#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <arpa/inet.h>

#include "log.h"
#include "ppp.h"
#include "ppp_auth.h"
#include "ppp_lcp.h"
#include "pwdb.h"

#define MSG_FAILED "Authentication failed"
#define MSG_SUCCESSED "Authentication successed"

#define HDR_LEN (sizeof(struct pap_hdr_t)-2)

#define PAP_REQ 1
#define PAP_ACK 2
#define PAP_NAK 3

char *strndup(const char *s, size_t n);

static struct auth_data_t* auth_data_init(struct ppp_t *ppp);
static void auth_data_free(struct ppp_t*, struct auth_data_t*);
static int lcp_send_conf_req(struct ppp_t*, struct auth_data_t*, uint8_t*);
static int lcp_recv_conf_req(struct ppp_t*, struct auth_data_t*, uint8_t*);
static int pap_start(struct ppp_t*, struct auth_data_t*);
static int pap_finish(struct ppp_t*, struct auth_data_t*);
static void pap_recv(struct ppp_handler_t*h);

struct pap_auth_data_t
{
	struct auth_data_t auth;
	struct ppp_handler_t h;
	struct ppp_t *ppp;
};

struct pap_hdr_t
{
	uint16_t proto;
	uint8_t code;
	uint8_t id;
	uint16_t len;
} __attribute__((packed));

struct pap_ack_t
{
	struct pap_hdr_t hdr;
	uint8_t msg_len;
	char msg[0];
} __attribute__((packed));

static struct ppp_auth_handler_t pap=
{
	.name="PAP",
	.init=auth_data_init,
	.free=auth_data_free,
	.send_conf_req=lcp_send_conf_req,
	.recv_conf_req=lcp_recv_conf_req,
	.start=pap_start,
	.finish=pap_finish,
};

static struct auth_data_t* auth_data_init(struct ppp_t *ppp)
{
	struct pap_auth_data_t *d=malloc(sizeof(*d));

	memset(d,0,sizeof(*d));
	d->auth.proto=PPP_PAP;
	d->ppp=ppp;

	return &d->auth;
}

static void auth_data_free(struct ppp_t *ppp,struct auth_data_t *auth)
{
	struct pap_auth_data_t *d=container_of(auth,typeof(*d),auth);

	free(d);
}

static int pap_start(struct ppp_t *ppp, struct auth_data_t *auth)
{
	struct pap_auth_data_t *d=container_of(auth,typeof(*d),auth);

	d->h.proto=PPP_PAP;
	d->h.recv=pap_recv;

	ppp_register_chan_handler(ppp,&d->h);

	return 0;
}
static int pap_finish(struct ppp_t *ppp, struct auth_data_t *auth)
{
	struct pap_auth_data_t *d=container_of(auth,typeof(*d),auth);

	ppp_unregister_handler(ppp,&d->h);

	return 0;
}

static int lcp_send_conf_req(struct ppp_t *ppp, struct auth_data_t *d, uint8_t *ptr)
{
	return 0;
}

static int lcp_recv_conf_req(struct ppp_t *ppp, struct auth_data_t *d, uint8_t *ptr)
{
	return LCP_OPT_ACK;
}

static void pap_send_ack(struct pap_auth_data_t *p, int id)
{
	uint8_t buf[128];
	struct pap_ack_t *msg=(struct pap_ack_t*)buf;
	msg->hdr.proto=htons(PPP_PAP);
	msg->hdr.code=PAP_ACK;
	msg->hdr.id=id;
	msg->hdr.len=htons(HDR_LEN+1+sizeof(MSG_SUCCESSED)-1);
	msg->msg_len=sizeof(MSG_SUCCESSED)-1;
	memcpy(msg->msg,MSG_SUCCESSED,sizeof(MSG_SUCCESSED));
	
	log_debug("send [PAP AuthAck id=%x \"%s\"]\n",id,MSG_SUCCESSED);
	
	ppp_chan_send(p->ppp,msg,ntohs(msg->hdr.len)+2);
}

static void pap_send_nak(struct pap_auth_data_t *p, int id)
{
	uint8_t buf[128];
	struct pap_ack_t *msg=(struct pap_ack_t*)buf;
	msg->hdr.proto=htons(PPP_PAP);
	msg->hdr.code=PAP_NAK;
	msg->hdr.id=id;
	msg->hdr.len=htons(HDR_LEN+1+sizeof(MSG_FAILED)-1);
	msg->msg_len=sizeof(MSG_FAILED)-1;
	memcpy(msg->msg,MSG_FAILED,sizeof(MSG_FAILED));
	
	log_debug("send [PAP AuthNak id=%x \"%s\"]\n",id,MSG_FAILED);
	
	ppp_chan_send(p->ppp,msg,ntohs(msg->hdr.len)+2);
}

static int pap_recv_req(struct pap_auth_data_t *p,struct pap_hdr_t *hdr)
{
	int ret, r;
	char *peer_id;
	char *passwd;
	const char *passwd2;
	int peer_id_len;
	int passwd_len;
	uint8_t *ptr=(uint8_t*)(hdr+1);

	log_debug("recv [PAP AuthReq id=%x]\n",hdr->id);

	peer_id_len=*(uint8_t*)ptr; ptr++;
	if (peer_id_len>ntohs(hdr->len)-sizeof(*hdr)+2-1)
	{
		log_warn("PAP: short packet received\n");
		return -1;
	}
	peer_id=(char*)ptr; ptr+=peer_id_len;

	passwd_len=*(uint8_t*)ptr; ptr++;
	if (passwd_len>ntohs(hdr->len)-sizeof(*hdr)+2-2-peer_id_len)
	{
		log_warn("PAP: short packet received\n");
		return -1;
	}

	peer_id=strndup((const char*)peer_id,peer_id_len);
	passwd=strndup((const char*)ptr,passwd_len);

	r = pwdb_check(p->ppp, peer_id, PPP_PAP, passwd);
	if (r == PWDB_NO_IMPL) {
		passwd2 = pwdb_get_passwd(p->ppp, peer_id);
		if (!passwd2 || strcmp(passwd2, passwd))
			r = PWDB_DENIED;
		else
			r = PWDB_SUCCESS;
	}
	if (r == PWDB_DENIED) {
		log_warn("PAP: authentication error\n");
		pap_send_nak(p, hdr->id);
		auth_failed(p->ppp);
		ret=-1;
		free(peer_id);
	} else {
		pap_send_ack(p, hdr->id);
		auth_successed(p->ppp, peer_id);
		ret = 0;
	}

	free(passwd);

	return ret;
}

static void pap_recv(struct ppp_handler_t *h)
{
	struct pap_auth_data_t *d=container_of(h,typeof(*d),h);
	struct pap_hdr_t *hdr=(struct pap_hdr_t *)d->ppp->chan_buf;

	if (d->ppp->chan_buf_size<sizeof(*hdr) || ntohs(hdr->len)<HDR_LEN || ntohs(hdr->len)<d->ppp->chan_buf_size-2)
	{
		log_warn("PAP: short packet received\n");
		return;
	}

	if (hdr->code==PAP_REQ) pap_recv_req(d,hdr);
	else
	{
		log_warn("PAP: unknown code received %x\n",hdr->code);
	}
}

static void __init auth_pap_init()
{
	ppp_auth_register_handler(&pap);
}