/*
 * libunbound/worker.c - worker thread or process that resolves
 *
 * Copyright (c) 2007, NLnet Labs. All rights reserved.
 *
 * This software is open source.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * 
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * 
 * Neither the name of the NLNET LABS nor the names of its contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * \file
 *
 * This file contains the worker process or thread that performs
 * the DNS resolving and validation. The worker is called by a procedure
 * and if in the background continues until exit, if in the foreground
 * returns from the procedure when done.
 */
#include "config.h"
#include "libunbound/worker.h"
#include "libunbound/context.h"
#include "libunbound/unbound.h"
#include "services/outside_network.h"
#include "services/mesh.h"
#include "services/localzone.h"
#include "services/cache/rrset.h"
#include "services/outbound_list.h"
#include "util/module.h"
#include "util/regional.h"
#include "util/random.h"
#include "util/config_file.h"
#include "util/netevent.h"
#include "util/storage/slabhash.h"
#include "util/net_help.h"
#include "util/data/dname.h"
#include "util/data/msgreply.h"

/** size of table used for random numbers. large to be more secure. */
#define RND_STATE_SIZE 256

/** delete libworker struct */
static void
libworker_delete(struct libworker* w)
{
	if(!w) return;
	if(w->env) {
		mesh_delete(w->env->mesh);
		context_release_alloc(w->ctx, w->env->alloc);
		ldns_buffer_free(w->env->scratch_buffer);
		regional_destroy(w->env->scratch);
		ub_randfree(w->env->rnd);
		free(w->env->rnd);
		free(w->env);
	}
	outside_network_delete(w->back);
	comm_point_delete(w->cmd_com);
	comm_point_delete(w->res_com);
	comm_base_delete(w->base);
	free(w);
}

/** setup fresh libworker struct */
static struct libworker*
libworker_setup(struct ub_val_ctx* ctx)
{
	unsigned int seed;
	struct libworker* w = (struct libworker*)calloc(1, sizeof(*w));
	struct config_file* cfg = ctx->env->cfg;
	if(!w) return NULL;
	w->ctx = ctx;
	w->env = (struct module_env*)malloc(sizeof(*w->env));
	if(!w->env) {
		free(w);
		return NULL;
	}
	*w->env = *ctx->env;
	w->env->alloc = context_obtain_alloc(ctx);
	if(!w->env->alloc) {
		libworker_delete(w);
		return NULL;
	}
	alloc_set_id_cleanup(w->env->alloc, &libworker_alloc_cleanup, w);
	w->env->scratch = regional_create_custom(cfg->msg_buffer_size);
	w->env->scratch_buffer = ldns_buffer_new(cfg->msg_buffer_size);
	if(!w->env->scratch || !w->env->scratch_buffer) {
		libworker_delete(w);
		return NULL;
	}
	w->env->rnd = (struct ub_randstate*)calloc(1, sizeof(*w->env->rnd));
	if(!w->env->rnd) {
		libworker_delete(w);
		return NULL;
	}
	w->env->worker = (struct worker*)w;
	seed = (unsigned int)time(NULL) ^ (unsigned int)getpid() ^
		(((unsigned int)w->thread_num)<<17);
	seed ^= (unsigned int)w->env->alloc->next_id;
	if(!ub_initstate(seed, w->env->rnd, RND_STATE_SIZE)) {
		seed = 0;
		libworker_delete(w);
		return NULL;
	}
	seed = 0;

	w->base = comm_base_create();
	if(!w->base) {
		libworker_delete(w);
		return NULL;
	}
	w->back = outside_network_create(w->base, cfg->msg_buffer_size,
		(size_t)cfg->outgoing_num_ports, cfg->out_ifs,
		cfg->num_out_ifs, cfg->do_ip4, cfg->do_ip6, -1, 
		cfg->do_tcp?cfg->outgoing_num_tcp:0,
		w->env->infra_cache, w->env->rnd);
	if(!w->back) {
		libworker_delete(w);
		return NULL;
	}
	w->env->mesh = mesh_create(&ctx->mods, w->env);
	if(!w->env->mesh) {
		libworker_delete(w);
		return NULL;
	}
	w->env->send_packet = &libworker_send_packet;
	w->env->send_query = &libworker_send_query;
	w->env->detach_subs = &mesh_detach_subs;
	w->env->attach_sub = &mesh_attach_sub;
	w->env->kill_sub = &mesh_state_delete;
	w->env->detect_cycle = &mesh_detect_cycle;
	return w;
}

static int 
libworker_handle_control_cmd(struct comm_point* c, void* arg, 
	int err, struct comm_reply* ATTR_UNUSED(rep))
{
	/*struct ub_val_ctx* ctx = (struct ub_val_ctx*)arg;*/
	if(err != NETEVENT_NOERROR) {
		if(err == NETEVENT_CLOSED) {
			/* parent closed pipe, must have exited somehow */
			/* it is of no use to go on, exit */
			exit(0);
		}
		log_err("internal error: control cmd err %d", err);
		exit(0);
	}
	return 0;
}

static int 
libworker_handle_result_write(struct comm_point* c, void* arg, 
	int err, struct comm_reply* ATTR_UNUSED(rep))
{
	/*struct ub_val_ctx* ctx = (struct ub_val_ctx*)arg;*/
	if(err != NETEVENT_NOERROR) {
		if(err == NETEVENT_CLOSED) {
			/* parent closed pipe, must have exited somehow */
			/* it is of no use to go on, exit */
			exit(0);
		}
		log_err("internal error: pipe comm err %d", err);
		exit(0);
	}
	return 0;
}

/** get bufsize for cfg */
static size_t
getbufsz(struct ub_val_ctx* ctx)
{
	size_t s = 65535;
	lock_basic_lock(&ctx->cfglock);
	s = ctx->env->cfg->msg_buffer_size;
	lock_basic_unlock(&ctx->cfglock);
	return s;
}

/** the background thread func */
static void*
libworker_dobg(void* arg)
{
	/* setup */
	struct ub_val_ctx* ctx = (struct ub_val_ctx*)arg;
	struct libworker* w = libworker_setup(ctx);
	size_t bufsz = getbufsz(ctx);
	log_thread_set(&w->thread_num);
	if(!w) {
		log_err("libunbound bg worker init failed, nomem");
		return NULL;
	}
	lock_basic_lock(&ctx->qqpipe_lock);
	if(!(w->cmd_com=comm_point_create_local(w->base, ctx->qqpipe[0], 
		bufsz, libworker_handle_control_cmd, w))) {
		lock_basic_unlock(&ctx->qqpipe_lock);
		log_err("libunbound bg worker init failed, no cmdcom");
		return NULL;
	}
	lock_basic_unlock(&ctx->qqpipe_lock);
	lock_basic_lock(&ctx->rrpipe_lock);
	/* TODO create writing local commpoint */
	if(!(w->res_com=comm_point_create_local(w->base, ctx->rrpipe[1], 
		bufsz, libworker_handle_result_write, w))) {
		lock_basic_unlock(&ctx->qqpipe_lock);
		log_err("libunbound bg worker init failed, no cmdcom");
		return NULL;
	}
	lock_basic_unlock(&ctx->rrpipe_lock);

	/* do the work */
	comm_base_dispatch(w->base);

	/* cleanup */
	libworker_delete(w);
	return NULL;
}

int libworker_bg(struct ub_val_ctx* ctx)
{
	/* fork or threadcreate */
	if(ctx->dothread) {
		ub_thread_create(&ctx->bg_tid, libworker_dobg, ctx);
	} else {
		switch((ctx->bg_pid=fork())) {
			case 0:
				lock_basic_unlock(&ctx->cfglock);
				(void)libworker_dobg(ctx);
				exit(0);
				break;
			case -1:
				lock_basic_unlock(&ctx->cfglock);
				return UB_FORKFAIL;
			default:
				break;
		}
	}
	lock_basic_unlock(&ctx->cfglock);
	return UB_NOERROR;
}

/** get msg reply struct (in temp region) */
static struct reply_info*
parse_reply(ldns_buffer* pkt, struct regional* region, struct query_info* qi)
{
	struct reply_info* rep;
	struct msg_parse* msg;
	if(!(msg = regional_alloc(region, sizeof(*msg)))) {
		return NULL;
	}
	memset(msg, 0, sizeof(*msg));
	ldns_buffer_set_position(pkt, 0);
	if(parse_packet(pkt, msg, region) != 0)
		return 0;
	if(!parse_create_msg(pkt, msg, NULL, qi, &rep, region)) {
		return 0;
	}
	return rep;
}

/** insert canonname */
static int
fill_canon(struct ub_val_result* res, uint8_t* s)
{
	char buf[255+2];
	dname_str(s, buf);
	res->canonname = strdup(buf);
	return res->canonname != 0;
}

/** fill data into result */
static int
fill_res(struct ub_val_result* res, struct ub_packed_rrset_key* answer,
	uint8_t* finalcname, struct query_info* rq)
{
	size_t i;
	struct packed_rrset_data* data;
	if(!answer) {
		if(finalcname) {
			if(!fill_canon(res, finalcname))
				return 0; /* out of memory */
		}
		res->data = (char**)calloc(1, sizeof(char*));
		res->len = (int*)calloc(1, sizeof(int));
		return (res->data && res->len);
	}
	data = (struct packed_rrset_data*)answer->entry.data;
	if(query_dname_compare(rq->qname, answer->rk.dname) != 0) {
		if(!fill_canon(res, answer->rk.dname))
			return 0; /* out of memory */
	} else
		res->canonname = res->qname;
	res->data = (char**)calloc(data->count+1, sizeof(char*));
	res->len = (int*)calloc(data->count+1, sizeof(int));
	if(!res->data || !res->len)
		return 0; /* out of memory */
	for(i=0; i<data->count; i++) {
		/* remove rdlength from rdata */
		res->len[i] = (int)(data->rr_len[i] - 2);
		res->data[i] = memdup(data->rr_data[i]+2, (size_t)res->len[i]);
		if(!res->data[i])
			return 0; /* out of memory */
	}
	res->data[data->count] = NULL;
	res->len[data->count] = 0;
	return 1;
}

/** callback with fg results */
static void
libworker_fg_done_cb(void* arg, int rcode, ldns_buffer* buf, enum sec_status s)
{
	struct query_info rq; /* replied query */
	struct reply_info* rep;
	struct libworker_fg_data* d = (struct libworker_fg_data*)arg;
	/* fg query is done; exit comm base */
	comm_base_exit(d->w->base);

	if(rcode != 0) {
		d->q->res->rcode = rcode;
		d->q->msg_security = 0;
		return;
	}

	d->q->res->rcode = LDNS_RCODE_SERVFAIL;
	d->q->msg_security = 0;
	d->q->msg = memdup(ldns_buffer_begin(buf), ldns_buffer_limit(buf));
	d->q->msg_len = ldns_buffer_limit(buf);
	if(!d->q->msg) {
		return; /* error in rcode */
	}

	/* canonname and results */
	rep = parse_reply(buf, d->w->env->scratch, &rq);
	if(!rep) {
		return; /* error parsing buf, or out of memory */
	}
	if(!fill_res(d->q->res, reply_find_answer_rrset(&rq, rep), 
		reply_find_final_cname_target(&rq, rep), &rq))
		return; /* out of memory */
	/* rcode, havedata, nxdomain, secure, bogus */
	d->q->res->rcode = (int)LDNS_RCODE_WIRE(d->q->msg);
	if(d->q->res->data && d->q->res->data[0])
		d->q->res->havedata = 1;
	if(d->q->res->rcode == LDNS_RCODE_NXDOMAIN)
		d->q->res->nxdomain = 1;
	if(s == sec_status_secure)
		d->q->res->secure = 1;
	if(s == sec_status_bogus)
		d->q->res->bogus = 1;

	d->q->msg_security = s;
}

/** setup qinfo and edns */
static int
setup_qinfo_edns(struct libworker* w, struct ctx_query* q, 
	struct query_info* qinfo, struct edns_data* edns)
{
	ldns_rdf* rdf;
	qinfo->qtype = (uint16_t)q->res->qtype;
	qinfo->qclass = (uint16_t)q->res->qclass;
	rdf = ldns_dname_new_frm_str(q->res->qname);
	if(!rdf) {
		return 0;
	}
	qinfo->qname = ldns_rdf_data(rdf);
	qinfo->qname_len = ldns_rdf_size(rdf);
	edns->edns_present = 1;
	edns->ext_rcode = 0;
	edns->edns_version = 0;
	edns->bits = EDNS_DO;
	if(ldns_buffer_capacity(w->back->udp_buff) < 65535)
		edns->udp_size = (uint16_t)ldns_buffer_capacity(
			w->back->udp_buff);
	else	edns->udp_size = 65535;
	ldns_rdf_free(rdf);
	return 1;
}

int libworker_fg(struct ub_val_ctx* ctx, struct ctx_query* q)
{
	struct libworker* w = libworker_setup(ctx);
	uint16_t qflags, qid;
	struct query_info qinfo;
	struct edns_data edns;
	struct libworker_fg_data d;
	if(!w)
		return UB_INITFAIL;
	if(!setup_qinfo_edns(w, q, &qinfo, &edns)) {
		libworker_delete(w);
		return UB_SYNTAX;
	}
	qid = 0;
	qflags = BIT_RD;
	d.q = q;
	d.w = w;
	/* see if there is a fixed answer */
	if(local_zones_answer(ctx->local_zones, &qinfo, &edns, 
		w->back->udp_buff, w->env->scratch)) {
		libworker_fg_done_cb(&d, LDNS_RCODE_NOERROR, 
			w->back->udp_buff, sec_status_insecure);
		libworker_delete(w);
		return UB_NOERROR;
	}
	/* process new query */
	if(!mesh_new_callback(w->env->mesh, &qinfo, qflags, &edns, 
		w->back->udp_buff, qid, libworker_fg_done_cb, &d)) {
		free(qinfo.qname);
		return UB_NOMEM;
	}
	free(qinfo.qname);

	/* wait for reply */
	comm_base_dispatch(w->base);

	libworker_delete(w);
	return UB_NOERROR;
}

void libworker_alloc_cleanup(void* arg)
{
	struct libworker* w = (struct libworker*)arg;
	slabhash_clear(&w->env->rrset_cache->table);
        slabhash_clear(w->env->msg_cache);
}

int libworker_send_packet(ldns_buffer* pkt, struct sockaddr_storage* addr,
        socklen_t addrlen, int timeout, struct module_qstate* q, int use_tcp)
{
	struct libworker* w = (struct libworker*)q->env->worker;
	if(use_tcp) {
		return pending_tcp_query(w->back, pkt, addr, addrlen,
			timeout, libworker_handle_reply, q, 
			q->env->rnd) != 0;
	}
	return pending_udp_query(w->back, pkt, addr, addrlen,
		timeout*1000, libworker_handle_reply, q, 
		q->env->rnd) != 0;
}

/** compare outbound entry qstates */
static int
outbound_entry_compare(void* a, void* b)
{
        struct outbound_entry* e1 = (struct outbound_entry*)a;
        struct outbound_entry* e2 = (struct outbound_entry*)b;
        if(e1->qstate == e2->qstate)
                return 1;
        return 0;
}

struct outbound_entry* libworker_send_query(uint8_t* qname, size_t qnamelen,
        uint16_t qtype, uint16_t qclass, uint16_t flags, int dnssec,
        struct sockaddr_storage* addr, socklen_t addrlen,
        struct module_qstate* q)
{
	struct libworker* w = (struct libworker*)q->env->worker;
	struct outbound_entry* e = (struct outbound_entry*)regional_alloc(
		q->region, sizeof(*e));
	if(!e)
		return NULL;
	e->qstate = q;
	e->qsent = outnet_serviced_query(w->back, qname,
		qnamelen, qtype, qclass, flags, dnssec, addr, addrlen,
		libworker_handle_service_reply, e, w->back->udp_buff,
		&outbound_entry_compare);
	if(!e->qsent) {
		return NULL;
	}
	return e;
}

int 
libworker_handle_reply(struct comm_point* c, void* arg, int error,
        struct comm_reply* reply_info)
{
	struct module_qstate* q = (struct module_qstate*)arg;
	struct libworker* lw = (struct libworker*)q->env->worker;
	struct outbound_entry e;
	e.qstate = q;
	e.qsent = NULL;

	if(error != 0) {
		mesh_report_reply(lw->env->mesh, &e, 0, reply_info);
		return 0;
	}
	/* sanity check. */
	if(!LDNS_QR_WIRE(ldns_buffer_begin(c->buffer))
		|| LDNS_OPCODE_WIRE(ldns_buffer_begin(c->buffer)) !=
			LDNS_PACKET_QUERY
		|| LDNS_QDCOUNT(ldns_buffer_begin(c->buffer)) > 1) {
		/* error becomes timeout for the module as if this reply
		 * never arrived. */
		mesh_report_reply(lw->env->mesh, &e, 0, reply_info);
		return 0;
	}
	mesh_report_reply(lw->env->mesh, &e, 1, reply_info);
	return 0;
}

int 
libworker_handle_service_reply(struct comm_point* c, void* arg, int error,
        struct comm_reply* reply_info)
{
	struct outbound_entry* e = (struct outbound_entry*)arg;
	struct libworker* lw = (struct libworker*)e->qstate->env->worker;

	if(error != 0) {
		mesh_report_reply(lw->env->mesh, e, 0, reply_info);
		return 0;
	}
	/* sanity check. */
	if(!LDNS_QR_WIRE(ldns_buffer_begin(c->buffer))
		|| LDNS_OPCODE_WIRE(ldns_buffer_begin(c->buffer)) !=
			LDNS_PACKET_QUERY
		|| LDNS_QDCOUNT(ldns_buffer_begin(c->buffer)) > 1) {
		/* error becomes timeout for the module as if this reply
		 * never arrived. */
		mesh_report_reply(lw->env->mesh, e, 0, reply_info);
		return 0;
	}
	mesh_report_reply(lw->env->mesh,  e, 1, reply_info);
	return 0;
}

/* --- fake callbacks for fptr_wlist to work --- */
int worker_handle_control_cmd(struct comm_point* ATTR_UNUSED(c), 
	void* ATTR_UNUSED(arg), int ATTR_UNUSED(error),
        struct comm_reply* ATTR_UNUSED(reply_info))
{
	log_assert(0);
	return 0;
}

int worker_handle_request(struct comm_point* ATTR_UNUSED(c), 
	void* ATTR_UNUSED(arg), int ATTR_UNUSED(error),
        struct comm_reply* ATTR_UNUSED(repinfo))
{
	log_assert(0);
	return 0;
}

int worker_handle_reply(struct comm_point* ATTR_UNUSED(c), 
	void* ATTR_UNUSED(arg), int ATTR_UNUSED(error),
        struct comm_reply* ATTR_UNUSED(reply_info))
{
	log_assert(0);
	return 0;
}

int worker_handle_service_reply(struct comm_point* ATTR_UNUSED(c), 
	void* ATTR_UNUSED(arg), int ATTR_UNUSED(error),
        struct comm_reply* ATTR_UNUSED(reply_info))
{
	log_assert(0);
	return 0;
}

void worker_sighandler(int ATTR_UNUSED(sig), void* ATTR_UNUSED(arg))
{
	log_assert(0);
}

int worker_send_packet(ldns_buffer* ATTR_UNUSED(pkt), 
	struct sockaddr_storage* ATTR_UNUSED(addr), 
	socklen_t ATTR_UNUSED(addrlen), int ATTR_UNUSED(timeout), 
	struct module_qstate* ATTR_UNUSED(q), int ATTR_UNUSED(use_tcp))
{
	log_assert(0);
	return 0;
}

struct outbound_entry* worker_send_query(uint8_t* ATTR_UNUSED(qname), 
	size_t ATTR_UNUSED(qnamelen), uint16_t ATTR_UNUSED(qtype), 
	uint16_t ATTR_UNUSED(qclass), uint16_t ATTR_UNUSED(flags), 
	int ATTR_UNUSED(dnssec), struct sockaddr_storage* ATTR_UNUSED(addr), 
	socklen_t ATTR_UNUSED(addrlen), struct module_qstate* ATTR_UNUSED(q))
{
	log_assert(0);
	return 0;
}

void 
worker_alloc_cleanup(void* ATTR_UNUSED(arg))
{
	log_assert(0);
}

int
acl_list_cmp(const void* ATTR_UNUSED(k1), const void* ATTR_UNUSED(k2))
{
	log_assert(0);
	return 0;
}