/*
 * Copyright (c) 2022 Omar Polo <op@omarpolo.com>
 * Copyright (c) 2007-2016 Reyk Floeter <reyk@openbsd.org>
 * Copyright (c) 2004, 2005 Esben Norby <norby@openbsd.org>
 * Copyright (c) 2004 Ryan McBride <mcbride@openbsd.org>
 * Copyright (c) 2002, 2003, 2004 Henning Brauer <henning@openbsd.org>
 * Copyright (c) 2001 Markus Friedl.  All rights reserved.
 * Copyright (c) 2001 Daniel Hartmeier.  All rights reserved.
 * Copyright (c) 2001 Theo de Raadt.  All rights reserved.
 *
 * 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 <sys/types.h>
#include <sys/queue.h>
#include <sys/tree.h>
#include <sys/uio.h>

#include <err.h>
#include <event.h>
#include <inttypes.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <stdarg.h>
#include <stdint.h>
#include <string.h>
#include <unistd.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <pwd.h>
#include <imsg.h>

#include "log.h"
#include "proc.h"

#include "galileo.h"

TAILQ_HEAD(files, file)		 files = TAILQ_HEAD_INITIALIZER(files);
static struct file {
	TAILQ_ENTRY(file)	 entry;
	FILE			*stream;
	char			*name;
	size_t			 ungetpos;
	size_t			 ungetsize;
	u_char			*ungetbuf;
	int			 eof_reached;
	int			 lineno;
	int			 errors;
} *file, *topfile;
struct file	*pushfile(const char *, int);
int		 popfile(void);
int		 yyparse(void);
int		 yylex(void);
int		 yyerror(const char *, ...)
    __attribute__((__format__ (printf, 1, 2)))
    __attribute__((__nonnull__ (1)));
int		 kw_cmp(const void *, const void *);
int		 lookup(char *);
int		 igetc(void);
int		 lgetc(int);
void		 lungetc(int);
int		 findeol(void);

TAILQ_HEAD(symhead, sym)	 symhead = TAILQ_HEAD_INITIALIZER(symhead);
struct sym {
	TAILQ_ENTRY(sym)	 entry;
	int			 used;
	int			 persist;
	char			*nam;
	char			*val;
};
int		 symset(const char *, const char *, int);
char		*symget(const char *);

int		 getservice(const char *);

static struct galileo	*conf = NULL;
static struct proxy	*pr = NULL;
static int		 errors;

typedef struct {
	union {
		int64_t		 number;
		char		*string;
	} v;
	int lineno;
} YYSTYPE;

%}

%token	INCLUDE ERROR
%token	CHROOT HOSTNAME NO PORT PREFORK PROXY SOURCE STYLESHEET TLS
%token	<v.number>	NUMBER
%token	<v.string>	STRING
%type	<v.number>	port
%type	<v.string>	string

%%

grammar		: /* empty */
		| grammar include '\n'
		| grammar '\n'
		| grammar varset '\n'
		| grammar main '\n'
		| grammar proxy '\n'
		| grammar error '\n'		{ file->errors++; }
		;

include		: INCLUDE string {
			struct file *nfile;

			if ((nfile = pushfile($2, 0)) == NULL) {
				yyerror("failed to include file %s", $2);
				free($2);
				YYERROR;
			}
			free($2);

			file = nfile;
			lungetc('\n');
		}
		;

varset		: STRING '=' STRING {
			char *s = $1;
			while (*s++) {
				if (isspace((unsigned char)*s)) {
					yyerror("macro name cannot contain "
					    "whitespace");
					free($1);
					free($3);
					YYERROR;
				}
			}
			if (symset($1, $3, 0) == -1)
				fatalx("cannot store variable");
			free($1);
			free($3);
		}
		;

main		: PREFORK NUMBER {
			if ($2 <= 0 || $2 > PROC_MAX_INSTANCES) {
				yyerror("invalid number of preforked "
				    "proxies: %"PRId64, $2);
				YYERROR;
			}
			conf->sc_prefork = $2;
		}
		| CHROOT STRING {
			size_t n;

			n = strlcpy(conf->sc_chroot, $2,
			    sizeof(conf->sc_chroot));
			if (n >= sizeof(conf->sc_chroot))
				yyerror("chroot path too long!");
			free($2);
		}
		;

proxy		: PROXY STRING {
			struct proxy	*p;
			size_t		 n;

			if ((p = calloc(1, sizeof(*p))) == NULL)
				fatal("calloc");

			n = strlcpy(p->pr_conf.host, $2,
			    sizeof(p->pr_conf.host));
			if (n >= sizeof(p->pr_conf.host)) {
				yyerror("server name too long");
				free($2);
				free(p);
				YYERROR;
			}
			free($2);

			pr = p;
		} '{' optnl proxyopts_l '}' {
			/* check if duplicate */
			if (proxy_match(conf, pr->pr_conf.host) != NULL)
				yyerror("duplicate proxy `%s'",
				    pr->pr_conf.host);

			TAILQ_INSERT_TAIL(&conf->sc_proxies, pr, pr_entry);

			if (*pr->pr_conf.proxy_addr == '\0')
				yyerror("missing source in proxy block `%s'",
				    pr->pr_conf.host);

			pr = NULL;
		}
		;

proxyopts_l	: proxyopts_l proxyoptsl nl
		| proxyoptsl optnl
		;

proxyoptsl	: SOURCE STRING proxyport {
			size_t n;

			n = strlcpy(pr->pr_conf.proxy_addr, $2,
			    sizeof(pr->pr_conf.proxy_addr));
			if (n >= sizeof(pr->pr_conf.proxy_addr))
				yyerror("proxy source too long!");

			if (*pr->pr_conf.proxy_name == '\0') {
				n = strlcpy(pr->pr_conf.proxy_name, $2,
				    sizeof(pr->pr_conf.proxy_name));
				if (n >= sizeof(pr->pr_conf.proxy_name))
					yyerror("proxy hostname too long!");
			}

			free($2);
		}
		| HOSTNAME STRING {
			size_t n;

			n = strlcpy(pr->pr_conf.proxy_name, $2,
			    sizeof(pr->pr_conf.proxy_name));
			if (n >= sizeof(pr->pr_conf.proxy_name))
				yyerror("proxy hostname too long!");
			free($2);
		}
		| STYLESHEET string {
			size_t n;

			n = strlcpy(pr->pr_conf.stylesheet, $2,
			    sizeof(pr->pr_conf.stylesheet));
			if (n >= sizeof(pr->pr_conf.stylesheet))
				yyerror("stylesheet path too long!");
			free($2);
		}
		| NO TLS {
			pr->pr_conf.no_tls = 1;
		}
		;

proxyport	: /* empty */ {
			strlcpy(pr->pr_conf.proxy_port, "1965",
			    sizeof(pr->pr_conf.proxy_port));
		}
		| PORT port {
			size_t len;
			int n;

			len = sizeof(pr->pr_conf.proxy_port);
			n = snprintf(pr->pr_conf.proxy_port, len,
			    "%"PRId64, $2);
			if (n < 0 || (size_t)n >= len)
				fatal("port number too long?");
		};

port		: NUMBER {
			if ($1 <= 0 || $1 > (int)USHRT_MAX) {
				yyerror("invalid port: %"PRId64, $1);
				YYERROR;
			}
			$$ = $1;
		}
		| STRING {
			int val;

			if ((val = getservice($1)) == -1) {
				yyerror("invalid port: %s", $1);
				free($1);
				YYERROR;
			}
			free($1);
			$$ = val;
		}
		;

string		: STRING string {
			if (asprintf(&$$, "%s%s", $1, $2) == -1)
				fatal("asprintf string");
			free($1);
			free($2);
		}
		| STRING
		;

optnl		: '\n' optnl
		|
		;

nl		: '\n' optnl
		;

%%

struct keywords {
	const char	*k_name;
	int		 k_val;
};

int
yyerror(const char *fmt, ...)
{
	va_list	 ap;
	char	*msg;

	file->errors++;
	va_start(ap, fmt);
	if (vasprintf(&msg, fmt, ap) == -1)
		fatal("yyerror vasprintf");
	va_end(ap);
	log_warnx("%s:%d: %s", file->name, yylval.lineno, msg);
	free(msg);
	return (0);
}

int
kw_cmp(const void *k, const void *e)
{
	return (strcmp(k, ((const struct keywords *)e)->k_name));
}

int
lookup(char *s)
{
	/* this has to be sorted always */
	static const struct keywords keywords[] = {
		{ "chroot",	CHROOT },
		{ "hostname",	HOSTNAME },
		{ "include",	INCLUDE },
		{ "no",		NO },
		{ "port",	PORT },
		{ "prefork",	PREFORK },
		{ "proxy",	PROXY },
		{ "source",	SOURCE },
		{ "stylesheet",	STYLESHEET},
		{ "tls",	TLS },
	};
	const struct keywords	*p;

	p = bsearch(s, keywords, nitems(keywords), sizeof(keywords[0]),
	    kw_cmp);

	if (p)
		return (p->k_val);
	else
		return (STRING);
}

#define START_EXPAND	1
#define DONE_EXPAND	2

static int	expanding;

int
igetc(void)
{
	int	c;

	while (1) {
		if (file->ungetpos > 0)
			c = file->ungetbuf[--file->ungetpos];
		else
			c = getc(file->stream);

		if (c == START_EXPAND)
			expanding = 1;
		else if (c == DONE_EXPAND)
			expanding = 0;
		else
			break;
	}
	return (c);
}

int
lgetc(int quotec)
{
	int		c, next;

	if (quotec) {
		if ((c = igetc()) == EOF) {
			yyerror("reached end of file while parsing "
			    "quoted string");
			if (file == topfile || popfile() == EOF)
				return (EOF);
			return (quotec);
		}
		return (c);
	}

	while ((c = igetc()) == '\\') {
		next = igetc();
		if (next != '\n') {
			c = next;
			break;
		}
		yylval.lineno = file->lineno;
		file->lineno++;
	}
	if (c == '\t' || c == ' ') {
		/* Compress blanks to a single space. */
		do {
			c = getc(file->stream);
		} while (c == '\t' || c == ' ');
		ungetc(c, file->stream);
		c = ' ';
	}

	if (c == EOF) {
		/*
		 * Fake EOL when hit EOF for the first time. This gets line
		 * count right if last line in included file is syntactically
		 * invalid and has no newline.
		 */
		if (file->eof_reached == 0) {
			file->eof_reached = 1;
			return ('\n');
		}
		while (c == EOF) {
			if (file == topfile || popfile() == EOF)
				return (EOF);
			c = igetc();
		}
	}
	return (c);
}

void
lungetc(int c)
{
	if (c == EOF)
		return;

	if (file->ungetpos >= file->ungetsize) {
		void *p = reallocarray(file->ungetbuf, file->ungetsize, 2);
		if (p == NULL)
			err(1, "%s", __func__);
		file->ungetbuf = p;
		file->ungetsize *= 2;
	}
	file->ungetbuf[file->ungetpos++] = c;
}

int
findeol(void)
{
	int	c;

	/* skip to either EOF or the first real EOL */
	while (1) {
		c = lgetc(0);
		if (c == '\n') {
			file->lineno++;
			break;
		}
		if (c == EOF)
			break;
	}
	return (ERROR);
}

int
yylex(void)
{
	char	 buf[8096];
	char	*p, *val;
	int	 quotec, next, c;
	int	 token;

top:
	p = buf;
	while ((c = lgetc(0)) == ' ' || c == '\t')
		; /* nothing */

	yylval.lineno = file->lineno;
	if (c == '#')
		while ((c = lgetc(0)) != '\n' && c != EOF)
			; /* nothing */
	if (c == '$' && !expanding) {
		while (1) {
			if ((c = lgetc(0)) == EOF)
				return (0);

			if (p + 1 >= buf + sizeof(buf) - 1) {
				yyerror("string too long");
				return (findeol());
			}
			if (isalnum(c) || c == '_') {
				*p++ = c;
				continue;
			}
			*p = '\0';
			lungetc(c);
			break;
		}
		val = symget(buf);
		if (val == NULL) {
			yyerror("macro '%s' not defined", buf);
			return (findeol());
		}
		p = val + strlen(val) - 1;
		lungetc(DONE_EXPAND);
		while (p >= val) {
			lungetc((unsigned char)*p);
			p--;
		}
		lungetc(START_EXPAND);
		goto top;
	}

	switch (c) {
	case '\'':
	case '"':
		quotec = c;
		while (1) {
			if ((c = lgetc(quotec)) == EOF)
				return (0);
			if (c == '\n') {
				file->lineno++;
				continue;
			} else if (c == '\\') {
				if ((next = lgetc(quotec)) == EOF)
					return (0);
				if (next == quotec || next == ' ' ||
				    next == '\t')
					c = next;
				else if (next == '\n') {
					file->lineno++;
					continue;
				} else
					lungetc(next);
			} else if (c == quotec) {
				*p = '\0';
				break;
			} else if (c == '\0') {
				yyerror("syntax error");
				return (findeol());
			}
			if (p + 1 >= buf + sizeof(buf) - 1) {
				yyerror("string too long");
				return (findeol());
			}
			*p++ = c;
		}
		yylval.v.string = strdup(buf);
		if (yylval.v.string == NULL)
			fatal("yylex: strdup");
		return (STRING);
	}

#define allowed_to_end_number(x) \
	(isspace(x) || x == ')' || x ==',' || x == '/' || x == '}' || x == '=')

	if (c == '-' || isdigit(c)) {
		do {
			*p++ = c;
			if ((size_t)(p-buf) >= sizeof(buf)) {
				yyerror("string too long");
				return (findeol());
			}
		} while ((c = lgetc(0)) != EOF && isdigit(c));
		lungetc(c);
		if (p == buf + 1 && buf[0] == '-')
			goto nodigits;
		if (c == EOF || allowed_to_end_number(c)) {
			const char *errstr = NULL;

			*p = '\0';
			yylval.v.number = strtonum(buf, LLONG_MIN,
			    LLONG_MAX, &errstr);
			if (errstr) {
				yyerror("\"%s\" invalid number: %s",
				    buf, errstr);
				return (findeol());
			}
			return (NUMBER);
		} else {
nodigits:
			while (p > buf + 1)
				lungetc((unsigned char)*--p);
			c = (unsigned char)*--p;
			if (c == '-')
				return (c);
		}
	}

#define allowed_in_string(x) \
	(isalnum(x) || (ispunct(x) && x != '(' && x != ')' && \
	x != '{' && x != '}' && \
	x != '!' && x != '=' && x != '#' && \
	x != ','))

	if (isalnum(c) || c == ':' || c == '_' || c == '/') {
		do {
			*p++ = c;
			if ((size_t)(p-buf) >= sizeof(buf)) {
				yyerror("string too long");
				return (findeol());
			}
		} while ((c = lgetc(0)) != EOF && (allowed_in_string(c)));
		lungetc(c);
		*p = '\0';
		if ((token = lookup(buf)) == STRING)
			if ((yylval.v.string = strdup(buf)) == NULL)
				fatal("yylex: strdup");
		return (token);
	}
	if (c == '\n') {
		yylval.lineno = file->lineno;
		file->lineno++;
	}
	if (c == EOF)
		return (0);
	return (c);
}

struct file *
pushfile(const char *name, int secret)
{
	struct file	*nfile;

	if ((nfile = calloc(1, sizeof(struct file))) == NULL) {
		log_warn("%s", __func__);
		return (NULL);
	}
	if ((nfile->name = strdup(name)) == NULL) {
		log_warn("%s", __func__);
		free(nfile);
		return (NULL);
	}
	if ((nfile->stream = fopen(nfile->name, "r")) == NULL) {
		free(nfile->name);
		free(nfile);
		return (NULL);
	}
	nfile->lineno = TAILQ_EMPTY(&files) ? 1 : 0;
	nfile->ungetsize = 16;
	nfile->ungetbuf = malloc(nfile->ungetsize);
	if (nfile->ungetbuf == NULL) {
		log_warn("%s", __func__);
		fclose(nfile->stream);
		free(nfile->name);
		free(nfile);
		return (NULL);
	}
	TAILQ_INSERT_TAIL(&files, nfile, entry);
	return (nfile);
}

int
popfile(void)
{
	struct file	*prev;

	if ((prev = TAILQ_PREV(file, files, entry)) != NULL)
		prev->errors += file->errors;

	TAILQ_REMOVE(&files, file, entry);
	fclose(file->stream);
	free(file->name);
	free(file->ungetbuf);
	free(file);
	file = prev;
	return (file ? 0 : EOF);
}

int
parse_config(const char *filename, struct galileo *env)
{
	struct sym	*sym, *next;
	size_t		 n;

	conf = env;

	n = strlcpy(conf->sc_conffile, filename, sizeof(conf->sc_conffile));
	if (n >= sizeof(conf->sc_conffile)) {
		log_warn("path too long: %s", filename);
		return (-1);
	}

	if ((file = pushfile(filename, 0)) == NULL) {
		log_warn("failed to open %s", filename);
		return (-1);
	}
	topfile = file;
	setservent(1);

	yyparse();
	if (TAILQ_EMPTY(&conf->sc_proxies))
		yyerror("no proxies defined");
	errors = file->errors;
	popfile();

	endservent();

	/* Free macros and check which have not been used. */
	TAILQ_FOREACH_SAFE(sym, &symhead, entry, next) {
		if (!sym->used)
			fprintf(stderr, "warning: macro `%s' not used\n",
			    sym->nam);
		if (!sym->persist) {
			free(sym->nam);
			free(sym->val);
			TAILQ_REMOVE(&symhead, sym, entry);
			free(sym);
		}
	}

	if (errors)
		return (-1);

	return (0);
}

int
symset(const char *nam, const char *val, int persist)
{
	struct sym	*sym;

	TAILQ_FOREACH(sym, &symhead, entry) {
		if (strcmp(nam, sym->nam) == 0)
			break;
	}

	if (sym != NULL) {
		if (sym->persist == 1)
			return (0);
		else {
			free(sym->nam);
			free(sym->val);
			TAILQ_REMOVE(&symhead, sym, entry);
			free(sym);
		}
	}
	if ((sym = calloc(1, sizeof(*sym))) == NULL)
		return (-1);

	sym->nam = strdup(nam);
	if (sym->nam == NULL) {
		free(sym);
		return (-1);
	}
	sym->val = strdup(val);
	if (sym->val == NULL) {
		free(sym->nam);
		free(sym);
		return (-1);
	}
	sym->used = 0;
	sym->persist = persist;
	TAILQ_INSERT_TAIL(&symhead, sym, entry);
	return (0);
}

int
cmdline_symset(char *s)
{
	char	*sym, *val;
	int	ret;

	if ((val = strrchr(s, '=')) == NULL)
		return (-1);
	sym = strndup(s, val - s);
	if (sym == NULL)
		fatal("%s: strndup", __func__);
	ret = symset(sym, val + 1, 1);
	free(sym);

	return (ret);
}

char *
symget(const char *nam)
{
	struct sym	*sym;

	TAILQ_FOREACH(sym, &symhead, entry) {
		if (strcmp(nam, sym->nam) == 0) {
			sym->used = 1;
			return (sym->val);
		}
	}
	return (NULL);
}

int
getservice(const char *n)
{
	struct servent	*s;
	const char	*errstr;
	long long	 llval;

	llval = strtonum(n, 0, UINT16_MAX, &errstr);
	if (errstr) {
		s = getservbyname(n, "tcp");
		if (s == NULL)
			s = getservbyname(n, "udp");
		if (s == NULL)
			return (-1);
		return (ntohs(s->s_port));
	}

	return ((unsigned short)llval);
}