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povik |
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/** |
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* \addtogroup uip |
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* @{ |
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*/ |
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/** |
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* \defgroup uiparp uIP Address Resolution Protocol |
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* @{ |
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* |
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* The Address Resolution Protocol ARP is used for mapping between IP |
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* addresses and link level addresses such as the Ethernet MAC |
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* addresses. ARP uses broadcast queries to ask for the link level |
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* address of a known IP address and the host which is configured with |
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* the IP address for which the query was meant, will respond with its |
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* link level address. |
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* |
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* \note This ARP implementation only supports Ethernet. |
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*/ |
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/** |
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* \file |
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* Implementation of the ARP Address Resolution Protocol. |
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* \author Adam Dunkels <adam@dunkels.com> |
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* |
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*/ |
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/* |
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* Copyright (c) 2001-2003, Adam Dunkels. |
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* All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in the |
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* documentation and/or other materials provided with the distribution. |
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* 3. The name of the author may not be used to endorse or promote |
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* products derived from this software without specific prior |
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* written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS |
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* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED |
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY |
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE |
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* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, |
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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* |
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* This file is part of the uIP TCP/IP stack. |
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* |
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* $Id: uip_arp.c,v 1.7.2.3 2003/10/06 22:42:30 adam Exp $ |
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* |
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*/ |
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#include "uip_arp.h" |
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#include <string.h> |
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struct arp_hdr { |
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struct uip_eth_hdr ethhdr; |
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u16_t hwtype; |
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u16_t protocol; |
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u8_t hwlen; |
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u8_t protolen; |
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u16_t opcode; |
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struct uip_eth_addr shwaddr; |
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u16_t sipaddr[2]; |
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struct uip_eth_addr dhwaddr; |
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u16_t dipaddr[2]; |
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}; |
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struct ethip_hdr { |
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struct uip_eth_hdr ethhdr; |
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/* IP header. */ |
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u8_t vhl, |
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tos, |
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len[2], |
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ipid[2], |
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ipoffset[2], |
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ttl, |
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proto; |
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u16_t ipchksum; |
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u16_t srcipaddr[2], |
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destipaddr[2]; |
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}; |
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#define ARP_REQUEST 1 |
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#define ARP_REPLY 2 |
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#define ARP_HWTYPE_ETH 1 |
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struct arp_entry { |
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u16_t ipaddr[2]; |
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struct uip_eth_addr ethaddr; |
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u8_t time; |
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}; |
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struct uip_eth_addr uip_ethaddr = {{UIP_ETHADDR0, |
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UIP_ETHADDR1, |
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UIP_ETHADDR2, |
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UIP_ETHADDR3, |
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UIP_ETHADDR4, |
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UIP_ETHADDR5}}; |
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static struct arp_entry arp_table[UIP_ARPTAB_SIZE]; |
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static u16_t ipaddr[2]; |
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static u8_t i, c; |
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static u8_t arptime; |
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static u8_t tmpage; |
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#define BUF ((struct arp_hdr *)&uip_buf[0]) |
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#define IPBUF ((struct ethip_hdr *)&uip_buf[0]) |
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/*-----------------------------------------------------------------------------------*/ |
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/** |
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* Initialize the ARP module. |
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* |
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*/ |
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/*-----------------------------------------------------------------------------------*/ |
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void |
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uip_arp_init(void) |
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{ |
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for(i = 0; i < UIP_ARPTAB_SIZE; ++i) { |
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memset(arp_table[i].ipaddr, 0, 4); |
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} |
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} |
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/*-----------------------------------------------------------------------------------*/ |
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/** |
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* Periodic ARP processing function. |
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* |
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* This function performs periodic timer processing in the ARP module |
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* and should be called at regular intervals. The recommended interval |
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* is 10 seconds between the calls. |
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* |
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*/ |
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/*-----------------------------------------------------------------------------------*/ |
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void |
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uip_arp_timer(void) |
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{ |
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struct arp_entry *tabptr; |
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++arptime; |
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for(i = 0; i < UIP_ARPTAB_SIZE; ++i) { |
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tabptr = &arp_table[i]; |
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if((tabptr->ipaddr[0] | tabptr->ipaddr[1]) != 0 && |
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arptime - tabptr->time >= UIP_ARP_MAXAGE) { |
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memset(tabptr->ipaddr, 0, 4); |
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} |
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} |
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} |
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/*-----------------------------------------------------------------------------------*/ |
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static void |
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uip_arp_update(u16_t *ipaddr, struct uip_eth_addr *ethaddr) |
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{ |
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register struct arp_entry *tabptr; |
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/* Walk through the ARP mapping table and try to find an entry to |
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update. If none is found, the IP -> MAC address mapping is |
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inserted in the ARP table. */ |
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for(i = 0; i < UIP_ARPTAB_SIZE; ++i) { |
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tabptr = &arp_table[i]; |
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/* Only check those entries that are actually in use. */ |
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if(tabptr->ipaddr[0] != 0 && |
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tabptr->ipaddr[1] != 0) { |
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/* Check if the source IP address of the incoming packet matches |
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the IP address in this ARP table entry. */ |
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if(ipaddr[0] == tabptr->ipaddr[0] && |
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ipaddr[1] == tabptr->ipaddr[1]) { |
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/* An old entry found, update this and return. */ |
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memcpy(tabptr->ethaddr.addr, ethaddr->addr, 6); |
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tabptr->time = arptime; |
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return; |
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} |
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} |
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} |
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/* If we get here, no existing ARP table entry was found, so we |
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create one. */ |
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/* First, we try to find an unused entry in the ARP table. */ |
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for(i = 0; i < UIP_ARPTAB_SIZE; ++i) { |
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tabptr = &arp_table[i]; |
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if(tabptr->ipaddr[0] == 0 && |
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tabptr->ipaddr[1] == 0) { |
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break; |
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} |
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} |
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/* If no unused entry is found, we try to find the oldest entry and |
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throw it away. */ |
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if(i == UIP_ARPTAB_SIZE) { |
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tmpage = 0; |
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c = 0; |
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for(i = 0; i < UIP_ARPTAB_SIZE; ++i) { |
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tabptr = &arp_table[i]; |
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if(arptime - tabptr->time > tmpage) { |
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tmpage = arptime - tabptr->time; |
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c = i; |
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} |
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} |
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i = c; |
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} |
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/* Now, i is the ARP table entry which we will fill with the new |
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information. */ |
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memcpy(tabptr->ipaddr, ipaddr, 4); |
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memcpy(tabptr->ethaddr.addr, ethaddr->addr, 6); |
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tabptr->time = arptime; |
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} |
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/*-----------------------------------------------------------------------------------*/ |
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/** |
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* ARP processing for incoming IP packets |
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* |
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* This function should be called by the device driver when an IP |
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* packet has been received. The function will check if the address is |
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* in the ARP cache, and if so the ARP cache entry will be |
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* refreshed. If no ARP cache entry was found, a new one is created. |
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* |
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* This function expects an IP packet with a prepended Ethernet header |
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* in the uip_buf[] buffer, and the length of the packet in the global |
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* variable uip_len. |
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*/ |
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/*-----------------------------------------------------------------------------------*/ |
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void |
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uip_arp_ipin(void) |
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{ |
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uip_len -= sizeof(struct uip_eth_hdr); |
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/* Only insert/update an entry if the source IP address of the |
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incoming IP packet comes from a host on the local network. */ |
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if((IPBUF->srcipaddr[0] & uip_arp_netmask[0]) != |
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(uip_hostaddr[0] & uip_arp_netmask[0])) { |
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return; |
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} |
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if((IPBUF->srcipaddr[1] & uip_arp_netmask[1]) != |
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(uip_hostaddr[1] & uip_arp_netmask[1])) { |
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return; |
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} |
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uip_arp_update(IPBUF->srcipaddr, &(IPBUF->ethhdr.src)); |
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return; |
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} |
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/*-----------------------------------------------------------------------------------*/ |
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/** |
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* ARP processing for incoming ARP packets. |
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* |
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* This function should be called by the device driver when an ARP |
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* packet has been received. The function will act differently |
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* depending on the ARP packet type: if it is a reply for a request |
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* that we previously sent out, the ARP cache will be filled in with |
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* the values from the ARP reply. If the incoming ARP packet is an ARP |
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* request for our IP address, an ARP reply packet is created and put |
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* into the uip_buf[] buffer. |
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* |
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* When the function returns, the value of the global variable uip_len |
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* indicates whether the device driver should send out a packet or |
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* not. If uip_len is zero, no packet should be sent. If uip_len is |
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* non-zero, it contains the length of the outbound packet that is |
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* present in the uip_buf[] buffer. |
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* |
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* This function expects an ARP packet with a prepended Ethernet |
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* header in the uip_buf[] buffer, and the length of the packet in the |
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* global variable uip_len. |
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*/ |
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/*-----------------------------------------------------------------------------------*/ |
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typedef struct arp_hdr aht; |
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void |
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uip_arp_arpin(void) |
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{ |
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int ul; |
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if(uip_len < sizeof(struct arp_hdr)) { |
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uip_len = 0; |
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return; |
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} |
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uip_len = 0; |
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switch(BUF->opcode) { |
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case HTONS(ARP_REQUEST): |
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/* ARP request. If it asked for our address, we send out a |
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reply. */ |
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if(BUF->dipaddr[0] == uip_hostaddr[0] && |
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BUF->dipaddr[1] == uip_hostaddr[1]) { |
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/* The reply opcode is 2. */ |
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BUF->opcode = HTONS(2); |
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memcpy(BUF->dhwaddr.addr, BUF->shwaddr.addr, 6); |
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memcpy(BUF->shwaddr.addr, uip_ethaddr.addr, 6); |
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memcpy(BUF->ethhdr.src.addr, uip_ethaddr.addr, 6); |
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memcpy(BUF->ethhdr.dest.addr, BUF->dhwaddr.addr, 6); |
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BUF->dipaddr[0] = BUF->sipaddr[0]; |
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BUF->dipaddr[1] = BUF->sipaddr[1]; |
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BUF->sipaddr[0] = uip_hostaddr[0]; |
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BUF->sipaddr[1] = uip_hostaddr[1]; |
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ul = BUF->hwlen; |
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BUF->ethhdr.type = HTONS(UIP_ETHTYPE_ARP); |
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uip_len = sizeof(struct arp_hdr); |
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} |
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break; |
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case HTONS(ARP_REPLY): |
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/* ARP reply. We insert or update the ARP table if it was meant |
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for us. */ |
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if(BUF->dipaddr[0] == uip_hostaddr[0] && |
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BUF->dipaddr[1] == uip_hostaddr[1]) { |
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uip_arp_update(BUF->sipaddr, &BUF->shwaddr); |
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} |
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break; |
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} |
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( void ) ul; |
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return; |
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} |
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/*-----------------------------------------------------------------------------------*/ |
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/** |
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* Prepend Ethernet header to an outbound IP packet and see if we need |
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* to send out an ARP request. |
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* |
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* This function should be called before sending out an IP packet. The |
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* function checks the destination IP address of the IP packet to see |
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* what Ethernet MAC address that should be used as a destination MAC |
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* address on the Ethernet. |
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* |
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* If the destination IP address is in the local network (determined |
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* by logical ANDing of netmask and our IP address), the function |
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* checks the ARP cache to see if an entry for the destination IP |
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* address is found. If so, an Ethernet header is prepended and the |
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* function returns. If no ARP cache entry is found for the |
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* destination IP address, the packet in the uip_buf[] is replaced by |
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* an ARP request packet for the IP address. The IP packet is dropped |
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* and it is assumed that they higher level protocols (e.g., TCP) |
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* eventually will retransmit the dropped packet. |
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* |
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* If the destination IP address is not on the local network, the IP |
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* address of the default router is used instead. |
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* |
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* When the function returns, a packet is present in the uip_buf[] |
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* buffer, and the length of the packet is in the global variable |
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* uip_len. |
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*/ |
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/*-----------------------------------------------------------------------------------*/ |
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void |
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uip_arp_out(void) |
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{ |
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struct arp_entry *tabptr; |
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/* Find the destination IP address in the ARP table and construct |
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the Ethernet header. If the destination IP addres isn't on the |
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local network, we use the default router's IP address instead. |
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If not ARP table entry is found, we overwrite the original IP |
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packet with an ARP request for the IP address. */ |
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/* Check if the destination address is on the local network. */ |
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if((IPBUF->destipaddr[0] & uip_arp_netmask[0]) != |
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(uip_hostaddr[0] & uip_arp_netmask[0]) || |
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(IPBUF->destipaddr[1] & uip_arp_netmask[1]) != |
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(uip_hostaddr[1] & uip_arp_netmask[1])) { |
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/* Destination address was not on the local network, so we need to |
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use the default router's IP address instead of the destination |
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address when determining the MAC address. */ |
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ipaddr[0] = uip_arp_draddr[0]; |
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ipaddr[1] = uip_arp_draddr[1]; |
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} else { |
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/* Else, we use the destination IP address. */ |
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ipaddr[0] = IPBUF->destipaddr[0]; |
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ipaddr[1] = IPBUF->destipaddr[1]; |
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383 |
} |
|
|
384 |
|
|
|
385 |
for(i = 0; i < UIP_ARPTAB_SIZE; ++i) { |
|
|
386 |
tabptr = &arp_table[i]; |
|
|
387 |
if(ipaddr[0] == tabptr->ipaddr[0] && |
|
|
388 |
ipaddr[1] == tabptr->ipaddr[1]) |
|
|
389 |
break; |
|
|
390 |
} |
|
|
391 |
|
|
|
392 |
if(i == UIP_ARPTAB_SIZE) { |
|
|
393 |
/* The destination address was not in our ARP table, so we |
|
|
394 |
overwrite the IP packet with an ARP request. */ |
|
|
395 |
|
|
|
396 |
memset(BUF->ethhdr.dest.addr, 0xff, 6); |
|
|
397 |
memset(BUF->dhwaddr.addr, 0x00, 6); |
|
|
398 |
memcpy(BUF->ethhdr.src.addr, uip_ethaddr.addr, 6); |
|
|
399 |
memcpy(BUF->shwaddr.addr, uip_ethaddr.addr, 6); |
|
|
400 |
|
|
|
401 |
BUF->dipaddr[0] = ipaddr[0]; |
|
|
402 |
BUF->dipaddr[1] = ipaddr[1]; |
|
|
403 |
BUF->sipaddr[0] = uip_hostaddr[0]; |
|
|
404 |
BUF->sipaddr[1] = uip_hostaddr[1]; |
|
|
405 |
BUF->opcode = HTONS(ARP_REQUEST); /* ARP request. */ |
|
|
406 |
BUF->hwtype = HTONS(ARP_HWTYPE_ETH); |
|
|
407 |
BUF->protocol = HTONS(UIP_ETHTYPE_IP); |
|
|
408 |
BUF->hwlen = 6; |
|
|
409 |
BUF->protolen = 4; |
|
|
410 |
BUF->ethhdr.type = HTONS(UIP_ETHTYPE_ARP); |
|
|
411 |
|
|
|
412 |
uip_appdata = &uip_buf[40 + UIP_LLH_LEN]; |
|
|
413 |
|
|
|
414 |
uip_len = sizeof(struct arp_hdr); |
|
|
415 |
return; |
|
|
416 |
} |
|
|
417 |
|
|
|
418 |
/* Build an ethernet header. */ |
|
|
419 |
memcpy(IPBUF->ethhdr.dest.addr, tabptr->ethaddr.addr, 6); |
|
|
420 |
memcpy(IPBUF->ethhdr.src.addr, uip_ethaddr.addr, 6); |
|
|
421 |
|
|
|
422 |
IPBUF->ethhdr.type = HTONS(UIP_ETHTYPE_IP); |
|
|
423 |
|
|
|
424 |
uip_len += sizeof(struct uip_eth_hdr); |
|
|
425 |
} |
|
|
426 |
/*-----------------------------------------------------------------------------------*/ |
|
|
427 |
|
|
|
428 |
/** @} */ |
|
|
429 |
/** @} */ |