[Swan-dev] Question on get_cookie() code

[D. Hugh Redelmeier]

| From: Andrew Cagney <andrew.cagney at gmail.com>

| On 5 January 2016 at 18:29, Paul Wouters <paul at nohats.ca> wrote:

| > void get_cookie(bool initiator, u_int8_t *cookie, int length,
| >                 const ip_address *addr)
| > {
| >         u_char buffer[SHA1_DIGEST_SIZE];
| >         SHA1_CTX ctx;
| >
| >         do {
| >                 if (initiator) {
| >                         get_rnd_bytes(cookie, length);
| >                 } else {
| >                         /* Responder cookie */
| >                         /* This looks as good as any way */
| >                         size_t addr_length;
| >                         static u_int32_t counter = 0;
| >                         unsigned char addr_buff[
| >                                 sizeof(union { struct in_addr A;
| >                                                struct in6_addr B;
| >                                        })];
| >
| >                         addr_length =
| >                                 addrbytesof(addr, addr_buff,
| >                                             sizeof(addr_buff));
| >                         SHA1Init(&ctx);
| >                         SHA1Update(&ctx, addr_buff, addr_length);
| >                         SHA1Update(&ctx, secret_of_the_day,
| >                                    sizeof(secret_of_the_day));
| >                         counter++;
| >                         SHA1Update(&ctx, (const void *) &counter,
| >                                    sizeof(counter));
| >                         SHA1Final(buffer, &ctx);
| >                         memcpy(cookie, buffer, length);
| >                 }
| >         } while (is_zero_cookie(cookie)); /* probably never loops */
| > }
| 
| It seems to be feeding SHA1 crud found on the stack?

I'm not seeing that.  Could you be more specific?