xref: /openbsd-src/usr.sbin/lpd/parse.y (revision 08f6ba1906d01c4a24fa700d568400f71bcf9611)

/*	$OpenBSD: parse.y,v 1.8 2021/10/15 15:01:28 naddy Exp $	*/

/*
 * Copyright (c) 2008 Gilles Chehade <gilles@poolp.org>
 * Copyright (c) 2008 Pierre-Yves Ritschard <pyr@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/socket.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/un.h>

#include <net/if.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <ifaddrs.h>
#include <inttypes.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#include "lpd.h"

#include "log.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, *topfile;
struct file	*pushfile(const char *, int);
int		 popfile(void);
int		 check_file_secrecy(int, const char *);
int		 yyparse(void);
int		 yylex(void);
int		 kw_cmp(const void *, const void *);
int		 lookup(char *);
int		 lgetc(int);
int		 lungetc(int);
int		 findeol(void);
int		 yyerror(const char *, ...)
    __attribute__((__format__ (printf, 1, 2)))
    __attribute__((__nonnull__ (1)));

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 = 0;

struct lpd_conf		*conf = NULL;

enum listen_options {
	LO_FAMILY	= 0x000001,
	LO_PORT		= 0x000002,
};

static struct listen_opts {
	char	       *ifx;
	int		family;
	int		proto;
	in_port_t	port;
	uint32_t       	options;
} listen_opts;

static void	config_free(struct lpd_conf *);
static void	create_listeners(struct listen_opts *);
static void	config_listener(struct listener *, struct listen_opts *);
static int	local(struct listen_opts *);
static int	host_v4(struct listen_opts *);
static int	host_v6(struct listen_opts *);
static int	host_dns(struct listen_opts *);
static int	interface(struct listen_opts *);
static int	is_if_in_group(const char *, const char *);

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

%}

%token	ERROR ARROW INCLUDE
%token	LISTEN ON PORT INET4 INET6 LOCAL SOCKET
%token	<v.string>	STRING
%token  <v.number>	NUMBER
%type	<v.number>	family_inet portno

%%

grammar		: /* empty */
		| grammar '\n'
		| grammar include '\n'
		| grammar varset '\n'
		| grammar main '\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)
				fatal("cannot store variable");
			free($1);
			free($3);
		}
		;

portno		: STRING {
			struct servent	*servent;
			servent = getservbyname($1, "tcp");
			if (servent == NULL) {
				yyerror("invalid port: %s", $1);
				free($1);
				YYERROR;
			}
			free($1);
			$$ = ntohs(servent->s_port);
		}
		| NUMBER {
			if ($1 <= 0 || $1 > (int)USHRT_MAX) {
				yyerror("invalid port: %" PRId64, $1);
				YYERROR;
			}
			$$ = $1;
		}
		;

family_inet	: INET4 { $$ = AF_INET; }
		| INET6 { $$ = AF_INET6; }
		;

opt_listen	: family_inet {
			if (listen_opts.options & LO_FAMILY) {
				yyerror("address family already specified");
				YYERROR;
			}
			listen_opts.options |= LO_FAMILY;
			listen_opts.family = $1;
		}
		| PORT portno {
			if (listen_opts.options & LO_PORT) {
				yyerror("port already specified");
				YYERROR;
			}
			listen_opts.options |= LO_PORT;
			listen_opts.port = htons($2);
		}
		;

listener	: opt_listen listener
		| /* empty */ {
			create_listeners(&listen_opts);
		}
		;

main		: LISTEN ON STRING {
			memset(&listen_opts, 0, sizeof listen_opts);
			listen_opts.ifx = $3;
			listen_opts.family = AF_UNSPEC;
			listen_opts.proto = PROTO_LPR;
			listen_opts.port = htons(PORT_LPR);
		} listener
		;
%%

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);
	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[] = {
		{ "include",		INCLUDE },
		{ "inet4",		INET4 },
		{ "inet6",		INET6 },
		{ "listen",		LISTEN },
		{ "on",			ON },
		{ "port",		PORT },
		{ "socket",		SOCKET },
	};
	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

char	*parsebuf;
int	 parseindex;
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 = (unsigned char)parsebuf[parseindex++];
			if (c != '\0')
				return (c);
			parsebuf = NULL;
		} else
			parseindex++;
	}

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

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

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

	while (c == EOF) {
		if (file == topfile || popfile() == EOF)
			return (EOF);
		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 + 1 >= MAXPUSHBACK)
		return (EOF);
	pushback_buffer[pushback_index++] = c;
	return (c);
}

int
findeol(void)
{
	int	c;

	parsebuf = NULL;
	pushback_index = 0;

	/* 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 == '$' && parsebuf == NULL) {
		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());
		}
		parsebuf = val;
		parseindex = 0;
		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)
			err(1, "%s", __func__);
		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);
		}
	}

	if (c == '=') {
		if ((c = lgetc(0)) != EOF && c == '>')
			return (ARROW);
		lungetc(c);
		c = '=';
	}

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

	if (isalnum(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)
				err(1, "%s", __func__);
		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("warn: cannot stat %s", fname);
		return (-1);
	}
	if (st.st_uid != 0 && st.st_uid != getuid()) {
		log_warnx("warn: %s: owner not root or current user", fname);
		return (-1);
	}
	if (st.st_mode & (S_IWGRP | S_IXGRP | S_IRWXO)) {
		log_warnx("warn: %s: group/world readable/writeable", fname);
		return (-1);
	}
	return (0);
}

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) {
		log_warn("%s: %s", __func__, nfile->name);
		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;
	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);
	file = prev;
	return (file ? 0 : EOF);
}

struct lpd_conf *
parse_config(const char *filename, int verbose)
{
	struct sym     *sym, *next;

	conf = calloc(1, sizeof(*conf));
	if (conf == NULL)
		return NULL;
	TAILQ_INIT(&conf->listeners);

	errors = 0;

	if ((file = pushfile(filename, 0)) == NULL) {
		config_free(conf);
		return NULL;
	}
	topfile = file;

	/*
	 * parse configuration
	 */
	setservent(1);
	yyparse();
	errors = file->errors;
	popfile();
	endservent();

	/* Free macros and check which have not been used. */
	TAILQ_FOREACH_SAFE(sym, &symhead, entry, next) {
		if ((verbose) && !sym->used)
			log_warnx("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) {
		config_free(conf);
		return NULL;
	}

	return conf;
}

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)
		errx(1, "%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);
}

static void
config_free(struct lpd_conf *c)
{
	struct listener *l;

	while ((l = TAILQ_FIRST(&c->listeners))) {
		TAILQ_REMOVE(&c->listeners, l, entry);
		free(l);
	}
	free(c);
}

static void
create_listeners(struct listen_opts *lo)
{
	if (local(lo))
		return;
	if (interface(lo))
		return;
	if (host_v4(lo))
		return;
	if (host_v6(lo))
		return;
	if (host_dns(lo))
		return;

	errx(1, "invalid virtual ip or interface: %s", lo->ifx);
}

static void
config_listener(struct listener *l,  struct listen_opts *lo)
{
	l->sock = -1;
	l->proto = lo->proto;

	TAILQ_INSERT_TAIL(&conf->listeners, l, entry);
}

static int
local(struct listen_opts *lo)
{
	struct sockaddr_un	*sun;
	struct listener		*h;

	if (lo->family != AF_UNSPEC && lo->family != AF_LOCAL)
		return 0;

	if (lo->ifx[0] != '/')
		return 0;

	h = calloc(1, sizeof(*h));
	sun = (struct sockaddr_un *)&h->ss;
	sun->sun_len = sizeof(*sun);
	sun->sun_family = AF_LOCAL;
	if (strlcpy(sun->sun_path, lo->ifx, sizeof(sun->sun_path))
	    >= sizeof(sun->sun_path))
		fatalx("path too long");

	config_listener(h,  lo);

	return (1);
}

static int
host_v4(struct listen_opts *lo)
{
	struct in_addr		 ina;
	struct sockaddr_in	*sain;
	struct listener		*h;

	if (lo->family != AF_UNSPEC && lo->family != AF_INET)
		return (0);

	memset(&ina, 0, sizeof(ina));
	if (inet_pton(AF_INET, lo->ifx, &ina) != 1)
		return (0);

	h = calloc(1, sizeof(*h));
	sain = (struct sockaddr_in *)&h->ss;
	sain->sin_len = sizeof(struct sockaddr_in);
	sain->sin_family = AF_INET;
	sain->sin_addr.s_addr = ina.s_addr;
	sain->sin_port = lo->port;

	config_listener(h,  lo);

	return (1);
}

static int
host_v6(struct listen_opts *lo)
{
	struct in6_addr		 ina6;
	struct sockaddr_in6	*sin6;
	struct listener		*h;

	if (lo->family != AF_UNSPEC && lo->family != AF_INET6)
		return (0);

	memset(&ina6, 0, sizeof(ina6));
	if (inet_pton(AF_INET6, lo->ifx, &ina6) != 1)
		return (0);

	h = calloc(1, sizeof(*h));
	sin6 = (struct sockaddr_in6 *)&h->ss;
	sin6->sin6_len = sizeof(struct sockaddr_in6);
	sin6->sin6_family = AF_INET6;
	sin6->sin6_port = lo->port;
	memcpy(&sin6->sin6_addr, &ina6, sizeof(ina6));

	config_listener(h,  lo);

	return (1);
}

static int
host_dns(struct listen_opts *lo)
{
	struct addrinfo		 hints, *res0, *res;
	int			 error, cnt = 0;
	struct sockaddr_in	*sain;
	struct sockaddr_in6	*sin6;
	struct listener		*h;

	memset(&hints, 0, sizeof(hints));
	hints.ai_family = lo->family;
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_flags = AI_ADDRCONFIG;
	error = getaddrinfo(lo->ifx, NULL, &hints, &res0);
	if (error == EAI_AGAIN || error == EAI_NODATA || error == EAI_NONAME)
		return (0);
	if (error) {
		log_warnx("warn: host_dns: could not parse \"%s\": %s", lo->ifx,
		    gai_strerror(error));
		return (-1);
	}

	for (res = res0; res; res = res->ai_next) {
		if (res->ai_family != AF_INET &&
		    res->ai_family != AF_INET6)
			continue;
		h = calloc(1, sizeof(*h));
		h->ss.ss_family = res->ai_family;
		if (res->ai_family == AF_INET) {
			sain = (struct sockaddr_in *)&h->ss;
			sain->sin_len = sizeof(struct sockaddr_in);
			sain->sin_addr.s_addr = ((struct sockaddr_in *)
			    res->ai_addr)->sin_addr.s_addr;
			sain->sin_port = lo->port;
		} else {
			sin6 = (struct sockaddr_in6 *)&h->ss;
			sin6->sin6_len = sizeof(struct sockaddr_in6);
			memcpy(&sin6->sin6_addr, &((struct sockaddr_in6 *)
			    res->ai_addr)->sin6_addr, sizeof(struct in6_addr));
			sin6->sin6_port = lo->port;
		}

		config_listener(h, lo);

		cnt++;
	}

	freeaddrinfo(res0);
	return (cnt);
}

static int
interface(struct listen_opts *lo)
{
	struct ifaddrs *ifap, *p;
	struct sockaddr_in	*sain;
	struct sockaddr_in6	*sin6;
	struct listener		*h;
	int			ret = 0;

	if (getifaddrs(&ifap) == -1)
		fatal("getifaddrs");

	for (p = ifap; p != NULL; p = p->ifa_next) {
		if (p->ifa_addr == NULL)
			continue;
		if (strcmp(p->ifa_name, lo->ifx) != 0 &&
		    !is_if_in_group(p->ifa_name, lo->ifx))
			continue;
		if (lo->family != AF_UNSPEC && lo->family != p->ifa_addr->sa_family)
			continue;

		h = calloc(1, sizeof(*h));

		switch (p->ifa_addr->sa_family) {
		case AF_INET:
			sain = (struct sockaddr_in *)&h->ss;
			*sain = *(struct sockaddr_in *)p->ifa_addr;
			sain->sin_len = sizeof(struct sockaddr_in);
			sain->sin_port = lo->port;
			break;

		case AF_INET6:
			sin6 = (struct sockaddr_in6 *)&h->ss;
			*sin6 = *(struct sockaddr_in6 *)p->ifa_addr;
			sin6->sin6_len = sizeof(struct sockaddr_in6);
			sin6->sin6_port = lo->port;
			break;

		default:
			free(h);
			continue;
		}

		config_listener(h, lo);
		ret = 1;
	}

	freeifaddrs(ifap);

	return ret;
}

static int
is_if_in_group(const char *ifname, const char *groupname)
{
        unsigned int		 len;
        struct ifgroupreq        ifgr;
        struct ifg_req          *ifg;
	int			 s;
	int			 ret = 0;

	if ((s = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
		err(1, "socket");

        memset(&ifgr, 0, sizeof(ifgr));
        if (strlcpy(ifgr.ifgr_name, ifname, IFNAMSIZ) >= IFNAMSIZ)
		errx(1, "interface name too large");

        if (ioctl(s, SIOCGIFGROUP, (caddr_t)&ifgr) == -1) {
                if (errno == EINVAL || errno == ENOTTY)
			goto end;
		err(1, "SIOCGIFGROUP");
        }

        len = ifgr.ifgr_len;
        ifgr.ifgr_groups = calloc(len/sizeof(struct ifg_req),
		sizeof(struct ifg_req));
        if (ioctl(s, SIOCGIFGROUP, (caddr_t)&ifgr) == -1)
                err(1, "SIOCGIFGROUP");

        ifg = ifgr.ifgr_groups;
        for (; ifg && len >= sizeof(struct ifg_req); ifg++) {
                len -= sizeof(struct ifg_req);
		if (strcmp(ifg->ifgrq_group, groupname) == 0) {
			ret = 1;
			break;
		}
        }
        free(ifgr.ifgr_groups);

end:
	close(s);
	return ret;
}