1 files changed, 66 insertions, 0 deletions
diff --git a/passgen.c b/passgen.c
new file mode 100644
index 0000000..f4f8960
--- /dev/null
+++ b/passgen.c
@@ -0,0 +1,66 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <time.h>
+#include <unistd.h>
+
+#define DEFAULT_GRAMMAR "Cvccvc!##"
+
+// i, o excluded due to potentially confusing 1/l/i + 0/o
+#define VOWELS "aeuy"
+#define CONSONANTS "bcdfghkmnprstvwxz"
+#define NUMBERS "1234567890"
+#define SYMBOLS "@#$%^&*_-+=()[]{}"
+
+int main(int argc, char *argv[])
+{
+  char *grammar = DEFAULT_GRAMMAR;
+  int grammar_size = sizeof(DEFAULT_GRAMMAR)-1;
+  
+  char password[grammar_size];
+
+  // seed RNG; this isn't very good, but it's enough
+  srand(time(NULL) << 2 + getpid() % 420 - 69);
+  
+  for (int i = 0; i < grammar_size; ++i) {
+    char c = grammar[i];
+
+    bool caps = false;
+    if (c >= 'A' && c <= 'Z') {
+      caps = true;
+      c += 'a' - 'A';
+    }
+
+    char *class;
+    int class_size = 0;
+#define setClass(cl) \
+    class = cl; \
+    class_size = sizeof(cl)-1;
+
+    switch (c) {
+    case 'c':
+      setClass(CONSONANTS);
+      break;
+    case 'v':
+      setClass(VOWELS);
+      break;
+    case '!':
+      setClass(SYMBOLS);
+      break;
+    case '#':
+      setClass(NUMBERS);
+      break;
+    default:
+      printf("ERROR: Invalid grammar character '%C'.\n", c);
+      return 1;
+    }
+
+    do {
+      password[i] = class[rand() % class_size] - (caps ? 'a' - 'A' : 0);
+    } while (i != 0 && password[i] == password[i-1]);
+  }
+
+  printf("%s\n", password);
+
+  return 0;
+}