Feat: Boilerplate for multiple impls

.vscode/settings.json

@@ -12,7 +12,8 @@
     "variant": "c",
     "array": "c",
     "md2.h": "c",
-    "io.h": "c"
+    "io.h": "c",
+    "md2_0.h": "c"
   },
   "editor.formatOnSave": true,
   "C_Cpp.default.includePath": [

.vscode/tasks.json

@@ -8,6 +8,7 @@
                 "-fdiagnostics-color=always",
                 "-g",
                 "${fileDirname}/*.c",
+                "${fileDirname}/md2_impls/*.c",
                 "-o",
                 "${fileDirname}/../md2"
             ],

Implementierung/Makefile

@@ -1,6 +1,6 @@
 
 
-SRC = src/main.c src/helper.c src/io.c src/md2.c
+SRC = src/main.c src/helper.c src/io.c src/md2.c src/md2_impls/md2_common.c src/md2_impls/md2_0.c
 OBJ = ${subst src,build,${SRC:.c=.o}}
 CC = gcc
 CFLAGS = -Ilib -ggdb
@@ -23,7 +23,7 @@ build:
 	mkdir build
 
 build/%.o: src/%.c
-	@mkdir -p build
+	@mkdir -p build/md2_impls
 	${CC} -c ${CFLAGS} -o $@ $<
 
 md2: ${OBJ} 

Implementierung/lib/md2.h

@@ -1,12 +1,16 @@
 #ifndef MD2_H
 #define MD2_H
 
+#include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/types.h>
 
+typedef void (*md2_hash_func)(size_t len, const uint8_t buf[], uint8_t out[16]);
+typedef void (*md2_checksum_func)(size_t len, uint8_t* buf);
+
 /**
  * @brief Calculates checksum of buf and stores it in out
  *
@@ -14,7 +18,7 @@
  * @param buf Location of the data
  * @param out Destination array of for the checksum
  */
-void md2_hash(size_t len, const uint8_t buf[], uint8_t out[16]);
+extern md2_hash_func md2_hash;
 
 /**
  * @brief Calculates checksum of buf and appends it to buf
@@ -23,7 +27,16 @@ void md2_hash(size_t len, const uint8_t buf[], uint8_t out[16]);
  * @param buf Location of the data. Make sure to reserve 16 bytes more so the
  * chechsum fits!
  */
-void md2_checksum(size_t len, uint8_t* buf);
+extern md2_checksum_func md2_checksum;
+
+/**
+ * @brief Choose the implementation to use
+ *
+ * @param i the implementation
+ * @return true when the implemenatation was changed
+ * @return false when the implementation does not exist
+ */
+bool md2_choose_implementation(int i);
 
 /**
  * @brief Takes a uint8_t array and converts it into a string
@@ -31,6 +44,6 @@ void md2_checksum(size_t len, uint8_t* buf);
  * @param hash the array containing the hash
  * @param stringHash pointer to store the string, has to have 32 bytes space
  */
-void encodeHash(uint8_t hash[16], char* stringHash);
+void md2_encode_hash(uint8_t hash[16], char* string_hash);
 
 #endif  // MD2_H

Implementierung/src/main.c

@@ -10,7 +10,7 @@ static bool runTest(const char* message, const char* expectedHash) {
   md2_hash(strlen(message), message, out);
 
   char hash[32];
-  encodeHash(out, hash);
+  md2_encode_hash(out, hash);
 
   bool ok = !strcmp(hash, expectedHash);
   printf("%s: md2(%s) %s == %s\n", "not ok" + (4 * ok), message, hash,
@@ -20,7 +20,7 @@ static bool runTest(const char* message, const char* expectedHash) {
 
 unsigned runTests(void) {
   unsigned failed = 0;
-  // Note: cases with n<2 are not tested here.
+  // src: https://datatracker.ietf.org/doc/html/rfc1319#appendix-A.5
   failed += !runTest("", "8350e5a3e24c153df2275c9f80692773");
   failed += !runTest("a", "32ec01ec4a6dac72c0ab96fb34c0b5d1");
   failed += !runTest("abc", "da853b0d3f88d99b30283a69e6ded6bb");
@@ -60,12 +60,20 @@ int main(int argc, char** argv) {
       break;
   }
 
+  if (!md2_choose_implementation(c.implementationToUse)) {
+    fprintf(stderr,
+            "%s: invalid argument, implementation '%d' does not exist!\n",
+            argv[0], c.implementationToUse);
+    return EXIT_FAILURE;
+  }
+
   printf(
       "Hashing file: %s\nUsing implementation: %d, doing benchmark: %d, "
       "benchmark cycles: %d\n",
       c.filename, c.implementationToUse, c.doBenchmark, c.benchmarkingCycles);
 
   // runTests();
+  // return 0;
   size_t len;
   uint8_t* data = read_file(c.filename, &len);
   if (data == NULL) {
@@ -81,7 +89,7 @@ int main(int argc, char** argv) {
 
   printf("Hash: ");
   char hash[32];
-  encodeHash(out, hash);
+  md2_encode_hash(out, hash);
   printf("%s\n", hash);
 
   free(data);

Implementierung/src/md2.c

@@ -1,107 +1,27 @@
 #include "../lib/md2.h"
 
+// include all implementations
+#include "../lib/md2_impls/md2_0.h"
+
+md2_hash_func md2_hash;
+md2_checksum_func md2_checksum;
+
 // The file "testfile" should lead to this hash:
 // fc982e558db259f298b43cd4c1241c66
 
-// Source: https://datatracker.ietf.org/doc/html/rfc1319
+void md2_encode_hash(uint8_t hash[16], char* string_hash) {
-static unsigned char PI_SUBST[256] = {
-    41,  46,  67,  201, 162, 216, 124, 1,   61,  54,  84,  161, 236, 240, 6,
-    19,  98,  167, 5,   243, 192, 199, 115, 140, 152, 147, 43,  217, 188, 76,
-    130, 202, 30,  155, 87,  60,  253, 212, 224, 22,  103, 66,  111, 24,  138,
-    23,  229, 18,  190, 78,  196, 214, 218, 158, 222, 73,  160, 251, 245, 142,
-    187, 47,  238, 122, 169, 104, 121, 145, 21,  178, 7,   63,  148, 194, 16,
-    137, 11,  34,  95,  33,  128, 127, 93,  154, 90,  144, 50,  39,  53,  62,
-    204, 231, 191, 247, 151, 3,   255, 25,  48,  179, 72,  165, 181, 209, 215,
-    94,  146, 42,  172, 86,  170, 198, 79,  184, 56,  210, 150, 164, 125, 182,
-    118, 252, 107, 226, 156, 116, 4,   241, 69,  157, 112, 89,  100, 113, 135,
-    32,  134, 91,  207, 101, 230, 45,  168, 2,   27,  96,  37,  173, 174, 176,
-    185, 246, 28,  70,  97,  105, 52,  64,  126, 15,  85,  71,  163, 35,  221,
-    81,  175, 58,  195, 92,  249, 206, 186, 197, 234, 38,  44,  83,  13,  110,
-    133, 40,  132, 9,   211, 223, 205, 244, 65,  129, 77,  82,  106, 220, 55,
-    200, 108, 193, 171, 250, 36,  225, 123, 8,   12,  189, 177, 74,  120, 136,
-    149, 139, 227, 99,  232, 109, 233, 203, 213, 254, 59,  0,   29,  57,  242,
-    239, 183, 14,  102, 88,  208, 228, 166, 119, 114, 248, 235, 117, 75,  10,
-    49,  68,  80,  180, 143, 237, 31,  26,  219, 153, 141, 51,  159, 17,  131,
-    20};
-
-void printBuf(size_t len, uint8_t buf[len]) {
-  for (int i = 0; i < len; i++) {
-    printf("'%02x',", buf[i]);
-  }
-  printf("\n");
-}
-
-void md2_checksum(size_t len, uint8_t* buf) {
-  uint8_t l = 0;
-
-  for (int i = 0; i < len / 16; i++) {
-    for (int j = 0; j < 16; j++) {
-      u_int8_t c = buf[i * 16 + j];
-      // reference is wrong. It says: Set C[j] to S[c xor L]. But it should be:
-      l = buf[len + j] ^= PI_SUBST[c ^ l];
-    }
-  }
-}
-
-void md2_hash(size_t len, const uint8_t buf[len], uint8_t out[16]) {
-  // === step 1 ===
-  int paddingNeeded = 16 - (len % 16);
-  uint8_t originalPadding = paddingNeeded;
-  len += paddingNeeded;
-
-  // printf("len: %d\n", len);
-
-  // +16 for the checksum
-  uint8_t* newBuf = calloc(len + 16, sizeof(uint8_t));
-  memcpy(newBuf, buf, len - paddingNeeded);
-
-  // printBuf(len + 16, newBuf);
-
-  while (paddingNeeded > 0) {
-    newBuf[len - paddingNeeded] = originalPadding;
-    paddingNeeded--;
-  }
-  // printf("buf with padding: ");
-  // printBuf(len + 16, newBuf);
-
-  // === step 2 ===
-  md2_checksum(len, newBuf);
-
-  // printf("buf with cecksum: ");
-  // printBuf(len + 16, newBuf);
-
-  // === step 3 ===
-  uint8_t* messageDigestBuf = calloc(48, sizeof(uint8_t));
-
-  // === step 4 ===
-  // <= because we need to hash the last block too
-  for (int i = 0; i <= (len + 16) / 16 - 1; i++) {
-    for (int j = 0; j < 16; j++) {
-      messageDigestBuf[16 + j] = newBuf[i * 16 + j];
-      messageDigestBuf[32 + j] =
-          (messageDigestBuf[16 + j] ^ messageDigestBuf[j]);
-    }
-
-    u_int8_t t = 0;
-
-    for (int j = 0; j < 18; j++) {
-      for (int k = 0; k < 48; k++) {
-        t = messageDigestBuf[k] = messageDigestBuf[k] ^ PI_SUBST[t];
-      }
-      t = (t + j) % 256;
-    }
-  }
-  // printf("messageDigestBuf: \n");
-  // printBuf(16, messageDigestBuf);
-
-  memcpy(out, messageDigestBuf, 16);
-
-  free(messageDigestBuf);
-  free(newBuf);
-}
-
-void encodeHash(uint8_t hash[16], char* stringHash) {
   for (int i = 0; i < 16; i++) {
-    sprintf(stringHash + (2 * i), "%02x", hash[i]);
+    sprintf(string_hash + (2 * i), "%02x", hash[i]);
+  }
+}
+
+bool md2_choose_implementation(int i) {
+  switch (i) {
+    case 0:
+      md2_hash = md2_hash_0;
+      return true;
+
+    default:
+      return false;
   }
 }