/*	$OpenBSD: parser.c,v 1.18 2005/07/01 18:59:15 fgsch Exp $ */

/*
 * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <err.h>
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "parser.h"

enum token_type {
	NOTOKEN,
	ENDTOKEN,
	KEYWORD,
	ADDRESS,
	FLAG,
	ASNUM,
	ASTYPE,
	PREFIX,
	PEERDESC,
	COMMUNITY,
	LOCALPREF,
	MED,
	NEXTHOP,
	PFTABLE,
	PREPNBR,
	PREPSELF,
	WEIGHT,
	FAMILY
};

struct token {
	enum token_type		 type;
	const char		*keyword;
	int			 value;
	const struct token	*next;
};

static const struct token t_main[];
static const struct token t_show[];
static const struct token t_show_fib[];
static const struct token t_show_rib[];
static const struct token t_show_neighbor[];
static const struct token t_show_neighbor_modifiers[];
static const struct token t_fib[];
static const struct token t_neighbor[];
static const struct token t_neighbor_modifiers[];
static const struct token t_show_as[];
static const struct token t_show_prefix[];
static const struct token t_show_ip[];
static const struct token t_network[];
static const struct token t_prefix[];
static const struct token t_set[];
static const struct token t_community[];
static const struct token t_localpref[];
static const struct token t_med[];
static const struct token t_nexthop[];
static const struct token t_pftable[];
static const struct token t_prepnbr[];
static const struct token t_prepself[];
static const struct token t_weight[];

static const struct token t_main[] = {
	{ KEYWORD,	"reload",	RELOAD,		NULL},
	{ KEYWORD,	"show",		SHOW,		t_show},
	{ KEYWORD,	"fib",		FIB,		t_fib},
	{ KEYWORD,	"neighbor",	NEIGHBOR,	t_neighbor},
	{ KEYWORD,	"network",	NONE,		t_network},
	{ ENDTOKEN,	"",		NONE,		NULL}
};

static const struct token t_show[] = {
	{ NOTOKEN,	"",		NONE,		NULL},
	{ KEYWORD,	"fib",		SHOW_FIB,	t_show_fib},
	{ KEYWORD,	"interfaces",	SHOW_INTERFACE,	NULL},
	{ KEYWORD,	"neighbor",	SHOW_NEIGHBOR,	t_show_neighbor},
	{ KEYWORD,	"nexthop",	SHOW_NEXTHOP,	NULL},
	{ KEYWORD,	"rib",		SHOW_RIB,	t_show_rib},
	{ KEYWORD,	"ip",		NONE,		t_show_ip},
	{ KEYWORD,	"summary",	SHOW_SUMMARY,	NULL},
	{ ENDTOKEN,	"",		NONE,		NULL}
};

static const struct token t_show_fib[] = {
	{ NOTOKEN,	"",		NONE,			NULL},
	{ FLAG,		"connected",	F_CONNECTED,		t_show_fib},
	{ FLAG,		"static",	F_STATIC,		t_show_fib},
	{ FLAG,		"bgp",		F_BGPD_INSERTED,	t_show_fib},
	{ FLAG,		"nexthop",	F_NEXTHOP,		t_show_fib},
	{ FAMILY,	"",		NONE,			t_show_fib},
	{ ADDRESS,	"",		NONE,			NULL},
	{ ENDTOKEN,	"",		NONE,			NULL}
};

static const struct token t_show_rib[] = {
	{ NOTOKEN,	"",		NONE,		NULL},
	{ PREFIX,	"",		NONE,		t_show_prefix},
	{ ASTYPE,	"as",		AS_ALL,		t_show_as},
	{ ASTYPE,	"source-as",	AS_SOURCE,	t_show_as},
	{ ASTYPE,	"transit-as",	AS_TRANSIT,	t_show_as},
	{ ASTYPE,	"empty-as",	AS_EMPTY,	NULL},
	{ KEYWORD,	"summary",	SHOW_SUMMARY,	NULL},
	{ ENDTOKEN,	"",		NONE,		NULL}
};

static const struct token t_show_neighbor[] = {
	{ NOTOKEN,	"",		NONE,	NULL},
	{ ADDRESS,	"",		NONE,	t_show_neighbor_modifiers},
	{ PEERDESC,	"",		NONE,	t_show_neighbor_modifiers},
	{ ENDTOKEN,	"",		NONE,	NULL}
};

static const struct token t_show_neighbor_modifiers[] = {
	{ NOTOKEN,	"",		NONE,			NULL},
	{ KEYWORD,	"timers",	SHOW_NEIGHBOR_TIMERS,	NULL},
	{ KEYWORD,	"messages",	SHOW_NEIGHBOR,		NULL},
	{ ENDTOKEN,	"",		NONE,			NULL}
};

static const struct token t_fib[] = {
	{ KEYWORD,	"couple",	FIB_COUPLE,	NULL},
	{ KEYWORD,	"decouple",	FIB_DECOUPLE,	NULL},
	{ ENDTOKEN,	"",		NONE,		NULL}
};

static const struct token t_neighbor[] = {
	{ ADDRESS,	"",		NONE,		t_neighbor_modifiers},
	{ PEERDESC,	"",		NONE,		t_neighbor_modifiers},
	{ ENDTOKEN,	"",		NONE,		NULL}
};

static const struct token t_neighbor_modifiers[] = {
	{ KEYWORD,	"up",		NEIGHBOR_UP,	NULL},
	{ KEYWORD,	"down",		NEIGHBOR_DOWN,	NULL},
	{ KEYWORD,	"clear",	NEIGHBOR_CLEAR,	NULL},
	{ ENDTOKEN,	"",		NONE,		NULL}
};

static const struct token t_show_as[] = {
	{ ASNUM,	"",		NONE,		NULL},
	{ ENDTOKEN,	"",		NONE,		NULL}
};

static const struct token t_show_prefix[] = {
	{ NOTOKEN,	"",		NONE,		NULL},
	{ FLAG,		"all",		F_LONGER,	NULL},
	{ FLAG,		"longer-prefixes", F_LONGER,	NULL},
	{ ENDTOKEN,	"",		NONE,		NULL}
};

static const struct token t_show_ip[] = {
	{ KEYWORD,	"bgp",		SHOW_RIB,	t_show_rib},
	{ ENDTOKEN,	"",		NONE,		NULL}
};

static const struct token t_network[] = {
	{ KEYWORD,	"add",		NETWORK_ADD,	t_prefix},
	{ KEYWORD,	"delete",	NETWORK_REMOVE,	t_prefix},
	{ KEYWORD,	"flush",	NETWORK_FLUSH,	NULL},
	{ KEYWORD,	"show",		NETWORK_SHOW,	NULL},
	{ ENDTOKEN,	"",		NONE,		NULL}
};

static const struct token t_prefix[] = {
	{ PREFIX,	"",		NONE,		t_set},
	{ ENDTOKEN,	"",		NONE,		NULL}
};

static const struct token t_set[] = {
	{ NOTOKEN,	"",			NONE,	NULL},
	{ KEYWORD,	"community",		NONE,	t_community},
	{ KEYWORD,	"localpref",		NONE,	t_localpref},
	{ KEYWORD,	"med",			NONE,	t_med},
	{ KEYWORD,	"metric",		NONE,	t_med},
	{ KEYWORD,	"nexthop",		NONE,	t_nexthop},
	{ KEYWORD,	"pftable",		NONE,	t_pftable},
	{ KEYWORD,	"prepend-neighbor",	NONE,	t_prepnbr},
	{ KEYWORD,	"prepend-self",		NONE,	t_prepself},
	{ KEYWORD,	"weight",		NONE,	t_weight},
	{ ENDTOKEN,	"",			NONE,	NULL}
};

static const struct token t_community[] = {
	{ COMMUNITY,	"",			NONE,	t_set},
	{ ENDTOKEN,	"",			NONE,	NULL}
};

static const struct token t_localpref[] = {
	{ LOCALPREF,	"",			NONE,	t_set},
	{ ENDTOKEN,	"",			NONE,	NULL}
};

static const struct token t_med[] = {
	{ MED,		"",			NONE,	t_set},
	{ ENDTOKEN,	"",			NONE,	NULL}
};

static const struct token t_nexthop[] = {
	{ NEXTHOP,	"",			NONE,	t_set},
	{ ENDTOKEN,	"",			NONE,	NULL}
};

static const struct token t_pftable[] = {
	{ PFTABLE,	"",			NONE,	t_set},
	{ ENDTOKEN,	"",			NONE,	NULL}
};

static const struct token t_prepnbr[] = {
	{ PREPNBR,	"",			NONE,	t_set},
	{ ENDTOKEN,	"",			NONE,	NULL}
};

static const struct token t_prepself[] = {
	{ PREPSELF,	"",			NONE,	t_set},
	{ ENDTOKEN,	"",			NONE,	NULL}
};

static const struct token t_weight[] = {
	{ WEIGHT,	"",			NONE,	t_set},
	{ ENDTOKEN,	"",			NONE,	NULL}
};


static struct parse_result	res;

const struct token	*match_token(const char *, const struct token []);
void			 show_valid_args(const struct token []);
int			 parse_addr(const char *, struct bgpd_addr *);
int			 parse_prefix(const char *, struct bgpd_addr *,
			     u_int8_t *);
int			 parse_asnum(const char *, u_int16_t *);
int			 parse_number(const char *, struct parse_result *,
			     enum token_type);
int			 getcommunity(const char *);
int			 parse_community(const char *, struct parse_result *);
int			 parse_nexthop(const char *, struct parse_result *);

struct parse_result *
parse(int argc, char *argv[])
{
	const struct token	*table = t_main;
	const struct token	*match;

	bzero(&res, sizeof(res));
	TAILQ_INIT(&res.set);

	while (argc > 0) {
		if ((match = match_token(argv[0], table)) == NULL) {
			fprintf(stderr, "valid commands/args:\n");
			show_valid_args(table);
			return (NULL);
		}

		argc--;
		argv++;

		if (match->type == NOTOKEN || match->next == NULL)
			break;

		table = match->next;
	}

	if (argc > 0) {
		fprintf(stderr, "superfluous argument: %s\n", argv[0]);
		return (NULL);
	}

	return (&res);
}

const struct token *
match_token(const char *word, const struct token table[])
{
	u_int			 i, match;
	const struct token	*t = NULL;
	struct filter_set	*fs;

	match = 0;

	for (i = 0; table[i].type != ENDTOKEN; i++) {
		switch (table[i].type) {
		case NOTOKEN:
			if (word == NULL || strlen(word) == 0) {
				match++;
				t = &table[i];
			}
			break;
		case KEYWORD:
			if (word != NULL && strncmp(word, table[i].keyword,
			    strlen(word)) == 0) {
				match++;
				t = &table[i];
				if (t->value)
					res.action = t->value;
			}
			break;
		case FLAG:
			if (word != NULL && strncmp(word, table[i].keyword,
			    strlen(word)) == 0) {
				match++;
				t = &table[i];
				res.flags |= t->value;
			}
			break;
		case FAMILY:
			if (word == NULL)
				break;
			if (!strcmp(word, "inet") || !strcmp(word, "IPv4")) {
				match++;
				t = &table[i];
				res.af = AF_INET;
			}
			if (!strcmp(word, "inet6") || !strcmp(word, "IPv6")) {
				match++;
				t = &table[i];
				res.af = AF_INET6;
			}
			break;
		case ADDRESS:
			if (parse_addr(word, &res.addr)) {
				match++;
				t = &table[i];
				if (t->value)
					res.action = t->value;
			}
			break;
		case PREFIX:
			if (parse_prefix(word, &res.addr, &res.prefixlen)) {
				match++;
				t = &table[i];
				if (t->value)
					res.action = t->value;
			}
			break;
		case ASTYPE:
			if (word != NULL && strncmp(word, table[i].keyword,
			    strlen(word)) == 0) {
				match++;
				t = &table[i];
				res.as.type = t->value;
			}
			break;
		case ASNUM:
			if (parse_asnum(word, &res.as.as)) {
				match++;
				t = &table[i];
			}
			break;
		case PEERDESC:
			if (!match && word != NULL && strlen(word) > 0) {
				if (strlcpy(res.peerdesc, word,
				    sizeof(res.peerdesc)) >=
				    sizeof(res.peerdesc))
					errx(1, "neighbor description too "
					    "long");
				match++;
				t = &table[i];
			}
			break;
		case COMMUNITY:
			if (word != NULL && strlen(word) > 0 &&
			    parse_community(word, &res)) {
				match++;
				t = &table[i];
			}
			break;
		case LOCALPREF:
		case MED:
		case PREPNBR:
		case PREPSELF:
		case WEIGHT:
			if (word != NULL && strlen(word) > 0 &&
			    parse_number(word, &res, table[i].type)) {
				match++;
				t = &table[i];
			}
			break;
		case NEXTHOP:
			if (word != NULL && strlen(word) > 0 &&
			    parse_nexthop(word, &res)) {
				match++;
				t = &table[i];
			}
			break;
		case PFTABLE:
			if (word != NULL && strlen(word) > 0) {
				if ((fs = calloc(1,
				    sizeof(struct filter_set))) == NULL)
					err(1, NULL);
				if (strlcpy(fs->action.pftable, word,
				    sizeof(fs->action.pftable)) >=
				    sizeof(fs->action.pftable))
					errx(1, "pftable name too long");
				TAILQ_INSERT_TAIL(&res.set, fs, entry);
				match++;
				t = &table[i];
			}
			break;
		case ENDTOKEN:
			break;
		}
	}

	if (match != 1) {
		if (match > 1)
			fprintf(stderr, "ambiguous argument: %s\n", word);
		if (match < 1)
			fprintf(stderr, "unknown argument: %s\n", word);
		return (NULL);
	}

	return (t);
}

void
show_valid_args(const struct token table[])
{
	int	i;

	for (i = 0; table[i].type != ENDTOKEN; i++) {
		switch (table[i].type) {
		case NOTOKEN:
			fprintf(stderr, "  <cr>\n");
			break;
		case KEYWORD:
		case FLAG:
		case ASTYPE:
			fprintf(stderr, "  %s\n", table[i].keyword);
			break;
		case ADDRESS:
			fprintf(stderr, "  <address>\n");
			break;
		case PREFIX:
			fprintf(stderr, "  <address>[/<len>]\n");
			break;
		case ASNUM:
			fprintf(stderr, "  <asnum>\n");
			break;
		case PEERDESC:
			fprintf(stderr, "  <neighbor description>\n");
			break;
		case COMMUNITY:
			fprintf(stderr, "  <community>\n");
			break;
		case LOCALPREF:
		case MED:
		case PREPNBR:
		case PREPSELF:
		case WEIGHT:
			fprintf(stderr, "  <number>\n");
			break;
		case NEXTHOP:
			fprintf(stderr, "  <address>\n");
			break;
		case PFTABLE:
			fprintf(stderr, "  <pftable>\n");
			break;
		case FAMILY:
			fprintf(stderr, "  [ inet | inet6 | IPv4 | IPv6 ]\n");
		case ENDTOKEN:
			break;
		}
	}
}

int
parse_addr(const char *word, struct bgpd_addr *addr)
{
	struct in_addr	ina;

	if (word == NULL)
		return (0);

	bzero(addr, sizeof(struct bgpd_addr));
	bzero(&ina, sizeof(ina));

	if (inet_pton(AF_INET, word, &ina)) {
		addr->af = AF_INET;
		addr->v4 = ina;
		return (1);
	}

	return (0);
}

int
parse_prefix(const char *word, struct bgpd_addr *addr, u_int8_t *prefixlen)
{
	struct in_addr	 ina;
	int		 bits = 32;

	if (word == NULL)
		return (0);

	bzero(addr, sizeof(struct bgpd_addr));
	bzero(&ina, sizeof(ina));

	if (strrchr(word, '/') != NULL) {
		if ((bits = inet_net_pton(AF_INET, word,
		    &ina, sizeof(ina))) == -1)
			return (0);
		addr->af = AF_INET;
		addr->v4.s_addr = ina.s_addr & htonl(prefixlen2mask(bits));
		*prefixlen = bits;
		return (1);
	} else {
		*prefixlen = 32;
		return (parse_addr(word, addr));
	}

	return (0);
}

int
parse_asnum(const char *word, u_int16_t *asnum)
{
	u_long	 ulval;
	char	*ep;

	if (word == NULL)
		return (0);

	errno = 0;
	ulval = strtoul(word, &ep, 0);
	if (word[0] == '\0' || *ep != '\0')
		return (0);
	if (errno == ERANGE && ulval == ULONG_MAX)
		return (0);
	if (ulval > USHRT_MAX)
		return (0);
	*asnum = (u_int16_t)ulval;
	return (1);
}

int
parse_number(const char *word, struct parse_result *r, enum token_type type)
{
	struct filter_set	*fs;
	u_long			 ulval;
	char			*ep;

	if (word == NULL)
		return (0);

	errno = 0;
	ulval = strtoul(word, &ep, 0);
	if (word[0] == '\0' || *ep != '\0')
		return (0);
	if (errno == ERANGE && ulval == ULONG_MAX)
		return (0);
	if (ulval > UINT_MAX)
		return (0);

	/* number was parseable */
	if ((fs = calloc(1, sizeof(struct filter_set))) == NULL)
		err(1, NULL);
	switch (type) {
	case LOCALPREF:
		fs->type = ACTION_SET_LOCALPREF;
		fs->action.metric = ulval;
		break;
	case MED:
		fs->type = ACTION_SET_MED;
		fs->action.metric = ulval;
		break;
	case PREPNBR:
		if (ulval > 128) {
			free(fs);
			return (0);
		}
		fs->type = ACTION_SET_PREPEND_PEER;
		fs->action.prepend = ulval;
		break;
	case PREPSELF:
		if (ulval > 128) {
			free(fs);
			return (0);
		}
		fs->type = ACTION_SET_PREPEND_SELF;
		fs->action.prepend = ulval;
		break;
	case WEIGHT:
		fs->type = ACTION_SET_WEIGHT;
		fs->action.metric = ulval;
		break;
	default:
		errx(1, "king bula sez bad things happen");
	}

	TAILQ_INSERT_TAIL(&r->set, fs, entry);
	return (1);
}

int
getcommunity(const char *s)
{
	char	*ep;
	u_long	 ulval;

	if (strcmp(s, "*") == 0)
		return (COMMUNITY_ANY);

	errno = 0;
	ulval = strtoul(s, &ep, 0);
	if (s[0] == '\0' || *ep != '\0')
		return (COMMUNITY_ERROR);
	if (errno == ERANGE && ulval == ULONG_MAX)
		return (COMMUNITY_ERROR);
	if (ulval > USHRT_MAX)
		return (COMMUNITY_ERROR);

	return (ulval);
}

int
parse_community(const char *word, struct parse_result *r)
{
	struct filter_set	*fs;
	char			*p;
	int			 i;
	u_int16_t		 as, type;

	/* Well-known communities */
	if (strcasecmp(word, "NO_EXPORT") == 0) {
		as = COMMUNITY_WELLKNOWN;
		type = COMMUNITY_NO_EXPORT;
		goto done;
	} else if (strcasecmp(word, "NO_ADVERTISE") == 0) {
		as = COMMUNITY_WELLKNOWN;
		type = COMMUNITY_NO_ADVERTISE;
		goto done;
	} else if (strcasecmp(word, "NO_EXPORT_SUBCONFED") == 0) {
		as = COMMUNITY_WELLKNOWN;
		type = COMMUNITY_NO_EXPSUBCONFED;
		goto done;
	} else if (strcasecmp(word, "NO_PEER") == 0) {
		as = COMMUNITY_WELLKNOWN;
		type = COMMUNITY_NO_PEER;
		goto done;
	}

	if ((p = strchr(word, ':')) == NULL) {
		fprintf(stderr, "Bad community syntax\n");
		return (0);
	}
	*p++ = 0;

	if ((i = getcommunity(word)) == COMMUNITY_ERROR) {
		fprintf(stderr, "\"%s\" is not a number or too big", word);
		return (0);
	}
	as = i;

	if ((i = getcommunity(p)) == COMMUNITY_ERROR) {
		fprintf(stderr, "\"%s\" is not a number or too big", p);
		return (0);
	}
	type = i;

done:
	if (as == 0 || as == USHRT_MAX) {
		fprintf(stderr, "Invalid community\n");
		return (0);
	}
	if (as == COMMUNITY_WELLKNOWN)
		switch (type) {
		case COMMUNITY_NO_EXPORT:
		case COMMUNITY_NO_ADVERTISE:
		case COMMUNITY_NO_EXPSUBCONFED:
			/* valid */
			break;
		default:
			/* unknown */
			fprintf(stderr, "Invalid well-known community\n");
			return (0);
		}

	if ((fs = calloc(1, sizeof(struct filter_set))) == NULL)
		err(1, NULL);
	fs->type = ACTION_SET_COMMUNITY;
	fs->action.community.as = as;
	fs->action.community.type = type;

	TAILQ_INSERT_TAIL(&r->set, fs, entry);
	return (1);
}

int
parse_nexthop(const char *word, struct parse_result *r)
{
	struct filter_set	*fs;

	if ((fs = calloc(1, sizeof(struct filter_set))) == NULL)
		err(1, NULL);

	if (strcmp(word, "blackhole") == 0)
		fs->type = ACTION_SET_NEXTHOP_BLACKHOLE;
	else if (strcmp(word, "reject") == 0)
		fs->type = ACTION_SET_NEXTHOP_REJECT;
	else if (strcmp(word, "no-modify") == 0)
		fs->type = ACTION_SET_NEXTHOP_NOMODIFY;
	else if (parse_addr(word, &fs->action.nexthop)) {
		fs->type = ACTION_SET_NEXTHOP;
	} else {
		free(fs);
		return (0);
	}

	TAILQ_INSERT_TAIL(&r->set, fs, entry);
	return (1);
}

/* XXX local copy from kroute.c, should go to a shared file */
in_addr_t
prefixlen2mask(u_int8_t prefixlen)
{
	if (prefixlen == 0)
		return (0);

	return (0xffffffff << (32 - prefixlen));
}