ssluse.c

    int err = SSL_get_error(conn->ssl[num].handle, (int)nread);

    switch(err) {
    case SSL_ERROR_NONE: /* this is not an error */
    case SSL_ERROR_ZERO_RETURN: /* no more data */
      break;
    case SSL_ERROR_WANT_READ:
    case SSL_ERROR_WANT_WRITE:
      /* there's data pending, re-invoke SSL_read() */
      *wouldblock = TRUE;
      return -1; /* basically EWOULDBLOCK */
    default:
      /* openssl/ssl.h says "look at error stack/return value/errno" */
      sslerror = ERR_get_error();
      failf(conn->data, "SSL read: %s, errno %d",
            ERR_error_string(sslerror, error_buffer),
            SOCKERRNO);
      return -1;
    }
  }
  return nread;
}

size_t Curl_ossl_version(char *buffer, size_t size)
{
#ifdef YASSL_VERSION
  /* yassl provides an OpenSSL API compatiblity layer so it looks identical
     to OpenSSL in all other aspects */
  return snprintf(buffer, size, "yassl/%s", YASSL_VERSION);
#else /* YASSL_VERSION */

#if(SSLEAY_VERSION_NUMBER >= 0x905000)
  {
    char sub[2];
    unsigned long ssleay_value;
    sub[1]='\0';
    ssleay_value=SSLeay();
    if(ssleay_value < 0x906000) {
      ssleay_value=SSLEAY_VERSION_NUMBER;
      sub[0]='\0';
    }
    else {
      if(ssleay_value&0xff0) {
        sub[0]=(char)(((ssleay_value>>4)&0xff) + 'a' -1);
      }
      else
        sub[0]='\0';
    }

    return snprintf(buffer, size, "OpenSSL/%lx.%lx.%lx%s",
                    (ssleay_value>>28)&0xf,
                    (ssleay_value>>20)&0xff,
                    (ssleay_value>>12)&0xff,
                    sub);
  }

#else /* SSLEAY_VERSION_NUMBER is less than 0.9.5 */

#if(SSLEAY_VERSION_NUMBER >= 0x900000)
  return snprintf(buffer, size, "OpenSSL/%lx.%lx.%lx",
                  (SSLEAY_VERSION_NUMBER>>28)&0xff,
                  (SSLEAY_VERSION_NUMBER>>20)&0xff,
                  (SSLEAY_VERSION_NUMBER>>12)&0xf);

#else /* (SSLEAY_VERSION_NUMBER >= 0x900000) */
  {
    char sub[2];
    sub[1]='\0';
    if(SSLEAY_VERSION_NUMBER&0x0f) {
      sub[0]=(SSLEAY_VERSION_NUMBER&0x0f) + 'a' -1;
    }
    else
      sub[0]='\0';

    return snprintf(buffer, size, "SSL/%x.%x.%x%s",
                    (SSLEAY_VERSION_NUMBER>>12)&0xff,
                    (SSLEAY_VERSION_NUMBER>>8)&0xf,
                    (SSLEAY_VERSION_NUMBER>>4)&0xf, sub);
  }
#endif /* (SSLEAY_VERSION_NUMBER >= 0x900000) */
#endif /* SSLEAY_VERSION_NUMBER is less than 0.9.5 */

#endif /* YASSL_VERSION */
}
#endif /* USE_SSLEAY */