r23806: update Samba4 with the latest ctdb code.

This doesn't get the ctdb code fully working in Samba4, it just gets
it building and not breaking non-clustered use of Samba. It will take
a bit longer to update some of the calling ctdb_cluster.c code to make
it work correctly in Samba4.

Note also that Samba4 now only links to the client portion of
ctdb. For the moment I am leaving the ctdbd as a separate daemon,
which you install separately from http://ctdb.samba.org/.
(This used to be commit b196077cbb55cbecad87065133c2d67198e31066)

2 files changed, 964 insertions, 0 deletions

diff --git a/source4/cluster/ctdb/takeover/ctdb_takeover.c b/source4/cluster/ctdb/takeover/ctdb_takeover.c
new file mode 100644
index 0000000000..862382d90a
--- /dev/null
+++ b/source4/cluster/ctdb/takeover/ctdb_takeover.c
@@ -0,0 +1,583 @@
+/* 
+   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 3 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, see <http://www.gnu.org/licenses/>.
+*/
+#include "includes.h"
+#include "lib/events/events.h"
+#include "lib/tdb/include/tdb.h"
+#include "system/network.h"
+#include "system/filesys.h"
+#include "system/wait.h"
+#include "../include/ctdb_private.h"
+
+
+#define TAKEOVER_TIMEOUT() timeval_current_ofs(5,0)
+
+#define CTDB_ARP_INTERVAL 1
+#define CTDB_ARP_REPEAT   3
+
+struct ctdb_takeover_arp {
+	struct ctdb_context *ctdb;
+	uint32_t count;
+	struct sockaddr_in sin;
+	struct ctdb_tcp_list *tcp_list;
+};
+
+/*
+  lists of tcp endpoints
+ */
+struct ctdb_tcp_list {
+	struct ctdb_tcp_list *prev, *next;
+	uint32_t vnn;
+	struct sockaddr_in saddr;
+	struct sockaddr_in daddr;
+};
+
+
+
+/*
+  send a gratuitous arp
+ */
+static void ctdb_control_send_arp(struct event_context *ev, struct timed_event *te, 
+				  struct timeval t, void *private_data)
+{
+	struct ctdb_takeover_arp *arp = talloc_get_type(private_data, 
+							struct ctdb_takeover_arp);
+	int ret;
+	struct ctdb_tcp_list *tcp;
+
+	ret = ctdb_sys_send_arp(&arp->sin, arp->ctdb->takeover.interface);
+	if (ret != 0) {
+		DEBUG(0,(__location__ "sending of arp failed (%s)\n", strerror(errno)));
+	}
+
+	for (tcp=arp->tcp_list;tcp;tcp=tcp->next) {
+		DEBUG(2,("sending tcp tickle ack for %u->%s:%u\n",
+			 (unsigned)ntohs(tcp->daddr.sin_port), 
+			 inet_ntoa(tcp->saddr.sin_addr),
+			 (unsigned)ntohs(tcp->saddr.sin_port)));
+		ret = ctdb_sys_send_ack(&tcp->saddr, &tcp->daddr);
+		if (ret != 0) {
+			DEBUG(0,(__location__ " Failed to send tcp tickle ack for %s\n",
+				 inet_ntoa(tcp->saddr.sin_addr)));
+		}
+	}
+
+	arp->count++;
+
+	if (arp->count == CTDB_ARP_REPEAT) {
+		talloc_free(arp);
+		return;
+	}
+	
+	event_add_timed(arp->ctdb->ev, arp->ctdb->takeover.last_ctx, 
+			timeval_current_ofs(CTDB_ARP_INTERVAL, 0), 
+			ctdb_control_send_arp, arp);
+}
+
+
+/*
+  take over an ip address
+ */
+int32_t ctdb_control_takeover_ip(struct ctdb_context *ctdb, TDB_DATA indata)
+{
+	int ret;
+	struct sockaddr_in *sin = (struct sockaddr_in *)indata.dptr;
+	struct ctdb_takeover_arp *arp;
+	char *ip = inet_ntoa(sin->sin_addr);
+	struct ctdb_tcp_list *tcp;
+
+	if (ctdb_sys_have_ip(ip)) {
+		return 0;
+	}
+
+	DEBUG(0,("Takover of IP %s/%u on interface %s\n", 
+		 ip, ctdb->nodes[ctdb->vnn]->public_netmask_bits, 
+		 ctdb->takeover.interface));
+	ret = ctdb_event_script(ctdb, "takeip %s %s %u",
+				ctdb->takeover.interface, 
+				ip,
+				ctdb->nodes[ctdb->vnn]->public_netmask_bits);
+	if (ret != 0) {
+		DEBUG(0,(__location__ " Failed to takeover IP %s on interface %s\n",
+			 ip, ctdb->takeover.interface));
+		return -1;
+	}
+
+	if (!ctdb->takeover.last_ctx) {
+		ctdb->takeover.last_ctx = talloc_new(ctdb);
+		CTDB_NO_MEMORY(ctdb, ctdb->takeover.last_ctx);
+	}
+
+	arp = talloc_zero(ctdb->takeover.last_ctx, struct ctdb_takeover_arp);
+	CTDB_NO_MEMORY(ctdb, arp);
+	
+	arp->ctdb = ctdb;
+	arp->sin = *sin;
+
+	/* add all of the known tcp connections for this IP to the
+	   list of tcp connections to send tickle acks for */
+	for (tcp=ctdb->tcp_list;tcp;tcp=tcp->next) {
+		if (sin->sin_addr.s_addr == tcp->daddr.sin_addr.s_addr) {
+			struct ctdb_tcp_list *t2 = talloc(arp, struct ctdb_tcp_list);
+			CTDB_NO_MEMORY(ctdb, t2);
+			*t2 = *tcp;
+			DLIST_ADD(arp->tcp_list, t2);
+		}
+	}
+
+	event_add_timed(arp->ctdb->ev, arp->ctdb->takeover.last_ctx, 
+			timeval_zero(), ctdb_control_send_arp, arp);
+
+	return ret;
+}
+
+/*
+  release an ip address
+ */
+int32_t ctdb_control_release_ip(struct ctdb_context *ctdb, TDB_DATA indata)
+{
+	struct sockaddr_in *sin = (struct sockaddr_in *)indata.dptr;
+	TDB_DATA data;
+	char *ip = inet_ntoa(sin->sin_addr);
+	int ret;
+	struct ctdb_tcp_list *tcp;
+
+	if (!ctdb_sys_have_ip(ip)) {
+		return 0;
+	}
+
+	DEBUG(0,("Release of IP %s/%u on interface %s\n", 
+		 ip, ctdb->nodes[ctdb->vnn]->public_netmask_bits, 
+		 ctdb->takeover.interface));
+
+	/* stop any previous arps */
+	talloc_free(ctdb->takeover.last_ctx);
+	ctdb->takeover.last_ctx = NULL;
+
+	ret = ctdb_event_script(ctdb, "releaseip %s %s %u",
+				ctdb->takeover.interface, 
+				ip,
+				ctdb->nodes[ctdb->vnn]->public_netmask_bits);
+	if (ret != 0) {
+		DEBUG(0,(__location__ " Failed to release IP %s on interface %s\n",
+			 ip, ctdb->takeover.interface));
+		return -1;
+	}
+
+	/* send a message to all clients of this node telling them
+	   that the cluster has been reconfigured and they should
+	   release any sockets on this IP */
+	data.dptr = (uint8_t *)ip;
+	data.dsize = strlen(ip)+1;
+
+	ctdb_daemon_send_message(ctdb, ctdb->vnn, CTDB_SRVID_RELEASE_IP, data);
+
+	/* tell other nodes about any tcp connections we were holding with this IP */
+	for (tcp=ctdb->tcp_list;tcp;tcp=tcp->next) {
+		if (tcp->vnn == ctdb->vnn && 
+		    sin->sin_addr.s_addr == tcp->daddr.sin_addr.s_addr) {
+			struct ctdb_control_tcp_vnn t;
+
+			t.vnn  = ctdb->vnn;
+			t.src  = tcp->saddr;
+			t.dest = tcp->daddr;
+
+			data.dptr = (uint8_t *)&t;
+			data.dsize = sizeof(t);
+
+			ctdb_daemon_send_control(ctdb, CTDB_BROADCAST_VNNMAP, 0, 
+						 CTDB_CONTROL_TCP_ADD,
+						 0, CTDB_CTRL_FLAG_NOREPLY, data, NULL, NULL);
+		}
+	}
+
+
+	return 0;
+}
+
+
+/*
+  setup the event script
+*/
+int ctdb_set_event_script(struct ctdb_context *ctdb, const char *script)
+{
+	ctdb->takeover.event_script = talloc_strdup(ctdb, script);
+	CTDB_NO_MEMORY(ctdb, ctdb->takeover.event_script);
+	return 0;
+}
+
+/*
+  setup the public address list from a file
+*/
+int ctdb_set_public_addresses(struct ctdb_context *ctdb, const char *alist)
+{
+	char **lines;
+	int nlines;
+	int i;
+
+	lines = file_lines_load(alist, &nlines, ctdb);
+	if (lines == NULL) {
+		ctdb_set_error(ctdb, "Failed to load public address list '%s'\n", alist);
+		return -1;
+	}
+	while (nlines > 0 && strcmp(lines[nlines-1], "") == 0) {
+		nlines--;
+	}
+
+	if (nlines != ctdb->num_nodes) {
+		DEBUG(0,("Number of lines in %s does not match number of nodes!\n", alist));
+		talloc_free(lines);
+		return -1;
+	}
+
+	for (i=0;i<nlines;i++) {
+		char *p;
+		struct in_addr in;
+
+		ctdb->nodes[i]->public_address = talloc_strdup(ctdb->nodes[i], lines[i]);
+		CTDB_NO_MEMORY(ctdb, ctdb->nodes[i]->public_address);
+		ctdb->nodes[i]->takeover_vnn = -1;
+
+		/* see if they supplied a netmask length */
+		p = strchr(ctdb->nodes[i]->public_address, '/');
+		if (!p) {
+			DEBUG(0,("You must supply a netmask for public address %s\n",
+				 ctdb->nodes[i]->public_address));
+			return -1;
+		}
+		*p = 0;
+		ctdb->nodes[i]->public_netmask_bits = atoi(p+1);
+
+		if (ctdb->nodes[i]->public_netmask_bits > 32) {
+			DEBUG(0, ("Illegal netmask for IP %s\n", ctdb->nodes[i]->public_address));
+			return -1;
+		}
+
+		if (inet_aton(ctdb->nodes[i]->public_address, &in) == 0) {
+			DEBUG(0,("Badly formed IP '%s' in public address list\n", ctdb->nodes[i]->public_address));
+			return -1;
+		}
+	}
+
+	talloc_free(lines);
+	return 0;
+}
+
+/*
+  see if two IPs are on the same subnet
+ */
+static bool ctdb_same_subnet(const char *ip1, const char *ip2, uint8_t netmask_bits)
+{
+	struct in_addr in1, in2;
+	uint32_t mask;
+
+	inet_aton(ip1, &in1);
+	inet_aton(ip2, &in2);
+
+	mask = ~((1LL<<(32-netmask_bits))-1);
+
+	if ((ntohl(in1.s_addr) & mask) != (ntohl(in2.s_addr) & mask)) {
+		return false;
+	}
+
+	return true;
+}
+
+/*
+  make any IP alias changes for public addresses that are necessary 
+ */
+int ctdb_takeover_run(struct ctdb_context *ctdb, struct ctdb_node_map *nodemap)
+{
+	int i, j;
+	int ret;
+
+	/* work out which node will look after each public IP */
+	for (i=0;i<nodemap->num;i++) {
+		if (nodemap->nodes[i].flags & NODE_FLAGS_CONNECTED) {
+			ctdb->nodes[i]->takeover_vnn = nodemap->nodes[i].vnn;
+		} else {
+			/* assign this dead nodes IP to the next higher node */
+			for (j=(i+1)%nodemap->num;
+			     j != i;
+			     j=(j+1)%nodemap->num) {
+				if ((nodemap->nodes[j].flags & NODE_FLAGS_CONNECTED) &&
+				    ctdb_same_subnet(ctdb->nodes[j]->public_address, 
+						     ctdb->nodes[i]->public_address, 
+						     ctdb->nodes[j]->public_netmask_bits)) {
+					ctdb->nodes[i]->takeover_vnn = nodemap->nodes[j].vnn;
+					break;
+				}
+			}
+			if (j == i) {
+				DEBUG(0,(__location__ " No node available on same network to take %s\n",
+					 ctdb->nodes[i]->public_address));
+				ctdb->nodes[i]->takeover_vnn = -1;	
+			}
+		}
+	}	
+
+	/* at this point ctdb->nodes[i]->takeover_vnn is the vnn which will own each IP */
+
+
+	/* now tell all nodes to delete any alias that they should not
+	   have.  This will be a NOOP on nodes that don't currently
+	   hold the given alias */
+	for (i=0;i<nodemap->num;i++) {
+		/* don't talk to unconnected nodes */
+		if (!(nodemap->nodes[i].flags & NODE_FLAGS_CONNECTED)) continue;
+
+		/* tell this node to delete all of the aliases that it should not have */
+		for (j=0;j<nodemap->num;j++) {
+			if (ctdb->nodes[j]->takeover_vnn != nodemap->nodes[i].vnn) {
+				ret = ctdb_ctrl_release_ip(ctdb, TAKEOVER_TIMEOUT(),
+							   nodemap->nodes[i].vnn, 
+							   ctdb->nodes[j]->public_address);
+				if (ret != 0) {
+					DEBUG(0,("Failed to tell vnn %u to release IP %s\n",
+						 nodemap->nodes[i].vnn,
+						 ctdb->nodes[j]->public_address));
+					return -1;
+				}
+			}
+		}
+	}
+
+	/* tell all nodes to get their own IPs */
+	for (i=0;i<nodemap->num;i++) {
+		ret = ctdb_ctrl_takeover_ip(ctdb, TAKEOVER_TIMEOUT(), 
+					    ctdb->nodes[i]->takeover_vnn, 
+					    ctdb->nodes[i]->public_address);
+		if (ret != 0) {
+			DEBUG(0,("Failed asking vnn %u to take over IP %s\n",
+				 ctdb->nodes[i]->takeover_vnn, 
+				 ctdb->nodes[i]->public_address));
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
+
+/*
+  called by a client to inform us of a TCP connection that it is managing
+  that should tickled with an ACK when IP takeover is done
+ */
+int32_t ctdb_control_tcp_client(struct ctdb_context *ctdb, uint32_t client_id, uint32_t vnn,
+				TDB_DATA indata)
+{
+	struct ctdb_client *client = ctdb_reqid_find(ctdb, client_id, struct ctdb_client);
+	struct ctdb_control_tcp *p = (struct ctdb_control_tcp *)indata.dptr;
+	struct ctdb_tcp_list *tcp;
+	struct ctdb_control_tcp_vnn t;
+	int ret;
+	TDB_DATA data;
+
+	tcp = talloc(client, struct ctdb_tcp_list);
+	CTDB_NO_MEMORY(ctdb, tcp);
+
+	tcp->vnn   = vnn;
+	tcp->saddr = p->src;
+	tcp->daddr = p->dest;
+
+	DLIST_ADD(client->tcp_list, tcp);
+
+	t.vnn  = vnn;
+	t.src  = p->src;
+	t.dest = p->dest;
+
+	data.dptr = (uint8_t *)&t;
+	data.dsize = sizeof(t);
+
+	/* tell all nodes about this tcp connection */
+	ret = ctdb_daemon_send_control(ctdb, CTDB_BROADCAST_VNNMAP, 0, 
+				       CTDB_CONTROL_TCP_ADD,
+				       0, CTDB_CTRL_FLAG_NOREPLY, data, NULL, NULL);
+	if (ret != 0) {
+		DEBUG(0,(__location__ " Failed to send CTDB_CONTROL_TCP_ADD\n"));
+		return -1;
+	}
+
+	return 0;
+}
+
+/*
+  see if two sockaddr_in are the same
+ */
+static bool same_sockaddr_in(struct sockaddr_in *in1, struct sockaddr_in *in2)
+{
+	return in1->sin_family == in2->sin_family &&
+		in1->sin_port == in2->sin_port &&
+		in1->sin_addr.s_addr == in2->sin_addr.s_addr;
+}
+
+/*
+  find a tcp address on a list
+ */
+static struct ctdb_tcp_list *ctdb_tcp_find(struct ctdb_tcp_list *list, 
+					   struct ctdb_tcp_list *tcp)
+{
+	while (list) {
+		if (same_sockaddr_in(&list->saddr, &tcp->saddr) &&
+		    same_sockaddr_in(&list->daddr, &tcp->daddr)) {
+			return list;
+		}
+		list = list->next;
+	}
+	return NULL;
+}
+
+/*
+  called by a daemon to inform us of a TCP connection that one of its
+  clients managing that should tickled with an ACK when IP takeover is
+  done
+ */
+int32_t ctdb_control_tcp_add(struct ctdb_context *ctdb, TDB_DATA indata)
+{
+	struct ctdb_control_tcp_vnn *p = (struct ctdb_control_tcp_vnn *)indata.dptr;
+	struct ctdb_tcp_list *tcp;
+
+	tcp = talloc(ctdb, struct ctdb_tcp_list);
+	CTDB_NO_MEMORY(ctdb, tcp);
+
+	tcp->vnn   = p->vnn;
+	tcp->saddr = p->src;
+	tcp->daddr = p->dest;
+
+	if (NULL == ctdb_tcp_find(ctdb->tcp_list, tcp)) {
+		DLIST_ADD(ctdb->tcp_list, tcp);
+		DEBUG(2,("Added tickle info for %s:%u from vnn %u\n",
+			 inet_ntoa(tcp->daddr.sin_addr), ntohs(tcp->daddr.sin_port),
+			 tcp->vnn));
+	} else {
+		DEBUG(4,("Already had tickle info for %s:%u from vnn %u\n",
+			 inet_ntoa(tcp->daddr.sin_addr), ntohs(tcp->daddr.sin_port),
+			 tcp->vnn));
+	}
+
+	return 0;
+}
+
+/*
+  called by a daemon to inform us of a TCP connection that one of its
+  clients managing that should tickled with an ACK when IP takeover is
+  done
+ */
+int32_t ctdb_control_tcp_remove(struct ctdb_context *ctdb, TDB_DATA indata)
+{
+	struct ctdb_control_tcp_vnn *p = (struct ctdb_control_tcp_vnn *)indata.dptr;
+	struct ctdb_tcp_list t, *tcp;
+
+	t.vnn   = p->vnn;
+	t.saddr = p->src;
+	t.daddr = p->dest;
+
+	tcp = ctdb_tcp_find(ctdb->tcp_list, &t);
+	if (tcp) {
+		DEBUG(2,("Removed tickle info for %s:%u from vnn %u\n",
+			 inet_ntoa(tcp->daddr.sin_addr), ntohs(tcp->daddr.sin_port),
+			 tcp->vnn));
+		DLIST_REMOVE(ctdb->tcp_list, tcp);
+		talloc_free(tcp);
+	}
+
+	return 0;
+}
+
+
+/*
+  called when a daemon restarts - wipes all tcp entries from that vnn
+ */
+int32_t ctdb_control_startup(struct ctdb_context *ctdb, uint32_t vnn)
+{
+	struct ctdb_tcp_list *tcp, *next;	
+	for (tcp=ctdb->tcp_list;tcp;tcp=next) {
+		next = tcp->next;
+		if (tcp->vnn == vnn) {
+			DLIST_REMOVE(ctdb->tcp_list, tcp);
+			talloc_free(tcp);
+		}
+
+		/* and tell the new guy about any that he should have
+		   from us */
+		if (tcp->vnn == ctdb->vnn) {
+			struct ctdb_control_tcp_vnn t;
+			TDB_DATA data;
+
+			t.vnn  = tcp->vnn;
+			t.src  = tcp->saddr;
+			t.dest = tcp->daddr;
+
+			data.dptr = (uint8_t *)&t;
+			data.dsize = sizeof(t);
+
+			ctdb_daemon_send_control(ctdb, vnn, 0, 
+						 CTDB_CONTROL_TCP_ADD,
+						 0, CTDB_CTRL_FLAG_NOREPLY, data, NULL, NULL);
+		}
+	}
+	return 0;
+}
+
+
+/*
+  called when a client structure goes away - hook to remove
+  elements from the tcp_list in all daemons
+ */
+void ctdb_takeover_client_destructor_hook(struct ctdb_client *client)
+{
+	while (client->tcp_list) {
+		TDB_DATA data;
+		struct ctdb_control_tcp_vnn p;
+		struct ctdb_tcp_list *tcp = client->tcp_list;
+		DLIST_REMOVE(client->tcp_list, tcp);
+		p.vnn = tcp->vnn;
+		p.src = tcp->saddr;
+		p.dest = tcp->daddr;
+		data.dptr = (uint8_t *)&p;
+		data.dsize = sizeof(p);
+		ctdb_daemon_send_control(client->ctdb, CTDB_BROADCAST_VNNMAP, 0, 
+					 CTDB_CONTROL_TCP_REMOVE,
+					 0, CTDB_CTRL_FLAG_NOREPLY, data, NULL, NULL);
+		talloc_free(tcp);
+	}
+}
+
+
+/*
+  release all IPs on shutdown
+ */
+void ctdb_release_all_ips(struct ctdb_context *ctdb)
+{
+	int i;
+
+	if (!ctdb->takeover.enabled) {
+		return;
+	}
+
+	for (i=0;i<ctdb->num_nodes;i++) {
+		struct ctdb_node *node = ctdb->nodes[i];
+		if (ctdb_sys_have_ip(node->public_address)) {
+			ctdb_event_script(ctdb, "releaseip %s %s %u",
+					  ctdb->takeover.interface, 
+					  node->public_address,
+					  node->public_netmask_bits);
+		}
+	}
+}
diff --git a/source4/cluster/ctdb/takeover/system.c b/source4/cluster/ctdb/takeover/system.c
new file mode 100644
index 0000000000..13f3d1501b
--- /dev/null
+++ b/source4/cluster/ctdb/takeover/system.c
@@ -0,0 +1,381 @@
+/* 
+   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 3 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, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "includes.h"
+#include "system/network.h"
+#include "system/filesys.h"
+#include "system/wait.h"
+#include "../include/ctdb_private.h"
+#include "lib/events/events.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.window   = htons(1234);
+	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 -1;
+	}
+
+	close(s);
+	return 0;
+}
+
+
+/*
+  see if we currently have an interface with the given IP
+
+  we try to bind to it, and if that fails then we don't have that IP
+  on an interface
+ */
+bool ctdb_sys_have_ip(const char *ip)
+{
+	struct sockaddr_in sin;
+	int s;
+	int ret;
+
+	sin.sin_port = 0;
+	inet_aton(ip, &sin.sin_addr);
+	sin.sin_family = AF_INET;
+	s = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
+	if (s == -1) {
+		return false;
+	}
+	ret = bind(s, (struct sockaddr *)&sin, sizeof(sin));
+	close(s);
+	return ret == 0;
+}
+
+/*
+  run the event script - varargs version
+ */
+static int ctdb_event_script_v(struct ctdb_context *ctdb, const char *fmt, va_list ap)
+{
+	char *options, *cmdstr;
+	int ret;
+	va_list ap2;
+	struct stat st;
+
+	if (stat(ctdb->takeover.event_script, &st) != 0 && 
+	    errno == ENOENT) {
+		DEBUG(0,("No event script found at '%s'\n", ctdb->takeover.event_script));
+		return 0;
+	}
+
+	va_copy(ap2, ap);
+	options  = talloc_vasprintf(ctdb, fmt, ap2);
+	va_end(ap2);
+	CTDB_NO_MEMORY(ctdb, options);
+
+	cmdstr = talloc_asprintf(ctdb, "%s %s", ctdb->takeover.event_script, options);
+	CTDB_NO_MEMORY(ctdb, cmdstr);
+
+	ret = system(cmdstr);
+	if (ret != -1) {
+		ret = WEXITSTATUS(ret);
+	}
+
+	talloc_free(cmdstr);
+	talloc_free(options);
+
+	return ret;
+}
+
+/*
+  run the event script
+ */
+int ctdb_event_script(struct ctdb_context *ctdb, const char *fmt, ...)
+{
+	va_list ap;
+	int ret;
+
+	va_start(ap, fmt);
+	ret = ctdb_event_script_v(ctdb, fmt, ap);
+	va_end(ap);
+
+	return ret;
+}
+
+
+struct ctdb_event_script_state {
+	struct ctdb_context *ctdb;
+	pid_t child;
+	void (*callback)(struct ctdb_context *, int);
+	int fd[2];
+};
+
+/* called when child is finished */
+static void ctdb_event_script_handler(struct event_context *ev, struct fd_event *fde, 
+				      uint16_t flags, void *p)
+{
+	struct ctdb_event_script_state *state = 
+		talloc_get_type(p, struct ctdb_event_script_state);
+	int status = -1;
+	waitpid(state->child, &status, 0);
+	if (status != -1) {
+		status = WEXITSTATUS(status);
+	}
+	state->callback(state->ctdb, status);
+	talloc_free(state);
+}
+
+
+/*
+  run the event script in the background, calling the callback when 
+  finished
+ */
+int ctdb_event_script_callback(struct ctdb_context *ctdb, 
+			       void (*callback)(struct ctdb_context *, int),
+			       const char *fmt, ...)
+{
+	struct ctdb_event_script_state *state;
+	va_list ap;
+	int ret;
+
+	state = talloc(ctdb, struct ctdb_event_script_state);
+	CTDB_NO_MEMORY(ctdb, state);
+
+	state->ctdb = ctdb;
+	state->callback = callback;
+	
+	ret = pipe(state->fd);
+	if (ret != 0) {
+		talloc_free(state);
+		return -1;
+	}
+
+	state->child = fork();
+
+	if (state->child == (pid_t)-1) {
+		close(state->fd[0]);
+		close(state->fd[1]);
+		talloc_free(state);
+		return -1;
+	}
+
+	if (state->child == 0) {
+		close(state->fd[0]);
+		va_start(ap, fmt);
+		ret = ctdb_event_script_v(ctdb, fmt, ap);
+		va_end(ap);
+		_exit(ret);
+	}
+
+	close(state->fd[1]);
+
+	event_add_fd(ctdb->ev, state, state->fd[0], EVENT_FD_READ|EVENT_FD_AUTOCLOSE,
+		     ctdb_event_script_handler, state);
+
+	return 0;
+}