/*
 * Copyright (c) 2022 Stefan Sperling <stsp@openbsd.org>
 * Copyright (c) 2016-2019, 2020-2021 Tracey Emery <tracey@traceyemery.net>
 * 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/time.h>
#include <sys/types.h>
#include <sys/queue.h>
#include <sys/stat.h>

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <event.h>
#include <imsg.h>
#include <limits.h>
#include <sha1.h>
#include <stdarg.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>

#include "got_error.h"
#include "got_path.h"

#include "log.h"
#include "gotd.h"

TAILQ_HEAD(files, file)		 files = TAILQ_HEAD_INITIALIZER(files);
static struct file {
	TAILQ_ENTRY(file)	 entry;
	FILE			*stream;
	char			*name;
	int			 lineno;
	int			 errors;
} *file;
struct file	*newfile(const char *, int);
static void	 closefile(struct file *);
int		 check_file_secrecy(int, const char *);
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		 lgetc(int);
int		 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 *);

static int		 errors;

static struct gotd		*gotd;
static struct gotd_repo		*new_repo;
static struct gotd_repo		*conf_new_repo(const char *);
static enum gotd_procid		 gotd_proc_id;

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

%}

%token	PATH ERROR ON UNIX_SOCKET UNIX_GROUP USER REPOSITORY

%token	<v.string>	STRING
%token	<v.number>	NUMBER
%type	<v.number>	boolean

%%

grammar		:
		| grammar '\n'
		| grammar main '\n'
		| grammar repository '\n'
		;

boolean		: STRING {
			if (strcasecmp($1, "1") == 0 ||
			    strcasecmp($1, "yes") == 0 ||
			    strcasecmp($1, "on") == 0)
				$$ = 1;
			else if (strcasecmp($1, "0") == 0 ||
			    strcasecmp($1, "off") == 0 ||
			    strcasecmp($1, "no") == 0)
				$$ = 0;
			else {
				yyerror("invalid boolean value '%s'", $1);
				free($1);
				YYERROR;
			}
			free($1);
		}
		| ON { $$ = 1; }
		| NUMBER { $$ = $1; }
		;

main		: UNIX_SOCKET STRING {
			if (gotd_proc_id == PROC_GOTD) {
				if (strlcpy(gotd->unix_socket_path, $2,
				    sizeof(gotd->unix_socket_path)) >=
				    sizeof(gotd->unix_socket_path)) {
					yyerror("%s: unix socket path too long",
					    __func__);
					free($2);
					YYERROR;
				}
			}
			free($2);
		}
		| UNIX_GROUP STRING {
			if (strlcpy(gotd->unix_group_name, $2,
			    sizeof(gotd->unix_group_name)) >=
			    sizeof(gotd->unix_group_name)) {
				yyerror("%s: unix group name too long",
				    __func__);
				free($2);
				YYERROR;
			}
			free($2);
		}
		| USER STRING {
			if (strlcpy(gotd->user_name, $2,
			    sizeof(gotd->user_name)) >=
			    sizeof(gotd->user_name)) {
				yyerror("%s: user name too long", __func__);
				free($2);
				YYERROR;
			}
			free($2);
		}
		;

repository	: REPOSITORY STRING {
			struct gotd_repo *repo;

			TAILQ_FOREACH(repo, &gotd->repos, entry) {
				if (strcmp(repo->name, $2) == 0) {
					yyerror("duplicate repository '%s'", $2);
					free($2);
					YYERROR;
				}
			}

			if (gotd_proc_id == PROC_GOTD) {
				new_repo = conf_new_repo($2);
			}
			free($2);
		}
		| REPOSITORY STRING {
			struct gotd_repo *repo;

			TAILQ_FOREACH(repo, &gotd->repos, entry) {
				if (strcmp(repo->name, $2) == 0) {
					yyerror("duplicate repository '%s'", $2);
					free($2);
					YYERROR;
				}
			}

			if (gotd_proc_id == PROC_GOTD) {
				new_repo = conf_new_repo($2);
			}
			free($2);
		} '{' optnl repoopts2 '}' {
		}
		;

repoopts1	: PATH STRING {
			if (gotd_proc_id == PROC_GOTD) {
				if (!got_path_is_absolute($2)) {
					yyerror("%s: path %s is not absolute",
					    __func__, $2);
					free($2);
					YYERROR;
				}
				if (strlcpy(new_repo->path, $2,
				    sizeof(new_repo->path)) >=
				    sizeof(new_repo->path)) {
					yyerror("%s: path truncated", __func__);
					free($2);
					YYERROR;
				}
			}
			free($2);
		}
		;

repoopts2	: repoopts2 repoopts1 nl
		| repoopts1 optnl
		;

nl		: '\n' optnl
		;

optnl		: '\n' optnl		/* zero or more newlines */
		| /* empty */
		;

%%

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)
		fatalx("yyerror vasprintf");
	va_end(ap);
	logit(LOG_CRIT, "%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[] = {
		{ "on",				ON },
		{ "path",			PATH },
		{ "repository",			REPOSITORY },
		{ "unix_group",			UNIX_GROUP },
		{ "unix_socket",		UNIX_SOCKET },
		{ "user",			USER },
	};
	const struct keywords *p;

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

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

#define MAXPUSHBACK	128

unsigned char *parsebuf;
int parseindex;
unsigned char pushback_buffer[MAXPUSHBACK];
int pushback_index = 0;

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

	if (parsebuf) {
		/* Read character from the parsebuffer instead of input. */
		if (parseindex >= 0) {
			c = parsebuf[parseindex++];
			if (c != '\0')
				return (c);
			parsebuf = NULL;
		} else
			parseindex++;
	}

	if (pushback_index)
		return (pushback_buffer[--pushback_index]);

	if (quotec) {
		c = getc(file->stream);
		if (c == EOF)
			yyerror("reached end of file while parsing "
			    "quoted string");
		return (c);
	}

	c = getc(file->stream);
	while (c == '\\') {
		next = getc(file->stream);
		if (next != '\n') {
			c = next;
			break;
		}
		yylval.lineno = file->lineno;
		file->lineno++;
		c = getc(file->stream);
	}

	return (c);
}

int
lungetc(int c)
{
	if (c == EOF)
		return (EOF);
	if (parsebuf) {
		parseindex--;
		if (parseindex >= 0)
			return (c);
	}
	if (pushback_index < MAXPUSHBACK-1)
		return (pushback_buffer[pushback_index++] = c);
	else
		return (EOF);
}

int
findeol(void)
{
	int c;

	parsebuf = NULL;

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

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

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

	yylval.lineno = file->lineno;
	if (c == '#') {
		c = lgetc(0);
		while (c != '\n' && c != EOF)
			c = lgetc(0); /* nothing */
	}
	if (c == '$' && parsebuf == NULL) {
		while (1) {
			c = lgetc(0);
			if (c == 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());
		}
		parsebuf = val;
		parseindex = 0;
		goto top;
	}

	switch (c) {
	case '\'':
	case '"':
		quotec = c;
		while (1) {
			c = lgetc(quotec);
			if (c == EOF)
				return (0);
			if (c == '\n') {
				file->lineno++;
				continue;
			} else if (c == '\\') {
				next = lgetc(quotec);
				if (next == EOF)
					return (0);
				if (next == quotec || c == ' ' || c == '\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)
			err(1, "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 ((unsigned)(p-buf) >= sizeof(buf)) {
				yyerror("string too long");
				return (findeol());
			}
			c = lgetc(0);
		} while (c != 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(*--p);
			c = *--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 == '_') {
		do {
			*p++ = c;
			if ((unsigned)(p-buf) >= sizeof(buf)) {
				yyerror("string too long");
				return (findeol());
			}
			c = lgetc(0);
		} while (c != EOF && (allowed_in_string(c)));
		lungetc(c);
		*p = '\0';
		token = lookup(buf);
		if (token == STRING) {
			yylval.v.string = strdup(buf);
			if (yylval.v.string == NULL)
				err(1, "yylex: strdup");
		}
		return (token);
	}
	if (c == '\n') {
		yylval.lineno = file->lineno;
		file->lineno++;
	}
	if (c == EOF)
		return (0);
	return (c);
}

int
check_file_secrecy(int fd, const char *fname)
{
	struct stat st;

	if (fstat(fd, &st)) {
		log_warn("cannot stat %s", fname);
		return (-1);
	}
	if (st.st_uid != 0 && st.st_uid != getuid()) {
		log_warnx("%s: owner not root or current user", fname);
		return (-1);
	}
	if (st.st_mode & (S_IWGRP | S_IXGRP | S_IRWXO)) {
		log_warnx("%s: group writable or world read/writable", fname);
		return (-1);
	}
	return (0);
}

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

	nfile = calloc(1, sizeof(struct file));
	if (nfile == NULL) {
		log_warn("calloc");
		return (NULL);
	}
	nfile->name = strdup(name);
	if (nfile->name == NULL) {
		log_warn("strdup");
		free(nfile);
		return (NULL);
	}
	nfile->stream = fopen(nfile->name, "r");
	if (nfile->stream == NULL) {
		/* no warning, we don't require a conf file */
		free(nfile->name);
		free(nfile);
		return (NULL);
	} else if (secret &&
	    check_file_secrecy(fileno(nfile->stream), nfile->name)) {
		fclose(nfile->stream);
		free(nfile->name);
		free(nfile);
		return (NULL);
	}
	nfile->lineno = 1;
	return (nfile);
}

static void
closefile(struct file *xfile)
{
	fclose(xfile->stream);
	free(xfile->name);
	free(xfile);
}

int
parse_config(const char *filename, enum gotd_procid proc_id,
    struct gotd *env)
{
	struct sym *sym, *next;

	memset(env, 0, sizeof(*env));

	gotd = env;
	gotd_proc_id = proc_id;
	TAILQ_INIT(&gotd->repos);

	/* Apply default values. */
	if (strlcpy(gotd->unix_socket_path, GOTD_UNIX_SOCKET,
	    sizeof(gotd->unix_socket_path)) >= sizeof(gotd->unix_socket_path)) {
		fprintf(stderr, "%s: unix socket path too long", __func__);
		return -1;
	}
	if (strlcpy(gotd->unix_group_name, GOTD_UNIX_GROUP,
	    sizeof(gotd->unix_group_name)) >= sizeof(gotd->unix_group_name)) {
		fprintf(stderr, "%s: unix group name too long", __func__);
		return -1;
	}
	if (strlcpy(gotd->user_name, GOTD_USER,
	    sizeof(gotd->user_name)) >= sizeof(gotd->user_name)) {
		fprintf(stderr, "%s: user name too long", __func__);
		return -1;
	}

	file = newfile(filename, 0);
	if (file == NULL) {
		/* just return, as we don't require a conf file */
		return (0);
	}

	yyparse();
	errors = file->errors;
	closefile(file);

	/* Free macros and check which have not been used. */
	TAILQ_FOREACH_SAFE(sym, &symhead, entry, next) {
		if ((gotd->verbosity > 1) && !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);
}

static struct gotd_repo *
conf_new_repo(const char *name)
{
	struct gotd_repo *repo;

	if (strchr(name, '\n') != NULL) {
		fatalx("%s: repository names must not contain linefeeds: %s",
		    getprogname(), name);
	}

	repo = calloc(1, sizeof(*repo));
	if (repo == NULL)
		fatalx("%s: calloc", __func__);

	if (strlcpy(repo->name, name, sizeof(repo->name)) >=
	    sizeof(repo->name))
		fatalx("%s: strlcpy", __func__);

	TAILQ_INSERT_TAIL(&gotd->repos, repo, entry);
	gotd->nrepos++;

	return repo;
};

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);
		}
	}
	sym = calloc(1, sizeof(*sym));
	if (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);
}

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);
}