samba-mirror/ctdb/takeover/system.c

/* 
   ctdb recovery code

   Copyright (C) Ronnie Sahlberg  2007
   Copyright (C) Andrew Tridgell  2007

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.

   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with this library; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#include "includes.h"
#include "system/network.h"
#include "system/filesys.h"
#include "system/wait.h"
#include "../include/ctdb_private.h"
#include <net/ethernet.h>
#include <net/if_arp.h>



/*
  send gratuitous arp reply after we have taken over an ip address

  saddr is the address we are trying to claim
  iface is the interface name we will be using to claim the address
 */
int ctdb_sys_send_arp(const struct sockaddr_in *saddr, const char *iface)
{
	int s, ret;
	struct sockaddr sa;
	struct ether_header *eh;
	struct arphdr *ah;
	struct ifreq if_hwaddr;
	unsigned char buffer[64]; /*minimum eth frame size */
	char *ptr;

	/* for now, we only handle AF_INET addresses */
	if (saddr->sin_family != AF_INET) {
		DEBUG(0,(__location__ " not an ipv4 address\n"));
		return -1;
	}

	s = socket(AF_INET, SOCK_PACKET, htons(ETHERTYPE_ARP));
	if (s == -1){
		DEBUG(0,(__location__ " failed to open raw socket\n"));
		return -1;
	}

	/* get the mac address */
	strcpy(if_hwaddr.ifr_name, iface);
	ret = ioctl(s, SIOCGIFHWADDR, &if_hwaddr);
	if ( ret < 0 ) {
		close(s);
		DEBUG(0,(__location__ " ioctl failed\n"));
		return -1;
	}
	if (if_hwaddr.ifr_hwaddr.sa_family != AF_LOCAL) {
		close(s);
		DEBUG(0,(__location__ " not an ethernet address\n"));
		return -1;
	}


	memset(buffer, 0 , 64);
	eh = (struct ether_header *)buffer;
	memset(eh->ether_dhost, 0xff, ETH_ALEN);
	memcpy(eh->ether_shost, if_hwaddr.ifr_hwaddr.sa_data, ETH_ALEN);
	eh->ether_type = htons(ETHERTYPE_ARP);

	ah = (struct arphdr *)&buffer[sizeof(struct ether_header)];
	ah->ar_hrd = htons(ARPHRD_ETHER);
	ah->ar_pro = htons(ETH_P_IP);
	ah->ar_hln = ETH_ALEN;
	ah->ar_pln = 4;

	/* send a gratious arp */
	ah->ar_op  = htons(ARPOP_REQUEST);
	ptr = (char *)&ah[1];
	memcpy(ptr, if_hwaddr.ifr_hwaddr.sa_data, ETH_ALEN);
	ptr+=ETH_ALEN;
	memcpy(ptr, &saddr->sin_addr, 4);	  
	ptr+=4;
	memset(ptr, 0, ETH_ALEN); 
	ptr+=ETH_ALEN;
	memcpy(ptr, &saddr->sin_addr, 4);	  
	ptr+=4;

	strncpy(sa.sa_data, iface, sizeof(sa.sa_data));
	ret = sendto(s, buffer, 64, 0, &sa, sizeof(sa));
	if (ret < 0 ){
		close(s);
		DEBUG(0,(__location__ " failed sendto\n"));
		return -1;
	}

	/* send unsolicited arp reply broadcast */
	ah->ar_op  = htons(ARPOP_REPLY);
	ptr = (char *)&ah[1];
	memcpy(ptr, if_hwaddr.ifr_hwaddr.sa_data, ETH_ALEN);
	ptr+=ETH_ALEN;
	memcpy(ptr, &saddr->sin_addr, 4);	  
	ptr+=4;
	memcpy(ptr, if_hwaddr.ifr_hwaddr.sa_data, ETH_ALEN);
	ptr+=ETH_ALEN;
	memcpy(ptr, &saddr->sin_addr, 4);	  
	ptr+=4;

	strncpy(sa.sa_data, iface, sizeof(sa.sa_data));
	ret = sendto(s, buffer, 64, 0, &sa, sizeof(sa));
	if (ret < 0 ){
		DEBUG(0,(__location__ " failed sendto\n"));
		return -1;
	}

	close(s);
	return 0;
}


/*
  uint16 checksum for n bytes
 */
static uint32_t uint16_checksum(uint16_t *data, size_t n)
{
	uint32_t sum=0;
	while (n>=2) {
		sum += (uint32_t)ntohs(*data);
		data++;
		n -= 2;
	}
	if (n == 1) {
		sum += (uint32_t)ntohs(*(uint8_t *)data);
	}
	return sum;
}

/*
  simple TCP checksum - assumes data is multiple of 2 bytes long
 */
static uint16_t tcp_checksum(uint16_t *data, size_t n, struct iphdr *ip)
{
	uint32_t sum = uint16_checksum(data, n);
	uint16_t sum2;
	sum += uint16_checksum((uint16_t *)&ip->saddr, sizeof(ip->saddr));
	sum += uint16_checksum((uint16_t *)&ip->daddr, sizeof(ip->daddr));
	sum += ip->protocol + n;
	sum = (sum & 0xFFFF) + (sum >> 16);
	sum = (sum & 0xFFFF) + (sum >> 16);
	sum2 = htons(sum);
	sum2 = ~sum2;
	if (sum2 == 0) {
		return 0xFFFF;
	}
	return sum2;
}

/*
  send tcp ack packet from the specified IP/port to the specified
  destination IP/port. 

  This is used to trigger the receiving host into sending its own ACK,
  which should trigger early detection of TCP reset by the client
  after IP takeover
 */
int ctdb_sys_send_ack(const struct sockaddr_in *dest, 
		      const struct sockaddr_in *src)
{
	int s, ret;
	uint32_t one = 1;
	struct {
		struct iphdr ip;
		struct tcphdr tcp;
	} pkt;

	/* for now, we only handle AF_INET addresses */
	if (src->sin_family != AF_INET || dest->sin_family != AF_INET) {
		DEBUG(0,(__location__ " not an ipv4 address\n"));
		return -1;
	}

	s = socket(AF_INET, SOCK_RAW, htons(IPPROTO_RAW));
	if (s == -1) {
		DEBUG(0,(__location__ " failed to open raw socket (%s)\n",
			 strerror(errno)));
		return -1;
	}

	ret = setsockopt(s, SOL_IP, IP_HDRINCL, &one, sizeof(one));
	if (ret != 0) {
		DEBUG(0,(__location__ " failed to setup IP headers (%s)\n",
			 strerror(errno)));
		close(s);
		return -1;
	}

	ZERO_STRUCT(pkt);
	pkt.ip.version  = 4;
	pkt.ip.ihl      = sizeof(pkt.ip)/4;
	pkt.ip.tot_len  = htons(sizeof(pkt));
	pkt.ip.ttl      = 255;
	pkt.ip.protocol = IPPROTO_TCP;
	pkt.ip.saddr    = src->sin_addr.s_addr;
	pkt.ip.daddr    = dest->sin_addr.s_addr;
	pkt.ip.check    = 0;

	pkt.tcp.source   = src->sin_port;
	pkt.tcp.dest     = dest->sin_port;
	pkt.tcp.ack      = 1;
	pkt.tcp.doff     = sizeof(pkt.tcp)/4;
	pkt.tcp.check    = tcp_checksum((uint16_t *)&pkt.tcp, sizeof(pkt.tcp), &pkt.ip);

	ret = sendto(s, &pkt, sizeof(pkt), 0, dest, sizeof(*dest));
	if (ret != sizeof(pkt)) {
		DEBUG(0,(__location__ " failed sendto (%s)\n", strerror(errno)));
	}
	close(s);

	return ret;
}



/*
  takeover an IP on an interface
 */
int ctdb_sys_take_ip(const char *ip, const char *interface)
{
	char *cmdstr;
	cmdstr = talloc_asprintf(NULL, "/sbin/ip addr add %s/32 dev %s 2> /dev/null",
				 ip, interface);
	if (cmdstr == NULL) {
		return -1;
	}
	system(cmdstr);
	talloc_free(cmdstr);
	return 0;
}

/*
  release an IP on an interface
 */
int ctdb_sys_release_ip(const char *ip, const char *interface)
{
	char *cmdstr;
	cmdstr = talloc_asprintf(NULL, "/sbin/ip addr del %s/32 dev %s 2> /dev/null",
				 ip, interface);
	if (cmdstr == NULL) {
		return -1;
	}
	system(cmdstr);
	talloc_free(cmdstr);
	return 0;
}