review abstain

I have no opinion on this merge request, just some minor comments
that you may wish to ignore or adapt at your discretion...

On Fri, Apr 08, 2011 at 03:41:24PM +0000, René Hummen wrote:
> 
> --- lib/core/solve.c	2011-01-24 10:21:17 +0000
> +++ lib/core/solve.c	2011-04-08 15:41:17 +0000
> @@ -28,11 +28,14 @@
>  
>  #include <errno.h>
> +#include <openssl/rand.h>
>  #include <stdint.h>
>  #include <string.h>
> +#include <strings.h>

nit:

#include <errno.h>
#include <stdint.h>
#include <string.h>
#include <strings.h>
#include <openssl/rand.h>

> @@ -43,104 +46,170 @@
> +static int hip_calculate_puzzle_solution(const struct puzzle_common *const compute_puzzle,
> +                                         unsigned char sha_digest[SHA_DIGEST_LENGTH],
> +                                         const int difficulty)
>  {
> +    HIP_IFEL(difficulty > max_puzzle_difficulty,
> +             -1, "difficulty exceeds max. configured difficulty\n");
> +
> +    HIP_IFEL(hip_build_digest(HIP_DIGEST_SHA1,
> +                              compute_puzzle,
> +                              sizeof(struct puzzle_common),
> +                              sha_digest),
> +             -1, "failed to compute hash digest\n");
> +
> +    /* check if position of first least significant 1-bit is higher than
> +     * difficulty */
> +    if (ffs(truncated_digest) > difficulty) {
> +        err = 0;
>      } else {
> +        err = 1;
> +    }
> +
> +out_err:
> +    return err;
> +}

I would suggest doing that without HIP_IFEL, that would even save two
lines in the if/else clause.

> +/**
> + * Solve a computational puzzle for HIP
> + *
> + * @param puzzle        puzzle to be solved
> + * @param difficulty    difficulty of the puzzle
> + * @param initiator_hit initiator HIT of the message exchange
> + * @param responder_hit responder HIT of the message exchange
> + * @param solution      computed puzzle solution
> + * @return 0 when solution was found, 1 in case no solution was found after
> + *         MAX_PUZZLE_SOLUTION_TRIES, -1 in case of an error
> + */
> +int hip_solve_puzzle(const uint8_t puzzle[PUZZLE_LENGTH],
> +                     const int difficulty,
> +                     const hip_hit_t initiator_hit,
> +                     const hip_hit_t responder_hit,
> +                     uint8_t solution[PUZZLE_LENGTH])

Having solution as third parameter would feel more natural to me.

> +/**
> + * Verify a computational puzzle for HIP
> + *
> + * @param puzzle        puzzle to be verified
> + * @param difficulty    difficulty of the puzzle
> + * @param initiator_hit initiator HIT of the message exchange
> + * @param responder_hit responder HIT of the message exchange
> + * @param solution      puzzle solution to be verified
> + * @return 0 when solution is correct, -1 otherwise
> + */
> +int hip_verify_puzzle_solution(const uint8_t puzzle[PUZZLE_LENGTH],
> +                               const uint8_t difficulty,
> +                               const hip_hit_t initiator_hit,
> +                               const hip_hit_t responder_hit,
> +                               const uint8_t solution[PUZZLE_LENGTH])

Having solution as third parameter would feel more natural to me.

> +    HIP_IFEL(hip_calculate_puzzle_solution(&compute_puzzle,
> +                                           sha_digest,
> +                                           difficulty),
> +             -1, "failed to verify puzzle solution\n");
> +
>  out_err:
>      return err;
>  }

I suggest doing this without HIP_IFEL.

> --- test/lib/core/solve.c	1970-01-01 00:00:00 +0000
> +++ test/lib/core/solve.c	2011-04-08 15:41:17 +0000
> @@ -0,0 +1,170 @@
> +
> +#include <check.h>
> +#include <openssl/rand.h>
> +#include <stdint.h>

nit:

#include <check.h>
#include <stdint.h>
#include <openssl/rand.h>

Diego