Move MD5 out into its own file.

This begins a programme of code reorganisation at the end of which I'd
like to end up with something almost legible :-)

1 files changed, 271 insertions, 0 deletions

diff --git a/md5.c b/md5.c
new file mode 100644
index 0000000..48c6aec
--- /dev/null
+++ b/md5.c
@@ -0,0 +1,271 @@
+/*
+ * Implement MsiGetFileHash().
+ *
+ * Experimenting with a small test program on Windows calling the
+ * original version of that function suggests that the hash it
+ * implements is just MD5, only repackaged as an array of four
+ * little-endian 32-bit words instead of the usual 16 bytes.
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+#include <stdbool.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include <err.h>
+
+#include "fake-lib.h"
+
+/* ----------------------------------------------------------------------
+ * Core MD5 algorithm: processes 16-word blocks into a message digest.
+ */
+
+typedef struct {
+    uint32_t h[4];
+} MD5_Core_State;
+
+struct MD5Context {
+    MD5_Core_State core;
+    unsigned char block[64];
+    int blkused;
+    uint64_t len;
+};
+
+#define F(x,y,z) ( ((x) & (y)) | ((~(x)) & (z)) )
+#define G(x,y,z) ( ((x) & (z)) | ((~(z)) & (y)) )
+#define H(x,y,z) ( (x) ^ (y) ^ (z) )
+#define I(x,y,z) ( (y) ^ ( (x) | ~(z) ) )
+
+#define rol(x,y) ( ((x) << (y)) | (((uint32_t)x) >> (32-y)) )
+
+#define subround(f,w,x,y,z,k,s,ti) \
+       w = x + rol(w + f(x,y,z) + block[k] + ti, s)
+
+static void MD5_Core_Init(MD5_Core_State * s)
+{
+    s->h[0] = 0x67452301;
+    s->h[1] = 0xefcdab89;
+    s->h[2] = 0x98badcfe;
+    s->h[3] = 0x10325476;
+}
+
+static void MD5_Block(MD5_Core_State * s, uint32_t * block)
+{
+    uint32_t a, b, c, d;
+
+    a = s->h[0];
+    b = s->h[1];
+    c = s->h[2];
+    d = s->h[3];
+
+    subround(F, a, b, c, d, 0, 7, 0xd76aa478);
+    subround(F, d, a, b, c, 1, 12, 0xe8c7b756);
+    subround(F, c, d, a, b, 2, 17, 0x242070db);
+    subround(F, b, c, d, a, 3, 22, 0xc1bdceee);
+    subround(F, a, b, c, d, 4, 7, 0xf57c0faf);
+    subround(F, d, a, b, c, 5, 12, 0x4787c62a);
+    subround(F, c, d, a, b, 6, 17, 0xa8304613);
+    subround(F, b, c, d, a, 7, 22, 0xfd469501);
+    subround(F, a, b, c, d, 8, 7, 0x698098d8);
+    subround(F, d, a, b, c, 9, 12, 0x8b44f7af);
+    subround(F, c, d, a, b, 10, 17, 0xffff5bb1);
+    subround(F, b, c, d, a, 11, 22, 0x895cd7be);
+    subround(F, a, b, c, d, 12, 7, 0x6b901122);
+    subround(F, d, a, b, c, 13, 12, 0xfd987193);
+    subround(F, c, d, a, b, 14, 17, 0xa679438e);
+    subround(F, b, c, d, a, 15, 22, 0x49b40821);
+    subround(G, a, b, c, d, 1, 5, 0xf61e2562);
+    subround(G, d, a, b, c, 6, 9, 0xc040b340);
+    subround(G, c, d, a, b, 11, 14, 0x265e5a51);
+    subround(G, b, c, d, a, 0, 20, 0xe9b6c7aa);
+    subround(G, a, b, c, d, 5, 5, 0xd62f105d);
+    subround(G, d, a, b, c, 10, 9, 0x02441453);
+    subround(G, c, d, a, b, 15, 14, 0xd8a1e681);
+    subround(G, b, c, d, a, 4, 20, 0xe7d3fbc8);
+    subround(G, a, b, c, d, 9, 5, 0x21e1cde6);
+    subround(G, d, a, b, c, 14, 9, 0xc33707d6);
+    subround(G, c, d, a, b, 3, 14, 0xf4d50d87);
+    subround(G, b, c, d, a, 8, 20, 0x455a14ed);
+    subround(G, a, b, c, d, 13, 5, 0xa9e3e905);
+    subround(G, d, a, b, c, 2, 9, 0xfcefa3f8);
+    subround(G, c, d, a, b, 7, 14, 0x676f02d9);
+    subround(G, b, c, d, a, 12, 20, 0x8d2a4c8a);
+    subround(H, a, b, c, d, 5, 4, 0xfffa3942);
+    subround(H, d, a, b, c, 8, 11, 0x8771f681);
+    subround(H, c, d, a, b, 11, 16, 0x6d9d6122);
+    subround(H, b, c, d, a, 14, 23, 0xfde5380c);
+    subround(H, a, b, c, d, 1, 4, 0xa4beea44);
+    subround(H, d, a, b, c, 4, 11, 0x4bdecfa9);
+    subround(H, c, d, a, b, 7, 16, 0xf6bb4b60);
+    subround(H, b, c, d, a, 10, 23, 0xbebfbc70);
+    subround(H, a, b, c, d, 13, 4, 0x289b7ec6);
+    subround(H, d, a, b, c, 0, 11, 0xeaa127fa);
+    subround(H, c, d, a, b, 3, 16, 0xd4ef3085);
+    subround(H, b, c, d, a, 6, 23, 0x04881d05);
+    subround(H, a, b, c, d, 9, 4, 0xd9d4d039);
+    subround(H, d, a, b, c, 12, 11, 0xe6db99e5);
+    subround(H, c, d, a, b, 15, 16, 0x1fa27cf8);
+    subround(H, b, c, d, a, 2, 23, 0xc4ac5665);
+    subround(I, a, b, c, d, 0, 6, 0xf4292244);
+    subround(I, d, a, b, c, 7, 10, 0x432aff97);
+    subround(I, c, d, a, b, 14, 15, 0xab9423a7);
+    subround(I, b, c, d, a, 5, 21, 0xfc93a039);
+    subround(I, a, b, c, d, 12, 6, 0x655b59c3);
+    subround(I, d, a, b, c, 3, 10, 0x8f0ccc92);
+    subround(I, c, d, a, b, 10, 15, 0xffeff47d);
+    subround(I, b, c, d, a, 1, 21, 0x85845dd1);
+    subround(I, a, b, c, d, 8, 6, 0x6fa87e4f);
+    subround(I, d, a, b, c, 15, 10, 0xfe2ce6e0);
+    subround(I, c, d, a, b, 6, 15, 0xa3014314);
+    subround(I, b, c, d, a, 13, 21, 0x4e0811a1);
+    subround(I, a, b, c, d, 4, 6, 0xf7537e82);
+    subround(I, d, a, b, c, 11, 10, 0xbd3af235);
+    subround(I, c, d, a, b, 2, 15, 0x2ad7d2bb);
+    subround(I, b, c, d, a, 9, 21, 0xeb86d391);
+
+    s->h[0] += a;
+    s->h[1] += b;
+    s->h[2] += c;
+    s->h[3] += d;
+}
+
+/* ----------------------------------------------------------------------
+ * Outer MD5 algorithm: take an arbitrary length byte string,
+ * convert it into 16-word blocks with the prescribed padding at
+ * the end, and pass those blocks to the core MD5 algorithm.
+ */
+
+#define BLKSIZE 64
+
+static void MD5Init(struct MD5Context *s)
+{
+    MD5_Core_Init(&s->core);
+    s->blkused = 0;
+    s->len = 0;
+}
+
+static void MD5Update(struct MD5Context *s, unsigned char const *p,
+                      unsigned len)
+{
+    unsigned char *q = (unsigned char *) p;
+    uint32_t wordblock[16];
+    int i;
+
+    /*
+     * Update the length field.
+     */
+    s->len += len;
+
+    if (s->blkused + len < BLKSIZE) {
+        /*
+         * Trivial case: just add to the block.
+         */
+        memcpy(s->block + s->blkused, q, len);
+        s->blkused += len;
+    } else {
+        /*
+         * We must complete and process at least one block.
+         */
+        while (s->blkused + len >= BLKSIZE) {
+            memcpy(s->block + s->blkused, q, BLKSIZE - s->blkused);
+            q += BLKSIZE - s->blkused;
+            len -= BLKSIZE - s->blkused;
+            /* Now process the block. Gather bytes little-endian into words */
+            for (i = 0; i < 16; i++) {
+                wordblock[i] =
+                    (((uint32_t) s->block[i * 4 + 3]) << 24) |
+                    (((uint32_t) s->block[i * 4 + 2]) << 16) |
+                    (((uint32_t) s->block[i * 4 + 1]) << 8) |
+                    (((uint32_t) s->block[i * 4 + 0]) << 0);
+            }
+            MD5_Block(&s->core, wordblock);
+            s->blkused = 0;
+        }
+        memcpy(s->block, q, len);
+        s->blkused = len;
+    }
+}
+
+static void MD5Final(uint32_t output[4], struct MD5Context *s)
+{
+    int i;
+    unsigned pad;
+    unsigned char c[64];
+    uint64_t len;
+
+    if (s->blkused >= 56)
+        pad = 56 + 64 - s->blkused;
+    else
+        pad = 56 - s->blkused;
+
+    len = s->len << 3;
+
+    memset(c, 0, pad);
+    c[0] = 0x80;
+    MD5Update(s, c, pad);
+
+    c[7] = (len >> (8*7)) & 0xFF;
+    c[6] = (len >> (8*6)) & 0xFF;
+    c[5] = (len >> (8*5)) & 0xFF;
+    c[4] = (len >> (8*4)) & 0xFF;
+    c[3] = (len >> (8*3)) & 0xFF;
+    c[2] = (len >> (8*2)) & 0xFF;
+    c[1] = (len >> (8*1)) & 0xFF;
+    c[0] = (len >> (8*0)) & 0xFF;
+
+    MD5Update(s, c, 8);
+
+    for (i = 0; i < 4; i++)
+        output[i] = s->core.h[i];
+}
+
+struct MsiHash {
+    uint32_t structure_size;
+    uint32_t hash_words[4];
+};
+
+uint32_t MsiGetFileHashW(const char16_t *filename, uint32_t options,
+                         struct MsiHash *hash)
+{
+    char *fname = ascii(filename, true);
+    uint32_t toret;
+    char buffer[4096];
+    int fd = -1, retd;
+    struct MD5Context ctx;
+
+    fd = open(fname, O_RDONLY);
+    if (fd < 0) {
+        /* Could do some better errno -> GetLastError translation here */
+        warnx("MsiGetFileHash(%s) -> ERROR_OPEN_FAILED", fname);
+        toret = 110;
+        goto cleanup;
+    }
+
+    MD5Init(&ctx);
+
+    while ((retd = read(fd, buffer, sizeof(buffer)) > 0))
+        MD5Update(&ctx, buffer, retd);
+    if (retd < 0) {
+        warnx("MsiGetFileHash(%s) -> ERROR_READ_FAULT", fname);
+        toret = 30;
+        goto cleanup;
+    }
+
+    MD5Final(hash->hash_words, &ctx);
+
+    warnx("MsiGetFileHash(%s) -> %08x:%08x:%08x:%08x", fname,
+          (unsigned)hash->hash_words[0], (unsigned)hash->hash_words[1],
+          (unsigned)hash->hash_words[2], (unsigned)hash->hash_words[3]);
+    toret = 0;
+
+  cleanup:
+    if (fd != -1)
+        close(fd);
+    sfree(fname);
+    return toret;
+}