( w += f(x, y, z) + data, w = w<<s | w>>(32-s), w += x )
> +
> +/*
> + * The core of the MD5 algorithm, this alters an existing MD5 hash to
> + * reflect the addition of 16 longwords of new data. MD5Update blocks
> + * the data and converts bytes into longwords for this routine.
> + */
> +static void MD5Transform(uint32_t buf[4], uint32_t const in[16])
> +{
> + register uint32_t a, b, c, d;
> +
> + a = buf[0];
> + b = buf[1];
> + c = buf[2];
> + d = buf[3];
> +
> + MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);
> + MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
> + MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);
> + MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
> + MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
> + MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);
> + MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);
> + MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);
> + MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);
> + MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
> + MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
> + MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
> + MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);
> + MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
> + MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
> + MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);
> +
> + MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);
> + MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);
> + MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
> + MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
> + MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);
> + MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);
> + MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
> + MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
> + MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
> + MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);
> + MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
> + MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);
> + MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
> + MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
> + MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);
> + MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);
> +
> + MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);
> + MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);
> + MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
> + MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
> + MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);
> + MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
> + MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
> + MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
> + MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
> + MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
> + MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
> + MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);
> + MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
> + MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
> + MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
> + MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);
> +
> + MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);
> + MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);
> + MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
> + MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);
> + MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);
> + MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
> + MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
> + MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);
> + MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
> + MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
> + MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);
> + MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
> + MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);
> + MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
> + MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
> + MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);
> +
> + buf[0] += a;
> + buf[1] += b;
> + buf[2] += c;
> + buf[3] += d;
> +}
> diff -r 4ab68bf4c37e tools/blktap2/drivers/md5.h
> --- /dev/null Thu Jan 01 00:00:00 1970 +0000
> +++ b/tools/blktap2/drivers/md5.h Fri Jun 04 15:22:04 2010 +0100
> @@ -0,0 +1,15 @@
> +#ifndef MD5_H
> +#define MD5_H
> +
> +#include <stdint.h>
> +#include <stddef.h>
> +
> +/**
> + * md5_sum - MD5 hash for a data block
> + * @addr: Pointers to the data area
> + * @len: Lengths of the data block
> + * @mac: Buffer for the hash
> + */
> +void md5_sum(const uint8_t *addr, const size_t len, uint8_t *mac);
> +
> +#endif
>
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>
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