#include <sys/stat.h>
#include "Arcfour.h"
+#define DEFAULT_SEED_LENGTH 2048;
+
// Command line options
const struct option opts[] = {
{ "seed", required_argument, 0, 's' },
+ { "seed-file", required_argument, 0, 'S' },
+ { "seed-length", required_argument, 0, 'L' },
{ "both", no_argument, 0, 'b' },
{ "verify", no_argument, 0, 'v' },
{ "create", no_argument, 0, 'c' },
" vbig [--seed SEED] --verify|--create PATH [SIZE]\n"
"\n"
"Options:\n"
- " --seed, -s Specify random seed\n"
- " --verify, -v Verify that PATH contains the expected contents\n"
- " --create, -c Create PATH with psuedo-random contents\n"
- " --flush, -f Flush cache\n"
- " --entire, -e Write until full; read until EOF\n"
- " --help, -h Display usage message\n"
- " --version, -V Display version string\n");
+ " --seed, -s Specify random seed as string\n"
+ " --seed-file, -S Read random seed from (start of) this file\n"
+ " --seed-length, -L Set (maximum) seed length to read from file\n"
+ " --verify, -v Verify that PATH contains the expected contents\n"
+ " --create, -c Create PATH with psuedo-random contents\n"
+ " --flush, -f Flush cache\n"
+ " --entire, -e Write until full; read until EOF\n"
+ " --help, -h Display usage message\n"
+ " --version, -V Display version string\n");
}
// Possible modes of operation
enum mode_type {
- NONE,
VERIFY,
CREATE,
BOTH
static long long execute(mode_type mode, bool entire, const char *show);
-static const char *seed = "hexapodia as the key insight";
+static const char default_seed[] = "hexapodia as the key insight";
+static void *seed;
+static size_t seedlen;
+static const char *seedpath;
static const char *path;
static bool entireopt = false;
static bool flush = false;
static long long size;
int main(int argc, char **argv) {
- mode_type mode = NONE;
+ mode_type mode = BOTH;
int n;
- while((n = getopt_long(argc, argv, "+s:vcefhV", opts, 0)) >= 0) {
+ char *ep;
+ while((n = getopt_long(argc, argv, "+s:S:L:vcefhV", opts, 0)) >= 0) {
switch(n) {
- case 's': seed = optarg; break;
+ case 's': seed = optarg; seedlen = strlen(optarg); break;
+ case 'S': seedpath = optarg; break;
+ case 'L':
+ seedlen = strtoul(optarg,&ep,0);
+ if(ep==optarg || *ep) fatal(0, "bad number for -S");
+ break;
case 'b': mode = BOTH; break;
case 'v': mode = VERIFY; break;
case 'c': mode = CREATE; break;
}
argc -= optind;
argv += optind;
- if(mode == NONE)
- fatal(0, "must specify one of --verify or --create");
if(argc > 2)
fatal(0, "excess arguments");
if(argc == 1 && mode == BOTH)
if(argc < (mode == VERIFY ? 1 : 2))
fatal(0, "insufficient arguments");
}
+ if(seed && seedpath)
+ fatal(0, "both --seed and --seed-file specified");
+ if(mode == BOTH && !seed && !seedpath) {
+#ifdef HAVE_RANDOM_DEVICE
+ seedpath = RANDOM_DEVICE;
+#else
+ fatal(0, "no --seed or --seed-file specified in --both mode"
+ " and random device not supported on this system");
+#endif
+ }
+ if(seedpath) {
+ if(!seedlen)
+ seedlen = DEFAULT_SEED_LENGTH;
+ FILE *seedfile = fopen(seedpath, "rb");
+ if(!seedfile)
+ fatal(errno, "%s", seedpath);
+ seed = malloc(seedlen);
+ if(!seed)
+ fatal(errno, "allocate seed");
+ seedlen = fread(seed, 1, seedlen, seedfile);
+ if(ferror(seedfile))
+ fatal(errno, "read %s", seedpath);
+ fclose(seedfile);
+ }
+ if (!seed) {
+ seed = (void*)default_seed;
+ seedlen = sizeof(default_seed)-1;
+ }
path = argv[0];
if(argc > 1) {
errno = 0;
}
static long long execute(mode_type mode, bool entire, const char *show) {
- Arcfour rng(seed, strlen(seed));
+ Arcfour rng((const char*)seed, seedlen);
FILE *fp = fopen(path, mode == VERIFY ? "rb" : "wb");
if(!fp)
fatal(errno, "%s", path);
setvbuf(fp, 0, _IONBF, 0);
char generated[4096], input[4096];
long long remain = size;
+ static const size_t rc4drop = 3072; // en.wikipedia.org/wiki/RC4#Security
+ assert(rc4drop <= sizeof(generated));
+ rng.stream(generated, rc4drop);
while(remain > 0) {
size_t bytesGenerated = (remain > (ssize_t)sizeof generated
? sizeof generated