// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
	// vim: ts=8 sw=2 smarttab
	
	/** \file
	 *
	 * This is an OSD class that implements methods for management
	 * and use of otp (one time password).
	 *
	 */
	
	#include <errno.h>
	#include <map>
	#include <list>
	
	#include <boost/range/adaptor/reversed.hpp>
	
	#include <liboath/oath.h>
	
	#include "include/types.h"
	#include "include/utime.h"
	#include "objclass/objclass.h"
	
	#include "common/errno.h"
	#include "common/Clock.h"
	
	#include "cls/otp/cls_otp_ops.h"
	#include "cls/otp/cls_otp_types.h"
	
	
	using namespace rados::cls::otp;
	
	
	CLS_VER(1,0)
	CLS_NAME(otp)
	
	#define ATTEMPTS_PER_WINDOW 5
	
	static string otp_header_key = "header";
	static string otp_key_prefix = "otp/";
	

	struct otp_header {
	  set<string> ids;
	
	  otp_header() {}
	
	  void encode(bufferlist &bl) const {
	    ENCODE_START(1, 1, bl);
	    encode(ids, bl);
	    ENCODE_FINISH(bl);
	  }
	  void decode(bufferlist::const_iterator &bl) {
	    DECODE_START(1, bl);
	    decode(ids, bl);
	    DECODE_FINISH(bl);
	  }
	};
	WRITE_CLASS_ENCODER(otp_header)
	
	struct otp_instance {
	  otp_info_t otp;
	
	  list<otp_check_t> last_checks; 
	  uint64_t last_success{0}; /* otp counter/step of last successful check */
	
	  otp_instance() {}
	
	  void encode(bufferlist &bl) const {
	    ENCODE_START(1, 1, bl);
	    encode(otp, bl);
	    encode(last_checks, bl);
	    encode(last_success, bl);
	    ENCODE_FINISH(bl);
	  }
	  void decode(bufferlist::const_iterator &bl) {
	    DECODE_START(1, bl);
	    decode(otp, bl);
	    decode(last_checks, bl);
	    decode(last_success, bl);
	    DECODE_FINISH(bl);
	  }
	
	  void trim_expired(const ceph::real_time& now);
	  void check(const string& token, const string& val, bool *update);
	  bool verify(const ceph::real_time& timestamp, const string& val);
	
	  void find(const string& token, otp_check_t *result);
	};
	WRITE_CLASS_ENCODER(otp_instance)
	
	
	void otp_instance::trim_expired(const ceph::real_time& now)
	{
	  ceph::real_time window_start = now - std::chrono::seconds(otp.step_size);
	
	  while (!last_checks.empty() &&
	         last_checks.front().timestamp < window_start) {
	    last_checks.pop_front();
	  }
	}
	
	void otp_instance::check(const string& token, const string& val, bool *update)
	{
	  ceph::real_time now = ceph::real_clock::now();
	  trim_expired(now);
	
	  if (last_checks.size() >= ATTEMPTS_PER_WINDOW) {
	    /* too many attempts */
	    *update = false;
	    return;
	  }
	
	  otp_check_t check;
	  check.token = token;
	  check.timestamp = now;
	  check.result = (verify(now, val) ? OTP_CHECK_SUCCESS : OTP_CHECK_FAIL);
	
	  last_checks.push_back(check);
	
	  *update = true;
	}
	
	bool otp_instance::verify(const ceph::real_time& timestamp, const string& val)
	{
	  uint64_t index;
	  uint32_t secs = (uint32_t)ceph::real_clock::to_time_t(timestamp);
	  int result = oath_totp_validate2(otp.seed_bin.c_str(), otp.seed_bin.length(),
	                                   secs, otp.step_size, otp.time_ofs, otp.window,
	                                   nullptr /* otp pos */,
	                                   val.c_str());
	  if (result == OATH_INVALID_OTP ||
	      result < 0) {
	    CLS_LOG(20, "otp check failed, result=%d", result);
	    return false;
	  }
	
	  index = result + (secs - otp.time_ofs) / otp.step_size;
	
	  if (index <= last_success) { /* already used value */
	    CLS_LOG(20, "otp, use of old token: index=%lld last_success=%lld", (long long)index, (long long)last_success);
	    return false;
	  }
	
	  last_success = index;
	
	  return true;
	}
	
	void otp_instance::find(const string& token, otp_check_t *result)
	{
	  ceph::real_time now = real_clock::now();
	  trim_expired(now);
	
	  for (auto& entry : boost::adaptors::reverse(last_checks)) {
	    if (entry.token == token) {
	      *result = entry;
	      return;
	    }
	  }
	  result->token = token;
	  result->result = OTP_CHECK_UNKNOWN;
	  result->timestamp = now;
	}
	
	static int get_otp_instance(cls_method_context_t hctx, const string& id, otp_instance *instance)
	{
	  bufferlist bl;
	  string key = otp_key_prefix + id;
	 
	  int r = cls_cxx_map_get_val(hctx, key, &bl);
	  if (r < 0) {
	    if (r != -ENOENT) {
	      CLS_ERR("error reading key %s: %d", key.c_str(), r);
	    }
	    return r;
	  }
	
	  try {
	    auto it = bl.cbegin();
	    decode(*instance, it);
	  } catch (const buffer::error &err) {
	    CLS_ERR("ERROR: failed to decode %s", key.c_str());
	    return -EIO;
	  }
	
	  return 0;
	}
	
	static int write_otp_instance(cls_method_context_t hctx, const otp_instance& instance)
	{
	  string key = otp_key_prefix + instance.otp.id;
	
	  bufferlist bl;
	  encode(instance, bl);
	
	  int r = cls_cxx_map_set_val(hctx, key, &bl);
	  if (r < 0) {
	    CLS_ERR("ERROR: %s(): failed to store key (otp id=%s, r=%d)", __func__, instance.otp.id.c_str(), r);
	    return r;
	  }
	
	  return 0;
	}
	
	static int remove_otp_instance(cls_method_context_t hctx, const string& id)
	{
	  string key = otp_key_prefix + id;
	
	  int r = cls_cxx_map_remove_key(hctx, key);
	  if (r < 0) {
	    CLS_ERR("ERROR: %s(): failed to remove key (otp id=%s, r=%d)", __func__, id.c_str(), r);
	    return r;
	  }
	
	  return 0;
	}
	
	static int read_header(cls_method_context_t hctx, otp_header *h)
	{
	  bufferlist bl;

	  encode(h, bl);
	  int r = cls_cxx_map_get_val(hctx, otp_header_key, &bl);

	  if (r == -ENOENT || r == -ENODATA) {
	    *h = otp_header();
	    return 0;

	  }

	  if (r < 0) {
	    CLS_ERR("ERROR: %s(): failed to read header (r=%d)", __func__, r);
	    return r;

	  }
	

	  if (bl.length() == 0) {

	    *h = otp_header();
	    return 0;
	  }
	
	  auto iter = bl.cbegin();
	  try {
	    decode(*h, iter);
	  } catch (buffer::error& err) {
	    CLS_ERR("failed to decode otp_header");
	    return -EIO;
	  }
	
	  return 0;
	}
	
	static int write_header(cls_method_context_t hctx, const otp_header& h)
	{
	  bufferlist bl;
	  encode(h, bl);
	
	  int r = cls_cxx_map_set_val(hctx, otp_header_key, &bl);
	  if (r < 0) {
	    CLS_ERR("failed to store header (r=%d)", r);
	    return r;
	  }
	
	  return 0;
	}
	
	static int parse_seed(const string& seed, SeedType seed_type, bufferlist *seed_bin)
	{
	  size_t slen = seed.length();
	  char secret[seed.length()];
	  char *psecret = secret;
	  int result;
	  bool need_free = false;
	
	  seed_bin->clear();
	
	  switch (seed_type) {
	    case OTP_SEED_BASE32:
	      need_free = true; /* oath_base32_decode allocates dest buffer */
	      result = oath_base32_decode(seed.c_str(), seed.length(),
	                                  &psecret, &slen);
	      break;
	    default: /* just assume hex is the default */
	      result = oath_hex2bin(seed.c_str(), psecret, &slen);
	  }
	  if (result != OATH_OK) {
	    CLS_LOG(20, "failed to parse seed");
	    return -EINVAL;
	  }
	
	  seed_bin->append(psecret, slen);
	
	  if (need_free) {
	    free(psecret);
	  }
	
	  return 0;
	}
	
	static int otp_set_op(cls_method_context_t hctx,
	                       bufferlist *in, bufferlist *out)
	{
	  CLS_LOG(20, "%s", __func__);
	  cls_otp_set_otp_op op;
	  try {
	    auto iter = in->cbegin();
	    decode(op, iter);
	  } catch (const buffer::error &err) {
	    CLS_ERR("ERROR: %s(): failed to decode request", __func__);
	    return -EINVAL;
	  }
	
	  otp_header h;
	  int r = read_header(hctx, &h);
	  if (r < 0) {
	    return r;
	  }
	
	  for (auto entry : op.entries) {
	    otp_instance instance;
	    r = get_otp_instance(hctx, entry.id, &instance);
	    if (r < 0 &&
	        r != -ENOENT) {
	      return r;
	    }
	    instance.otp = entry;
	
	    r = parse_seed(instance.otp.seed, instance.otp.seed_type, &instance.otp.seed_bin);
	    if (r < 0) {
	      return r;
	    }
	
	    r = write_otp_instance(hctx, instance);
	    if (r < 0) {
	      return r;
	    }
	
	    h.ids.insert(entry.id);
	  }
	
	  r = write_header(hctx, h);
	  if (r < 0) {
	    return r;
	  }
	
	  return 0;
	}
	
	static int otp_remove_op(cls_method_context_t hctx,
	                          bufferlist *in, bufferlist *out)
	{
	  CLS_LOG(20, "%s", __func__);
	  cls_otp_remove_otp_op op;
	  try {
	    auto iter = in->cbegin();
	    decode(op, iter);
	  } catch (const buffer::error &err) {
	    CLS_ERR("ERROR: %s(): failed to decode request", __func__);
	    return -EINVAL;
	  }
	
	  otp_header h;
	  bool removed_existing = false;
	  int r = read_header(hctx, &h);
	  if (r < 0) {
	    return r;
	  }
	
	  for (auto id : op.ids) {
	    bool existed = (h.ids.find(id) != h.ids.end());
	    removed_existing = (removed_existing || existed);
	
	    if (!existed) {
	      continue;
	    }
	
	    r = remove_otp_instance(hctx, id);
	    if (r < 0) {
	      return r;
	    }
	
	    h.ids.erase(id);
	  }
	
	  if (removed_existing) {
	    r = write_header(hctx, h);
	    if (r < 0) {
	      return r;
	    }
	  }
	
	  return 0;
	}
	
	static int otp_get_op(cls_method_context_t hctx,
	                          bufferlist *in, bufferlist *out)
	{
	  CLS_LOG(20, "%s", __func__);
	  cls_otp_get_otp_op op;
	  try {
	    auto iter = in->cbegin();
	    decode(op, iter);
	  } catch (const buffer::error &err) {
	    CLS_ERR("ERROR: %s(): failed to decode request", __func__);
	    return -EINVAL;
	  }
	
	  cls_otp_get_otp_reply result;
	
	  otp_header h;
	  int r;
	
	  r = read_header(hctx, &h);
	  if (r < 0) {
	    return r;
	  }
	
	  if (op.get_all) {
	    op.ids.clear();
	    for (auto id : h.ids) {
	      op.ids.push_back(id);
	    }
	  }
	
	  for (auto id : op.ids) {
	    bool exists = (h.ids.find(id) != h.ids.end());
	
	    if (!exists) {
	      continue;
	    }
	
	    otp_instance instance;
	    r = get_otp_instance(hctx, id, &instance);
	    if (r < 0) {
	      return r;
	    }
	
	    result.found_entries.push_back(instance.otp);
	  }
	
	  encode(result, *out);
	
	  return 0;
	}
	
	static int otp_check_op(cls_method_context_t hctx,
	                          bufferlist *in, bufferlist *out)
	{
	  CLS_LOG(20, "%s", __func__);
	  cls_otp_check_otp_op op;
	  try {
	    auto iter = in->cbegin();
	    decode(op, iter);
	  } catch (const buffer::error &err) {
	    CLS_ERR("ERROR: %s(): failed to decode request", __func__);
	    return -EINVAL;
	  }
	
	  otp_header h;
	  int r;
	
	  otp_instance instance;
	
	  r = get_otp_instance(hctx, op.id, &instance);
	  if (r < 0) {
	    return r;
	  }
	
	  bool update{false};
	  instance.check(op.token, op.val, &update);
	
	  if (update) {
	    r = write_otp_instance(hctx, instance);
	    if (r < 0) {
	      return r;
	    }
	  }
	
	  return 0;
	}
	
	static int otp_get_result(cls_method_context_t hctx,
	                          bufferlist *in, bufferlist *out)
	{
	  CLS_LOG(20, "%s", __func__);
	  cls_otp_check_otp_op op;
	  try {
	    auto iter = in->cbegin();
	    decode(op, iter);
	  } catch (const buffer::error &err) {
	    CLS_ERR("ERROR: %s(): failed to decode request", __func__);
	    return -EINVAL;
	  }
	
	  otp_header h;
	  int r;
	
	  otp_instance instance;
	
	  r = get_otp_instance(hctx, op.id, &instance);
	  if (r < 0) {
	    return r;
	  }
	
	  cls_otp_get_result_reply reply;
	  instance.find(op.token, &reply.result);
	  encode(reply, *out);
	
	  return 0;
	}
	
	static int otp_get_current_time_op(cls_method_context_t hctx,
	                        bufferlist *in, bufferlist *out)
	{
	  CLS_LOG(20, "%s", __func__);
	  cls_otp_get_current_time_op op;
	  try {
	    auto iter = in->cbegin();
	    decode(op, iter);
	  } catch (const buffer::error &err) {
	    CLS_ERR("ERROR: %s(): failed to decode request", __func__);
	    return -EINVAL;
	  }
	
	  cls_otp_get_current_time_reply reply;
	  reply.time = real_clock::now();
	  encode(reply, *out);
	
	  return 0;
	}
	
	CLS_INIT(otp)
	{
	  CLS_LOG(20, "Loaded otp class!");
	
	  oath_init();
	
	  cls_handle_t h_class;
	  cls_method_handle_t h_set_otp_op;
	  cls_method_handle_t h_get_otp_op;
	  cls_method_handle_t h_check_otp_op;
	  cls_method_handle_t h_get_result_op; /*
	                                        * need to check and get check result in two phases. The
	                                        * reason is that we need to update failure internally,
	                                        * however, there's no way to both return a failure and
	                                        * update, because a failure will cancel the operation,
	                                        * and write operations will not return a value. So
	                                        * we're returning a success, potentially updating the
	                                        * status internally, then a subsequent request can try
	                                        * to fetch the status. If it fails it means that failed
	                                        * to authenticate.
	                                        */
	  cls_method_handle_t h_remove_otp_op;
	  cls_method_handle_t h_get_current_time_op;
	
	  cls_register("otp", &h_class);
	  cls_register_cxx_method(h_class, "otp_set",
	                          CLS_METHOD_RD | CLS_METHOD_WR,
	                          otp_set_op, &h_set_otp_op);
	  cls_register_cxx_method(h_class, "otp_get",
	                          CLS_METHOD_RD,
	                          otp_get_op, &h_get_otp_op);
	  cls_register_cxx_method(h_class, "otp_check",
	                          CLS_METHOD_RD | CLS_METHOD_WR,
	                          otp_check_op, &h_check_otp_op);
	  cls_register_cxx_method(h_class, "otp_get_result",
	                          CLS_METHOD_RD,
	                          otp_get_result, &h_get_result_op);
	  cls_register_cxx_method(h_class, "otp_remove",
	                          CLS_METHOD_RD | CLS_METHOD_WR,
	                          otp_remove_op, &h_remove_otp_op);
	  cls_register_cxx_method(h_class, "get_current_time",
	                          CLS_METHOD_RD,
	                          otp_get_current_time_op, &h_get_current_time_op);
	
	  return;
	}