/*************************************************************************
* (C) 2014 AITNET ltd - Sofia/Bulgaria - <misho@aitnet.org>
*  by Michael Pounov <misho@elwix.org>
*
* $Author: misho $
* $Id: srv.c,v 1.8 2014/02/24 22:28:54 misho Exp $
*
**************************************************************************
The ELWIX and AITNET software is distributed under the following
terms:

All of the documentation and software included in the ELWIX and AITNET
Releases is copyrighted by ELWIX - Sofia/Bulgaria <info@elwix.org>

Copyright 2004 - 2014
	by Michael Pounov <misho@elwix.org>.  All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.
2. 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.
3. All advertising materials mentioning features or use of this software
   must display the following acknowledgement:
This product includes software developed by Michael Pounov <misho@elwix.org>
ELWIX - Embedded LightWeight unIX and its contributors.
4. Neither the name of AITNET 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 AITNET 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.
*/
#include "global.h"
#include "exec.h"
#include "buf.h"
#include "srv.h"


static void *
timeoutSession(sched_task_t *task)
{
	rpack_t *pkt = TASK_DATA(task);

	ETRACE();

	if (bf)
		flushBuffer(cli.fd);

	/* drop session */
	if (cli.fd > 2)
		close(cli.fd);
	rpack_resize(pkt, TFTP_PKT_MAX);
	memset(&cli, 0, sizeof cli);

	taskExit(task, NULL);
}

static void *
txPkt(sched_task_t *task)
{
	int wlen;
	rpack_t *pkt = TASK_DATA(task);
	struct tftp_hdr *tftp = (struct tftp_hdr*) RPACK_BUF(pkt);

	ETRACE();

	wlen = sendto(TASK_FD(task), RPACK_BUF(pkt), TASK_DATLEN(task), 
			0, &cli.addr.sa, cli.addr.sa.sa_len);
	if (wlen == -1)
		ESYSERR(0);
	else if (wlen != TASK_DATLEN(task)) {
		EERROR(EIO, "Sended %d bytes != packet %d bytes", 
				wlen, TASK_DATLEN(task));
		schedEvent(TASK_ROOT(task), execProg, "error", 0, NULL, TFTP_OPC_ERROR);
		schedCancelby(TASK_ROOT(task), taskTIMER, CRITERIA_CALL, 
				timeoutSession, NULL);
		schedEvent(TASK_ROOT(task), timeoutSession, NULL, 0, TASK_DATA(task), 0);
	} else
		EVERBOSE(2, "Sended %d bytes", wlen);
	/* on error or argument, drop session */
	if (TASK_ARG(task) == (void*) -1 || ntohs(tftp->tftp_opc) == TFTP_OPC_ERROR) {
		schedEvent(TASK_ROOT(task), execProg, "error", 0, NULL, TFTP_OPC_ERROR);
		schedCancelby(TASK_ROOT(task), taskTIMER, CRITERIA_CALL, 
				timeoutSession, NULL);
		schedEvent(TASK_ROOT(task), timeoutSession, NULL, 0, TASK_DATA(task), 0);
	}

	taskExit(task, NULL);
}

static void *
txData(sched_task_t *task)
{
	rpack_t *pkt = TASK_DATA(task);
	u_short code = 0, n = htons(TFTP_OPC_DATA);
	int len;

	ETRACE();

	RPACK_REWIND(pkt);
	rpack_uint16(pkt, &n, 0);
	n = htons(cli.seq);
	rpack_uint16(pkt, &n, 0);

	/* max file size check */
	if (cli.tsiz && cli.tsiz < cli.seq * cli.siz) {
		len = cli.tsiz - (cli.seq - 1) * cli.siz;
		cli.close = 42;	/* last sended packet, should be close! */
	} else
		len = cli.siz;

	len = pread(cli.fd, RPACK_NEXT(pkt), len, (cli.seq - 1) * cli.siz);
	if (len == -1) {
		ESYSERR(0);
		code = htons(3);
		goto end;
	} else {
		rpack_rnext(pkt, len);
		EVERBOSE(3, "Read from file %s %d bytes", cli.file, len);
	}

	if (cli.siz - len)
		cli.close = 42;	/* last sended packet, should be close! */

	schedEvent(TASK_ROOT(task), txPkt, NULL, TASK_FD(task), 
			TASK_DATA(task), RPACK_OFF(pkt));
	taskExit(task, NULL);
end:
	RPACK_REWIND(pkt);
	n = htons(TFTP_OPC_ERROR);
	rpack_uint16(pkt, &n, 0);
	rpack_uint16(pkt, &code, 0);
	rpack_rdata(pkt, errs[ntohs(code)].err_msg, strlen(errs[ntohs(code)].err_msg) + 1);

	schedEvent(TASK_ROOT(task), txPkt, (void*) -1, TASK_FD(task), 
			TASK_DATA(task), RPACK_OFF(pkt));
	taskExit(task, NULL);
}

static void *
txAck(sched_task_t *task)
{
	rpack_t *pkt = TASK_DATA(task);
	u_short n = htons(TFTP_OPC_ACK);

	ETRACE();

	RPACK_REWIND(pkt);
	rpack_uint16(pkt, &n, 0);
	n = htons(cli.seq);
	rpack_uint16(pkt, &n, 0);

	schedEvent(TASK_ROOT(task), txPkt, NULL, TASK_FD(task), 
			TASK_DATA(task), RPACK_OFF(pkt));

	if (cli.close) {
		schedEvent(TASK_ROOT(task), execProg, "complete", 0, NULL, TFTP_OPC_WRQ);
		schedCancelby(TASK_ROOT(task), taskTIMER, CRITERIA_CALL, timeoutSession, NULL);
		schedEvent(TASK_ROOT(task), timeoutSession, NULL, 0, TASK_DATA(task), 0);
		EVERBOSE(2, "Finish WRQ request");
		schedResumeby(TASK_ROOT(task), CRITERIA_ID, 0);
	}
	taskExit(task, NULL);
}

static int
getOpts(rpack_t * __restrict pkt, int rlen)
{
	char *opt, *val;
	int len;

	if (!rlen)
		return -1;

	do {
		/* option */
		len = str_getString(RPACK_NEXT(pkt), RPACK_REMAIN(pkt), NULL);
		if (len == -1)
			return -1;
		else
			rlen -= len;
		opt = (char*) rpack_rnext(pkt, len);
		if (!opt)
			return -1;
		EVERBOSE(7, "opt=%s rlen=%d", opt, rlen);
		/* value */
		len = str_getString(RPACK_NEXT(pkt), RPACK_REMAIN(pkt), NULL);
		if (len == -1)
			return -1;
		else
			rlen -= len;
		val = (char*) rpack_rnext(pkt, len);
		if (!val)
			return -1;
		EVERBOSE(7, "val=%s rlen=%d", val, rlen);

		if (!strcasecmp(opt, TFTP_OPT_BLKSIZE))
			cli.tmp = strtol(val, NULL, 10);
		else if (!strcasecmp(opt, TFTP_OPT_TSIZE))
			cli.tsiz = strtoll(val, NULL, 10);
		else if (!strcasecmp(opt, TFTP_OPT_TIMEOUT))
			cli.tout.tv_sec = strtol(val, NULL, 10);
		else if (!strcasecmp(opt, TFTP_OPT_ROLLOVER)) {
			cli.roll = strtol(val, NULL, 10);
			cli.roll++;
		}
	} while (rlen > 0);

	EVERBOSE(4, "blksize=%u tsize=%llu timeout=%d rollover=%u", 
			cli.siz, cli.tsiz, (int) cli.tout.tv_sec, cli.roll - 1);
	return 0;
}

static void *
txOack(sched_task_t *task)
{
	rpack_t *pkt = TASK_DATA(task);
	u_short n = htons(TFTP_OPC_OACK);
	struct stat sb;
	char szStr[STRSIZ];

	ETRACE();

	RPACK_REWIND(pkt);
	rpack_uint16(pkt, &n, 0);

	/* if opcode is RRQ and tsize is 0 then we must return file size to client */
	if (cli.opc == TFTP_OPC_RRQ && !cli.tsiz && stat(cli.file, &sb) != -1)
		cli.tsiz = sb.st_size;

	if (cli.siz > TFTP_LOAD_MAX) {
		memset(szStr, 0, sizeof szStr);
		snprintf(szStr, sizeof szStr, "%u", cli.siz);
		rpack_rdata(pkt, TFTP_OPT_BLKSIZE, strlen(TFTP_OPT_BLKSIZE) + 1);
		rpack_rdata(pkt, szStr, strlen(szStr) + 1);
	}
	if (cli.tsiz) {
		memset(szStr, 0, sizeof szStr);
		snprintf(szStr, sizeof szStr, "%llu", cli.tsiz);
		rpack_rdata(pkt, TFTP_OPT_TSIZE, strlen(TFTP_OPT_TSIZE) + 1);
		rpack_rdata(pkt, szStr, strlen(szStr) + 1);
	}
	if (cli.tout.tv_sec) {
		memset(szStr, 0, sizeof szStr);
		snprintf(szStr, sizeof szStr, "%d", (int) cli.tout.tv_sec);
		rpack_rdata(pkt, TFTP_OPT_TIMEOUT, strlen(TFTP_OPT_TIMEOUT) + 1);
		rpack_rdata(pkt, szStr, strlen(szStr) + 1);
	}
	if (cli.roll) {
		memset(szStr, 0, sizeof szStr);
		snprintf(szStr, sizeof szStr, "%u", cli.roll - 1);
		rpack_rdata(pkt, TFTP_OPT_ROLLOVER, strlen(TFTP_OPT_ROLLOVER) + 1);
		rpack_rdata(pkt, szStr, strlen(szStr) + 1);
	}

	EVERBOSE(4, "blksize=%u tsize=%llu timeout=%d rollover=%u", 
			cli.siz, cli.tsiz, (int) cli.tout.tv_sec, cli.roll - 1);
	schedCallOnce(TASK_ROOT(task), txPkt, NULL, TASK_FD(task), 
			TASK_DATA(task), RPACK_OFF(pkt));
	taskExit(task, NULL);
}

static void *
RQ(sched_task_t *task)
{
	rpack_t *pkt = TASK_DATA(task);
	struct tftp_hdr *tftp = (struct tftp_hdr*) RPACK_BUF(pkt);
	int len, rlen = TASK_DATLEN(task) - 2;
	char *str;
	u_short code = 0;

	ETRACE();

	cli.siz = TFTP_LOAD_MAX;
	cli.opc = ntohs(rpack_uint16(pkt, NULL, 0));
	if (!RW && cli.opc == TFTP_OPC_WRQ) {
		code = htons(2);
		goto end;
	}
	len = str_getString(RPACK_NEXT(pkt), rlen, &str);
	if (len == -1)
		goto end;
	else {
		strlcpy(cli.file, (char*) RPACK_NEXT(pkt), sizeof cli.file);
		rlen -= len;
		rpack_rnext(pkt, len);
	}
	len = str_getString((const u_char*) str, rlen, NULL);
	if (len == -1)
		goto end;
	else {
		rlen -= len;
		rpack_rnext(pkt, len);
		if (!strcasecmp(str, TFTP_MODE_ASCII))
			strlcpy(cli.mode, TFTP_MODE_ASCII, sizeof cli.mode);
		else if (!strcasecmp(str, TFTP_MODE_OCTET))
			strlcpy(cli.mode, TFTP_MODE_OCTET, sizeof cli.mode);
		else if (!strcasecmp(str, TFTP_MODE_MAIL)) {
			strlcpy(cli.mode, TFTP_MODE_MAIL, sizeof cli.mode);
			code = htons(4);
			goto end;
		} else {
			code = htons(1);
			goto end;
		}
	}

	switch (cli.opc) {
		case TFTP_OPC_RRQ:
			code = O_RDONLY;
			EVERBOSE(2, "RRQ:: file=%s mode=%s\n", cli.file, cli.mode);
			break;
		case TFTP_OPC_WRQ:
			code = O_WRONLY | O_CREAT;
			str = (char*) cfg_getAttribute(&cfg, "tftpd", "override");
			if (!str || tolower(*str) != 'y')
				code |= O_EXCL;
			EVERBOSE(2, "WRQ:: file=%s mode=%s\n", cli.file, cli.mode);
			break;
	}

	cli.fd = open(cli.file, code, 0644);
	if (cli.fd == -1) {
		if (errno == EACCES)
			code = htons(2);
		else if (errno == ENFILE)
			code = htons(3);
		else if (errno == EEXIST)
			code = htons(6);
		else if (errno == ENOENT)
			code = htons(1);
		else
			code = htons(0);
		ESYSERR(0);
		goto end;
	} else
		cli.seq = 0;

	schedEvent(TASK_ROOT(task), execProg, "request", 0, NULL, cli.opc);

	if (!getOpts(pkt, rlen)) {
		if (cli.tmp > TFTP_LOAD_MAX) {
			if (rpack_resize(pkt, cli.tmp + 4))
				ELIBERR(elwix);
			else
				cli.siz = cli.tmp;
		}
		if (cli.tout.tv_sec) {
			schedCancelby(TASK_ROOT(task), taskTIMER, CRITERIA_CALL, 
					timeoutSession, NULL);
			schedTimer(TASK_ROOT(task), timeoutSession, NULL, 
					cli.tout, TASK_DATA(task), 0);
		}
		schedEvent(TASK_ROOT(task), txOack, NULL, TASK_FD(task), 
				TASK_DATA(task), 0);
	} else if (cli.opc == TFTP_OPC_WRQ) {
		/* ack */
		tftp->tftp_opc = htons(TFTP_OPC_ACK);
		RPACK_REWIND(pkt);
		rpack_uint16(pkt, NULL, 0);
		rpack_uint16(pkt, &cli.seq, 0);

		schedEvent(TASK_ROOT(task), txPkt, NULL, TASK_FD(task), 
				TASK_DATA(task), RPACK_OFF(pkt));
	} else
		schedEvent(TASK_ROOT(task), txData, NULL, TASK_FD(task), 
				TASK_DATA(task), 0);

	cli.seq = 1;	/* 1st ack */
	taskExit(task, NULL);
end:
	tftp->tftp_opc = htons(TFTP_OPC_ERROR);
	RPACK_REWIND(pkt);
	rpack_uint16(pkt, NULL, 0);
	rpack_uint16(pkt, &code, 0);
	rpack_rdata(pkt, errs[ntohs(code)].err_msg, strlen(errs[ntohs(code)].err_msg) + 1);

	schedEvent(TASK_ROOT(task), txPkt, (void*) -1, TASK_FD(task), 
			TASK_DATA(task), RPACK_OFF(pkt));
	taskExit(task, NULL);
}

static void *
ACK(sched_task_t *task)
{
	rpack_t *pkt = TASK_DATA(task);
	struct tftp_hdr *tftp = (struct tftp_hdr*) RPACK_BUF(pkt);
	u_short code;

	ETRACE();

	RPACK_REWIND(pkt);
	code = rpack_uint16(pkt, NULL, 0);
	if (ntohs(code) != TFTP_OPC_ACK) {
		code = htons(5);
		goto end;
	}

	code = rpack_uint16(pkt, NULL, 0);
	if (ntohs(code) > cli.seq || (ntohs(code) < (cli.seq - 1))) {
		code = htons(5);
		goto end;
	} else if (ntohs(code) == cli.seq) {
		/* check for rollover seq id */
		if (cli.roll && cli.seq == USHRT_MAX)
			cli.seq = cli.roll - 1;
		else
			cli.seq++;
	}

	EVERBOSE(3, "ACK:: seq=%hu; my new seq=%hu;", ntohs(code), cli.seq);

	if (!cli.close)
		schedEvent(TASK_ROOT(task), txData, NULL, TASK_FD(task), 
				TASK_DATA(task), 0);
	else {
		schedEvent(TASK_ROOT(task), execProg, "complete", 0, NULL, TFTP_OPC_RRQ);
		schedCancelby(TASK_ROOT(task), taskTIMER, CRITERIA_CALL, timeoutSession, NULL);
		schedEvent(TASK_ROOT(task), timeoutSession, NULL, 0, TASK_DATA(task), 0);
		EVERBOSE(2, "Finish RRQ request");
	}
	taskExit(task, NULL);
end:
	tftp->tftp_opc = htons(TFTP_OPC_ERROR);
	RPACK_REWIND(pkt);
	rpack_uint16(pkt, NULL, 0);
	rpack_uint16(pkt, &code, 0);
	rpack_rdata(pkt, errs[ntohs(code)].err_msg, strlen(errs[ntohs(code)].err_msg) + 1);

	schedEvent(TASK_ROOT(task), txPkt, (void*) -1, TASK_FD(task), 
			TASK_DATA(task), RPACK_OFF(pkt));
	taskExit(task, NULL);
}

static void *
DATA(sched_task_t *task)
{
	rpack_t *pkt = TASK_DATA(task);
	struct tftp_hdr *tftp = (struct tftp_hdr*) RPACK_BUF(pkt);
	u_short code;
	int len;

	ETRACE();

	RPACK_REWIND(pkt);
	code = rpack_uint16(pkt, NULL, 0);
	if (ntohs(code) != TFTP_OPC_DATA) {
		code = htons(5);
		goto end;
	}

	code = rpack_uint16(pkt, NULL, 0);
	if (ntohs(code) < cli.seq || ntohs(code) > cli.seq + 1) {
		code = htons(5);
		goto end;
	} else
		cli.seq = ntohs(code);

	/* max file size check */
	len = TASK_DATLEN(task) - RPACK_OFF(pkt);
	if (cli.tsiz && cli.tsiz < cli.seq * cli.siz)
		len = MIN(len, cli.tsiz - (cli.seq - 1) * cli.siz);
	if (len < cli.siz)
		cli.close = 42;	/* last received packet, should be close! */

	EVERBOSE(3, "DATA:: seq=%hu; len=%d", cli.seq, len);

	if (len > 0) {
		if (!bf)
			len = pwrite(cli.fd, RPACK_NEXT(pkt), len, (cli.seq - 1) * cli.siz);
		else
			len = bfwrite(cli.fd, RPACK_NEXT(pkt), len);
		if (len == -1) {
			ESYSERR(0);
			code = htons(3);
			goto end;
		} else
			rpack_rnext(pkt, len);
	}
	EVERBOSE(3, "Written to file %s %d bytes", cli.file, len);

	schedEvent(TASK_ROOT(task), txAck, NULL, TASK_FD(task), TASK_DATA(task), 0);
	taskExit(task, NULL);
end:
	tftp->tftp_opc = htons(TFTP_OPC_ERROR);
	RPACK_REWIND(pkt);
	rpack_uint16(pkt, NULL, 0);
	rpack_uint16(pkt, &code, 0);
	rpack_rdata(pkt, errs[ntohs(code)].err_msg, strlen(errs[ntohs(code)].err_msg) + 1);

	schedEvent(TASK_ROOT(task), txPkt, (void*) -1, TASK_FD(task), 
			TASK_DATA(task), RPACK_OFF(pkt));
	taskExit(task, NULL);
}

void *
rxPkt(sched_task_t *task)
{
	sockaddr_t sa;
	socklen_t salen = sizeof sa;
	int rlen;
	rpack_t *pkt = TASK_DATA(task);
	struct tftp_hdr *tftp = (struct tftp_hdr*) RPACK_BUF(pkt);
	u_short code;

	ETRACE();

	memset(RPACK_BUF(pkt), 0, RPACK_LEN(pkt));
	rlen = recvfrom(TASK_FD(task), RPACK_BUF(pkt), RPACK_LEN(pkt), 0, &sa.sa, &salen);
	if (rlen == -1) {
		ESYSERR(0);
		goto end;
	} else if (!cli.addr.sa.sa_len) {
		cli.addr = sa;
		RPACK_REWIND(pkt);
		switch (ntohs(tftp->tftp_opc)) {
			case TFTP_OPC_RRQ:
			case TFTP_OPC_WRQ:
				schedEvent(TASK_ROOT(task), RQ, NULL, TASK_FD(task), 
						TASK_DATA(task), rlen);
				break;
			case TFTP_OPC_ERROR:
			default:
				RPACK_REWIND(pkt);
				code = htons(TFTP_OPC_ERROR);
				rpack_uint16(pkt, &code, 0);
				code = htons(4);
				rpack_uint16(pkt, &code, 0);
				rpack_rdata(pkt, errs[4].err_msg, strlen(errs[4].err_msg) + 1);

				schedEvent(TASK_ROOT(task), txPkt, (void*) -1, TASK_FD(task), 
						TASK_DATA(task), RPACK_OFF(pkt));
				goto end;
		}
	} else if (memcmp(&cli.addr, &sa, salen)) {
		EERROR(LOG_WARNING, "Packet dropped!!!\n"
				"Get frame from different address for this session");
		goto end;
	} else
		switch (ntohs(tftp->tftp_opc)) {
			case TFTP_OPC_ACK:
				schedEvent(TASK_ROOT(task), ACK, NULL, TASK_FD(task), 
						TASK_DATA(task), rlen);
				break;
			case TFTP_OPC_DATA:
				schedEvent(TASK_ROOT(task), DATA, NULL, TASK_FD(task), 
						TASK_DATA(task), rlen);
				break;
			case TFTP_OPC_OACK:
			case TFTP_OPC_ERROR:
			default:
				RPACK_REWIND(pkt);
				code = htons(TFTP_OPC_ERROR);
				rpack_uint16(pkt, &code, 0);
				code = htons(4);
				rpack_uint16(pkt, &code, 0);
				rpack_rdata(pkt, errs[4].err_msg, strlen(errs[4].err_msg) + 1);

				schedEvent(TASK_ROOT(task), txPkt, (void*) -1, TASK_FD(task), 
						TASK_DATA(task), RPACK_OFF(pkt));
				goto end;
		}

	schedCancelby(TASK_ROOT(task), taskTIMER, CRITERIA_CALL, timeoutSession, NULL);
	schedTimer(TASK_ROOT(task), timeoutSession, NULL, 
			cli.tout.tv_sec ? cli.tout : timeout, TASK_DATA(task), 0);
end:
	schedReadSelf(task);
	taskExit(task, NULL);
}