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Diffstat (limited to 'net/inet/arp.c')
| -rw-r--r-- | net/inet/arp.c | 1228 |
1 files changed, 1228 insertions, 0 deletions
diff --git a/net/inet/arp.c b/net/inet/arp.c new file mode 100644 index 000000000..67174bb7b --- /dev/null +++ b/net/inet/arp.c @@ -0,0 +1,1228 @@ +/* linux/net/inet/arp.c + * + * Copyright (C) 1994 by Florian La Roche + * + * This module implements the Address Resolution Protocol ARP (RFC 826), + * which is used to convert IP addresses (or in the future maybe other + * high-level addresses into a low-level hardware address (like an Ethernet + * address). + * + * FIXME: + * Experiment with better retransmit timers + * Clean up the timer deletions + * If you create a proxy entry set your interface address to the address + * and then delete it, proxies may get out of sync with reality - check this + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + * + * + * Fixes: + * Alan Cox : Removed the ethernet assumptions in Florian's code + * Alan Cox : Fixed some small errors in the ARP logic + * Alan Cox : Allow >4K in /proc + * Alan Cox : Make ARP add its own protocol entry + * + * Ross Martin : Rewrote arp_rcv() and arp_get_info() + * Stephen Henson : Add AX25 support to arp_get_info() + * Alan Cox : Drop data when a device is downed. + * Alan Cox : Use init_timer(). + * Alan Cox : Double lock fixes. + * Martin Seine : Move the arphdr structure + * to if_arp.h for compatibility + * with BSD based programs. + * Andrew Tridgell : Added ARP netmask code and + * re-arranged proxy handling + */ + +#include <linux/types.h> +#include <linux/string.h> +#include <linux/kernel.h> +#include <linux/sched.h> +#include <linux/config.h> +#include <linux/socket.h> +#include <linux/sockios.h> +#include <linux/errno.h> +#include <linux/if_arp.h> +#include <linux/in.h> +#include <asm/system.h> +#include <asm/segment.h> +#include <stdarg.h> +#include <linux/inet.h> +#include <linux/netdevice.h> +#include <linux/etherdevice.h> +#include "ip.h" +#include "route.h" +#include "protocol.h" +#include "tcp.h" +#include <linux/skbuff.h> +#include "sock.h" +#include "arp.h" +#ifdef CONFIG_AX25 +#include "ax25.h" +#endif + + +/* + * This structure defines the ARP mapping cache. As long as we make changes + * in this structure, we keep interrupts of. But normally we can copy the + * hardware address and the device pointer in a local variable and then make + * any "long calls" to send a packet out. + */ + +struct arp_table +{ + struct arp_table *next; /* Linked entry list */ + unsigned long last_used; /* For expiry */ + unsigned int flags; /* Control status */ + unsigned long ip; /* ip address of entry */ + unsigned long mask; /* netmask - used for generalised proxy arps (tridge) */ + unsigned char ha[MAX_ADDR_LEN]; /* Hardware address */ + unsigned char hlen; /* Length of hardware address */ + unsigned short htype; /* Type of hardware in use */ + struct device *dev; /* Device the entry is tied to */ + + /* + * The following entries are only used for unresolved hw addresses. + */ + + struct timer_list timer; /* expire timer */ + int retries; /* remaining retries */ + struct sk_buff_head skb; /* list of queued packets */ +}; + + +/* + * Configurable Parameters (don't touch unless you know what you are doing + */ + +/* + * If an arp request is send, ARP_RES_TIME is the timeout value until the + * next request is send. + */ + +#define ARP_RES_TIME (250*(HZ/10)) + +/* + * The number of times an arp request is send, until the host is + * considered unreachable. + */ + +#define ARP_MAX_TRIES 3 + +/* + * After that time, an unused entry is deleted from the arp table. + */ + +#define ARP_TIMEOUT (600*HZ) + +/* + * How often is the function 'arp_check_retries' called. + * An entry is invalidated in the time between ARP_TIMEOUT and + * (ARP_TIMEOUT+ARP_CHECK_INTERVAL). + */ + +#define ARP_CHECK_INTERVAL (60 * HZ) + +/* Forward declarations. */ +static void arp_check_expire (unsigned long); +static struct arp_table *arp_lookup(unsigned long paddr, int exact); + + +static struct timer_list arp_timer = + { NULL, NULL, ARP_CHECK_INTERVAL, 0L, &arp_check_expire }; + +/* + * The default arp netmask is just 255.255.255.255 which means it's + * a single machine entry. Only proxy entries can have other netmasks + * +*/ + +#define DEF_ARP_NETMASK (~0) + + +/* + * The size of the hash table. Must be a power of two. + * Maybe we should remove hashing in the future for arp and concentrate + * on Patrick Schaaf's Host-Cache-Lookup... + */ + + +#define ARP_TABLE_SIZE 16 + +/* The ugly +1 here is to cater for proxy entries. They are put in their + own list for efficiency of lookup. If you don't want to find a proxy + entry then don't look in the last entry, otherwise do +*/ + +#define FULL_ARP_TABLE_SIZE (ARP_TABLE_SIZE+1) + +struct arp_table *arp_tables[FULL_ARP_TABLE_SIZE] = +{ + NULL, +}; + + +/* + * The last bits in the IP address are used for the cache lookup. + * A special entry is used for proxy arp entries + */ + +#define HASH(paddr) (htonl(paddr) & (ARP_TABLE_SIZE - 1)) +#define PROXY_HASH ARP_TABLE_SIZE + +/* + * Check if there are too old entries and remove them. If the ATF_PERM + * flag is set, they are always left in the arp cache (permanent entry). + * Note: Only fully resolved entries, which don't have any packets in + * the queue, can be deleted, since ARP_TIMEOUT is much greater than + * ARP_MAX_TRIES*ARP_RES_TIME. + */ + +static void arp_check_expire(unsigned long dummy) +{ + int i; + unsigned long now = jiffies; + unsigned long flags; + save_flags(flags); + cli(); + + for (i = 0; i < FULL_ARP_TABLE_SIZE; i++) + { + struct arp_table *entry; + struct arp_table **pentry = &arp_tables[i]; + + while ((entry = *pentry) != NULL) + { + if ((now - entry->last_used) > ARP_TIMEOUT + && !(entry->flags & ATF_PERM)) + { + *pentry = entry->next; /* remove from list */ + del_timer(&entry->timer); /* Paranoia */ + kfree_s(entry, sizeof(struct arp_table)); + } + else + pentry = &entry->next; /* go to next entry */ + } + } + restore_flags(flags); + + /* + * Set the timer again. + */ + + del_timer(&arp_timer); + arp_timer.expires = ARP_CHECK_INTERVAL; + add_timer(&arp_timer); +} + + +/* + * Release all linked skb's and the memory for this entry. + */ + +static void arp_release_entry(struct arp_table *entry) +{ + struct sk_buff *skb; + unsigned long flags; + + save_flags(flags); + cli(); + /* Release the list of `skb' pointers. */ + while ((skb = skb_dequeue(&entry->skb)) != NULL) + { + skb_device_lock(skb); + restore_flags(flags); + dev_kfree_skb(skb, FREE_WRITE); + } + restore_flags(flags); + del_timer(&entry->timer); + kfree_s(entry, sizeof(struct arp_table)); + return; +} + +/* + * Purge a device from the ARP queue + */ + +void arp_device_down(struct device *dev) +{ + int i; + unsigned long flags; + + /* + * This is a bit OTT - maybe we need some arp semaphores instead. + */ + save_flags(flags); + cli(); + for (i = 0; i < FULL_ARP_TABLE_SIZE; i++) + { + struct arp_table *entry; + struct arp_table **pentry = &arp_tables[i]; + + while ((entry = *pentry) != NULL) + { + if(entry->dev==dev) + { + *pentry = entry->next; /* remove from list */ + del_timer(&entry->timer); /* Paranoia */ + kfree_s(entry, sizeof(struct arp_table)); + } + else + pentry = &entry->next; /* go to next entry */ + } + } + restore_flags(flags); +} + + +/* + * Create and send an arp packet. If (dest_hw == NULL), we create a broadcast + * message. + */ + +void arp_send(int type, int ptype, unsigned long dest_ip, + struct device *dev, unsigned long src_ip, + unsigned char *dest_hw, unsigned char *src_hw) +{ + struct sk_buff *skb; + struct arphdr *arp; + unsigned char *arp_ptr; + + /* + * No arp on this interface. + */ + + if(dev->flags&IFF_NOARP) + return; + + /* + * Allocate a buffer + */ + + skb = alloc_skb(sizeof(struct arphdr)+ 2*(dev->addr_len+4) + + dev->hard_header_len, GFP_ATOMIC); + if (skb == NULL) + { + printk("ARP: no memory to send an arp packet\n"); + return; + } + skb->len = sizeof(struct arphdr) + dev->hard_header_len + 2*(dev->addr_len+4); + skb->arp = 1; + skb->dev = dev; + skb->free = 1; + + /* + * Fill the device header for the ARP frame + */ + + dev->hard_header(skb->data,dev,ptype,dest_hw?dest_hw:dev->broadcast,src_hw?src_hw:NULL,skb->len,skb); + + /* Fill out the arp protocol part. */ + arp = (struct arphdr *) (skb->data + dev->hard_header_len); + arp->ar_hrd = htons(dev->type); +#ifdef CONFIG_AX25 + arp->ar_pro = (dev->type != ARPHRD_AX25)? htons(ETH_P_IP) : htons(AX25_P_IP); +#else + arp->ar_pro = htons(ETH_P_IP); +#endif + arp->ar_hln = dev->addr_len; + arp->ar_pln = 4; + arp->ar_op = htons(type); + + arp_ptr=(unsigned char *)(arp+1); + + memcpy(arp_ptr, src_hw, dev->addr_len); + arp_ptr+=dev->addr_len; + memcpy(arp_ptr, &src_ip,4); + arp_ptr+=4; + if (dest_hw != NULL) + memcpy(arp_ptr, dest_hw, dev->addr_len); + else + memset(arp_ptr, 0, dev->addr_len); + arp_ptr+=dev->addr_len; + memcpy(arp_ptr, &dest_ip, 4); + + dev_queue_xmit(skb, dev, 0); +} + + +/* + * This function is called, if an entry is not resolved in ARP_RES_TIME. + * Either resend a request, or give it up and free the entry. + */ + +static void arp_expire_request (unsigned long arg) +{ + struct arp_table *entry = (struct arp_table *) arg; + struct arp_table **pentry; + unsigned long hash; + unsigned long flags; + + save_flags(flags); + cli(); + + /* + * Since all timeouts are handled with interrupts enabled, there is a + * small chance, that this entry has just been resolved by an incoming + * packet. This is the only race condition, but it is handled... + */ + + if (entry->flags & ATF_COM) + { + restore_flags(flags); + return; + } + + if (--entry->retries > 0) + { + unsigned long ip = entry->ip; + struct device *dev = entry->dev; + + /* Set new timer. */ + del_timer(&entry->timer); + entry->timer.expires = ARP_RES_TIME; + add_timer(&entry->timer); + restore_flags(flags); + arp_send(ARPOP_REQUEST, ETH_P_ARP, ip, dev, dev->pa_addr, + NULL, dev->dev_addr); + return; + } + + /* + * Arp request timed out. Delete entry and all waiting packets. + * If we give each entry a pointer to itself, we don't have to + * loop through everything again. Maybe hash is good enough, but + * I will look at it later. + */ + + hash = HASH(entry->ip); + + /* proxy entries shouldn't really time out so this is really + only here for completeness + */ + if (entry->flags & ATF_PUBL) + pentry = &arp_tables[PROXY_HASH]; + else + pentry = &arp_tables[hash]; + while (*pentry != NULL) + { + if (*pentry == entry) + { + *pentry = entry->next; /* delete from linked list */ + del_timer(&entry->timer); + restore_flags(flags); + arp_release_entry(entry); + return; + } + pentry = &(*pentry)->next; + } + restore_flags(flags); + printk("Possible ARP queue corruption.\n"); + /* + * We should never arrive here. + */ +} + + +/* + * This will try to retransmit everything on the queue. + */ + +static void arp_send_q(struct arp_table *entry, unsigned char *hw_dest) +{ + struct sk_buff *skb; + + unsigned long flags; + + /* + * Empty the entire queue, building its data up ready to send + */ + + if(!(entry->flags&ATF_COM)) + { + printk("arp_send_q: incomplete entry for %s\n", + in_ntoa(entry->ip)); + return; + } + + save_flags(flags); + + cli(); + while((skb = skb_dequeue(&entry->skb)) != NULL) + { + IS_SKB(skb); + skb_device_lock(skb); + restore_flags(flags); + if(!skb->dev->rebuild_header(skb->data,skb->dev,skb->raddr,skb)) + { + skb->arp = 1; + if(skb->sk==NULL) + dev_queue_xmit(skb, skb->dev, 0); + else + dev_queue_xmit(skb,skb->dev,skb->sk->priority); + } + else + { + /* This routine is only ever called when 'entry' is + complete. Thus this can't fail. */ + printk("arp_send_q: The impossible occurred. Please notify Alan.\n"); + printk("arp_send_q: active entity %s\n",in_ntoa(entry->ip)); + printk("arp_send_q: failed to find %s\n",in_ntoa(skb->raddr)); + } + } + restore_flags(flags); +} + + +/* + * Delete an ARP mapping entry in the cache. + */ + +void arp_destroy(unsigned long ip_addr, int force) +{ + int checked_proxies = 0; + struct arp_table *entry; + struct arp_table **pentry; + unsigned long hash = HASH(ip_addr); + + cli(); + pentry = &arp_tables[hash]; + if (! *pentry) /* also check proxy entries */ + pentry = &arp_tables[PROXY_HASH]; + + while ((entry = *pentry) != NULL) + { + if (entry->ip == ip_addr) + { + if ((entry->flags & ATF_PERM) && !force) + return; + *pentry = entry->next; + del_timer(&entry->timer); + sti(); + arp_release_entry(entry); + return; + } + pentry = &entry->next; + if (!checked_proxies && ! *pentry) + { /* ugly. we have to make sure we check proxy + entries as well */ + checked_proxies = 1; + pentry = &arp_tables[PROXY_HASH]; + } + } + sti(); +} + + +/* + * Receive an arp request by the device layer. Maybe I rewrite it, to + * use the incoming packet for the reply. The time for the current + * "overhead" isn't that high... + */ + +int arp_rcv(struct sk_buff *skb, struct device *dev, struct packet_type *pt) +{ +/* + * We shouldn't use this type conversion. Check later. + */ + + struct arphdr *arp = (struct arphdr *)skb->h.raw; + unsigned char *arp_ptr= (unsigned char *)(arp+1); + struct arp_table *entry; + struct arp_table *proxy_entry; + int addr_hint,hlen,htype; + unsigned long hash; + unsigned char ha[MAX_ADDR_LEN]; /* So we can enable ints again. */ + long sip,tip; + unsigned char *sha,*tha; + +/* + * The hardware length of the packet should match the hardware length + * of the device. Similarly, the hardware types should match. The + * device should be ARP-able. Also, if pln is not 4, then the lookup + * is not from an IP number. We can't currently handle this, so toss + * it. + */ + if (arp->ar_hln != dev->addr_len || + dev->type != ntohs(arp->ar_hrd) || + dev->flags & IFF_NOARP || + arp->ar_pln != 4) + { + kfree_skb(skb, FREE_READ); + return 0; + } + +/* + * Another test. + * The logic here is that the protocol being looked up by arp should + * match the protocol the device speaks. If it doesn't, there is a + * problem, so toss the packet. + */ + switch(dev->type) + { +#ifdef CONFIG_AX25 + case ARPHRD_AX25: + if(arp->ar_pro != htons(AX25_P_IP)) + { + kfree_skb(skb, FREE_READ); + return 0; + } + break; +#endif + case ARPHRD_ETHER: + case ARPHRD_ARCNET: + if(arp->ar_pro != htons(ETH_P_IP)) + { + kfree_skb(skb, FREE_READ); + return 0; + } + break; + + default: + printk("ARP: dev->type mangled!\n"); + kfree_skb(skb, FREE_READ); + return 0; + } + +/* + * Extract fields + */ + + hlen = dev->addr_len; + htype = dev->type; + + sha=arp_ptr; + arp_ptr+=hlen; + memcpy(&sip,arp_ptr,4); + arp_ptr+=4; + tha=arp_ptr; + arp_ptr+=hlen; + memcpy(&tip,arp_ptr,4); + +/* + * Check for bad requests for 127.0.0.1. If this is one such, delete it. + */ + if(tip == INADDR_LOOPBACK) + { + kfree_skb(skb, FREE_READ); + return 0; + } + +/* + * Process entry. The idea here is we want to send a reply if it is a + * request for us or if it is a request for someone else that we hold + * a proxy for. We want to add an entry to our cache if it is a reply + * to us or if it is a request for our address. + * (The assumption for this last is that if someone is requesting our + * address, they are probably intending to talk to us, so it saves time + * if we cache their address. Their address is also probably not in + * our cache, since ours is not in their cache.) + * + * Putting this another way, we only care about replies if they are to + * us, in which case we add them to the cache. For requests, we care + * about those for us and those for our proxies. We reply to both, + * and in the case of requests for us we add the requester to the arp + * cache. + */ + + addr_hint = ip_chk_addr(tip); + + if(arp->ar_op == htons(ARPOP_REPLY)) + { + if(addr_hint!=IS_MYADDR) + { +/* + * Replies to other machines get tossed. + */ + kfree_skb(skb, FREE_READ); + return 0; + } +/* + * Fall through to code below that adds sender to cache. + */ + } + else + { +/* + * It is now an arp request + */ + if(addr_hint != IS_MYADDR) + { +/* + * To get in here, it is a request for someone else. We need to + * check if that someone else is one of our proxies. If it isn't, + * we can toss it. + */ + cli(); + for(proxy_entry=arp_tables[PROXY_HASH]; + proxy_entry; + proxy_entry = proxy_entry->next) + { + /* we will respond to a proxy arp request + if the masked arp table ip matches the masked + tip. This allows a single proxy arp table + entry to be used on a gateway machine to handle + all requests for a whole network, rather than + having to use a huge number of proxy arp entries + and having to keep them uptodate. + */ + if (proxy_entry->htype == htype && + !((proxy_entry->ip^tip)&proxy_entry->mask)) + break; + + } + if (proxy_entry) + { + memcpy(ha, proxy_entry->ha, hlen); + sti(); + arp_send(ARPOP_REPLY,ETH_P_ARP,sip,dev,tip,sha,ha); + kfree_skb(skb, FREE_READ); + return 0; + } + else + { + sti(); + kfree_skb(skb, FREE_READ); + return 0; + } + } + else + { +/* + * To get here, it must be an arp request for us. We need to reply. + */ + arp_send(ARPOP_REPLY,ETH_P_ARP,sip,dev,tip,sha,dev->dev_addr); + } + } + + +/* + * Now all replies are handled. Next, anything that falls through to here + * needs to be added to the arp cache, or have its entry updated if it is + * there. + */ + + hash = HASH(sip); + cli(); + for(entry=arp_tables[hash];entry;entry=entry->next) + if(entry->ip==sip && entry->htype==htype) + break; + + if(entry) + { +/* + * Entry found; update it. + */ + memcpy(entry->ha, sha, hlen); + entry->hlen = hlen; + entry->last_used = jiffies; + if (!(entry->flags & ATF_COM)) + { +/* + * This entry was incomplete. Delete the retransmit timer + * and switch to complete status. + */ + del_timer(&entry->timer); + entry->flags |= ATF_COM; + sti(); +/* + * Send out waiting packets. We might have problems, if someone is + * manually removing entries right now -- entry might become invalid + * underneath us. + */ + arp_send_q(entry, sha); + } + else + { + sti(); + } + } + else + { +/* + * No entry found. Need to add a new entry to the arp table. + */ + entry = (struct arp_table *)kmalloc(sizeof(struct arp_table),GFP_ATOMIC); + if(entry == NULL) + { + sti(); + printk("ARP: no memory for new arp entry\n"); + + kfree_skb(skb, FREE_READ); + return 0; + } + + entry->mask = DEF_ARP_NETMASK; + entry->ip = sip; + entry->hlen = hlen; + entry->htype = htype; + entry->flags = ATF_COM; + init_timer(&entry->timer); + memcpy(entry->ha, sha, hlen); + entry->last_used = jiffies; + entry->dev = skb->dev; + skb_queue_head_init(&entry->skb); + entry->next = arp_tables[hash]; + arp_tables[hash] = entry; + sti(); + } + +/* + * Replies have been sent, and entries have been added. All done. + */ + kfree_skb(skb, FREE_READ); + return 0; +} + + +/* + * Find an arp mapping in the cache. If not found, post a request. + */ + +int arp_find(unsigned char *haddr, unsigned long paddr, struct device *dev, + unsigned long saddr, struct sk_buff *skb) +{ + struct arp_table *entry; + unsigned long hash; + switch (ip_chk_addr(paddr)) + { + case IS_MYADDR: + printk("ARP: arp called for own IP address\n"); + memcpy(haddr, dev->dev_addr, dev->addr_len); + skb->arp = 1; + return 0; + case IS_BROADCAST: + memcpy(haddr, dev->broadcast, dev->addr_len); + skb->arp = 1; + return 0; + } + + hash = HASH(paddr); + cli(); + + /* + * Find an entry + */ + entry = arp_lookup(paddr, 0); + + if (entry != NULL) /* It exists */ + { + if (!(entry->flags & ATF_COM)) + { + /* + * A request was already send, but no reply yet. Thus + * queue the packet with the previous attempt + */ + + if (skb != NULL) + { + skb_queue_tail(&entry->skb, skb); + skb_device_unlock(skb); + } + sti(); + return 1; + } + + /* + * Update the record + */ + + entry->last_used = jiffies; + memcpy(haddr, entry->ha, dev->addr_len); + if (skb) + skb->arp = 1; + sti(); + return 0; + } + + /* + * Create a new unresolved entry. + */ + + entry = (struct arp_table *) kmalloc(sizeof(struct arp_table), + GFP_ATOMIC); + if (entry != NULL) + { + entry->mask = DEF_ARP_NETMASK; + entry->ip = paddr; + entry->hlen = dev->addr_len; + entry->htype = dev->type; + entry->flags = 0; + memset(entry->ha, 0, dev->addr_len); + entry->dev = dev; + entry->last_used = jiffies; + init_timer(&entry->timer); + entry->timer.function = arp_expire_request; + entry->timer.data = (unsigned long)entry; + entry->timer.expires = ARP_RES_TIME; + entry->next = arp_tables[hash]; + arp_tables[hash] = entry; + add_timer(&entry->timer); + entry->retries = ARP_MAX_TRIES; + skb_queue_head_init(&entry->skb); + if (skb != NULL) + { + skb_queue_tail(&entry->skb, skb); + skb_device_unlock(skb); + } + } + else + { + if (skb != NULL && skb->free) + kfree_skb(skb, FREE_WRITE); + } + sti(); + + /* + * If we didn't find an entry, we will try to send an ARP packet. + */ + + arp_send(ARPOP_REQUEST, ETH_P_ARP, paddr, dev, saddr, NULL, + dev->dev_addr); + + return 1; +} + + +/* + * Write the contents of the ARP cache to a PROCfs file. + */ + +#define HBUFFERLEN 30 + +int arp_get_info(char *buffer, char **start, off_t offset, int length) +{ + int len=0; + off_t begin=0; + off_t pos=0; + int size; + struct arp_table *entry; + char hbuffer[HBUFFERLEN]; + int i,j,k; + const char hexbuf[] = "0123456789ABCDEF"; + + size = sprintf(buffer,"IP address HW type Flags HW address Mask\n"); + + pos+=size; + len+=size; + + cli(); + for(i=0; i<FULL_ARP_TABLE_SIZE; i++) + { + for(entry=arp_tables[i]; entry!=NULL; entry=entry->next) + { +/* + * Convert hardware address to XX:XX:XX:XX ... form. + */ +#ifdef CONFIG_AX25 + + if(entry->htype==ARPHRD_AX25) + strcpy(hbuffer,ax2asc((ax25_address *)entry->ha)); + else { +#endif + + for(k=0,j=0;k<HBUFFERLEN-3 && j<entry->hlen;j++) + { + hbuffer[k++]=hexbuf[ (entry->ha[j]>>4)&15 ]; + hbuffer[k++]=hexbuf[ entry->ha[j]&15 ]; + hbuffer[k++]=':'; + } + hbuffer[--k]=0; + +#ifdef CONFIG_AX25 + } +#endif + size = sprintf(buffer+len, + "%-17s0x%-10x0x%-10x%s", + in_ntoa(entry->ip), + (unsigned int)entry->htype, + entry->flags, + hbuffer); + size += sprintf(buffer+len+size, + " %-17s\n", + entry->mask==DEF_ARP_NETMASK? + "*":in_ntoa(entry->mask)); + + len+=size; + pos=begin+len; + + if(pos<offset) + { + len=0; + begin=pos; + } + if(pos>offset+length) + break; + } + } + sti(); + + *start=buffer+(offset-begin); /* Start of wanted data */ + len-=(offset-begin); /* Start slop */ + if(len>length) + len=length; /* Ending slop */ + return len; +} + + +/* + * This will find an entry in the ARP table by looking at the IP address. + * If exact is true then only exact IP matches will be allowed + * for proxy entries, otherwise the netmask will be used + */ + +static struct arp_table *arp_lookup(unsigned long paddr, int exact) +{ + struct arp_table *entry; + unsigned long hash = HASH(paddr); + + for (entry = arp_tables[hash]; entry != NULL; entry = entry->next) + if (entry->ip == paddr) break; + + /* it's possibly a proxy entry (with a netmask) */ + if (!entry) + for (entry=arp_tables[PROXY_HASH]; entry != NULL; entry = entry->next) + if (exact? (entry->ip==paddr) : !((entry->ip^paddr)&entry->mask)) + break; + + return entry; +} + + +/* + * Set (create) an ARP cache entry. + */ + +static int arp_req_set(struct arpreq *req) +{ + struct arpreq r; + struct arp_table *entry; + struct sockaddr_in *si; + int htype, hlen; + unsigned long ip; + struct rtable *rt; + + memcpy_fromfs(&r, req, sizeof(r)); + + /* We only understand about IP addresses... */ + if (r.arp_pa.sa_family != AF_INET) + return -EPFNOSUPPORT; + + /* + * Find out about the hardware type. + * We have to be compatible with BSD UNIX, so we have to + * assume that a "not set" value (i.e. 0) means Ethernet. + */ + + switch (r.arp_ha.sa_family) { + case ARPHRD_ETHER: + htype = ARPHRD_ETHER; + hlen = ETH_ALEN; + break; + case ARPHRD_ARCNET: + htype = ARPHRD_ARCNET; + hlen = 1; /* length of arcnet addresses */ + break; +#ifdef CONFIG_AX25 + case ARPHRD_AX25: + htype = ARPHRD_AX25; + hlen = 7; + break; +#endif + default: + return -EPFNOSUPPORT; + } + + si = (struct sockaddr_in *) &r.arp_pa; + ip = si->sin_addr.s_addr; + if (ip == 0) + { + printk("ARP: SETARP: requested PA is 0.0.0.0 !\n"); + return -EINVAL; + } + + /* + * Is it reachable directly ? + */ + + rt = ip_rt_route(ip, NULL, NULL); + if (rt == NULL) + return -ENETUNREACH; + + /* + * Is there an existing entry for this address? + */ + + cli(); + + /* + * Find the entry + */ + entry = arp_lookup(ip, 1); + + /* + * Do we need to create a new entry + */ + + if (entry == NULL) + { + unsigned long hash = HASH(ip); + if (r.arp_flags & ATF_PUBL) + hash = PROXY_HASH; + + entry = (struct arp_table *) kmalloc(sizeof(struct arp_table), + GFP_ATOMIC); + if (entry == NULL) + { + sti(); + return -ENOMEM; + } + entry->ip = ip; + entry->hlen = hlen; + entry->htype = htype; + init_timer(&entry->timer); + entry->next = arp_tables[hash]; + arp_tables[hash] = entry; + skb_queue_head_init(&entry->skb); + } + /* + * We now have a pointer to an ARP entry. Update it! + */ + + memcpy(&entry->ha, &r.arp_ha.sa_data, hlen); + entry->last_used = jiffies; + entry->flags = r.arp_flags | ATF_COM; + if ((entry->flags & ATF_PUBL) && (entry->flags & ATF_NETMASK)) + { + si = (struct sockaddr_in *) &r.arp_netmask; + entry->mask = si->sin_addr.s_addr; + } + else + entry->mask = DEF_ARP_NETMASK; + entry->dev = rt->rt_dev; + sti(); + + return 0; +} + + +/* + * Get an ARP cache entry. + */ + +static int arp_req_get(struct arpreq *req) +{ + struct arpreq r; + struct arp_table *entry; + struct sockaddr_in *si; + + /* + * We only understand about IP addresses... + */ + + memcpy_fromfs(&r, req, sizeof(r)); + + if (r.arp_pa.sa_family != AF_INET) + return -EPFNOSUPPORT; + + /* + * Is there an existing entry for this address? + */ + + si = (struct sockaddr_in *) &r.arp_pa; + cli(); + entry = arp_lookup(si->sin_addr.s_addr,0); + + if (entry == NULL) + { + sti(); + return -ENXIO; + } + + /* + * We found it; copy into structure. + */ + + memcpy(r.arp_ha.sa_data, &entry->ha, entry->hlen); + r.arp_ha.sa_family = entry->htype; + r.arp_flags = entry->flags; + sti(); + + /* + * Copy the information back + */ + + memcpy_tofs(req, &r, sizeof(r)); + return 0; +} + + +/* + * Handle an ARP layer I/O control request. + */ + +int arp_ioctl(unsigned int cmd, void *arg) +{ + struct arpreq r; + struct sockaddr_in *si; + int err; + + switch(cmd) + { + case SIOCDARP: + if (!suser()) + return -EPERM; + err = verify_area(VERIFY_READ, arg, sizeof(struct arpreq)); + if(err) + return err; + memcpy_fromfs(&r, arg, sizeof(r)); + if (r.arp_pa.sa_family != AF_INET) + return -EPFNOSUPPORT; + si = (struct sockaddr_in *) &r.arp_pa; + arp_destroy(si->sin_addr.s_addr, 1); + return 0; + case SIOCGARP: + err = verify_area(VERIFY_WRITE, arg, sizeof(struct arpreq)); + if(err) + return err; + return arp_req_get((struct arpreq *)arg); + case SIOCSARP: + if (!suser()) + return -EPERM; + err = verify_area(VERIFY_READ, arg, sizeof(struct arpreq)); + if(err) + return err; + return arp_req_set((struct arpreq *)arg); + default: + return -EINVAL; + } + /*NOTREACHED*/ + return 0; +} + + +/* + * Called once on startup. + */ + +static struct packet_type arp_packet_type = +{ + 0, /* Should be: __constant_htons(ETH_P_ARP) - but this _doesn't_ come out constant! */ + 0, /* copy */ + arp_rcv, + NULL, + NULL +}; + +void arp_init (void) +{ + /* Register the packet type */ + arp_packet_type.type=htons(ETH_P_ARP); + dev_add_pack(&arp_packet_type); + /* Start with the regular checks for expired arp entries. */ + add_timer(&arp_timer); +} + |