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#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"
#include "standard.h"
#include "rand.h"
#include <stdlib.h>
#include <string.h>
#include <assert.h>
struct session_token_ctx {
int mask;
int count;
int curr_word;
int bytes_left_in_curr_word;
struct randctx isaac_ctx;
char *alphabet;
size_t alphabet_length;
size_t token_length;
};
typedef struct session_token_ctx * Session_Token;
static inline int get_new_byte(struct session_token_ctx *ctx) {
int output;
if (ctx->bytes_left_in_curr_word == 0) {
if (ctx->count > 255) {
isaac(&ctx->isaac_ctx);
ctx->count = 0;
}
ctx->curr_word = ctx->isaac_ctx.randrsl[ctx->count];
ctx->count++;
ctx->bytes_left_in_curr_word = 4;
}
output = ctx->curr_word & 0xFF;
ctx->bytes_left_in_curr_word--;
ctx->curr_word >>= 8;
return output;
}
static int get_mask(int v) {
v--;
v |= v >> 1;
v |= v >> 2;
v |= v >> 4;
return v;
}
MODULE = Session::Token PACKAGE = Session::Token
PROTOTYPES: ENABLE
Session_Token
_new_context(seed, alphabet, token_length)
SV *seed
SV *alphabet
size_t token_length
CODE:
struct session_token_ctx *ctx;
char *seedp;
size_t len;
len = SvCUR(seed);
seedp = SvPV(seed, len);
assert(sizeof(ctx->isaac_ctx.randrsl) == 1024);
if (len != 1024) {
croak("unexpected seed length: %lu", len);
}
ctx = malloc(sizeof(struct session_token_ctx));
memset(ctx, '\0', sizeof(struct session_token_ctx));
memcpy(&ctx->isaac_ctx.randrsl, seedp, 1024);
randinit(&ctx->isaac_ctx, TRUE);
isaac(&ctx->isaac_ctx);
ctx->alphabet_length = SvCUR(alphabet);
ctx->alphabet = malloc(ctx->alphabet_length);
memcpy(ctx->alphabet, SvPV(alphabet, ctx->alphabet_length), ctx->alphabet_length);
ctx->token_length = token_length;
ctx->mask = get_mask(ctx->alphabet_length);
RETVAL = ctx;
OUTPUT:
RETVAL
void
DESTROY(ctx)
Session_Token ctx
CODE:
free(ctx->alphabet);
free(ctx);
SV *
get(ctx)
Session_Token ctx
CODE:
SV *output;
char *outputp;
size_t i, curr;
output = newSVpvn("", 0);
SvGROW(output, ctx->token_length);
SvCUR_set(output, ctx->token_length);
outputp = SvPV(output, ctx->token_length);
for (i=0; i<ctx->token_length; i++) {
while((curr = (get_new_byte(ctx) & ctx->mask)) >= ctx->alphabet_length) ;
outputp[i] = ctx->alphabet[curr];
}
RETVAL = output;
OUTPUT:
RETVAL
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