//    OpenVPN -- An application to securely tunnel IP networks
//               over a single port, with support for SSL/TLS-based
//               session authentication and key exchange,
//               packet encryption, packet authentication, and
//               packet compression.
//
//    Copyright (C) 2012-2020 OpenVPN Inc.
//
//    This program is free software: you can redistribute it and/or modify
//    it under the terms of the GNU Affero General Public License Version 3
//    as published by the Free Software Foundation.
//
//    This program is distributed in the hope that it will be useful,
//    but WITHOUT ANY WARRANTY; without even the implied warranty of
//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//    GNU Affero General Public License for more details.
//
//    You should have received a copy of the GNU Affero General Public License
//    along with this program in the COPYING file.
//    If not, see <http://www.gnu.org/licenses/>.

// Enumerate iOS network interfaces

#ifndef OPENVPN_NETCONF_ENUMIFACE_H
#define OPENVPN_NETCONF_ENUMIFACE_H

#include <sys/types.h>
#include <sys/socket.h>
#include <ifaddrs.h>

#ifdef OPENVPN_PLATFORM_IPHONE
#include <openvpn/netconf/ios/net-route.h>
#else
#include <net/route.h>
#endif

#include <cstring>
#include <string>
#include <sstream>
#include <memory>

#include <openvpn/common/size.hpp>
#include <openvpn/common/exception.hpp>
#include <openvpn/addr/ip.hpp>

namespace openvpn {
    class EnumIface
    {
    public:
      OPENVPN_EXCEPTION(enum_iface_error);

      EnumIface()
	: ifinfo(alloc_if_addrs(), free_if_addrs)
      {
      }

      std::string to_string() const
      {
	std::ostringstream os;
	os << "INTERFACES:" << std::endl;
	for (const ifaddrs* i = ifinfo.get(); i->ifa_next; i = i->ifa_next)
	  render(i, os);
	return os.str();
      }

      bool iface_up(const char *iface) const
      {
	for (const ifaddrs* i = ifinfo.get(); i->ifa_next; i = i->ifa_next)
	  {
	    if (!std::strcmp(iface, i->ifa_name)
		&& (i->ifa_flags & RTF_UP)
		&& IP::Addr::sockaddr_defined(i->ifa_addr))
	      return true;
	  }
	return false;
      }

    protected:
      static void render(const ifaddrs* i, std::ostream& os)
      {
	try {
	  os << i->ifa_name;
	  os << ' ' << render_flags(i->ifa_flags);
	  if (i->ifa_addr)
	    {
	      const IP::Addr a = IP::Addr::from_sockaddr(i->ifa_addr);
	      if (a.defined())
		os << ' ' << a;
	    }
	  if (i->ifa_netmask)
	    {
	      const IP::Addr nm = IP::Addr::from_sockaddr(i->ifa_netmask);
	      if (nm.defined())
		{
		  try {
		    unsigned int pl = nm.prefix_len();
		    os << '/' << pl;
		  }
		  catch (const std::exception&)
		    {
		    }
		}
	    }
	  if (i->ifa_dstaddr)
	    {
	      const IP::Addr dst = IP::Addr::from_sockaddr(i->ifa_dstaddr);
	      if (dst.defined())
		os << " (" << dst << ')';
	    }
	}
	catch (const std::exception&)
	  {
	    os << " ERROR";
	  }
	os << std::endl;
      }

      static std::string render_flags(const u_int flags)
      {
	struct flag_info {
	  u_int flag;
	  char c;
	};
	static const struct flag_info flag_info[] = {
#         ifdef RTF_UP
            { RTF_UP, 'U' },            // Route usable
#         endif
#         ifdef RTF_GATEWAY
            { RTF_GATEWAY, 'G' },       // Destination requires forwarding by intermediary
#         endif
#         ifdef RTF_HOST
            { RTF_HOST, 'H' },          // Host entry (net otherwise)
#         endif
#         ifdef RTF_REJECT
            { RTF_REJECT, 'R' },        // Host or net unreachable
#         endif
#         ifdef RTF_DYNAMIC
            { RTF_DYNAMIC, 'D' },       // Created dynamically (by redirect)
#         endif
#         ifdef RTF_MODIFIED
            { RTF_MODIFIED, 'M' },      // Modified dynamically (by redirect)
#         endif
#         ifdef RTF_CLONING
            { RTF_CLONING, 'C' },       // Generate new routes on use
#         endif
#         ifdef RTF_XRESOLVE
            { RTF_XRESOLVE, 'X' },      // External daemon translates proto to link address
#         endif
#         ifdef RTF_LLINFO
            { RTF_LLINFO, 'L' },        // Valid protocol to link address translation
#         endif
#         ifdef RTF_STATIC
            { RTF_STATIC, 'S' },        // Manually added
#         endif
#         ifdef RTF_BLACKHOLE
            { RTF_BLACKHOLE, 'B' },     // Just discard packets (during updates)
#         endif
#         ifdef RTF_PROTO2
            { RTF_PROTO2, '2' },        // Protocol specific routing flag #2
#         endif
#         ifdef RTF_PROTO1
            { RTF_PROTO1, '1' },        // Protocol specific routing flag #1
#         endif
#         ifdef RTF_PRCLONING
            { RTF_PRCLONING, 'c' },     // Protocol-specified generate new routes on use
#         endif
#         ifdef RTF_WASCLONED
            { RTF_WASCLONED, 'W' },     // Route was generated as a result of cloning
#         endif
#         ifdef RTF_PROTO3
            { RTF_PROTO3, '3' },        // Protocol specific routing flag #3
#         endif
#         ifdef RTF_BROADCAST
            { RTF_BROADCAST, 'b' },     // The route represents a broadcast address
#         endif
#         ifdef RTF_MULTICAST
            { RTF_MULTICAST, 'm' },     // The route represents a multicast address
#         endif
#         ifdef RTF_IFSCOPE
            { RTF_IFSCOPE, 'I' },       // Route is associated with an interface scope
#         endif
#         ifdef RTF_IFREF
            { RTF_IFREF, 'i' },         // Route is holding a reference to the interface
#         endif
#         ifdef RTF_PROXY
            { RTF_PROXY, 'Y' },         // Proxying; cloned routes will not be scoped
#         endif
#         ifdef RTF_ROUTER
            { RTF_ROUTER, 'r' },        // Host is a default router
#         endif
	  { 0, '\0' },
	};

	std::string ret;
	for (const struct flag_info *fi = flag_info; fi->flag; ++fi)
	  if (flags & fi->flag)
	    ret += fi->c;
	return ret;
      }

      static ifaddrs* alloc_if_addrs()
      {
	ifaddrs* ifa = nullptr;
	::getifaddrs(&ifa);
	return ifa;
      }

      static void free_if_addrs(ifaddrs* p)
      {
	// delete method for pointer returned by getifaddrs
	freeifaddrs(p);
      }

      std::unique_ptr<ifaddrs, decltype(&free_if_addrs)> ifinfo;
    };
}

#endif