/** @file

Copyright (c) 2005 - 2016, Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent

**/

#include "Ip4Impl.h"

/**
  Allocate a route entry then initialize it with the Dest/Netmask
  and Gateway.

  @param[in]  Dest                  The destination network
  @param[in]  Netmask               The destination network mask
  @param[in]  GateWay               The nexthop address

  @return NULL if failed to allocate memory, otherwise the newly created
          route entry.

**/
IP4_ROUTE_ENTRY *
Ip4CreateRouteEntry (
  IN IP4_ADDR  Dest,
  IN IP4_ADDR  Netmask,
  IN IP4_ADDR  GateWay
  )
{
  IP4_ROUTE_ENTRY  *RtEntry;

  RtEntry = AllocatePool (sizeof (IP4_ROUTE_ENTRY));

  if (RtEntry == NULL) {
    return NULL;
  }

  InitializeListHead (&RtEntry->Link);

  RtEntry->RefCnt  = 1;
  RtEntry->Dest    = Dest;
  RtEntry->Netmask = Netmask;
  RtEntry->NextHop = GateWay;
  RtEntry->Flag    = 0;

  return RtEntry;
}

/**
  Free the route table entry. It is reference counted.

  @param  RtEntry               The route entry to free.

**/
VOID
Ip4FreeRouteEntry (
  IN IP4_ROUTE_ENTRY  *RtEntry
  )
{
  ASSERT (RtEntry->RefCnt > 0);

  if (--RtEntry->RefCnt == 0) {
    FreePool (RtEntry);
  }
}

/**
  Allocate and initialize an IP4 route cache entry.

  @param[in]  Dst                   The destination address
  @param[in]  Src                   The source address
  @param[in]  GateWay               The next hop address
  @param[in]  Tag                   The tag from the caller. This marks all the cache
                                    entries spawned from one route table entry.

  @return NULL if failed to allocate memory for the cache, other point
          to the created route cache entry.

**/
IP4_ROUTE_CACHE_ENTRY *
Ip4CreateRouteCacheEntry (
  IN IP4_ADDR  Dst,
  IN IP4_ADDR  Src,
  IN IP4_ADDR  GateWay,
  IN UINTN     Tag
  )
{
  IP4_ROUTE_CACHE_ENTRY  *RtCacheEntry;

  RtCacheEntry = AllocatePool (sizeof (IP4_ROUTE_CACHE_ENTRY));

  if (RtCacheEntry == NULL) {
    return NULL;
  }

  InitializeListHead (&RtCacheEntry->Link);

  RtCacheEntry->RefCnt  = 1;
  RtCacheEntry->Dest    = Dst;
  RtCacheEntry->Src     = Src;
  RtCacheEntry->NextHop = GateWay;
  RtCacheEntry->Tag     = Tag;

  return RtCacheEntry;
}

/**
  Free the route cache entry. It is reference counted.

  @param  RtCacheEntry          The route cache entry to free.

**/
VOID
Ip4FreeRouteCacheEntry (
  IN IP4_ROUTE_CACHE_ENTRY  *RtCacheEntry
  )
{
  ASSERT (RtCacheEntry->RefCnt > 0);

  if (--RtCacheEntry->RefCnt == 0) {
    FreePool (RtCacheEntry);
  }
}

/**
  Initialize an empty route cache table.

  @param[in, out]  RtCache               The route cache table to initialize.

**/
VOID
Ip4InitRouteCache (
  IN OUT IP4_ROUTE_CACHE  *RtCache
  )
{
  UINT32  Index;

  for (Index = 0; Index < IP4_ROUTE_CACHE_HASH_VALUE; Index++) {
    InitializeListHead (&(RtCache->CacheBucket[Index]));
  }
}

/**
  Clean up a route cache, that is free all the route cache
  entries enqueued in the cache.

  @param[in]  RtCache               The route cache table to clean up

**/
VOID
Ip4CleanRouteCache (
  IN IP4_ROUTE_CACHE  *RtCache
  )
{
  LIST_ENTRY             *Entry;
  LIST_ENTRY             *Next;
  IP4_ROUTE_CACHE_ENTRY  *RtCacheEntry;
  UINT32                 Index;

  for (Index = 0; Index < IP4_ROUTE_CACHE_HASH_VALUE; Index++) {
    NET_LIST_FOR_EACH_SAFE (Entry, Next, &(RtCache->CacheBucket[Index])) {
      RtCacheEntry = NET_LIST_USER_STRUCT (Entry, IP4_ROUTE_CACHE_ENTRY, Link);

      RemoveEntryList (Entry);
      Ip4FreeRouteCacheEntry (RtCacheEntry);
    }
  }
}

/**
  Create an empty route table, includes its internal route cache

  @return NULL if failed to allocate memory for the route table, otherwise
          the point to newly created route table.

**/
IP4_ROUTE_TABLE *
Ip4CreateRouteTable (
  VOID
  )
{
  IP4_ROUTE_TABLE  *RtTable;
  UINT32           Index;

  RtTable = AllocatePool (sizeof (IP4_ROUTE_TABLE));

  if (RtTable == NULL) {
    return NULL;
  }

  RtTable->RefCnt   = 1;
  RtTable->TotalNum = 0;

  for (Index = 0; Index <= IP4_MASK_MAX; Index++) {
    InitializeListHead (&(RtTable->RouteArea[Index]));
  }

  RtTable->Next = NULL;

  Ip4InitRouteCache (&RtTable->Cache);
  return RtTable;
}

/**
  Free the route table and its associated route cache. Route
  table is reference counted.

  @param[in]  RtTable               The route table to free.

**/
VOID
Ip4FreeRouteTable (
  IN IP4_ROUTE_TABLE  *RtTable
  )
{
  LIST_ENTRY       *Entry;
  LIST_ENTRY       *Next;
  IP4_ROUTE_ENTRY  *RtEntry;
  UINT32           Index;

  ASSERT (RtTable->RefCnt > 0);

  if (--RtTable->RefCnt > 0) {
    return;
  }

  //
  // Free all the route table entry and its route cache.
  //
  for (Index = 0; Index <= IP4_MASK_MAX; Index++) {
    NET_LIST_FOR_EACH_SAFE (Entry, Next, &(RtTable->RouteArea[Index])) {
      RtEntry = NET_LIST_USER_STRUCT (Entry, IP4_ROUTE_ENTRY, Link);

      RemoveEntryList (Entry);
      Ip4FreeRouteEntry (RtEntry);
    }
  }

  Ip4CleanRouteCache (&RtTable->Cache);

  FreePool (RtTable);
}

/**
  Remove all the cache entries bearing the Tag. When a route cache
  entry is created, it is tagged with the address of route entry
  from which it is spawned. When a route entry is deleted, the cache
  entries spawned from it are also deleted.

  @param  RtCache               Route cache to remove the entries from
  @param  Tag                   The Tag of the entries to remove

**/
VOID
Ip4PurgeRouteCache (
  IN OUT IP4_ROUTE_CACHE  *RtCache,
  IN     UINTN            Tag
  )
{
  LIST_ENTRY             *Entry;
  LIST_ENTRY             *Next;
  IP4_ROUTE_CACHE_ENTRY  *RtCacheEntry;
  UINT32                 Index;

  for (Index = 0; Index < IP4_ROUTE_CACHE_HASH_VALUE; Index++) {
    NET_LIST_FOR_EACH_SAFE (Entry, Next, &RtCache->CacheBucket[Index]) {
      RtCacheEntry = NET_LIST_USER_STRUCT (Entry, IP4_ROUTE_CACHE_ENTRY, Link);

      if (RtCacheEntry->Tag == Tag) {
        RemoveEntryList (Entry);
        Ip4FreeRouteCacheEntry (RtCacheEntry);
      }
    }
  }
}

/**
  Add a route entry to the route table. All the IP4_ADDRs are in
  host byte order.

  @param[in, out]  RtTable      Route table to add route to
  @param[in]       Dest         The destination of the network
  @param[in]       Netmask      The netmask of the destination
  @param[in]       Gateway      The next hop address

  @retval EFI_ACCESS_DENIED     The same route already exists
  @retval EFI_OUT_OF_RESOURCES  Failed to allocate memory for the entry
  @retval EFI_SUCCESS           The route is added successfully.

**/
EFI_STATUS
Ip4AddRoute (
  IN OUT IP4_ROUTE_TABLE  *RtTable,
  IN     IP4_ADDR         Dest,
  IN     IP4_ADDR         Netmask,
  IN     IP4_ADDR         Gateway
  )
{
  LIST_ENTRY       *Head;
  LIST_ENTRY       *Entry;
  IP4_ROUTE_ENTRY  *RtEntry;

  //
  // All the route entries with the same netmask length are
  // linke to the same route area
  //
  Head = &(RtTable->RouteArea[NetGetMaskLength (Netmask)]);

  //
  // First check whether the route exists
  //
  NET_LIST_FOR_EACH (Entry, Head) {
    RtEntry = NET_LIST_USER_STRUCT (Entry, IP4_ROUTE_ENTRY, Link);

    if (IP4_NET_EQUAL (RtEntry->Dest, Dest, Netmask) && (RtEntry->NextHop == Gateway)) {
      return EFI_ACCESS_DENIED;
    }
  }

  //
  // Create a route entry and insert it to the route area.
  //
  RtEntry = Ip4CreateRouteEntry (Dest, Netmask, Gateway);

  if (RtEntry == NULL) {
    return EFI_OUT_OF_RESOURCES;
  }

  if (Gateway == IP4_ALLZERO_ADDRESS) {
    RtEntry->Flag = IP4_DIRECT_ROUTE;
  }

  InsertHeadList (Head, &RtEntry->Link);
  RtTable->TotalNum++;

  return EFI_SUCCESS;
}

/**
  Remove a route entry and all the route caches spawn from it.

  @param  RtTable           The route table to remove the route from
  @param  Dest              The destination network
  @param  Netmask           The netmask of the Dest
  @param  Gateway           The next hop address

  @retval EFI_SUCCESS           The route entry is successfully removed
  @retval EFI_NOT_FOUND         There is no route entry in the table with that
                                property.

**/
EFI_STATUS
Ip4DelRoute (
  IN OUT IP4_ROUTE_TABLE  *RtTable,
  IN     IP4_ADDR         Dest,
  IN     IP4_ADDR         Netmask,
  IN     IP4_ADDR         Gateway
  )
{
  LIST_ENTRY       *Head;
  LIST_ENTRY       *Entry;
  LIST_ENTRY       *Next;
  IP4_ROUTE_ENTRY  *RtEntry;

  Head = &(RtTable->RouteArea[NetGetMaskLength (Netmask)]);

  NET_LIST_FOR_EACH_SAFE (Entry, Next, Head) {
    RtEntry = NET_LIST_USER_STRUCT (Entry, IP4_ROUTE_ENTRY, Link);

    if (IP4_NET_EQUAL (RtEntry->Dest, Dest, Netmask) && (RtEntry->NextHop == Gateway)) {
      Ip4PurgeRouteCache (&RtTable->Cache, (UINTN)RtEntry);
      RemoveEntryList (Entry);
      Ip4FreeRouteEntry (RtEntry);

      RtTable->TotalNum--;
      return EFI_SUCCESS;
    }
  }

  return EFI_NOT_FOUND;
}

/**
  Find a route cache with the dst and src. This is used by ICMP
  redirect message process. All kinds of redirect is treated as
  host redirect according to RFC1122. So, only route cache entries
  are modified according to the ICMP redirect message.

  @param[in]  RtTable               The route table to search the cache for
  @param[in]  Dest                  The destination address
  @param[in]  Src                   The source address

  @return NULL if no route entry to the (Dest, Src). Otherwise the point
          to the correct route cache entry.

**/
IP4_ROUTE_CACHE_ENTRY *
Ip4FindRouteCache (
  IN IP4_ROUTE_TABLE  *RtTable,
  IN IP4_ADDR         Dest,
  IN IP4_ADDR         Src
  )
{
  LIST_ENTRY             *Entry;
  IP4_ROUTE_CACHE_ENTRY  *RtCacheEntry;
  UINT32                 Index;

  Index = IP4_ROUTE_CACHE_HASH (Dest, Src);

  NET_LIST_FOR_EACH (Entry, &RtTable->Cache.CacheBucket[Index]) {
    RtCacheEntry = NET_LIST_USER_STRUCT (Entry, IP4_ROUTE_CACHE_ENTRY, Link);

    if ((RtCacheEntry->Dest == Dest) && (RtCacheEntry->Src == Src)) {
      NET_GET_REF (RtCacheEntry);
      return RtCacheEntry;
    }
  }

  return NULL;
}

/**
  Search the route table for a most specific match to the Dst. It searches
  from the longest route area (mask length == 32) to the shortest route area
  (default routes). In each route area, it will first search the instance's
  route table, then the default route table. This is required by the following
  requirements:
  1. IP search the route table for a most specific match
  2. The local route entries have precedence over the default route entry.

  @param[in]  RtTable               The route table to search from
  @param[in]  Dst                   The destination address to search

  @return NULL if no route matches the Dst, otherwise the point to the
          most specific route to the Dst.

**/
IP4_ROUTE_ENTRY *
Ip4FindRouteEntry (
  IN IP4_ROUTE_TABLE  *RtTable,
  IN IP4_ADDR         Dst
  )
{
  LIST_ENTRY       *Entry;
  IP4_ROUTE_ENTRY  *RtEntry;
  IP4_ROUTE_TABLE  *Table;
  INTN             Index;

  RtEntry = NULL;

  for (Index = IP4_MASK_MAX; Index >= 0; Index--) {
    for (Table = RtTable; Table != NULL; Table = Table->Next) {
      NET_LIST_FOR_EACH (Entry, &Table->RouteArea[Index]) {
        RtEntry = NET_LIST_USER_STRUCT (Entry, IP4_ROUTE_ENTRY, Link);

        if (IP4_NET_EQUAL (RtEntry->Dest, Dst, RtEntry->Netmask)) {
          NET_GET_REF (RtEntry);
          return RtEntry;
        }
      }
    }
  }

  return NULL;
}

/**
  Search the route table to route the packet. Return/create a route
  cache if there is a route to the destination.

  @param[in]  RtTable               The route table to search from
  @param[in]  Dest                  The destination address to search for
  @param[in]  Src                   The source address to search for
  @param[in]  SubnetMask            The subnet mask of the Src address, this field is
                                    used to check if the station is using /32 subnet.
  @param[in]  AlwaysTryDestAddr     Always try to use the dest address as next hop even
                                    though we can't find a matching route entry. This
                                    field is only valid when using /32 subnet.

  @return NULL if failed to route packet, otherwise a route cache
          entry that can be used to route packet.

**/
IP4_ROUTE_CACHE_ENTRY *
Ip4Route (
  IN IP4_ROUTE_TABLE  *RtTable,
  IN IP4_ADDR         Dest,
  IN IP4_ADDR         Src,
  IN IP4_ADDR         SubnetMask,
  IN BOOLEAN          AlwaysTryDestAddr
  )
{
  LIST_ENTRY             *Head;
  LIST_ENTRY             *Entry;
  LIST_ENTRY             *Next;
  IP4_ROUTE_CACHE_ENTRY  *RtCacheEntry;
  IP4_ROUTE_CACHE_ENTRY  *Cache;
  IP4_ROUTE_ENTRY        *RtEntry;
  IP4_ADDR               NextHop;
  UINT32                 Count;

  ASSERT (RtTable != NULL);

  Head         = &RtTable->Cache.CacheBucket[IP4_ROUTE_CACHE_HASH (Dest, Src)];
  RtCacheEntry = Ip4FindRouteCache (RtTable, Dest, Src);

  //
  // If found, promote the cache entry to the head of the hash bucket. LRU
  //
  if (RtCacheEntry != NULL) {
    RemoveEntryList (&RtCacheEntry->Link);
    InsertHeadList (Head, &RtCacheEntry->Link);
    return RtCacheEntry;
  }

  //
  // Search the route table for the most specific route
  //
  RtEntry = Ip4FindRouteEntry (RtTable, Dest);

  if (RtEntry == NULL) {
    if (SubnetMask != IP4_ALLONE_ADDRESS) {
      return NULL;
    } else if (!AlwaysTryDestAddr) {
      return NULL;
    }
  }

  //
  // Found a route to the Dest, if it is a direct route, the packet
  // will be sent directly to the destination, such as for connected
  // network. Otherwise, it is an indirect route, the packet will be
  // sent to the next hop router.
  //
  // When using /32 subnet mask, the packet will always be sent to the direct
  // destination first, if we can't find a matching route cache.
  //
  if ((SubnetMask == IP4_ALLONE_ADDRESS) || ((RtEntry->Flag & IP4_DIRECT_ROUTE) != 0)) {
    NextHop = Dest;
  } else {
    NextHop = RtEntry->NextHop;
  }

  if (RtEntry != NULL) {
    Ip4FreeRouteEntry (RtEntry);
  }

  //
  // Create a route cache entry, and tag it as spawned from this route entry
  // For /32 subnet mask, the default route in RtEntry will be used if failed
  // to send the packet to driect destination address.
  //
  RtCacheEntry = Ip4CreateRouteCacheEntry (Dest, Src, NextHop, (UINTN)RtEntry);

  if (RtCacheEntry == NULL) {
    return NULL;
  }

  InsertHeadList (Head, &RtCacheEntry->Link);
  NET_GET_REF (RtCacheEntry);

  //
  // Each bucket of route cache can contain at most 64 entries.
  // Remove the entries at the tail of the bucket. These entries
  // are likely to be used least.
  //
  Count = 0;
  NET_LIST_FOR_EACH_SAFE (Entry, Next, Head) {
    if (++Count < IP4_ROUTE_CACHE_MAX) {
      continue;
    }

    Cache = NET_LIST_USER_STRUCT (Entry, IP4_ROUTE_CACHE_ENTRY, Link);

    RemoveEntryList (Entry);
    Ip4FreeRouteCacheEntry (Cache);
  }

  return RtCacheEntry;
}

/**
  Build a EFI_IP4_ROUTE_TABLE to be returned to the caller of
  GetModeData. The EFI_IP4_ROUTE_TABLE is clumsy to use in the
  internal operation of the IP4 driver.

  @param[in]  IpInstance        The IP4 child that requests the route table.

  @retval EFI_SUCCESS           The route table is successfully build
  @retval EFI_OUT_OF_RESOURCES  Failed to allocate the memory for the route table.

**/
EFI_STATUS
Ip4BuildEfiRouteTable (
  IN IP4_PROTOCOL  *IpInstance
  )
{
  LIST_ENTRY           *Entry;
  IP4_ROUTE_TABLE      *RtTable;
  IP4_ROUTE_ENTRY      *RtEntry;
  EFI_IP4_ROUTE_TABLE  *Table;
  UINT32               Count;
  INT32                Index;

  RtTable = IpInstance->RouteTable;

  if (IpInstance->EfiRouteTable != NULL) {
    FreePool (IpInstance->EfiRouteTable);

    IpInstance->EfiRouteTable = NULL;
    IpInstance->EfiRouteCount = 0;
  }

  Count = RtTable->TotalNum;

  if (RtTable->Next != NULL) {
    Count += RtTable->Next->TotalNum;
  }

  if (Count == 0) {
    return EFI_SUCCESS;
  }

  Table = AllocatePool (sizeof (EFI_IP4_ROUTE_TABLE) * Count);

  if (Table == NULL) {
    return EFI_OUT_OF_RESOURCES;
  }

  //
  // Copy the route entry to EFI route table. Keep the order of
  // route entry copied from most specific to default route. That
  // is, interlevel the route entry from the instance's route area
  // and those from the default route table's route area.
  //
  Count = 0;

  for (Index = IP4_MASK_MAX; Index >= 0; Index--) {
    for (RtTable = IpInstance->RouteTable; RtTable != NULL; RtTable = RtTable->Next) {
      NET_LIST_FOR_EACH (Entry, &(RtTable->RouteArea[Index])) {
        RtEntry = NET_LIST_USER_STRUCT (Entry, IP4_ROUTE_ENTRY, Link);

        EFI_IP4 (Table[Count].SubnetAddress)  = HTONL (RtEntry->Dest & RtEntry->Netmask);
        EFI_IP4 (Table[Count].SubnetMask)     = HTONL (RtEntry->Netmask);
        EFI_IP4 (Table[Count].GatewayAddress) = HTONL (RtEntry->NextHop);

        Count++;
      }
    }
  }

  IpInstance->EfiRouteTable = Table;
  IpInstance->EfiRouteCount = Count;
  return EFI_SUCCESS;
}