/* Copyright (c) Dovecot authors, see top-level COPYING file */

#include "lib.h"

#include "str.h"

#include "hex-binary.h"

#include "hmac.h"

#include "md5.h"

#include "dsasl-client-private.h"

struct cram_md5_dsasl_client {

  struct dsasl_client client;

  const char *challenge;

};

static enum dsasl_client_result

mech_cram_md5_input(struct dsasl_client *client,

        const unsigned char *input, size_t input_len,

        const char **error_r)

{

  struct cram_md5_dsasl_client *cclient =

    container_of(client, struct cram_md5_dsasl_client, client);

  const unsigned char *p = input, *pend = input + input_len;

  if (p >= pend) {

    *error_r = "Server sent empty challenge";

    return DSASL_CLIENT_RESULT_ERR_PROTOCOL;

  }

  if (*p != '<') {

    *error_r = "Server sent invalid challenge begin";

    return DSASL_CLIENT_RESULT_ERR_PROTOCOL;

  }

  p++;

  for (; (p + 1) < pend; p++) {

    if (*p <= 32 || *p == 127 || *p == '>') {

      *error_r = "Server sent invalid challenge";

      return DSASL_CLIENT_RESULT_ERR_PROTOCOL;

    }

  }

  if (p >= pend || *p != '>') {

    *error_r = "Server sent invalid challenge end";

    return DSASL_CLIENT_RESULT_ERR_PROTOCOL;

  }

  p++;

  i_assert(p == pend);

  if (input_len < 5) {

    *error_r = "Server sent invalid challenge";

    return DSASL_CLIENT_RESULT_ERR_PROTOCOL;

  }

  cclient->challenge = p_strndup(client->pool, input, input_len);

  return DSASL_CLIENT_RESULT_OK;

}

static enum dsasl_client_result

mech_cram_md5_output(struct dsasl_client *client,

         const unsigned char **output_r, size_t *output_len_r,

         const char **error_r)

{

  struct cram_md5_dsasl_client *cclient =

    container_of(client, struct cram_md5_dsasl_client, client);

  string_t *str;

  if (client->set.authid == NULL) {

    *error_r = "authid not set";

    return DSASL_CLIENT_RESULT_ERR_INTERNAL;

  }

  if (client->password == NULL) {

    *error_r = "password not set";

    return DSASL_CLIENT_RESULT_ERR_INTERNAL;

  }

  if (cclient->challenge == NULL) {

    *output_r = uchar_empty_ptr;

    *output_len_r = 0;

    return DSASL_CLIENT_RESULT_OK;

  }

  struct hmac_context ctx;

  unsigned char digest[MD5_RESULTLEN];

  hmac_init(&ctx, (const unsigned char *)client->password,

      strlen(client->password), &hash_method_md5);

  hmac_update(&ctx, cclient->challenge, strlen(cclient->challenge));

  hmac_final(&ctx, digest);

  str = str_new(client->pool, 256);

  str_append(str, client->set.authid);

  str_append_c(str, ' ');

  binary_to_hex_append(str, digest, sizeof(digest));

  *output_r = str_data(str);

  *output_len_r = str_len(str);

  return DSASL_CLIENT_RESULT_OK;

}

const struct dsasl_client_mech dsasl_client_mech_cram_md5 = {

  .name = SASL_MECH_NAME_CRAM_MD5,

  .struct_size = sizeof(struct cram_md5_dsasl_client),

  .input = mech_cram_md5_input,

  .output = mech_cram_md5_output,

};