[syslinux:lwip] lwip: Update the undi driver so it handles (in theory) all network types supported by undi

syslinux-bot for Eric W. Biederman ebiederm at xmission.com
Fri Apr 22 20:06:08 PDT 2011


Commit-ID:  52bf1d13548a86cc00012d30eb6af1179b363123
Gitweb:     http://syslinux.zytor.com/commit/52bf1d13548a86cc00012d30eb6af1179b363123
Author:     Eric W. Biederman <ebiederm at xmission.com>
AuthorDate: Mon, 11 Apr 2011 23:30:45 -0700
Committer:  Eric W. Biederman <ebiederm at xmission.com>
CommitDate: Tue, 12 Apr 2011 14:41:24 -0700

lwip: Update the undi driver so it handles (in theory) all network types supported by undi

This involves on transmmit using theundi protocol types and letting
the undi layer put on the link level header,  On receive this
involves using the undi parsing of the link level header and generation
of the link level type.  This involves cloning etharp into undi.c
so we have our own set of arp functions that don't care how long
your hardware address is.

Using ethernet link layer frames directly removes a number of weird
limmitations so I do that by default when I know I am on ethernet
but that is not necessary, and a quick hack to change
undi_is_ethernet to always return false show that this code works
on whatever flavor of network adapter you have.

Signed-off-by: Eric W. Biederman <ebiederm at xmission.com>


---
 core/lwip/src/api/tcpip.c        |    1 +
 core/lwip/src/include/lwipopts.h |    1 +
 core/lwip/src/netif/undiif.c     | 1056 +++++++++++++++++++++++++++++++++++---
 3 files changed, 982 insertions(+), 76 deletions(-)

diff --git a/core/lwip/src/api/tcpip.c b/core/lwip/src/api/tcpip.c
index 002df90..9c0ba5b 100644
--- a/core/lwip/src/api/tcpip.c
+++ b/core/lwip/src/api/tcpip.c
@@ -137,6 +137,7 @@ arp_timer(void *arg)
   LWIP_UNUSED_ARG(arg);
   LWIP_DEBUGF(TCPIP_DEBUG, ("tcpip: etharp_tmr()\n"));
   etharp_tmr();
+  undiarp_tmr();
   sys_timeout(ARP_TMR_INTERVAL, arp_timer, NULL);
 }
 #endif /* LWIP_ARP */
diff --git a/core/lwip/src/include/lwipopts.h b/core/lwip/src/include/lwipopts.h
index 1fee104..0b84534 100644
--- a/core/lwip/src/include/lwipopts.h
+++ b/core/lwip/src/include/lwipopts.h
@@ -55,4 +55,5 @@
 #define LWIP_PLATFORM_HTONS(x)	bswap_16(x)
 #define LWIP_PLATFORM_HTONL(x)	bswap_32(x)
 
+void undiarp_tmr(void);
 #endif /* __LWIPOPTS_H__ */
diff --git a/core/lwip/src/netif/undiif.c b/core/lwip/src/netif/undiif.c
index a925e28..9d8a84d 100644
--- a/core/lwip/src/netif/undiif.c
+++ b/core/lwip/src/netif/undiif.c
@@ -33,6 +33,8 @@
  * This file is part of the lwIP TCP/IP stack.
  *
  * Author: Adam Dunkels <adam at sics.se>
+ * Author: H. Peter Anvin <hpa@@zytor.com>
+ * Author: Eric Biederman <ebiederm at xmission.com>
  *
  */
 
@@ -64,13 +66,95 @@
 #include <syslinux/pxe_api.h>
 #include <dprintf.h>
 
+#if LWIP_AUTOIP
+#error "AUTOIP not supported"
+#endif
+#if ETH_PAD_SIZE
+#error "ETH_PAD_SIZE not supported"
+#endif
+
+/** the time an ARP entry stays valid after its last update,
+ *  for ARP_TMR_INTERVAL = 5000, this is
+ *  (240 * 5) seconds = 20 minutes.
+ */
+#define UNDIARP_MAXAGE 240
+/** the time an ARP entry stays pending after first request,
+ *  for ARP_TMR_INTERVAL = 5000, this is
+ *  (2 * 5) seconds = 10 seconds.
+ * 
+ *  @internal Keep this number at least 2, otherwise it might
+ *  run out instantly if the timeout occurs directly after a request.
+ */
+#define UNDIARP_MAXPENDING 2
+
+typedef u8_t hwaddr_t[NETIF_MAX_HWADDR_LEN];
+
+#ifdef PACK_STRUCT_USE_INCLUDES
+#  include "arch/bpstruct.h"
+#endif
+PACK_STRUCT_BEGIN
+/** the ARP message */
+struct arp_hdr {
+  PACK_STRUCT_FIELD(u16_t hwtype);
+  PACK_STRUCT_FIELD(u16_t proto);
+  PACK_STRUCT_FIELD(u16_t _hwlen_protolen);
+  PACK_STRUCT_FIELD(u16_t opcode);
+} PACK_STRUCT_STRUCT;
+PACK_STRUCT_END
+#ifdef PACK_STRUCT_USE_INCLUDES
+#  include "arch/epstruct.h"
+#endif
+
+static inline int arp_hdr_len(struct netif *netif)
+{
+  return sizeof(struct arp_hdr) + (netif->hwaddr_len + sizeof(uint32_t))*2;
+}
+
+enum undiarp_state {
+  UNDIARP_STATE_EMPTY = 0,
+  UNDIARP_STATE_PENDING,
+  UNDIARP_STATE_STABLE
+};
+
+struct undiarp_entry {
+#if ARP_QUEUEING
+  /** 
+   * Pointer to queue of pending outgoing packets on this ARP entry.
+   */
+  struct etharp_q_entry *q;
+#endif
+  struct ip_addr ipaddr;
+  u8_t hwaddr[NETIF_MAX_HWADDR_LEN];
+  enum undiarp_state state;
+  u8_t ctime;
+  struct netif *netif;
+};
+
 #define PKTBUF_SIZE	2048
 
 /* Define those to better describe your network interface. */
 #define IFNAME0 'u'
 #define IFNAME1 'n'
 
+static uint16_t undi_hw_type;
 static struct netif undi_netif;
+static struct undiarp_entry arp_table[ARP_TABLE_SIZE];
+#if !LWIP_NETIF_HWADDRHINT
+static u8_t undiarp_cached_entry;
+#endif
+
+/**
+ * Try hard to create a new entry - we want the IP address to appear in
+ * the cache (even if this means removing an active entry or so). */
+#define UNDIARP_TRY_HARD 1
+#define UNDIARP_FIND_ONLY  2
+
+
+static inline bool undi_is_ethernet(struct netif *netif)
+{
+   (void)netif;
+   return undi_hw_type == ETHER_TYPE;
+}
 
 /**
  * In this function, the hardware should be initialized.
@@ -93,6 +177,9 @@ low_level_init(struct netif *netif)
 	 undi_info.BaseIo, undi_info.IntNumber, undi_info.MaxTranUnit,
 	 undi_info.HwType);
 
+  /* Remember the hardware type for arp */
+  undi_hw_type = undi_info.HwType;
+
   /* set MAC hardware address length */
   netif->hwaddr_len = undi_info.HwAddrLen;
 
@@ -108,8 +195,10 @@ low_level_init(struct netif *netif)
   dprintf("\n");
 
   /* device capabilities */
+  netif->flags = NETIF_FLAG_BROADCAST | NETIF_FLAG_LINK_UP;
   /* don't set NETIF_FLAG_ETHARP if this device is not an ethernet one */
-  netif->flags = NETIF_FLAG_BROADCAST | NETIF_FLAG_ETHARP | NETIF_FLAG_LINK_UP;
+  if (undi_is_ethernet(netif))
+    netif->flags |= NETIF_FLAG_ETHARP;
 
   /* Install the interrupt vector */
   pxe_irq_vector = undi_info.IntNumber;
@@ -135,61 +224,634 @@ low_level_init(struct netif *netif)
  *       to become availale since the stack doesn't retry to send a packet
  *       dropped because of memory failure (except for the TCP timers).
  */
-
-/*
- * XXX: This assumes an Ethernet media type.
- */
 static err_t
-low_level_output(struct netif *netif, struct pbuf *p)
+undi_transmit(struct netif *netif, struct pbuf *pbuf,
+  hwaddr_t *dest, uint16_t undi_protocol)
 {
   struct pxe_xmit {
     t_PXENV_UNDI_TRANSMIT xmit;
     t_PXENV_UNDI_TBD tbd;
   };
   static __lowmem struct pxe_xmit pxe;
+  static __lowmem hwaddr_t low_dest;
   static __lowmem char pkt_buf[PKTBUF_SIZE];
-  char *r;
-  /* struct undiif *undiif = netif->state; */
-  struct pbuf *q;
-  static char eth_broadcast[6] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
 
-  (void)netif;
+  /* Drop jumbo frames */
+  if ((pbuf->tot_len > sizeof(pkt_buf)) || (pbuf->tot_len > netif->mtu))
+    return ERR_ARG;
 
-#if ETH_PAD_SIZE
-  pbuf_header(p, -ETH_PAD_SIZE); /* drop the padding word */
+  pbuf_copy_partial( pbuf, pkt_buf, pbuf->tot_len, 0);
+  if (dest)
+    memcpy(low_dest, dest, netif->hwaddr_len);
+
+  do {
+    memset(&pxe, 0, sizeof pxe);
+
+    pxe.xmit.Protocol = undi_protocol;
+    pxe.xmit.XmitFlag = dest? XMT_DESTADDR : XMT_BROADCAST;
+    pxe.xmit.DestAddr = FAR_PTR(&low_dest);
+    pxe.xmit.TBD = FAR_PTR(&pxe.tbd);
+    pxe.tbd.ImmedLength = pbuf->tot_len;
+    pxe.tbd.Xmit = FAR_PTR(pkt_buf);
+
+    pxe_call(PXENV_UNDI_TRANSMIT, &pxe.xmit);
+  } while (pxe.xmit.Status == PXENV_STATUS_OUT_OF_RESOURCES);
+
+  LINK_STATS_INC(link.xmit);
+
+  return ERR_OK;
+}
+
+static err_t
+undi_send_unknown(struct netif *netif, struct pbuf *pbuf)
+{
+  return undi_transmit(netif, pbuf, NULL, P_UNKNOWN);
+}
+
+static err_t
+undi_send_ip(struct netif *netif, struct pbuf *pbuf, hwaddr_t  *dst)
+{
+  return undi_transmit(netif, pbuf, dst, P_IP);
+}
+
+static err_t
+undi_send_arp(struct netif *netif, struct pbuf *pbuf, hwaddr_t  *dst)
+{
+  return undi_transmit(netif, pbuf, dst, P_ARP);
+}
+
+/**
+ * Send an ARP request packet asking for ipaddr.
+ *
+ * @param netif the lwip network interface on which to send the request
+ * @param ipaddr the IP address for which to ask
+ * @return ERR_OK if the request has been sent
+ *         ERR_MEM if the ARP packet couldn't be allocated
+ *         any other err_t on failure
+ */
+static err_t
+undiarp_request(struct netif *netif, struct ip_addr *ipaddr)
+{
+  struct pbuf *p;
+  err_t result = ERR_OK;
+  struct arp_hdr *hdr;
+  u8_t *hdr_ptr;
+
+  LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_request: sending ARP request.\n"));
+
+  /* allocate a pbuf for the outgoing ARP request packet */
+  p = pbuf_alloc(PBUF_RAW, arp_hdr_len(netif), PBUF_RAM);
+  /* could allocate a pbuf for an ARP request? */
+  if (p == NULL) {
+    LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS,
+      ("etharp_raw: could not allocate pbuf for ARP request.\n"));
+    ETHARP_STATS_INC(etharp.memerr);
+    return ERR_MEM;
+  }
+  LWIP_ASSERT("check that first pbuf can hold arp_hdr_len bytesr",
+              (p->len >= arp_hdr_len(netif)));
+
+  hdr = p->payload;
+  LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("undiarp_request: sending raw ARP packet.\n"));
+  hdr->opcode = htons(ARP_REQUEST);
+  hdr->hwtype = htons(undi_hw_type);
+  hdr->proto = htons(ETHTYPE_IP);
+  /* set hwlen and protolen together */
+  hdr->_hwlen_protolen = htons((netif->hwaddr_len << 8) | sizeof(struct ip_addr));
+
+  hdr_ptr = (unsigned char *)(hdr + 1);
+  memcpy(hdr_ptr, netif->hwaddr, netif->hwaddr_len);
+  hdr_ptr += netif->hwaddr_len;
+  memcpy(hdr_ptr, &netif->ip_addr, 4);
+  hdr_ptr += 4;
+    memset(hdr_ptr, 0, netif->hwaddr_len);
+  hdr_ptr += netif->hwaddr_len;
+  memcpy(hdr_ptr, ipaddr, 4);
+  
+  /* send ARP query */
+  result = undi_send_arp(netif, p, NULL);
+  ETHARP_STATS_INC(etharp.xmit);
+  /* free ARP query packet */
+  pbuf_free(p);
+  p = NULL;
+  /* could not allocate pbuf for ARP request */
+
+  return result;
+}
+
+#if ARP_QUEUEING
+/**
+ * Free a complete queue of etharp entries
+ *
+ * @param q a qeueue of etharp_q_entry's to free
+ */
+static void
+free_undiarp_q(struct etharp_q_entry *q)
+{
+  struct etharp_q_entry *r;
+  LWIP_ASSERT("q != NULL", q != NULL);
+  LWIP_ASSERT("q->p != NULL", q->p != NULL);
+  while (q) {
+    r = q;
+    q = q->next;
+    LWIP_ASSERT("r->p != NULL", (r->p != NULL));
+    pbuf_free(r->p);
+    memp_free(MEMP_ARP_QUEUE, r);
+  }
+}
 #endif
 
-  r = pkt_buf;
-  for (q = p; q != NULL; q = q->next) {
-    /* Send the data from the pbuf to the interface, one pbuf at a
-       time. The size of the data in each pbuf is kept in the ->len
-       variable. */
-    memcpy(r, q->payload, q->len);
-    r += q->len;
+/**
+ * Clears expired entries in the ARP table.
+ *
+ * This function should be called every ETHARP_TMR_INTERVAL microseconds (5 seconds),
+ * in order to expire entries in the ARP table.
+ */
+void
+undiarp_tmr(void)
+{
+  u8_t i;
+
+  LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer\n"));
+  /* remove expired entries from the ARP table */
+  for (i = 0; i < ARP_TABLE_SIZE; ++i) {
+    arp_table[i].ctime++;
+    if (((arp_table[i].state == UNDIARP_STATE_STABLE) &&
+         (arp_table[i].ctime >= UNDIARP_MAXAGE)) ||
+        ((arp_table[i].state == UNDIARP_STATE_PENDING)  &&
+         (arp_table[i].ctime >= UNDIARP_MAXPENDING))) {
+         /* pending or stable entry has become old! */
+      LWIP_DEBUGF(UNDIARP_DEBUG, ("etharp_timer: expired %s entry %"U16_F".\n",
+           arp_table[i].state == UNDIARP_STATE_STABLE ? "stable" : "pending", (u16_t)i));
+      /* clean up entries that have just been expired */
+      /* remove from SNMP ARP index tree */
+      snmp_delete_arpidx_tree(arp_table[i].netif, &arp_table[i].ipaddr);
+#if ARP_QUEUEING
+      /* and empty packet queue */
+      if (arp_table[i].q != NULL) {
+        /* remove all queued packets */
+        LWIP_DEBUGF(ETHARP_DEBUG, ("etharp_timer: freeing entry %"U16_F", packet queue %p.\n", (u16_t)i, (void *)(arp_table[i].q)));
+        free_undiarp_q(arp_table[i].q);
+        arp_table[i].q = NULL;
+      }
+#endif
+      /* recycle entry for re-use */      
+      arp_table[i].state = UNDIARP_STATE_EMPTY;
+    }
+#if ARP_QUEUEING
+    /* still pending entry? (not expired) */
+    if (arp_table[i].state == UNDIARP_STATE_PENDING) {
+        /* resend an ARP query here? */
+    }
+#endif
   }
+}
+
+/**
+ * Search the ARP table for a matching or new entry.
+ * 
+ * If an IP address is given, return a pending or stable ARP entry that matches
+ * the address. If no match is found, create a new entry with this address set,
+ * but in state ETHARP_EMPTY. The caller must check and possibly change the
+ * state of the returned entry.
+ * 
+ * If ipaddr is NULL, return a initialized new entry in state ETHARP_EMPTY.
+ * 
+ * In all cases, attempt to create new entries from an empty entry. If no
+ * empty entries are available and UNDIARP_TRY_HARD flag is set, recycle
+ * old entries. Heuristic choose the least important entry for recycling.
+ *
+ * @param ipaddr IP address to find in ARP cache, or to add if not found.
+ * @param flags
+ * - UNDIARP_TRY_HARD: Try hard to create a entry by allowing recycling of
+ * active (stable or pending) entries.
+ *  
+ * @return The ARP entry index that matched or is created, ERR_MEM if no
+ * entry is found or could be recycled.
+ */
+static s8_t
+#if LWIP_NETIF_HWADDRHINT
+find_entry(struct ip_addr *ipaddr, u8_t flags, struct netif *netif)
+#else /* LWIP_NETIF_HWADDRHINT */
+find_entry(struct ip_addr *ipaddr, u8_t flags)
+#endif /* LWIP_NETIF_HWADDRHINT */
+{
+  s8_t old_pending = ARP_TABLE_SIZE, old_stable = ARP_TABLE_SIZE;
+  s8_t empty = ARP_TABLE_SIZE;
+  u8_t i = 0, age_pending = 0, age_stable = 0;
+#if ARP_QUEUEING
+  /* oldest entry with packets on queue */
+  s8_t old_queue = ARP_TABLE_SIZE;
+  /* its age */
+  u8_t age_queue = 0;
+#endif
 
-  //printf("undiif_output, len = %d ", r - pkt_buf);
+  /* First, test if the last call to this function asked for the
+   * same address. If so, we're really fast! */
+  if (ipaddr) {
+    /* ipaddr to search for was given */
+#if LWIP_NETIF_HWADDRHINT
+    if ((netif != NULL) && (netif->addr_hint != NULL)) {
+      /* per-pcb cached entry was given */
+      u8_t per_pcb_cache = *(netif->addr_hint);
+      if ((per_pcb_cache < ARP_TABLE_SIZE) && arp_table[per_pcb_cache].state == UNDIARP_STATE_STABLE) {
+        /* the per-pcb-cached entry is stable */
+        if (ip_addr_cmp(ipaddr, &arp_table[per_pcb_cache].ipaddr)) {
+          /* per-pcb cached entry was the right one! */
+          ETHARP_STATS_INC(etharp.cachehit);
+          return per_pcb_cache;
+        }
+      }
+    }
+#else /* #if LWIP_NETIF_HWADDRHINT */
+    if (arp_table[undiarp_cached_entry].state == UNDIARP_STATE_STABLE) {
+      /* the cached entry is stable */
+      if (ip_addr_cmp(ipaddr, &arp_table[undiarp_cached_entry].ipaddr)) {
+        /* cached entry was the right one! */
+        ETHARP_STATS_INC(etharp.cachehit);
+        return undiarp_cached_entry;
+      }
+    }
+#endif /* #if LWIP_NETIF_HWADDRHINT */
+  }
 
-  do {
-      memset(&pxe, 0, sizeof pxe);
+  /**
+   * a) do a search through the cache, remember candidates
+   * b) select candidate entry
+   * c) create new entry
+   */
 
-      pxe.xmit.Protocol = 0;	/* XXX: P_UNKNOWN: MAC layer */
-      pxe.xmit.XmitFlag = !memcmp(pkt_buf, eth_broadcast, sizeof eth_broadcast);
-      pxe.xmit.DestAddr = FAR_PTR(&pxe.tbd); /* This is what gPXE does?? */
-      pxe.xmit.TBD = FAR_PTR(&pxe.tbd);
-      pxe.tbd.ImmedLength = r - pkt_buf;
-      pxe.tbd.Xmit = FAR_PTR(pkt_buf);
+  /* a) in a single search sweep, do all of this
+   * 1) remember the first empty entry (if any)
+   * 2) remember the oldest stable entry (if any)
+   * 3) remember the oldest pending entry without queued packets (if any)
+   * 4) remember the oldest pending entry with queued packets (if any)
+   * 5) search for a matching IP entry, either pending or stable
+   *    until 5 matches, or all entries are searched for.
+   */
 
-      pxe_call(PXENV_UNDI_TRANSMIT, &pxe.xmit);
-  } while (pxe.xmit.Status == PXENV_STATUS_OUT_OF_RESOURCES);
+  for (i = 0; i < ARP_TABLE_SIZE; ++i) {
+    /* no empty entry found yet and now we do find one? */
+    if ((empty == ARP_TABLE_SIZE) && (arp_table[i].state == UNDIARP_STATE_EMPTY)) {
+      LWIP_DEBUGF(ETHARP_DEBUG, ("find_entry: found empty entry %"U16_F"\n", (u16_t)i));
+      /* remember first empty entry */
+      empty = i;
+    }
+    /* pending entry? */
+    else if (arp_table[i].state == UNDIARP_STATE_PENDING) {
+      /* if given, does IP address match IP address in ARP entry? */
+      if (ipaddr && ip_addr_cmp(ipaddr, &arp_table[i].ipaddr)) {
+        LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: found matching pending entry %"U16_F"\n", (u16_t)i));
+        /* found exact IP address match, simply bail out */
+#if LWIP_NETIF_HWADDRHINT
+        NETIF_SET_HINT(netif, i);
+#else /* #if LWIP_NETIF_HWADDRHINT */
+        undiarp_cached_entry = i;
+#endif /* #if LWIP_NETIF_HWADDRHINT */
+        return i;
+#if ARP_QUEUEING
+      /* pending with queued packets? */
+      } else if (arp_table[i].q != NULL) {
+        if (arp_table[i].ctime >= age_queue) {
+          old_queue = i;
+          age_queue = arp_table[i].ctime;
+        }
+#endif
+      /* pending without queued packets? */
+      } else {
+        if (arp_table[i].ctime >= age_pending) {
+          old_pending = i;
+          age_pending = arp_table[i].ctime;
+        }
+      }        
+    }
+    /* stable entry? */
+    else if (arp_table[i].state == UNDIARP_STATE_STABLE) {
+      /* if given, does IP address match IP address in ARP entry? */
+      if (ipaddr && ip_addr_cmp(ipaddr, &arp_table[i].ipaddr)) {
+        LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: found matching stable entry %"U16_F"\n", (u16_t)i));
+        /* found exact IP address match, simply bail out */
+#if LWIP_NETIF_HWADDRHINT
+        NETIF_SET_HINT(netif, i);
+#else /* #if LWIP_NETIF_HWADDRHINT */
+        undiarp_cached_entry = i;
+#endif /* #if LWIP_NETIF_HWADDRHINT */
+        return i;
+      /* remember entry with oldest stable entry in oldest, its age in maxtime */
+      } else if (arp_table[i].ctime >= age_stable) {
+        old_stable = i;
+        age_stable = arp_table[i].ctime;
+      }
+    }
+  }
+  /* { we have no match } => try to create a new entry */
+   
+  /* no empty entry found and not allowed to recycle? */
+  if (((empty == ARP_TABLE_SIZE) && ((flags & UNDIARP_TRY_HARD) == 0))
+      /* or don't create new entry, only search? */
+      || ((flags & UNDIARP_FIND_ONLY) != 0)) {
+    LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: no empty entry found and not allowed to recycle\n"));
+    return (s8_t)ERR_MEM;
+  }
+  
+  /* b) choose the least destructive entry to recycle:
+   * 1) empty entry
+   * 2) oldest stable entry
+   * 3) oldest pending entry without queued packets
+   * 4) oldest pending entry with queued packets
+   * 
+   * { UNDIARP_TRY_HARD is set at this point }
+   */ 
 
-#if ETH_PAD_SIZE
-  pbuf_header(p, ETH_PAD_SIZE); /* reclaim the padding word */
+  /* 1) empty entry available? */
+  if (empty < ARP_TABLE_SIZE) {
+    i = empty;
+    LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: selecting empty entry %"U16_F"\n", (u16_t)i));
+  }
+  /* 2) found recyclable stable entry? */
+  else if (old_stable < ARP_TABLE_SIZE) {
+    /* recycle oldest stable*/
+    i = old_stable;
+    LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: selecting oldest stable entry %"U16_F"\n", (u16_t)i));
+#if ARP_QUEUEING
+    /* no queued packets should exist on stable entries */
+    LWIP_ASSERT("arp_table[i].q == NULL", arp_table[i].q == NULL);
+#endif
+  /* 3) found recyclable pending entry without queued packets? */
+  } else if (old_pending < ARP_TABLE_SIZE) {
+    /* recycle oldest pending */
+    i = old_pending;
+    LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: selecting oldest pending entry %"U16_F" (without queue)\n", (u16_t)i));
+#if ARP_QUEUEING
+  /* 4) found recyclable pending entry with queued packets? */
+  } else if (old_queue < ARP_TABLE_SIZE) {
+    /* recycle oldest pending */
+    i = old_queue;
+    LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("find_entry: selecting oldest pending entry %"U16_F", freeing packet queue %p\n", (u16_t)i, (void *)(arp_table[i].q)));
+    free_undiarp_q(arp_table[i].q);
+    arp_table[i].q = NULL;
 #endif
+    /* no empty or recyclable entries found */
+  } else {
+    return (s8_t)ERR_MEM;
+  }
 
-  LINK_STATS_INC(link.xmit);
+  /* { empty or recyclable entry found } */
+  LWIP_ASSERT("i < ARP_TABLE_SIZE", i < ARP_TABLE_SIZE);
 
-  return ERR_OK;
+  if (arp_table[i].state != UNDIARP_STATE_EMPTY)
+  {
+    snmp_delete_arpidx_tree(arp_table[i].netif, &arp_table[i].ipaddr);
+  }
+  /* recycle entry (no-op for an already empty entry) */
+  arp_table[i].state = UNDIARP_STATE_EMPTY;
+
+  /* IP address given? */
+  if (ipaddr != NULL) {
+    /* set IP address */
+    ip_addr_set(&arp_table[i].ipaddr, ipaddr);
+  }
+  arp_table[i].ctime = 0;
+#if LWIP_NETIF_HWADDRHINT
+  NETIF_SET_HINT(netif, i);
+#else /* #if LWIP_NETIF_HWADDRHINT */
+  undiarp_cached_entry = i;
+#endif /* #if LWIP_NETIF_HWADDRHINT */
+  return (err_t)i;
+}
+
+
+/**
+ * Send an ARP request for the given IP address and/or queue a packet.
+ *
+ * If the IP address was not yet in the cache, a pending ARP cache entry
+ * is added and an ARP request is sent for the given address. The packet
+ * is queued on this entry.
+ *
+ * If the IP address was already pending in the cache, a new ARP request
+ * is sent for the given address. The packet is queued on this entry.
+ *
+ * If the IP address was already stable in the cache, and a packet is
+ * given, it is directly sent and no ARP request is sent out. 
+ * 
+ * If the IP address was already stable in the cache, and no packet is
+ * given, an ARP request is sent out.
+ * 
+ * @param netif The lwIP network interface on which ipaddr
+ * must be queried for.
+ * @param ipaddr The IP address to be resolved.
+ * @param q If non-NULL, a pbuf that must be delivered to the IP address.
+ * q is not freed by this function.
+ *
+ * @note q must only be ONE packet, not a packet queue!
+ *
+ * @return
+ * - ERR_BUF Could not make room for Ethernet header.
+ * - ERR_MEM Hardware address unknown, and no more ARP entries available
+ *   to query for address or queue the packet.
+ * - ERR_MEM Could not queue packet due to memory shortage.
+ * - ERR_RTE No route to destination (no gateway to external networks).
+ * - ERR_ARG Non-unicast address given, those will not appear in ARP cache.
+ *
+ */
+static err_t
+undiarp_query(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
+{
+  err_t result = ERR_MEM;
+  s8_t i; /* ARP entry index */
+
+  /* non-unicast address? */
+  if (ip_addr_isbroadcast(ipaddr, netif) ||
+      ip_addr_ismulticast(ipaddr) ||
+      ip_addr_isany(ipaddr)) {
+    LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("undiarp_query: will not add non-unicast IP address to ARP cache\n"));
+    return ERR_ARG;
+  }
+
+  /* find entry in ARP cache, ask to create entry if queueing packet */
+#if LWIP_NETIF_HWADDRHINT
+  i = find_entry(ipaddr, UNDIARP_TRY_HARD, netif);
+#else /* LWIP_NETIF_HWADDRHINT */
+  i = find_entry(ipaddr, UNDIARP_TRY_HARD);
+#endif /* LWIP_NETIF_HWADDRHINT */
+
+  /* could not find or create entry? */
+  if (i < 0) {
+    LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("undiarp_query: could not create ARP entry\n"));
+    if (q) {
+      LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("undiarp_query: packet dropped\n"));
+      ETHARP_STATS_INC(etharp.memerr);
+    }
+    return (err_t)i;
+  }
+
+  /* mark a fresh entry as pending (we just sent a request) */
+  if (arp_table[i].state == UNDIARP_STATE_EMPTY) {
+    arp_table[i].state = UNDIARP_STATE_PENDING;
+  }
+
+  /* { i is either a STABLE or (new or existing) PENDING entry } */
+  LWIP_ASSERT("arp_table[i].state == PENDING or STABLE",
+  ((arp_table[i].state == UNDIARP_STATE_PENDING) ||
+   (arp_table[i].state == UNDIARP_STATE_STABLE)));
+
+  /* do we have a pending entry? or an implicit query request? */
+  if ((arp_table[i].state == UNDIARP_STATE_PENDING) || (q == NULL)) {
+    /* try to resolve it; send out ARP request */
+    result = undiarp_request(netif, ipaddr);
+    if (result != ERR_OK) {
+      /* ARP request couldn't be sent */
+      /* We don't re-send arp request in undiarp_tmr, but we still queue packets,
+         since this failure could be temporary, and the next packet calling
+         etharp_query again could lead to sending the queued packets. */
+    }
+  }
+  
+  /* packet given? */
+  if (q != NULL) {
+    /* stable entry? */
+    if (arp_table[i].state == UNDIARP_STATE_STABLE) {
+      /* we have a valid IP->hardware address mapping */
+      /* send the packet */
+      result = undi_send_ip(netif, q, &(arp_table[i].hwaddr));
+    /* pending entry? (either just created or already pending */
+    } else if (arp_table[i].state == UNDIARP_STATE_PENDING) {
+#if ARP_QUEUEING /* queue the given q packet */
+      struct pbuf *p;
+      int copy_needed = 0;
+      /* IF q includes a PBUF_REF, PBUF_POOL or PBUF_RAM, we have no choice but
+       * to copy the whole queue into a new PBUF_RAM (see bug #11400) 
+       * PBUF_ROMs can be left as they are, since ROM must not get changed. */
+      p = q;
+      while (p) {
+        LWIP_ASSERT("no packet queues allowed!", (p->len != p->tot_len) || (p->next == 0));
+        if(p->type != PBUF_ROM) {
+          copy_needed = 1;
+          break;
+        }
+        p = p->next;
+      }
+      if(copy_needed) {
+        /* copy the whole packet into new pbufs */
+        p = pbuf_alloc(PBUF_RAW, p->tot_len, PBUF_RAM);
+        if(p != NULL) {
+          if (pbuf_copy(p, q) != ERR_OK) {
+            pbuf_free(p);
+            p = NULL;
+          }
+        }
+      } else {
+        /* referencing the old pbuf is enough */
+        p = q;
+        pbuf_ref(p);
+      }
+      /* packet could be taken over? */
+      if (p != NULL) {
+        /* queue packet ... */
+        struct etharp_q_entry *new_entry;
+        /* allocate a new arp queue entry */
+        new_entry = memp_malloc(MEMP_ARP_QUEUE);
+        if (new_entry != NULL) {
+          new_entry->next = 0;
+          new_entry->p = p;
+          if(arp_table[i].q != NULL) {
+            /* queue was already existent, append the new entry to the end */
+            struct etharp_q_entry *r;
+            r = arp_table[i].q;
+            while (r->next != NULL) {
+              r = r->next;
+            }
+            r->next = new_entry;
+          } else {
+            /* queue did not exist, first item in queue */
+            arp_table[i].q = new_entry;
+          }
+          LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("undiarp_query: queued packet %p on ARP entry %"S16_F"\n", (void *)q, (s16_t)i));
+          result = ERR_OK;
+        } else {
+          /* the pool MEMP_ARP_QUEUE is empty */
+          pbuf_free(p);
+          LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: could not queue a copy of PBUF_REF packet %p (out of memory)\n", (void *)q));
+          /* { result == ERR_MEM } through initialization */
+        }
+      } else {
+        ETHARP_STATS_INC(etharp.memerr);
+        LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: could not queue a copy of PBUF_REF packet %p (out of memory)\n", (void *)q));
+        /* { result == ERR_MEM } through initialization */
+      }
+#else /* ARP_QUEUEING == 0 */
+      /* q && state == PENDING && ARP_QUEUEING == 0 => result = ERR_MEM */
+      /* { result == ERR_MEM } through initialization */
+      LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_query: Ethernet destination address unknown, queueing disabled, packet %p dropped\n", (void *)q));
+#endif
+    }
+  }
+  return result;
+}
+
+/**
+ * Resolve and fill-in address header for outgoing IP packet.
+ *
+ * For IP multicast and broadcast, corresponding Ethernet addresses
+ * are selected and the packet is transmitted on the link.
+ *
+ * For unicast addresses, the packet is submitted to etharp_query(). In
+ * case the IP address is outside the local network, the IP address of
+ * the gateway is used.
+ *
+ * @param netif The lwIP network interface which the IP packet will be sent on.
+ * @param q The pbuf(s) containing the IP packet to be sent.
+ * @param ipaddr The IP address of the packet destination.
+ *
+ * @return
+ * - ERR_RTE No route to destination (no gateway to external networks),
+ * or the return type of either etharp_query() or etharp_send_ip().
+ */
+static err_t
+undiarp_output(struct netif *netif, struct pbuf *q, struct ip_addr *ipaddr)
+{
+  static __lowmem t_PXENV_UNDI_GET_MCAST_ADDR get_mcast;
+  hwaddr_t *dest;
+
+  if (undi_is_ethernet(netif))
+    return etharp_output(netif, q, ipaddr);
+
+  /* Assume unresolved hardware address */
+  dest = NULL;
+
+  /* Determine on destination hardware address. Broadcasts and multicasts
+   * are special, other IP addresses are looked up in the ARP table.
+   */
+  if (ip_addr_isbroadcast(ipaddr, netif)) {
+    dest = NULL;
+  }
+  else if (ip_addr_ismulticast(ipaddr)) {
+    memset(&get_mcast, 0, sizeof get_mcast);
+    memcpy(&get_mcast.InetAddr, ipaddr, sizeof(get_mcast.InetAddr));
+    pxe_call(PXENV_UNDI_GET_MCAST_ADDR, &get_mcast);
+    dest = (hwaddr_t *)&get_mcast.MediaAddr;
+  }
+  else {
+    /* outside local network? */
+    if (!ip_addr_netcmp(ipaddr, &netif->ip_addr, &netif->netmask)) {
+      /* interface has default gateway? */
+      if (netif->gw.addr != 0) {
+        /* send to hardware address of default gateway IP address */
+        ipaddr = &(netif->gw);
+      /* no default gateway available */
+      } else {
+        /* no route to destination error (default gateway missing) */
+        return ERR_RTE;
+      }
+    }
+    /* queue on destination Ethernet address belonging to ipaddr */
+    return undiarp_query(netif, ipaddr, q);
+  }
+  
+  /* continuation for multicast/broadcast destinations */
+  /* obtain source Ethernet address of the given interface */
+  /* send packet directly on the link */
+  return undi_send_ip(netif, q, dest);
 }
 
 static void get_packet_fragment(t_PXENV_UNDI_ISR *isr)
@@ -221,18 +883,10 @@ low_level_input(t_PXENV_UNDI_ISR *isr)
 
   //printf("undiif_input, len = %d\n", len);
 
-#if ETH_PAD_SIZE
-  len += ETH_PAD_SIZE; /* allow room for Ethernet padding */
-#endif
-
   /* We allocate a pbuf chain of pbufs from the pool. */
   p = pbuf_alloc(PBUF_RAW, len, PBUF_POOL);
 
   if (p != NULL) {
-#if ETH_PAD_SIZE
-    pbuf_header(p, -ETH_PAD_SIZE); /* drop the padding word */
-#endif
-
     /*
      * We iterate over the pbuf chain until we have read the entire
      * packet into the pbuf.
@@ -265,10 +919,6 @@ low_level_input(t_PXENV_UNDI_ISR *isr)
       }
     }
 
-#if ETH_PAD_SIZE
-    pbuf_header(p, ETH_PAD_SIZE); /* reclaim the padding word */
-#endif
-
     LINK_STATS_INC(link.recv);
   } else {
     /*
@@ -285,6 +935,231 @@ low_level_input(t_PXENV_UNDI_ISR *isr)
   return p;
 }
 
+
+/**
+ * Update (or insert) a IP/MAC address pair in the ARP cache.
+ *
+ * If a pending entry is resolved, any queued packets will be sent
+ * at this point.
+ * 
+ * @param ipaddr IP address of the inserted ARP entry.
+ * @param ethaddr Ethernet address of the inserted ARP entry.
+ * @param flags Defines behaviour:
+ * - ETHARP_TRY_HARD Allows ARP to insert this as a new item. If not specified,
+ * only existing ARP entries will be updated.
+ *
+ * @return
+ * - ERR_OK Succesfully updated ARP cache.
+ * - ERR_MEM If we could not add a new ARP entry when ETHARP_TRY_HARD was set.
+ * - ERR_ARG Non-unicast address given, those will not appear in ARP cache.
+ *
+ * @see pbuf_free()
+ */
+static err_t
+update_arp_entry(struct netif *netif, struct ip_addr *ipaddr,
+		 hwaddr_t *lladdr, u8_t flags)
+{
+  s8_t i;
+  LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("update_arp_entry()\n"));
+  LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("update_arp_entry: %"U16_F".%"U16_F".%"U16_F".%"U16_F" - %02"X16_F":%02"X16_F":%02"X16_F":%02"X16_F":%02"X16_F":%02"X16_F"\n",
+                                        ip4_addr1(ipaddr), ip4_addr2(ipaddr), ip4_addr3(ipaddr), ip4_addr4(ipaddr), 
+                                        lladdr->addr[0], lladdr->addr[1], lladdr->addr[2],
+                                        lladdr->addr[3], lladdr->addr[4], lladdr->addr[5]));
+  /* non-unicast address? */
+  if (ip_addr_isany(ipaddr) ||
+      ip_addr_isbroadcast(ipaddr, netif) ||
+      ip_addr_ismulticast(ipaddr)) {
+    LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("update_arp_entry: will not add non-unicast IP address to ARP cache\n"));
+    return ERR_ARG;
+  }
+  /* find or create ARP entry */
+#if LWIP_NETIF_HWADDRHINT
+  i = find_entry(ipaddr, flags, netif);
+#else /* LWIP_NETIF_HWADDRHINT */
+  i = find_entry(ipaddr, flags);
+#endif /* LWIP_NETIF_HWADDRHINT */
+  /* bail out if no entry could be found */
+  if (i < 0)
+    return (err_t)i;
+  
+  /* mark it stable */
+  arp_table[i].state = UNDIARP_STATE_STABLE;
+  /* record network interface */
+  arp_table[i].netif = netif;
+
+  /* insert in SNMP ARP index tree */
+  snmp_insert_arpidx_tree(netif, &arp_table[i].ipaddr);
+
+  LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("update_arp_entry: updating stable entry %"S16_F"\n", (s16_t)i));
+  /* update address */
+  memcpy(arp_table[i].hwaddr, lladdr, netif->hwaddr_len);
+
+  /* reset time stamp */
+  arp_table[i].ctime = 0;
+#if ARP_QUEUEING
+  /* this is where we will send out queued packets! */
+  while (arp_table[i].q != NULL) {
+    struct pbuf *p;
+    /* remember remainder of queue */
+    struct etharp_q_entry *q = arp_table[i].q;
+    /* pop first item off the queue */
+    arp_table[i].q = q->next;
+    /* get the packet pointer */
+    p = q->p;
+    /* now queue entry can be freed */
+    memp_free(MEMP_ARP_QUEUE, q);
+    /* send the queued IP packet */
+    undi_send_ip(netif, p, lladdr);
+    /* free the queued IP packet */
+    pbuf_free(p);
+  }
+#endif
+  return ERR_OK;
+}
+
+/**
+ * Responds to ARP requests to us. Upon ARP replies to us, add entry to cache  
+ * send out queued IP packets. Updates cache with snooped address pairs.
+ *
+ * Should be called for incoming ARP packets. The pbuf in the argument
+ * is freed by this function.
+ *
+ * @param netif The lwIP network interface on which the ARP packet pbuf arrived.
+ * @param ethaddr Ethernet address of netif.
+ * @param p The ARP packet that arrived on netif. Is freed by this function.
+ *
+ * @return NULL
+ *
+ * @see pbuf_free()
+ */
+static void
+undiarp_input(struct netif *netif, struct pbuf *p)
+{
+  struct arp_hdr *hdr;
+  /* these are aligned properly, whereas the ARP header fields might not be */
+  struct ip_addr sipaddr, dipaddr;
+  hwaddr_t hwaddr_remote;
+  u8_t *hdr_ptr;
+  u8_t for_us;
+
+  LWIP_ERROR("netif != NULL", (netif != NULL), return;);
+  
+  /* drop short ARP packets: we have to check for p->len instead of p->tot_len here
+     since a struct arp_hdr is pointed to p->payload, so it musn't be chained! */
+  if (p->len < arp_hdr_len(netif)) {
+    LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING,
+      ("undiarp_input: packet dropped, too short (%"S16_F"/%"S16_F")\n", p->tot_len,
+      (s16_t)SIZEOF_ETHARP_PACKET));
+    printf("short arp packet\n");
+    ETHARP_STATS_INC(etharp.lenerr);
+    ETHARP_STATS_INC(etharp.drop);
+    pbuf_free(p);
+    return;
+  }
+
+  hdr = p->payload;
+  /* RFC 826 "Packet Reception": */
+  if ((hdr->hwtype != htons(undi_hw_type)) ||
+      (hdr->_hwlen_protolen != htons((netif->hwaddr_len << 8) | sizeof(struct ip_addr))) ||
+      (hdr->proto != htons(ETHTYPE_IP))) {
+    LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING,
+      ("undiarp_input: packet dropped, wrong hw type, hwlen, proto, or protolen (%"U16_F"/%"U16_F"/%"U16_F"/%"U16_F"/%"U16_F")\n",
+      hdr->hwtype, ARPH_HWLEN(hdr), hdr->proto, ARPH_PROTOLEN(hdr)));
+    ETHARP_STATS_INC(etharp.proterr);
+    ETHARP_STATS_INC(etharp.drop);
+    printf("malformed arp packet\n");
+    pbuf_free(p);
+    return;
+  }
+  ETHARP_STATS_INC(etharp.recv);
+
+  /* Copy struct ip_addr2 to aligned ip_addr, to support compilers without
+   * structure packing (not using structure copy which breaks strict-aliasing rules). */
+  hdr_ptr = (unsigned char *)(hdr + 1);
+  memcpy(hwaddr_remote, hdr_ptr, netif->hwaddr_len);
+  hdr_ptr += netif->hwaddr_len;
+  memcpy(&sipaddr, hdr_ptr, sizeof(sipaddr));
+  hdr_ptr += sizeof(sipaddr);
+  hdr_ptr += netif->hwaddr_len;
+  memcpy(&dipaddr, hdr_ptr, sizeof(dipaddr));
+
+  /* this interface is not configured? */
+  if (netif->ip_addr.addr == 0) {
+    for_us = 0;
+  } else {
+    /* ARP packet directed to us? */
+    for_us = ip_addr_cmp(&dipaddr, &(netif->ip_addr));
+  }
+
+  /* ARP message directed to us? */
+  if (for_us) {
+    /* add IP address in ARP cache; assume requester wants to talk to us.
+     * can result in directly sending the queued packets for this host. */
+    update_arp_entry(netif, &sipaddr, &hwaddr_remote, UNDIARP_TRY_HARD);
+  /* ARP message not directed to us? */
+  } else {
+    /* update the source IP address in the cache, if present */
+    update_arp_entry(netif, &sipaddr, &hwaddr_remote, 0);
+  }
+
+  /* now act on the message itself */
+  switch (htons(hdr->opcode)) {
+  /* ARP request? */
+  case ARP_REQUEST:
+    /* ARP request. If it asked for our address, we send out a
+     * reply. In any case, we time-stamp any existing ARP entry,
+     * and possiby send out an IP packet that was queued on it. */
+
+    LWIP_DEBUGF (ETHARP_DEBUG | LWIP_DBG_TRACE, ("undiarp_input: incoming ARP request\n"));
+    /* ARP request for our address? */
+    if (for_us) {
+
+      LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("undiarp_input: replying to ARP request for our IP address\n"));
+      /* Re-use pbuf to send ARP reply.
+         Since we are re-using an existing pbuf, we can't call etharp_raw since
+         that would allocate a new pbuf. */
+      hdr->opcode = htons(ARP_REPLY);
+      hdr_ptr = (unsigned char *)(hdr + 1);
+      memcpy(hdr_ptr, &netif->hwaddr, netif->hwaddr_len);
+      hdr_ptr += netif->hwaddr_len;
+      memcpy(hdr_ptr, &dipaddr, sizeof(dipaddr));
+      hdr_ptr += sizeof(dipaddr);
+      memcpy(hdr_ptr, &hwaddr_remote, netif->hwaddr_len);
+      hdr_ptr += netif->hwaddr_len;
+      memcpy(hdr_ptr, &sipaddr, sizeof(sipaddr));
+
+      /* return ARP reply */
+      undi_send_arp(netif, p, &hwaddr_remote);
+    /* we are not configured? */
+    } else if (netif->ip_addr.addr == 0) {
+      /* { for_us == 0 and netif->ip_addr.addr == 0 } */
+      LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("undiarp_input: we are unconfigured, ARP request ignored.\n"));
+    /* request was not directed to us */
+    } else {
+      /* { for_us == 0 and netif->ip_addr.addr != 0 } */
+      LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("undiarp_input: ARP request was not for us.\n"));
+    }
+    break;
+  case ARP_REPLY:
+    /* ARP reply. We already updated the ARP cache earlier. */
+    LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("undiarp_input: incoming ARP reply\n"));
+#if (LWIP_DHCP && DHCP_DOES_ARP_CHECK)
+    /* DHCP wants to know about ARP replies from any host with an
+     * IP address also offered to us by the DHCP server. We do not
+     * want to take a duplicate IP address on a single network.
+     * @todo How should we handle redundant (fail-over) interfaces? */
+    dhcp_arp_reply(netif, &sipaddr);
+#endif
+    break;
+  default:
+    LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("undiarp_input: ARP unknown opcode type %"S16_F"\n", htons(hdr->opcode)));
+    ETHARP_STATS_INC(etharp.err);
+    break;
+  }
+  /* free ARP packet */
+  pbuf_free(p);
+}
+
 /**
  * This function should be called when a packet is ready to be read
  * from the interface. It uses the function low_level_input() that
@@ -296,37 +1171,70 @@ low_level_input(t_PXENV_UNDI_ISR *isr)
  */
 void undiif_input(t_PXENV_UNDI_ISR *isr)
 {
-  struct eth_hdr *ethhdr;
   struct pbuf *p;
+  u8_t undi_prot;
+  u16_t llhdr_len;
+
+  /* From the first isr capture the essential information */
+  undi_prot = isr->ProtType;
+  llhdr_len = isr->FrameHeaderLength;
 
   /* move received packet into a new pbuf */
   p = low_level_input(isr);
   /* no packet could be read, silently ignore this */
   if (p == NULL) return;
-  /* points to packet payload, which starts with an Ethernet header */
-  ethhdr = p->payload;
 
-  switch (htons(ethhdr->type)) {
-  /* IP or ARP packet? */
-  case ETHTYPE_IP:
-  case ETHTYPE_ARP:
+  if (undi_is_ethernet(&undi_netif)) {
+    /* points to packet payload, which starts with an Ethernet header */
+    struct eth_hdr *ethhdr = p->payload;
+    
+    switch (htons(ethhdr->type)) {
+    /* IP or ARP packet? */
+    case ETHTYPE_IP:
+    case ETHTYPE_ARP:
 #if PPPOE_SUPPORT
-  /* PPPoE packet? */
-  case ETHTYPE_PPPOEDISC:
-  case ETHTYPE_PPPOE:
+    /* PPPoE packet? */
+    case ETHTYPE_PPPOEDISC:
+    case ETHTYPE_PPPOE:
 #endif /* PPPOE_SUPPORT */
-    /* full packet send to tcpip_thread to process */
-    if (undi_netif.input(p, &undi_netif)!=ERR_OK)
-     { LWIP_DEBUGF(NETIF_DEBUG, ("undiif_input: IP input error\n"));
-       pbuf_free(p);
-       p = NULL;
-     }
-    break;
+      /* full packet send to tcpip_thread to process */
+      if (ethernet_input(p, &undi_netif)!=ERR_OK)
+       { LWIP_DEBUGF(NETIF_DEBUG, ("undiif_input: IP input error\n"));
+         pbuf_free(p);
+         p = NULL;
+       }
+      break;
 
-  default:
-    pbuf_free(p);
-    p = NULL;
-    break;
+    default:
+      pbuf_free(p);
+      p = NULL;
+      break;
+    }
+  } else {
+    if (pbuf_header(p, -(s16_t)llhdr_len)) {
+      LWIP_ASSERT("Can't move link level header in packet", 0);
+      pbuf_free(p);
+      p = NULL;
+    } else {
+      switch(undi_prot) {
+      case P_IP:
+        /* pass to IP layer */
+        ip_input(p, &undi_netif);
+        break;
+      
+      case P_ARP:
+        /* pass p to ARP module */
+        undiarp_input(&undi_netif, p);
+        break;
+
+      default:
+        ETHARP_STATS_INC(etharp.proterr);
+        ETHARP_STATS_INC(etharp.drop);
+        pbuf_free(p);
+        p = NULL;
+        break;
+      }
+    }
   }
 }
 
@@ -342,7 +1250,7 @@ void undiif_input(t_PXENV_UNDI_ISR *isr)
  *         ERR_MEM if private data couldn't be allocated
  *         any other err_t on error
  */
-static err_t
+err_t
 undiif_init(struct netif *netif)
 {
   LWIP_ASSERT("netif != NULL", (netif != NULL));
@@ -361,12 +1269,8 @@ undiif_init(struct netif *netif)
   netif->state   = NULL;	/* Private pointer if we need it */
   netif->name[0] = IFNAME0;
   netif->name[1] = IFNAME1;
-  /* We directly use etharp_output() here to save a function call.
-   * You can instead declare your own function an call etharp_output()
-   * from it if you have to do some checks before sending (e.g. if link
-   * is available...) */
-  netif->output = etharp_output;
-  netif->linkoutput = low_level_output;
+  netif->output = undiarp_output;
+  netif->linkoutput = undi_send_unknown;
 
   /* initialize the hardware */
   low_level_init(netif);
@@ -399,7 +1303,7 @@ err_t undi_tcpip_start(struct ip_addr *ipaddr,
 	 ((uint8_t *)gw)[2],
 	 ((uint8_t *)gw)[3]);
   err = netifapi_netif_add(&undi_netif, ipaddr, netmask, gw, NULL,
-			   undiif_init, ethernet_input);
+			   undiif_init, ip_input);
   if (err)
     return err;
 



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