path: root/usr.sbin/nsd/ipc.c

/*
 * ipc.c - Interprocess communication routines. Handlers read and write.
 *
 * Copyright (c) 2001-2011, NLnet Labs. All rights reserved.
 *
 * See LICENSE for the license.
 *
 */

#include "config.h"
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include "ipc.h"
#include "buffer.h"
#include "xfrd-tcp.h"
#include "nsd.h"
#include "namedb.h"
#include "xfrd.h"
#include "xfrd-notify.h"

/* set is_ok for the zone according to the zone message */
static zone_type* handle_xfrd_zone_state(struct nsd* nsd, buffer_type* packet);
/* write ipc ZONE_STATE message into the buffer */
static void write_zone_state_packet(buffer_type* packet, zone_type* zone);
/* attempt to send NSD_STATS command to child fd */
static void send_stat_to_child(struct main_ipc_handler_data* data, int fd);
/* write IPC expire notification msg to a buffer */
static void xfrd_write_expire_notification(buffer_type* buffer, xfrd_zone_t* zone);
/* send reload request over the IPC channel */
static void xfrd_send_reload_req(xfrd_state_t* xfrd);
/* send quit request over the IPC channel */
static void xfrd_send_quit_req(xfrd_state_t* xfrd);
/* get SOA INFO out of IPC packet buffer */
static void xfrd_handle_ipc_SOAINFO(xfrd_state_t* xfrd, buffer_type* packet);
/* perform read part of handle ipc for xfrd */
static void xfrd_handle_ipc_read(netio_handler_type *handler, xfrd_state_t* xfrd);

static zone_type*
handle_xfrd_zone_state(struct nsd* nsd, buffer_type* packet)
{
	uint8_t ok;
	const dname_type *dname;
	domain_type *domain;
	zone_type *zone;

	ok = buffer_read_u8(packet);
	dname = (dname_type*)buffer_current(packet);
	DEBUG(DEBUG_IPC,1, (LOG_INFO, "handler zone state %s is %s",
		dname_to_string(dname, NULL), ok?"ok":"expired"));
	/* find in zone_types, if does not exist, we cannot serve anyway */
	/* find zone in config, since that one always exists */
	domain = domain_table_find(nsd->db->domains, dname);
	if(!domain) {
		DEBUG(DEBUG_IPC,1, (LOG_INFO, "zone state msg, empty zone (domain %s)",
			dname_to_string(dname, NULL)));
		return NULL;
	}
	zone = domain_find_zone(domain);
	if(!zone || dname_compare(domain_dname(zone->apex), dname) != 0) {
		DEBUG(DEBUG_IPC,1, (LOG_INFO, "zone state msg, empty zone (zone %s)",
			dname_to_string(dname, NULL)));
		return NULL;
	}
	assert(zone);
	/* only update zone->is_ok if needed to minimize copy-on-write
	   of memory pages shared after fork() */
	if(ok && !zone->is_ok)
		zone->is_ok = 1;
	if(!ok && zone->is_ok)
		zone->is_ok = 0;
	return zone;
}

void
child_handle_parent_command(netio_type *ATTR_UNUSED(netio),
		      netio_handler_type *handler,
		      netio_event_types_type event_types)
{
	sig_atomic_t mode;
	int len;
	struct ipc_handler_conn_data *data =
		(struct ipc_handler_conn_data *) handler->user_data;
	if (!(event_types & NETIO_EVENT_READ)) {
		return;
	}

	if(data->conn->is_reading) {
		int ret = conn_read(data->conn);
		if(ret == -1) {
			log_msg(LOG_ERR, "handle_parent_command: error in conn_read: %s",
				strerror(errno));
			data->conn->is_reading = 0;
			return;
		}
		if(ret == 0) {
			return; /* continue later */
		}
		/* completed */
		data->conn->is_reading = 0;
		buffer_flip(data->conn->packet);
		(void)handle_xfrd_zone_state(data->nsd, data->conn->packet);
		return;
	}

	if ((len = read(handler->fd, &mode, sizeof(mode))) == -1) {
		log_msg(LOG_ERR, "handle_parent_command: read: %s",
			strerror(errno));
		return;
	}
	if (len == 0)
	{
		/* parent closed the connection. Quit */
		data->nsd->mode = NSD_QUIT;
		return;
	}

	switch (mode) {
	case NSD_STATS:
	case NSD_QUIT:
		data->nsd->mode = mode;
		break;
	case NSD_ZONE_STATE:
		data->conn->is_reading = 1;
		data->conn->total_bytes = 0;
		data->conn->msglen = 0;
		data->conn->fd = handler->fd;
		buffer_clear(data->conn->packet);
		break;
	default:
		log_msg(LOG_ERR, "handle_parent_command: bad mode %d",
			(int) mode);
		break;
	}
}

void
parent_handle_xfrd_command(netio_type *ATTR_UNUSED(netio),
		      netio_handler_type *handler,
		      netio_event_types_type event_types)
{
	sig_atomic_t mode;
	int len;
	struct ipc_handler_conn_data *data =
		(struct ipc_handler_conn_data *) handler->user_data;
	if (!(event_types & NETIO_EVENT_READ)) {
		return;
	}

	if(data->conn->is_reading) {
		/* handle ZONE_STATE forward to children */
		int ret = conn_read(data->conn);
		size_t i;
		zone_type* zone;
		if(ret == -1) {
			log_msg(LOG_ERR, "main xfrd listener: error in conn_read: %s",
				strerror(errno));
			data->conn->is_reading = 0;
			return;
		}
		if(ret == 0) {
			return; /* continue later */
		}
		/* completed */
		data->conn->is_reading = 0;
		buffer_flip(data->conn->packet);
		zone = handle_xfrd_zone_state(data->nsd, data->conn->packet);
		if(!zone)
			return;
		/* forward to all children */
		for (i = 0; i < data->nsd->child_count; ++i) {
			if(!zone->dirty[i]) {
				zone->dirty[i] = 1;
				stack_push(data->nsd->children[i].dirty_zones, zone);
				data->nsd->children[i].handler->event_types |=
					NETIO_EVENT_WRITE;
			}
		}
		return;
	}

	if ((len = read(handler->fd, &mode, sizeof(mode))) == -1) {
		log_msg(LOG_ERR, "handle_xfrd_command: read: %s",
			strerror(errno));
		return;
	}
	if (len == 0)
	{
		DEBUG(DEBUG_IPC,1, (LOG_ERR, "handle_xfrd_command: xfrd closed channel."));
		close(handler->fd);
		handler->fd = -1;
		return;
	}

	switch (mode) {
	case NSD_RELOAD:
		data->nsd->signal_hint_reload = 1;
		break;
	case NSD_QUIT:
		data->nsd->mode = mode;
		break;
	case NSD_REAP_CHILDREN:
		data->nsd->signal_hint_child = 1;
		break;
	case NSD_ZONE_STATE:
		data->conn->is_reading = 1;
		data->conn->total_bytes = 0;
		data->conn->msglen = 0;
		data->conn->fd = handler->fd;
		buffer_clear(data->conn->packet);
		break;
	default:
		log_msg(LOG_ERR, "handle_xfrd_command: bad mode %d",
			(int) mode);
		break;
	}
}

static void
write_zone_state_packet(buffer_type* packet, zone_type* zone)
{
	sig_atomic_t cmd = NSD_ZONE_STATE;
	uint8_t ok = zone->is_ok;
	uint16_t sz;
	if(!zone->apex) {
		return;
	}
	sz = dname_total_size(domain_dname(zone->apex)) + 1;
	sz = htons(sz);

	buffer_clear(packet);
	buffer_write(packet, &cmd, sizeof(cmd));
	buffer_write(packet, &sz, sizeof(sz));
	buffer_write(packet, &ok, sizeof(ok));
	buffer_write(packet, domain_dname(zone->apex),
		dname_total_size(domain_dname(zone->apex)));
	buffer_flip(packet);
}

static void
send_stat_to_child(struct main_ipc_handler_data* data, int fd)
{
	sig_atomic_t cmd = NSD_STATS;
	if(write(fd, &cmd, sizeof(cmd)) == -1) {
		if(errno == EAGAIN || errno == EINTR)
			return; /* try again later */
		log_msg(LOG_ERR, "svrmain: problems sending stats to child %d command: %s",
			(int)data->child->pid, strerror(errno));
		return;
	}
	data->child->need_to_send_STATS = 0;
}

int packet_read_query_section(buffer_type *packet, uint8_t* dest, uint16_t* qtype, uint16_t* qclass);
static void
debug_print_fwd_name(int ATTR_UNUSED(len), buffer_type* packet, int acl_num)
{
	uint8_t qnamebuf[MAXDOMAINLEN];
	uint16_t qtype, qclass;
	const dname_type* dname;
	region_type* tempregion = region_create(xalloc, free);

	size_t bufpos = buffer_position(packet);
	buffer_rewind(packet);
	buffer_skip(packet, 12);
	if(packet_read_query_section(packet, qnamebuf, &qtype, &qclass)) {
		dname = dname_make(tempregion, qnamebuf, 1);
		log_msg(LOG_INFO, "main: fwd packet for %s, acl %d",
			dname_to_string(dname,0), acl_num);
	} else {
		log_msg(LOG_INFO, "main: fwd packet badqname, acl %d", acl_num);
	}
	buffer_set_position(packet, bufpos);
	region_destroy(tempregion);
}

static void
send_quit_to_child(struct main_ipc_handler_data* data, int fd)
{
	sig_atomic_t cmd = NSD_QUIT;
	if(write(fd, &cmd, sizeof(cmd)) == -1) {
		if(errno == EAGAIN || errno == EINTR)
			return; /* try again later */
		log_msg(LOG_ERR, "svrmain: problems sending quit to child %d command: %s",
			(int)data->child->pid, strerror(errno));
		return;
	}
	data->child->need_to_send_QUIT = 0;
	DEBUG(DEBUG_IPC,2, (LOG_INFO, "main: sent quit to child %d",
		(int)data->child->pid));
}

void
parent_handle_child_command(netio_type *ATTR_UNUSED(netio),
		      netio_handler_type *handler,
		      netio_event_types_type event_types)
{
	sig_atomic_t mode;
	int len;
	struct main_ipc_handler_data *data =
		(struct main_ipc_handler_data*)handler->user_data;

	/* do a nonblocking write to the child if it is ready. */
	if (event_types & NETIO_EVENT_WRITE) {
		if(!data->busy_writing_zone_state &&
			!data->child->need_to_send_STATS &&
			!data->child->need_to_send_QUIT &&
			!data->child->need_to_exit &&
			data->child->dirty_zones->num > 0) {
			/* create packet from next dirty zone */
			zone_type* zone = (zone_type*)stack_pop(data->child->dirty_zones);
			assert(zone);
			zone->dirty[data->child_num] = 0;
			data->busy_writing_zone_state = 1;
			write_zone_state_packet(data->write_conn->packet, zone);
			data->write_conn->msglen = buffer_limit(data->write_conn->packet);
			data->write_conn->total_bytes = sizeof(uint16_t); /* len bytes already in packet */
			data->write_conn->fd = handler->fd;
		}
		if(data->busy_writing_zone_state) {
			/* write more of packet */
			int ret = conn_write(data->write_conn);
			if(ret == -1) {
				log_msg(LOG_ERR, "handle_child_cmd %d: could not write: %s",
					(int)data->child->pid, strerror(errno));
				data->busy_writing_zone_state = 0;
			} else if(ret == 1) {
				data->busy_writing_zone_state = 0; /* completed */
			}
		} else if(data->child->need_to_send_STATS &&
			  !data->child->need_to_exit) {
			send_stat_to_child(data, handler->fd);
		} else if(data->child->need_to_send_QUIT) {
			send_quit_to_child(data, handler->fd);
			if(!data->child->need_to_send_QUIT)
				handler->event_types = NETIO_EVENT_READ;
		}
		if(!data->busy_writing_zone_state &&
			!data->child->need_to_send_STATS &&
			!data->child->need_to_send_QUIT &&
			data->child->dirty_zones->num == 0) {
			handler->event_types = NETIO_EVENT_READ;
		}
	}

	if (!(event_types & NETIO_EVENT_READ)) {
		return;
	}

	if (data->forward_mode) {
		int got_acl;
		/* forward the data to xfrd */
		DEBUG(DEBUG_IPC,2, (LOG_INFO,
			"main passed packet readup %d", (int)data->got_bytes));
		if(data->got_bytes < sizeof(data->total_bytes))
		{
			if ((len = read(handler->fd,
				(char*)&data->total_bytes+data->got_bytes,
				sizeof(data->total_bytes)-data->got_bytes)) == -1) {
				log_msg(LOG_ERR, "handle_child_command: read: %s",
					strerror(errno));
				return;
			}
			if(len == 0) {
				/* EOF */
				data->forward_mode = 0;
				return;
			}
			data->got_bytes += len;
			if(data->got_bytes < sizeof(data->total_bytes))
				return;
			data->total_bytes = ntohs(data->total_bytes);
			buffer_clear(data->packet);
			if(data->total_bytes > buffer_capacity(data->packet)) {
				log_msg(LOG_ERR, "internal error: ipc too large");
				exit(1);
			}
			return;
		}
		/* read the packet */
		if(data->got_bytes-sizeof(data->total_bytes) < data->total_bytes) {
			if((len = read(handler->fd, buffer_current(data->packet),
				data->total_bytes - (data->got_bytes-sizeof(data->total_bytes))
				)) == -1 ) {
				log_msg(LOG_ERR, "handle_child_command: read: %s",
					strerror(errno));
				return;
			}
			if(len == 0) {
				/* EOF */
				data->forward_mode = 0;
				return;
			}
			data->got_bytes += len;
			buffer_skip(data->packet, len);
			/* read rest later */
			return;
		}
		/* read the acl number */
		got_acl = data->got_bytes - sizeof(data->total_bytes) - data->total_bytes;
		if((len = read(handler->fd, (char*)&data->acl_num+got_acl,
			sizeof(data->acl_num)-got_acl)) == -1 ) {
			log_msg(LOG_ERR, "handle_child_command: read: %s",
				strerror(errno));
			return;
		}
		if(len == 0) {
			/* EOF */
			data->forward_mode = 0;
			return;
		}
		got_acl += len;
		data->got_bytes += len;
		if(got_acl >= (int)sizeof(data->acl_num)) {
			uint16_t len = htons(data->total_bytes);
			DEBUG(DEBUG_IPC,2, (LOG_INFO,
				"main fwd passed packet write %d", (int)data->got_bytes));
#ifndef NDEBUG
			if(nsd_debug_level >= 2)
				debug_print_fwd_name(len, data->packet, data->acl_num);
#endif
			data->forward_mode = 0;
			mode = NSD_PASS_TO_XFRD;
			if(!write_socket(*data->xfrd_sock, &mode, sizeof(mode)) ||
			   !write_socket(*data->xfrd_sock, &len, sizeof(len)) ||
			   !write_socket(*data->xfrd_sock, buffer_begin(data->packet),
				data->total_bytes) ||
			   !write_socket(*data->xfrd_sock, &data->acl_num,
			   	sizeof(data->acl_num))) {
				log_msg(LOG_ERR, "error in ipc fwd main2xfrd: %s",
					strerror(errno));
			}
		}
		return;
	}

	/* read command from ipc */
	if ((len = read(handler->fd, &mode, sizeof(mode))) == -1) {
		log_msg(LOG_ERR, "handle_child_command: read: %s",
			strerror(errno));
		return;
	}
	if (len == 0)
	{
		size_t i;
		if(handler->fd != -1) close(handler->fd);
		for(i=0; i<data->nsd->child_count; ++i)
			if(data->nsd->children[i].child_fd == handler->fd) {
				data->nsd->children[i].child_fd = -1;
				data->nsd->children[i].has_exited = 1;
				DEBUG(DEBUG_IPC,1, (LOG_INFO,
					"server %d closed cmd channel",
					(int) data->nsd->children[i].pid));
			}
		handler->fd = -1;
		parent_check_all_children_exited(data->nsd);
		return;
	}

	switch (mode) {
	case NSD_QUIT:
		data->nsd->mode = mode;
		break;
	case NSD_STATS:
		data->nsd->signal_hint_stats = 1;
		break;
	case NSD_REAP_CHILDREN:
		data->nsd->signal_hint_child = 1;
		break;
	case NSD_PASS_TO_XFRD:
		/* set mode for handle_child_command; echo to xfrd. */
		data->forward_mode = 1;
		data->got_bytes = 0;
		data->total_bytes = 0;
		break;
	default:
		log_msg(LOG_ERR, "handle_child_command: bad mode %d",
			(int) mode);
		break;
	}
}

void
parent_check_all_children_exited(struct nsd* nsd)
{
	size_t i;
	for(i=0; i < nsd->child_count; i++) {
		if(!nsd->children[i].need_to_exit)
		      return;
		if(!nsd->children[i].has_exited)
		      return;
	}
	nsd->mode = NSD_QUIT_SYNC;
	DEBUG(DEBUG_IPC,2, (LOG_INFO, "main: all children exited. quit sync."));
}

void
parent_handle_reload_command(netio_type *ATTR_UNUSED(netio),
		      netio_handler_type *handler,
		      netio_event_types_type event_types)
{
	sig_atomic_t mode;
	int len;
	size_t i;
	struct nsd *nsd = (struct nsd*) handler->user_data;
	if (!(event_types & NETIO_EVENT_READ)) {
		return;
	}
	/* read command from ipc */
	if ((len = read(handler->fd, &mode, sizeof(mode))) == -1) {
		log_msg(LOG_ERR, "handle_reload_command: read: %s",
			strerror(errno));
		return;
	}
	if (len == 0)
	{
		if(handler->fd != -1) {
			close(handler->fd);
			handler->fd = -1;
		}
		log_msg(LOG_ERR, "handle_reload_cmd: reload closed cmd channel");
		return;
	}
	switch (mode) {
	case NSD_QUIT_SYNC:
		/* set all children to exit, only then notify xfrd. */
		/* so that buffered packets to pass to xfrd can arrive. */
		for(i=0; i < nsd->child_count; i++) {
			nsd->children[i].need_to_exit = 1;
			if(nsd->children[i].pid > 0 &&
			   nsd->children[i].child_fd != -1) {
				nsd->children[i].need_to_send_QUIT = 1;
				nsd->children[i].handler->event_types
					|= NETIO_EVENT_WRITE;
			} else {
				if(nsd->children[i].child_fd == -1)
					nsd->children[i].has_exited = 1;
			}
		}
		parent_check_all_children_exited(nsd);
		break;
	default:
		log_msg(LOG_ERR, "handle_reload_command: bad mode %d",
			(int) mode);
		break;
	}
}

static void
xfrd_write_expire_notification(buffer_type* buffer, xfrd_zone_t* zone)
{
	sig_atomic_t cmd = NSD_ZONE_STATE;
	uint8_t ok = 1;
	uint16_t sz = dname_total_size(zone->apex) + 1;
	sz = htons(sz);
	if(zone->state == xfrd_zone_expired)
		ok = 0;

	DEBUG(DEBUG_IPC,1, (LOG_INFO,
		"xfrd encoding ipc zone state msg for zone %s state %d.",
		zone->apex_str, (int)zone->state));

	buffer_clear(buffer);
	buffer_write(buffer, &cmd, sizeof(cmd));
	buffer_write(buffer, &sz, sizeof(sz));
	buffer_write(buffer, &ok, sizeof(ok));
	buffer_write(buffer, zone->apex, dname_total_size(zone->apex));
	buffer_flip(buffer);
}

static void
xfrd_send_reload_req(xfrd_state_t* xfrd)
{
	sig_atomic_t req = NSD_RELOAD;
	/* ask server_main for a reload */
	if(write(xfrd->ipc_handler.fd, &req, sizeof(req)) == -1) {
		if(errno == EAGAIN || errno == EINTR)
			return; /* try again later */
		log_msg(LOG_ERR, "xfrd: problems sending reload command: %s",
			strerror(errno));
		return;
	}
	DEBUG(DEBUG_IPC,1, (LOG_INFO, "xfrd: asked nsd to reload new updates"));
	xfrd_prepare_zones_for_reload();
	xfrd->reload_cmd_last_sent = xfrd_time();
	xfrd->need_to_send_reload = 0;
	xfrd->can_send_reload = 0;
}

static void
xfrd_send_quit_req(xfrd_state_t* xfrd)
{
	sig_atomic_t cmd = NSD_QUIT;
	xfrd->ipc_send_blocked = 1;
	xfrd->ipc_handler.event_types &= (~NETIO_EVENT_WRITE);
	xfrd->sending_zone_state = 0;
	DEBUG(DEBUG_IPC,1, (LOG_INFO, "xfrd: ipc send ackreload(quit)"));
	if(write_socket(xfrd->ipc_handler.fd, &cmd, sizeof(cmd)) == -1) {
		log_msg(LOG_ERR, "xfrd: error writing ack to main: %s",
			strerror(errno));
	}
	xfrd->need_to_send_quit = 0;
}

static void
xfrd_handle_ipc_SOAINFO(xfrd_state_t* xfrd, buffer_type* packet)
{
	xfrd_soa_t soa;
	xfrd_soa_t* soa_ptr = &soa;
	xfrd_zone_t* zone;
	/* dname is sent in memory format */
	const dname_type* dname = (const dname_type*)buffer_begin(packet);

	/* find zone and decode SOA */
	zone = (xfrd_zone_t*)rbtree_search(xfrd->zones, dname);
	buffer_skip(packet, dname_total_size(dname));

	if(!buffer_available(packet, sizeof(uint32_t)*6 + sizeof(uint8_t)*2)) {
		/* NSD has zone without any info */
		DEBUG(DEBUG_IPC,1, (LOG_INFO, "SOAINFO for %s lost zone",
			dname_to_string(dname,0)));
		soa_ptr = NULL;
	} else {
		/* read soa info */
		memset(&soa, 0, sizeof(soa));
		/* left out type, klass, count for speed */
		soa.type = htons(TYPE_SOA);
		soa.klass = htons(CLASS_IN);
		soa.ttl = htonl(buffer_read_u32(packet));
		soa.rdata_count = htons(7);
		soa.prim_ns[0] = buffer_read_u8(packet);
		if(!buffer_available(packet, soa.prim_ns[0]))
			return;
		buffer_read(packet, soa.prim_ns+1, soa.prim_ns[0]);
		soa.email[0] = buffer_read_u8(packet);
		if(!buffer_available(packet, soa.email[0]))
			return;
		buffer_read(packet, soa.email+1, soa.email[0]);

		soa.serial = htonl(buffer_read_u32(packet));
		soa.refresh = htonl(buffer_read_u32(packet));
		soa.retry = htonl(buffer_read_u32(packet));
		soa.expire = htonl(buffer_read_u32(packet));
		soa.minimum = htonl(buffer_read_u32(packet));
		DEBUG(DEBUG_IPC,1, (LOG_INFO, "SOAINFO for %s %u",
			dname_to_string(dname,0), ntohl(soa.serial)));
	}

	if(!zone) {
		DEBUG(DEBUG_IPC,1, (LOG_INFO, "xfrd: zone %s master zone updated",
			dname_to_string(dname,0)));
		notify_handle_master_zone_soainfo(xfrd->notify_zones,
			dname, soa_ptr);
		return;
	}
	xfrd_handle_incoming_soa(zone, soa_ptr, xfrd_time());
}

void
xfrd_handle_ipc(netio_type* ATTR_UNUSED(netio),
	netio_handler_type *handler,
	netio_event_types_type event_types)
{
	xfrd_state_t* xfrd = (xfrd_state_t*)handler->user_data;
        if ((event_types & NETIO_EVENT_READ))
	{
		/* first attempt to read as a signal from main
		 * could block further send operations */
		xfrd_handle_ipc_read(handler, xfrd);
	}
        if ((event_types & NETIO_EVENT_WRITE))
	{
		if(xfrd->ipc_send_blocked) { /* wait for SOA_END */
			handler->event_types = NETIO_EVENT_READ;
			return;
		}
		/* if necessary prepare a packet */
		if(!(xfrd->can_send_reload && xfrd->need_to_send_reload) &&
			!xfrd->need_to_send_quit &&
			!xfrd->sending_zone_state &&
			xfrd->dirty_zones->num > 0) {
			xfrd_zone_t* zone = (xfrd_zone_t*)stack_pop(xfrd->dirty_zones);
			assert(zone);
			zone->dirty = 0;
			xfrd->sending_zone_state = 1;
			xfrd_write_expire_notification(xfrd->ipc_conn_write->packet, zone);
			xfrd->ipc_conn_write->msglen = buffer_limit(xfrd->ipc_conn_write->packet);
			/* skip length bytes; they are encoded in the packet, after cmd */
			xfrd->ipc_conn_write->total_bytes = sizeof(uint16_t);
		}
		/* write a bit */
		if(xfrd->sending_zone_state) {
			/* call conn_write */
			int ret = conn_write(xfrd->ipc_conn_write);
			if(ret == -1) {
				log_msg(LOG_ERR, "xfrd: error in write ipc: %s", strerror(errno));
				xfrd->sending_zone_state = 0;
			}
			else if(ret == 1) { /* done */
				xfrd->sending_zone_state = 0;
			}
		} else if(xfrd->need_to_send_quit) {
			xfrd_send_quit_req(xfrd);
		} else if(xfrd->can_send_reload && xfrd->need_to_send_reload) {
			xfrd_send_reload_req(xfrd);
		}
		if(!(xfrd->can_send_reload && xfrd->need_to_send_reload) &&
			!xfrd->need_to_send_quit &&
			!xfrd->sending_zone_state &&
			xfrd->dirty_zones->num == 0) {
			handler->event_types = NETIO_EVENT_READ; /* disable writing for now */
		}
	}

}

static void
xfrd_handle_ipc_read(netio_handler_type *handler, xfrd_state_t* xfrd)
{
        sig_atomic_t cmd;
        int len;

	if(xfrd->ipc_conn->is_reading==2) {
		buffer_type* tmp = xfrd->ipc_pass;
		uint32_t acl_num;
		/* read acl_num */
		int ret = conn_read(xfrd->ipc_conn);
		if(ret == -1) {
			log_msg(LOG_ERR, "xfrd: error in read ipc: %s", strerror(errno));
			xfrd->ipc_conn->is_reading = 0;
			return;
		}
		if(ret == 0)
			return;
		buffer_flip(xfrd->ipc_conn->packet);
		xfrd->ipc_pass = xfrd->ipc_conn->packet;
		xfrd->ipc_conn->packet = tmp;
		xfrd->ipc_conn->is_reading = 0;
		acl_num = buffer_read_u32(xfrd->ipc_pass);
		xfrd_handle_passed_packet(xfrd->ipc_conn->packet, acl_num);
		return;
	}
	if(xfrd->ipc_conn->is_reading) {
		/* reading an IPC message */
		int ret = conn_read(xfrd->ipc_conn);
		if(ret == -1) {
			log_msg(LOG_ERR, "xfrd: error in read ipc: %s", strerror(errno));
			xfrd->ipc_conn->is_reading = 0;
			return;
		}
		if(ret == 0)
			return;
		buffer_flip(xfrd->ipc_conn->packet);
		if(xfrd->ipc_is_soa) {
			xfrd->ipc_conn->is_reading = 0;
			xfrd_handle_ipc_SOAINFO(xfrd, xfrd->ipc_conn->packet);
		} else 	{
			/* use ipc_conn to read remaining data as well */
			buffer_type* tmp = xfrd->ipc_pass;
			xfrd->ipc_conn->is_reading=2;
			xfrd->ipc_pass = xfrd->ipc_conn->packet;
			xfrd->ipc_conn->packet = tmp;
			xfrd->ipc_conn->total_bytes = sizeof(xfrd->ipc_conn->msglen);
			xfrd->ipc_conn->msglen = sizeof(uint32_t);
			buffer_clear(xfrd->ipc_conn->packet);
			buffer_set_limit(xfrd->ipc_conn->packet, xfrd->ipc_conn->msglen);
		}
		return;
	}

        if((len = read(handler->fd, &cmd, sizeof(cmd))) == -1) {
                log_msg(LOG_ERR, "xfrd_handle_ipc: read: %s",
                        strerror(errno));
                return;
        }
        if(len == 0)
        {
		/* parent closed the connection. Quit */
		DEBUG(DEBUG_IPC,1, (LOG_INFO, "xfrd: main closed connection."));
		xfrd->shutdown = 1;
		return;
        }

        switch(cmd) {
        case NSD_QUIT:
        case NSD_SHUTDOWN:
		DEBUG(DEBUG_IPC,1, (LOG_INFO, "xfrd: main send shutdown cmd."));
                xfrd->shutdown = 1;
                break;
	case NSD_SOA_BEGIN:
		DEBUG(DEBUG_IPC,1, (LOG_INFO, "xfrd: ipc recv SOA_BEGIN"));
		/* reload starts sending SOA INFOs; don't block */
		xfrd->parent_soa_info_pass = 1;
		/* reset the nonblocking ipc write;
		   the new parent does not want half a packet */
		xfrd->sending_zone_state = 0;
		break;
	case NSD_SOA_INFO:
		DEBUG(DEBUG_IPC,1, (LOG_INFO, "xfrd: ipc recv SOA_INFO"));
		assert(xfrd->parent_soa_info_pass);
		xfrd->ipc_is_soa = 1;
		xfrd->ipc_conn->is_reading = 1;
                break;
	case NSD_SOA_END:
		/* reload has finished */
		DEBUG(DEBUG_IPC,1, (LOG_INFO, "xfrd: ipc recv SOA_END"));
		xfrd->can_send_reload = 1;
		xfrd->parent_soa_info_pass = 0;
		xfrd->ipc_send_blocked = 0;
		handler->event_types |= NETIO_EVENT_WRITE;
		xfrd_reopen_logfile();
		xfrd_check_failed_updates();
		xfrd_send_expy_all_zones();
		break;
	case NSD_PASS_TO_XFRD:
		DEBUG(DEBUG_IPC,1, (LOG_INFO, "xfrd: ipc recv PASS_TO_XFRD"));
		xfrd->ipc_is_soa = 0;
		xfrd->ipc_conn->is_reading = 1;
		break;
	case NSD_RELOAD:
		/* main tells us that reload is done, stop ipc send to main */
		DEBUG(DEBUG_IPC,1, (LOG_INFO, "xfrd: ipc recv RELOAD"));
		handler->event_types |= NETIO_EVENT_WRITE;
		xfrd->need_to_send_quit = 1;
		break;
        default:
                log_msg(LOG_ERR, "xfrd_handle_ipc: bad mode %d (%d)", (int)cmd,
			ntohl(cmd));
                break;
        }

	if(xfrd->ipc_conn->is_reading) {
		/* setup read of info */
		xfrd->ipc_conn->total_bytes = 0;
		xfrd->ipc_conn->msglen = 0;
		buffer_clear(xfrd->ipc_conn->packet);
	}
}