1 files changed, 254 insertions, 0 deletions
diff --git a/main.c b/main.c
new file mode 100644
index 0000000..e0f7a99
--- /dev/null
+++ b/main.c
@@ -0,0 +1,254 @@
+#include "randgen.h"
+#include "htable.h"
+
+#include <assert.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+
+/*
+    Generates a random id of length `size-1` consisting of characters in the set
+    [1-6] and places it in the buffer pointed to by `id`. The buffer is NULL
+    terminated.
+*/
+int get_random_id(struct randgen *randgen, char *id, size_t size)
+{
+    size_t n = 0;
+    unsigned char buf[512];
+    size_t i;
+
+    assert(randgen != NULL);
+    assert(id != NULL);
+    assert(size > 0);
+
+    while (n < size-1)
+    {
+        if (randgen_generate(randgen, buf, sizeof(buf)) == -1)
+            return -1;
+
+        for (i = 0; i < sizeof(buf) && n < size-1; ++i)
+        {
+            if (buf[i] >= '1' && buf[i] <= '6')
+            {
+                id[n++] = buf[i];
+            }
+        }
+    }
+
+    id[size-1] = '\0';
+
+    return 0;
+}
+
+/*
+    Makes a copy of the supplied string. If `len` is < 0, strlen() is used to
+    calculate the string length. The resulting string is always NULL terminated.
+*/
+char *my_strdup(const char *s, int len)
+{
+    char *result;
+    assert(s != NULL);
+    if (len < 0)
+        len = strlen(s);
+    result = (char *) malloc(sizeof(char) * (len+1));
+    memcpy(result, s, len);
+    result[len] = '\0';
+    return result;
+}
+
+/*
+    Parse a line from a diceware dictionary file. An acceptable line is of the
+    form:
+
+        11111 aaabbbccc
+
+    where 11111 is the word id in decimal digits and aaabbbccc is a word
+    stopping at first whitespace.
+
+    Returns a pointer to a htable_entry on success, NULL otherwise. Calls
+    exit() if memory could not be allocated.
+*/
+struct htable_entry *parse_line(const char *line)
+{
+    struct htable_entry *entry;
+    char id[32];
+    char word[256];
+
+    assert(line != NULL);
+
+    if (sscanf(line, "%31[1-6] %255s", id, word) != 2)
+    {
+        return NULL;
+    }
+
+    entry = (struct htable_entry *) malloc(sizeof(*entry));
+    if (!entry)
+    {
+        fprintf(stderr, "%s\n", strerror(errno));
+        exit(EXIT_FAILURE);
+    }
+
+    entry->id = my_strdup(id, -1);
+    entry->word = my_strdup(word, -1);
+
+    return entry;
+}
+
+/*
+    Loads a diceware dictionary file. Returns 0 on success and -1 on error.
+*/
+int load_dictionary(const char *filename, struct htable *dict)
+{
+    FILE *fp;
+    int rc = -1;
+    struct htable_entry *entry;
+    char line[256];
+
+    if ((fp = fopen(filename, "r")) == NULL)
+    {
+        fprintf(stderr, "could not open %s: %s\n", filename, strerror(errno));
+        goto cleanup;
+    }
+
+    while (1)
+    {
+        if (!fgets(line, sizeof(line), fp))
+            break;
+
+        if ((entry = parse_line(line)) == NULL)
+            continue;
+
+        htable_put(dict, entry);
+    }
+
+    rc = 0;
+
+cleanup:
+
+    if (fp)
+        fclose(fp);
+
+    return rc;
+}
+
+/*
+    Returns a random word from a dictionary.
+*/
+char *get_random_word(struct randgen *randgen, struct htable *dict)
+{
+    struct htable_entry *entry;
+    char id[6];
+
+    assert(randgen != NULL);
+    assert(dict != NULL);
+
+    if (get_random_id(randgen, id, sizeof(id)) == -1)
+    {
+        fprintf(stderr, "%s\n", "get_random_id failed");
+        return NULL;
+    }
+
+    entry = htable_get(dict, id);
+
+    if (!entry)
+    {
+        fprintf(stderr, "no such word: %s\n", id);
+        return NULL;
+    }
+
+    return entry->word;
+}
+
+void usage(const char *prog)
+{
+    static const char *usagestr =
+        "%s [-d DICTIONARY] [-n COUNT]"
+#ifndef _WIN32
+        " [-r DEVICE]"
+#endif
+        "\n\n"
+        "\t-d use DICTIONARY as the dictionary file\n"
+        "\t-n output COUNT words\n"
+#ifndef _WIN32
+        "\t-r read random bytes from DEVICE\n"
+#endif
+        "\n";
+
+    fprintf(stderr, usagestr, prog);
+
+    exit(EXIT_FAILURE);
+}
+
+int main(int argc, char **argv)
+{
+    const char *dictfilename = "diceware.txt";
+    const char *randomdevice = NULL;
+
+    int words = 6;
+    int i = 0;
+    struct htable dict;
+    struct randgen *randgen = NULL;
+    int rc = 0;
+
+    memset(&dict, 0, sizeof(dict));
+
+    for (i = 1; i < argc; ++i)
+    {
+        if (!strcmp(argv[i], "-d") && i+1 < argc)
+        {
+            dictfilename = argv[++i];
+        }
+        else if (!strcmp(argv[i], "-n") && i+1 < argc)
+        {
+            words = atoi(argv[++i]);
+        }
+#ifndef _WIN32
+        else if (!strcmp(argv[i], "-r") && i+1 < argc)
+        {
+            randomdevice = argv[++i];
+        }
+#endif
+        else if (!strcmp(argv[i], "-h"))
+        {
+            usage(argv[0]);
+        }
+        else
+        {
+            usage(argv[0]);
+        }
+    }
+
+    if ((randgen = randgen_open(randomdevice)) == NULL)
+        goto error;
+
+    htable_init(&dict, 11000);
+
+    if (load_dictionary(dictfilename, &dict) == -1)
+        goto error;
+
+    for (i = 0; i < words; ++i)
+    {
+        char *word = get_random_word(randgen, &dict);
+        if (!word)
+        {
+            goto error;
+        }
+        printf("%s%s", i ? " " : "", word);
+    }
+
+    printf("\n");
+
+    goto finally;
+
+error:
+
+    rc = 1;
+
+finally:
+
+    randgen_close(randgen);
+
+    htable_deinit(&dict);
+
+    return rc;
+}