gtls.c

/*
 * This function is called after the TCP connect has completed. Setup the TLS
 * layer and do all necessary magic.
 */
/* We use connssl->connecting_state to keep track of the connection status;
   there are three states: 'ssl_connect_1' (not started yet or complete),
   'ssl_connect_2_reading' (waiting for data from server), and
   'ssl_connect_2_writing' (waiting to be able to write).
 */
static CURLcode
gtls_connect_common(struct connectdata *conn,
                    int sockindex,
                    bool nonblocking,
                    bool *done)
{
  int rc;
  struct ssl_connect_data *connssl = &conn->ssl[sockindex];

  /* Initiate the connection, if not already done */
  if(ssl_connect_1==connssl->connecting_state) {
    rc = gtls_connect_step1 (conn, sockindex);
    if(rc)
      return rc;
  }

  rc = handshake(conn, sockindex, TRUE, nonblocking);
  if(rc)
    /* handshake() sets its own error message with failf() */
    return rc;

  /* Finish connecting once the handshake is done */
  if(ssl_connect_1==connssl->connecting_state) {
    rc = gtls_connect_step3(conn, sockindex);
    if(rc)
      return rc;
  }

  *done = ssl_connect_1==connssl->connecting_state;

  return CURLE_OK;
}

CURLcode
Curl_gtls_connect_nonblocking(struct connectdata *conn,
                              int sockindex,
                              bool *done)
{
  return gtls_connect_common(conn, sockindex, TRUE, done);
}

CURLcode
Curl_gtls_connect(struct connectdata *conn,
                  int sockindex)

{
  CURLcode retcode;
  bool done = FALSE;

  retcode = gtls_connect_common(conn, sockindex, FALSE, &done);
  if(retcode)
    return retcode;

  DEBUGASSERT(done);

  return CURLE_OK;
}

static ssize_t gtls_send(struct connectdata *conn,
                         int sockindex,
                         const void *mem,
                         size_t len,
                         CURLcode *curlcode)
{
  ssize_t rc = gnutls_record_send(conn->ssl[sockindex].session, mem, len);

  if(rc < 0 ) {
    *curlcode = (rc == GNUTLS_E_AGAIN)
      ? CURLE_AGAIN
      : CURLE_SEND_ERROR;

    rc = -1;
  }

  return rc;
}

void Curl_gtls_close_all(struct SessionHandle *data)
{
  /* FIX: make the OpenSSL code more generic and use parts of it here */
  (void)data;
}

static void close_one(struct connectdata *conn,
                      int idx)
{
  if(conn->ssl[idx].session) {
    gnutls_bye(conn->ssl[idx].session, GNUTLS_SHUT_RDWR);
    gnutls_deinit(conn->ssl[idx].session);
    conn->ssl[idx].session = NULL;
  }
  if(conn->ssl[idx].cred) {
    gnutls_certificate_free_credentials(conn->ssl[idx].cred);
    conn->ssl[idx].cred = NULL;
  }
#ifdef USE_TLS_SRP
  if(conn->ssl[idx].srp_client_cred) {
    gnutls_srp_free_client_credentials(conn->ssl[idx].srp_client_cred);
    conn->ssl[idx].srp_client_cred = NULL;
  }
#endif
}

void Curl_gtls_close(struct connectdata *conn, int sockindex)
{
  close_one(conn, sockindex);
}

/*
 * This function is called to shut down the SSL layer but keep the
 * socket open (CCC - Clear Command Channel)
 */
int Curl_gtls_shutdown(struct connectdata *conn, int sockindex)
{
  ssize_t result;
  int retval = 0;
  struct SessionHandle *data = conn->data;
  int done = 0;
  char buf[120];

  /* This has only been tested on the proftpd server, and the mod_tls code
     sends a close notify alert without waiting for a close notify alert in
     response. Thus we wait for a close notify alert from the server, but
     we do not send one. Let's hope other servers do the same... */

  if(data->set.ftp_ccc == CURLFTPSSL_CCC_ACTIVE)
      gnutls_bye(conn->ssl[sockindex].session, GNUTLS_SHUT_WR);

  if(conn->ssl[sockindex].session) {
    while(!done) {
      int what = Curl_socket_ready(conn->sock[sockindex],
                                   CURL_SOCKET_BAD, SSL_SHUTDOWN_TIMEOUT);
      if(what > 0) {
        /* Something to read, let's do it and hope that it is the close
           notify alert from the server */
        result = gnutls_record_recv(conn->ssl[sockindex].session,
                                    buf, sizeof(buf));
        switch(result) {
        case 0:
          /* This is the expected response. There was no data but only
             the close notify alert */
          done = 1;
          break;
        case GNUTLS_E_AGAIN:
        case GNUTLS_E_INTERRUPTED:
          infof(data, "GNUTLS_E_AGAIN || GNUTLS_E_INTERRUPTED\n");
          break;
        default:
          retval = -1;
          done = 1;
          break;
        }
      }
      else if(0 == what) {
        /* timeout */
        failf(data, "SSL shutdown timeout");
        done = 1;
        break;
      }
      else {
        /* anything that gets here is fatally bad */
        failf(data, "select/poll on SSL socket, errno: %d", SOCKERRNO);
        retval = -1;
        done = 1;
      }
    }
    gnutls_deinit(conn->ssl[sockindex].session);
  }
  gnutls_certificate_free_credentials(conn->ssl[sockindex].cred);

#ifdef USE_TLS_SRP
  if(data->set.ssl.authtype == CURL_TLSAUTH_SRP
     && data->set.ssl.username != NULL)
    gnutls_srp_free_client_credentials(conn->ssl[sockindex].srp_client_cred);
#endif

  conn->ssl[sockindex].cred = NULL;
  conn->ssl[sockindex].session = NULL;

  return retval;
}

static ssize_t gtls_recv(struct connectdata *conn, /* connection data */
                         int num,                  /* socketindex */
                         char *buf,                /* store read data here */
                         size_t buffersize,        /* max amount to read */
                         CURLcode *curlcode)
{
  ssize_t ret;

  ret = gnutls_record_recv(conn->ssl[num].session, buf, buffersize);
  if((ret == GNUTLS_E_AGAIN) || (ret == GNUTLS_E_INTERRUPTED)) {
    *curlcode = CURLE_AGAIN;
    return -1;
  }

  if(ret == GNUTLS_E_REHANDSHAKE) {
    /* BLOCKING call, this is bad but a work-around for now. Fixing this "the
       proper way" takes a whole lot of work. */
    CURLcode rc = handshake(conn, num, FALSE, FALSE);
    if(rc)
      /* handshake() writes error message on its own */
      *curlcode = rc;
    else
      *curlcode = CURLE_AGAIN; /* then return as if this was a wouldblock */
    return -1;
  }

  if(ret < 0) {
    failf(conn->data, "GnuTLS recv error (%d): %s",
          (int)ret, gnutls_strerror((int)ret));
    *curlcode = CURLE_RECV_ERROR;
    return -1;
  }

  return ret;
}

void Curl_gtls_session_free(void *ptr)
{
  free(ptr);
}

size_t Curl_gtls_version(char *buffer, size_t size)
{
  return snprintf(buffer, size, "GnuTLS/%s", gnutls_check_version(NULL));
}

int Curl_gtls_seed(struct SessionHandle *data)
{
  /* we have the "SSL is seeded" boolean static to prevent multiple
     time-consuming seedings in vain */
  static bool ssl_seeded = FALSE;

  /* Quickly add a bit of entropy */
#ifndef USE_GNUTLS_NETTLE
  gcry_fast_random_poll();
#endif

  if(!ssl_seeded || data->set.str[STRING_SSL_RANDOM_FILE] ||
     data->set.str[STRING_SSL_EGDSOCKET]) {

    /* TODO: to a good job seeding the RNG
       This may involve the gcry_control function and these options:
       GCRYCTL_SET_RANDOM_SEED_FILE
       GCRYCTL_SET_RNDEGD_SOCKET
    */
    ssl_seeded = TRUE;
  }
  return 0;
}

void Curl_gtls_random(struct SessionHandle *data,
                      unsigned char *entropy,
                      size_t length)
{
#if defined(USE_GNUTLS_NETTLE)
  (void)data;
  gnutls_rnd(GNUTLS_RND_RANDOM, entropy, length);
#elif defined(USE_GNUTLS)
  Curl_gtls_seed(data); /* Initiate the seed if not already done */
  gcry_randomize(entropy, length, GCRY_STRONG_RANDOM);
#endif
}

void Curl_gtls_md5sum(unsigned char *tmp, /* input */
                      size_t tmplen,
                      unsigned char *md5sum, /* output */
                      size_t md5len)
{
#if defined(USE_GNUTLS_NETTLE)
  struct md5_ctx MD5pw;
  md5_init(&MD5pw);
  md5_update(&MD5pw, (unsigned int)tmplen, tmp);
  md5_digest(&MD5pw, (unsigned int)md5len, md5sum);
#elif defined(USE_GNUTLS)
  gcry_md_hd_t MD5pw;
  gcry_md_open(&MD5pw, GCRY_MD_MD5, 0);
  gcry_md_write(MD5pw, tmp, tmplen);
  memcpy(md5sum, gcry_md_read (MD5pw, 0), md5len);
  gcry_md_close(MD5pw);
#endif
}

#endif /* USE_GNUTLS */