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https://github.com/lwip-tcpip/lwip.git
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Prevent non-unicast addresses from polluting the ARP cache.
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@ -49,6 +49,8 @@ struct eth_addr {
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};
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struct eth_hdr {
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/* Ethernet header is 14 bytes, this breaks natural alignment on
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* subsequent (TCP/IP) protocol header fields. */
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#if ETH_PAD_SIZE
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u8_t padding[ETH_PAD_SIZE];
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#endif
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@ -79,20 +79,20 @@ enum etharp_state {
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ETHARP_STATE_EMPTY,
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ETHARP_STATE_PENDING,
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ETHARP_STATE_STABLE,
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/** @internal convenience transitional state used in etharp_tmr() */
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/** @internal transitional state used in etharp_tmr() for convenience*/
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ETHARP_STATE_EXPIRED
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};
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struct etharp_entry {
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struct ip_addr ipaddr;
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struct eth_addr ethaddr;
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enum etharp_state state;
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#if ARP_QUEUEING
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/**
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* Pointer to queue of pending outgoing packets on this ARP entry.
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* Must be at most a single packet for now. */
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struct pbuf *p;
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*/
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struct pbuf *p;
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#endif
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struct ip_addr ipaddr;
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struct eth_addr ethaddr;
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enum etharp_state state;
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u8_t ctime;
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};
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@ -233,12 +233,14 @@ find_arp_entry(void)
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* - ARP_INSERT_FLAG Allows ARP to insert this as a new item. If not specified,
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* only existing ARP entries will be updated.
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*
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* @return pbuf If non-NULL, a packet that was queued on a pending entry.
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* You should sent it and must call pbuf_free() afterwards.
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* @return
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* - ERR_OK Succesfully updated ARP cache.
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* - ERR_MEM If we could not add a new ARP entry when ARP_INSERT_FLAG was set.
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* - ERR_ARG Non-unicast address given, those will not appear in ARP cache.
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*
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* @see pbuf_free()
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*/
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static struct pbuf *
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err_t
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update_arp_entry(struct netif *netif, struct ip_addr *ipaddr, struct eth_addr *ethaddr, u8_t flags)
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{
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s8_t i, k;
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@ -248,10 +250,12 @@ update_arp_entry(struct netif *netif, struct ip_addr *ipaddr, struct eth_addr *e
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ip4_addr1(ipaddr), ip4_addr2(ipaddr), ip4_addr3(ipaddr), ip4_addr4(ipaddr),
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ethaddr->addr[0], ethaddr->addr[1], ethaddr->addr[2],
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ethaddr->addr[3], ethaddr->addr[4], ethaddr->addr[5]));
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/* do not update for 0.0.0.0 addresses */
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if (ipaddr->addr == 0) {
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LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("update_arp_entry: will not add 0.0.0.0 to ARP cache\n"));
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return NULL;
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/* non-unicast address? */
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if (ip_addr_isany(ipaddr) ||
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ip_addr_isbroadcast(ipaddr, netif) ||
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ip_addr_ismulticast(ipaddr)) {
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LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("update_arp_entry: will not add non-unicast IP address to ARP cache\n"));
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return ERR_ARG;
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}
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/* Walk through the ARP mapping table and try to find an entry to update.
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* If none is found, a new IP -> MAC address mapping is inserted. */
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@ -300,7 +304,7 @@ update_arp_entry(struct netif *netif, struct ip_addr *ipaddr, struct eth_addr *e
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}
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#endif
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/* IP addresses should only occur once in the ARP entry, we are done */
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return NULL;
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return ERR_OK;
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}
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} /* if STABLE */
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} /* for all ARP entries */
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@ -315,9 +319,9 @@ update_arp_entry(struct netif *netif, struct ip_addr *ipaddr, struct eth_addr *e
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LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("update_arp_entry: adding entry to table\n"));
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/* find an empty or old entry. */
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i = find_arp_entry();
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if (i == ERR_MEM) {
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if (i < 0) {
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LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("update_arp_entry: no available entry found\n"));
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return NULL;
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return (err_t)i;
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}
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/* set IP address */
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ip_addr_set(&arp_table[i].ipaddr, ipaddr);
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@ -610,10 +614,11 @@ etharp_output(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
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* If the IP address was already stable in the cache, the packet is
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* directly sent. An ARP request is sent out.
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*
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* @param netif The lwIP network interface where ipaddr
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* @param netif The lwIP network interface on which ipaddr
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* must be queried for.
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* @param ipaddr The IP address to be resolved.
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* @param q If non-NULL, a pbuf that must be delivered to the IP address.
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* q is not freed by this function.
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*
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* @return
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* - ERR_BUF Could not make room for Ethernet header.
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@ -621,12 +626,8 @@ etharp_output(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
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* to query for address or queue the packet.
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* - ERR_MEM Could not queue packet due to memory shortage.
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* - ERR_RTE No route to destination (no gateway to external networks).
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*
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* @note Might be used in the future by manual IP configuration
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* as well.
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* - ERR_ARG Non-unicast address given, those will not appear in ARP cache.
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*
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* TODO: use the ctime field to see how long ago an ARP request was sent,
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* possibly retry.
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*/
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err_t etharp_query(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
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{
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@ -636,6 +637,14 @@ err_t etharp_query(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
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s8_t i; /* ARP entry index */
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u8_t k; /* Ethernet address octet index */
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/* non-unicast address? */
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if (ip_addr_isany(ipaddr) ||
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ip_addr_isbroadcast(ipaddr, netif) ||
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ip_addr_ismulticast(ipaddr)) {
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LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE, ("etharp_query: will not add non-unicast IP address to ARP cache\n"));
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return ERR_ARG;
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}
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/* Do three things in this order (by design):
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*
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* 1) send out ARP request
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