2 * userv service (or standalone program) for per-user IP subranges.
4 * When invoked appropriately, it creates a point-to-point network
5 * interface with specified parameters. It arranges for packets sent out
6 * via that interface by the kernel to appear on its own stdout in SLIP or
7 * CSLIP encoding, and packets injected into its own stdin to be given to
8 * the kernel as if received on that interface. Optionally, additional
9 * routes can be set up to arrange for traffic for other address ranges to
10 * be routed through the new interface.
12 * This is the service program, which is invoked as root from userv (or may
13 * be invoked firectly).
15 * Its arguments are supposed to be, in order, as follows:
17 * The first two arguments are usually supplied by the userv
18 * configuration. See the file `ipif/ipif' in the source tree, which
19 * is installed in /etc/userv/services.d/ipif by `make install':
23 * Specifies address ranges and gids which own them. The default
24 * configuration supplies /etc/userv/ipif-networks, which is then read
25 * for a list of entries, one per line.
28 * Serves to separate the user-supplied and therefore untrusted
29 * arguments from the trusted first argument.
31 * The remaining arguments are supplied by the (untrusted) caller:
33 * <local-addr>,<peer-addr>,<mtu>,<proto>
35 * As for slattach. The only supported protocol is slip.
36 * Alternatively, set to `debug' to print debugging info and
37 * exit. <local-addr> is address of the interface to be created
38 * on the local system; <peer-addr> is the address of the
39 * point-to-point peer. They must be actual addresses (not
42 * <prefix>/<mask>,<prefix>/<mask>,...
44 * List of additional routes to add for this interface. routes will
45 * be set up on the local system arranging for packets for those
46 * networks to be sent via the created interface. <prefix> must be an
47 * IPv4 address, and mask must be an integer (dotted-quad masks are
48 * not supported). If no additional routes are to be set up, use `-'
49 * or supply an empty argument.
51 * Each <config> item - whether a line in a file such as
52 * /etc/userv/ipif-networks, or the single trusted argument supplied
53 * on the service program command line - is one of:
56 * ./<config-file-name>
57 * ../<config-file-name>
59 * Reads a file which contains lines which are each <config>
62 * <gid>,[=][-|+]<prefix>/<len>(-|+<prefix>/<len>...)[,<junk>]
64 * Indicates that <gid> may allocate addresses in the relevant address
65 * range (<junk> is ignored). <gid> must be numeric. To specify a
66 * single host address, you must specify a mask of /32. If `=' is
67 * specified then the specific subrange is only allowed for the local
68 * endpoint address, but not for remote addresses.
70 * More than one range may be given, with each range prefixed
71 * by + or -. In this case each address range in the rule will
72 * scanned in order, and the first range in the rule that matches
73 * any desired rule will count: if that first matching range is
74 * prefixed by `+' (or nothing) then the rule applies, if it
75 * is prefixed by `-' (or nothing matches), the rule does not.
78 * Means that anything is to be permitted. This should not appear in
79 * /etc/userv/ipif-networks, as that would permit any user on the
80 * system to create any interfaces with any addresses and routes
81 * attached. It is provided so that root can usefully invoke the ipif
82 * service program directly (not via userv), without needing to set up
83 * permissions in /etc/userv/ipif-networks.
87 * Comment. Blank lines are also ignored.
89 * NB: Permission is granted if _any_ config entry matches the request.
91 * The service program should be run from userv with no-disconnect-hup.
94 * This file is part of ipif, part of userv-utils
96 * Copyright 1996-2013 Ian Jackson <ijackson@chiark.greenend.org.uk>
97 * Copyright 1998 David Damerell <damerell@chiark.greenend.org.uk>
99 * Chancellor Masters and Scholars of the University of Cambridge
100 * Copyright 2010 Tony Finch <fanf@dotat.at>
102 * This is free software; you can redistribute it and/or modify it
103 * under the terms of the GNU General Public License as published by
104 * the Free Software Foundation; either version 3 of the License, or
105 * (at your option) any later version.
107 * This program is distributed in the hope that it will be useful, but
108 * WITHOUT ANY WARRANTY; without even the implied warranty of
109 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
110 * General Public License for more details.
112 * You should have received a copy of the GNU General Public License
113 * along with userv-utils; if not, see http://www.gnu.org/licenses/.
129 #include <sys/types.h>
130 #include <sys/wait.h>
131 #include <sys/stat.h>
133 #include <sys/types.h>
134 #include <sys/ioctl.h>
135 #include <sys/socket.h>
137 #include <sys/stat.h>
140 #include <linux/if.h>
141 #include <linux/if_tun.h>
144 #define MAXEXROUTES 50
147 static const unsigned long gidmaxval
= (unsigned long)((gid_t
)-2);
148 static const char *const protos_ok
[]= { "slip", 0 };
149 static const int signals
[]= { SIGHUP
, SIGINT
, SIGTERM
, 0 };
151 static const char *configstr
, *proto
;
152 static unsigned long localaddr
, peeraddr
, mtu
;
153 static int localpming
, peerpming
;
154 static int localallow
, peerallow
, allallow
;
155 static int nexroutes
;
156 static struct exroute
{
157 unsigned long prefix
, mask
;
159 char prefixtxt
[ATXTLEN
], masktxt
[ATXTLEN
];
160 } exroutes
[MAXEXROUTES
];
162 static char localtxt
[ATXTLEN
];
163 static char peertxt
[ATXTLEN
];
165 static struct pplace
{
166 struct pplace
*parent
;
167 const char *filename
;
176 static void terminate(int estatus
) {
181 static void fatal(const char *fmt
, ...)
182 __attribute__((format(printf
,1,2)));
183 static void fatal(const char *fmt
, ...) {
187 fputs("userv-ipif service: fatal error: ",stderr
);
188 vfprintf(stderr
, fmt
, al
);
193 static void sysfatal(const char *fmt
, ...)
194 __attribute__((format(printf
,1,2)));
195 static void sysfatal(const char *fmt
, ...) {
202 fputs("userv-ipif service: fatal system error: ",stderr
);
203 vfprintf(stderr
, fmt
, al
);
204 fprintf(stderr
,": %s\n", strerror(e
));
209 static void badusage(const char *fmt
, ...)
210 __attribute__((format(printf
,1,2)));
211 static void badusage(const char *fmt
, ...) {
217 "userv-ipif service: %s:%d: ",
218 cpplace
->filename
, cpplace
->lineno
);
220 fputs("userv-ipif service: invalid usage: ",stderr
);
223 vfprintf(stderr
, fmt
, al
);
227 for (cpp
=cpplace
->parent
; cpp
; cpp
=cpp
->parent
) {
229 "userv-ipif service: %s:%d: ... in file included from here\n",
230 cpp
->filename
, cpp
->lineno
);
236 static char *ip2txt(unsigned long addr
, char *buf
) {
237 sprintf(buf
, "%lu.%lu.%lu.%lu",
245 static unsigned long eat_number(const char **argp
, const char *what
,
246 unsigned long min
, unsigned long max
,
247 const char *endchars
, int *endchar_r
) {
248 /* If !endchars then the endchar must be a nul, otherwise it may be
249 * a nul (resulting in *argp set to 0) or something else (*argp set
250 * to point to after delim, *endchar_r set to delim).
251 * *endchar_r may be 0.
257 if (!*argp
) { badusage("missing number %s",what
); }
258 rv
= strtoul(*argp
,&ep
,0);
259 if ((endchar
= *ep
)) {
260 if (!endchars
) badusage("junk after number %s",what
);
261 if (!strchr(endchars
,endchar
))
262 badusage("invalid character or delimiter `%c' in or after number, %s:"
263 " expected %s (or none?)", endchar
,what
,endchars
);
268 if (endchar_r
) *endchar_r
= endchar
;
269 if (rv
< min
|| rv
> max
) badusage("number %s value %lu out of range %lu..%lu",
274 static int addrnet_overlap(unsigned long p1
, unsigned long m1
,
275 unsigned long p2
, unsigned long m2
) {
279 return (p1
& mask
) == (p2
& mask
);
282 static void addrnet_mustdiffer(const char *w1
, unsigned long p1
, unsigned long m1
,
283 const char *w2
, unsigned long p2
, unsigned long m2
) {
284 if (!addrnet_overlap(p1
,m1
,p2
,m2
)) return;
285 badusage("%s %08lx/%08lx overlaps/clashes with %s %08lx/%08lx",
289 static unsigned long eat_addr(const char **argp
, const char *what
,
290 const char *endchars
, int *endchar_r
) {
299 sprintf(whatbuf
,"%s byte #%d",what
,i
);
300 rv
|= eat_number(argp
,whatbuf
, 0,255, i
<3 ?
"." : endchars
, endchar_r
);
306 static void eat_prefixmask(const char **argp
, const char *what
,
307 const char *endchars
, int *endchar_r
,
308 unsigned long *prefix_r
, unsigned long *mask_r
, int *len_r
) {
309 /* mask_r and len_r may be 0 */
312 unsigned long prefix
, mask
;
314 prefix
= eat_addr(argp
,what
, "/",0);
315 sprintf(whatbuf
,"%s length",what
);
316 len
= eat_number(argp
,whatbuf
, 0,32, endchars
,endchar_r
);
318 mask
= len ?
(~0UL << (32-len
)) : 0UL;
319 if (prefix
& ~mask
) badusage("%s prefix %08lx not fully contained in mask %08lx",
322 if (mask_r
) *mask_r
= mask
;
323 if (len_r
) *len_r
= len
;
326 static int addrnet_isin(unsigned long prefix
, unsigned long mask
,
327 unsigned long mprefix
, unsigned long mmask
) {
328 return !(~mask
& mmask
) && (prefix
& mmask
) == mprefix
;
331 /* Totally hideous algorithm for parsing the config file lines.
332 * For each config file line, we first see if its gid applies. If not
333 * we skip it. Otherwise, we do
335 * which sets <foo>pming to 1
336 * for each range. <foo>pming may be 0 if we've determined that
337 * this line does not apply to <foo>.
339 * which calls permit_range_thing for each <foo>
340 * which checks to see if <foo> is inside the relevant
341 * range (for +) or overlaps it (for -) and updates
342 * <foo>allow and <foo>pming.
345 static void permit_begin(void) {
348 localpming
= peerpming
= 1;
349 for (i
=0; i
<nexroutes
; i
++) exroutes
[i
].pming
= 1;
352 static void permit_range_thing(unsigned long tprefix
, unsigned long tmask
,
353 const char *what
, int *tallow
, int *tpming
,
354 unsigned long pprefix
, unsigned long pmask
,
355 int plus
, int *any
) {
357 if (!addrnet_isin(tprefix
,tmask
, pprefix
,pmask
)) return;
358 if (*tpming
) *tallow
= 1;
360 if (!addrnet_overlap(tprefix
,tmask
, pprefix
,pmask
)) return;
363 if (!proto
) printf(" %c%s", plus?
'+':'-', what
);
367 static void permit_range(unsigned long prefix
, unsigned long mask
,
368 int plus
, int localonly
) {
372 assert(!(prefix
& ~mask
));
375 permit_range_thing(localaddr
,~0UL,"local", &localallow
,&localpming
,
376 prefix
,mask
, plus
,&any
);
379 permit_range_thing(peeraddr
,~0UL, "peer-addr", &peerallow
,&peerpming
,
380 prefix
,mask
, plus
,&any
);
381 for (i
=0; i
<nexroutes
; i
++) {
382 sprintf(idbuf
,"route#%d",i
);
383 permit_range_thing(exroutes
[i
].prefix
,exroutes
[i
].mask
, idbuf
,
384 &exroutes
[i
].allow
,&exroutes
[i
].pming
,
385 prefix
,mask
, plus
,&any
);
389 if (!any
) fputs(" nothing",stdout
);
392 static void pconfig(const char *configstr
, int truncated
);
394 static void pfile(const char *filename
) {
398 struct pplace npp
, *cpp
;
400 for (cpp
=cpplace
; cpp
; cpp
=cpp
->parent
) {
401 if (!strcmp(cpp
->filename
,filename
))
402 badusage("recursive configuration file `%s'",filename
);
405 file
= fopen(filename
,"r");
407 badusage("cannot open configuration file `%s': %s", filename
, strerror(errno
));
409 if (!proto
) printf("config file `%s':\n",filename
);
412 npp
.filename
= filename
;
416 while (fgets(buf
, sizeof(buf
), file
)) {
421 truncated
= (buf
[l
-1] != '\n');
422 while (l
>0 && isspace((unsigned char) buf
[l
-1])) l
--;
427 while ((c
= getc(file
)) != EOF
&& c
!= '\n');
431 pconfig(buf
,truncated
);
434 badusage("failed while reading configuration file: %s", strerror(errno
));
439 static void pconfig(const char *configstr
, int truncated
) {
440 unsigned long fgid
, tgid
, pprefix
, pmask
;
441 int plen
, localonly
, plus
, rangeix
, delim
;
446 switch (configstr
[0]) {
449 permit_range(0UL,0UL,1,0);
456 if (truncated
) badusage("filename too long (`%.100s...')",configstr
);
461 if (!isdigit((unsigned char)configstr
[0]))
462 badusage("unknown configuration directive");
464 fgid
= eat_number(&configstr
,"gid", 0,gidmaxval
, ",",0);
466 if (!proto
) printf(" %5lu", fgid
);
468 gidlist
= getenv("USERV_GID");
469 if (!gidlist
) fatal("USERV_GID not set");
472 if (!proto
) printf(" no matching gid\n");
475 tgid
= eat_number(&gidlist
,"userv-gid", 0,gidmaxval
, " ",0);
476 if (tgid
== fgid
) break;
479 if (configstr
[0] == '=') {
490 switch (configstr
[0]) {
491 case '-': plus
= 0; /* fall through */
492 case '+': configstr
++;
497 sprintf(whattxt
, "%s-prefix#%d",
498 plus ?
"permitted" : "notpermitted",
500 eat_prefixmask(&configstr
,whattxt
, ",+-",&delim
,
501 &pprefix
,&pmask
,&plen
);
502 if (!configstr
&& truncated
)
503 badusage("gid,prefix/len,... spec too long");
506 printf(" %c%s/%d:", plus?
'+':'-',ip2txt(pprefix
,ptxt
), plen
);
508 permit_range(pprefix
,pmask
,plus
,localonly
);
509 if (delim
==',') break;
511 plus
= delim
=='-' ?
0 : 1;
520 static void checkallow(int allow
, const char *what
,
521 const char *prefixtxt
, const char *masktxt
) {
523 fprintf(stderr
,"userv-ipif service: access denied for %s, %s/%s\n",
524 what
, prefixtxt
, masktxt
);
528 static void parseargs(int argc
, const char *const *argv
) {
529 unsigned long routeaddr
, routemask
;
531 const char *const *cprotop
;
533 char erwhatbuf
[100], erwhatbuf2
[100];
535 if (argc
< NARGS
+1) { badusage("too few arguments"); }
536 if (argc
> NARGS
+1) { badusage("too many arguments"); }
541 if (strcmp(carg
,"--")) badusage("separator argument `--' not found, got `%s'",carg
);
544 localaddr
= eat_addr(&carg
,"local-addr", ",",0);
545 peeraddr
= eat_addr(&carg
,"peer-addr", ",",0);
546 mtu
= eat_number(&carg
,"mtu", 576,65536, ",",0);
547 localallow
= peerallow
= 0;
549 if (!strcmp(carg
,"debug")) {
552 for (cprotop
= protos_ok
;
553 (proto
= *cprotop
) && strcmp(proto
,carg
);
555 if (!proto
) fatal("invalid protocol");
558 addrnet_mustdiffer("local-addr",localaddr
,~0UL, "peer-addr",peeraddr
,~0UL);
561 if (strcmp(carg
,"-")) {
565 if (nexroutes
== MAXEXROUTES
)
566 fatal("too many extra routes (only %d allowed)",MAXEXROUTES
);
567 sprintf(erwhatbuf
,"route#%d",nexroutes
);
569 eat_prefixmask(&carg
,erwhatbuf
, ",",0, &routeaddr
,&routemask
,0);
570 if (routemask
== ~0UL) {
571 addrnet_mustdiffer(erwhatbuf
,routeaddr
,routemask
, "local-addr",localaddr
,~0UL);
572 addrnet_mustdiffer(erwhatbuf
,routeaddr
,routemask
, "peer-addr",peeraddr
,~0UL);
574 for (i
=0; i
<nexroutes
; i
++) {
575 sprintf(erwhatbuf2
,"route#%d",i
);
576 addrnet_mustdiffer(erwhatbuf
,routeaddr
,routemask
,
577 erwhatbuf2
,exroutes
[i
].prefix
,exroutes
[i
].mask
);
579 exroutes
[nexroutes
].prefix
= routeaddr
;
580 exroutes
[nexroutes
].mask
= routemask
;
581 exroutes
[nexroutes
].allow
= 0;
582 ip2txt(routeaddr
,exroutes
[nexroutes
].prefixtxt
);
583 ip2txt(routemask
,exroutes
[nexroutes
].masktxt
);
587 ip2txt(localaddr
,localtxt
);
588 ip2txt(peeraddr
,peertxt
);
591 static void checkpermit(void) {
596 checkallow(localallow
,"local-addr", localtxt
,"32");
597 checkallow(peerallow
,"peer-addr", peertxt
,"32");
598 for (i
=0; i
<nexroutes
; i
++) {
599 sprintf(erwhatbuf
, "route#%d", i
);
600 checkallow(exroutes
[i
].allow
, erwhatbuf
, exroutes
[i
].prefixtxt
, exroutes
[i
].masktxt
);
602 if (!allallow
) fatal("access denied");
605 static void dumpdebug(void) __attribute__((noreturn
));
606 static void dumpdebug(void) {
610 printf("protocol: debug\n"
611 "local: %08lx == %s\n"
612 "peer: %08lx == %s\n"
619 for (i
=0; i
<nexroutes
; i
++) {
620 sprintf(erwhatbuf
, "route#%d:", i
);
621 printf("%-9s %08lx/%08lx == %s/%s\n",
623 exroutes
[i
].prefix
, exroutes
[i
].mask
,
624 exroutes
[i
].prefixtxt
, exroutes
[i
].masktxt
);
626 if (ferror(stdout
) || fclose(stdout
)) sysfatal("flush stdout");
631 static int task(const char *desc
) {
636 if (pid
== (pid_t
)-1) sysfatal("fork for task");
640 pidr
= waitpid(pid
,&status
,0);
641 if (pidr
!=(pid_t
)-1) break;
642 if (errno
==EINTR
) continue;
643 sysfatal("waitpid for task");
647 if (WIFEXITED(status
)) {
648 if (WEXITSTATUS(status
))
649 fatal("userv-ipif service: %s exited with error exit status %d\n",
650 desc
, WEXITSTATUS(status
));
651 } else if (WIFSIGNALED(status
)) {
652 fatal("userv-ipif service: %s died due to signal %s%s\n",
653 desc
, strsignal(WTERMSIG(status
)),
654 WCOREDUMP(status
) ?
" (core dumped)" : "");
656 fatal("userv-ipif service: %s unexpectedly terminated"
657 " with unknown status code %d\n", desc
, status
);
663 static void createif(void) {
664 static const char ifnamepat
[]= "userv%d";
668 memset(&ifr
,0,sizeof(ifr
));
669 ifr
.ifr_flags
= IFF_TUN
| IFF_NO_PI
;
671 assert(sizeof(ifr
.ifr_name
) >= sizeof(ifnamepat
));
672 strcpy(ifr
.ifr_name
, ifnamepat
);
674 tunfd
= open("/dev/net/tun", O_RDWR
);
675 if (!tunfd
) sysfatal("open /dev/net/tun");
677 r
= fcntl(tunfd
, F_GETFD
);
678 if (r
==-1) sysfatal("fcntl(tunfd,F_GETFD)");
679 r
= fcntl(tunfd
, F_SETFD
, r
|FD_CLOEXEC
);
680 if (r
==-1) sysfatal("fcntl(tunfd,F_SETFD,|FD_CLOEXEC)");
682 r
= ioctl(tunfd
, TUNSETIFF
, (void*)&ifr
);
683 if (r
) sysfatal("ioctl TUNSETIFF");
685 /* ifr.ifr_name might not be null-terminated. crazy abi. */
686 ifname
= malloc(sizeof(ifr
.ifr_name
)+1);
687 if (!ifname
) sysfatal("malloc for interface name");
688 memcpy(ifname
, ifr
.ifr_name
, sizeof(ifr
.ifr_name
));
689 ifname
[sizeof(ifr
.ifr_name
)]= 0;
692 static void netconfigure(void) {
696 if (task("ifconfig")) {
697 sprintf(mtutxt
,"%lu",mtu
);
699 execlp("ifconfig", "ifconfig", ifname
, localtxt
,
700 "netmask","255.255.255.255", "pointopoint",peertxt
, "-broadcast",
701 "mtu",mtutxt
, "up", (char*)0);
702 sysfatal("cannot exec ifconfig");
705 for (i
=0; i
<nexroutes
; i
++) {
707 execlp("route","route", "add", "-net",exroutes
[i
].prefixtxt
,
708 "netmask",exroutes
[i
].masktxt
,
709 "gw",peertxt
, "dev",ifname
, (char*)0);
710 sysfatal("cannot exec route (for route)");
715 static void setnonblock(int fd
) {
717 r
= fcntl(fd
,F_GETFL
);
718 if (r
==-1) sysfatal("fcntl F_GETFL");
719 r
= fcntl(fd
,F_SETFL
, r
|O_NONBLOCK
);
720 if (r
==-1) sysfatal("fcntl F_SETFL O_NONBLOCK");
723 static void rx_packet(const uint8_t *packet
, int len
) {
727 int r
= write(tunfd
, packet
, len
);
729 if (errno
==EINTR
) continue;
730 if (errno
==EAGAIN
|| errno
==ENOMEM
) return; /* oh well */
731 sysfatal("error writing packet to tun (transmitting)");
738 static int output_waiting
, input_waiting
;
740 #define SLIP_END 0300
741 #define SLIP_ESC 0333
742 #define SLIP_ESC_END 0334
743 #define SLIP_ESC_ESC 0335
745 static void more_rx_data(uint8_t *input_buf
, uint8_t *output_buf
) {
746 /* we make slip_data never contain continuation of a packet */
747 /* input_buf is passed as a parameter since it's in copydata's stack frame */
749 static int output_len
;
751 uint8_t *op
= output_buf
+ output_len
;
752 const uint8_t *ip
= input_buf
+ scanned
;
753 const uint8_t *ip_end
= input_buf
+ input_waiting
;
757 if (ip
>=ip_end
) break;
760 rx_packet(output_buf
, op
-output_buf
);
762 eaten
= ip
- input_buf
;
766 if (ip
>=ip_end
) { /* rescan this when there's more */ ip
--; break; }
768 if (c
==SLIP_ESC_END
) c
=SLIP_END
;
769 else if (c
==SLIP_ESC_ESC
) c
=SLIP_ESC
;
770 else fatal("unexpected byte 0%o after SLIP_ESC",c
);
772 if (op
== output_buf
+mtu
)
773 fatal("SLIP packet exceeds mtu");
777 output_len
= op
- output_buf
;
778 scanned
= ip
- input_buf
;
780 input_waiting
-= eaten
;
781 memmove(input_buf
, input_buf
+eaten
, input_waiting
);
785 static void tx_packet(uint8_t *output_buf
, const uint8_t *ip
, int inlen
) {
786 /* output_buf is passed as a parameter since it's in copydata's stack frame */
787 assert(!output_waiting
);
788 uint8_t *op
= output_buf
;
793 if (c
==SLIP_END
) { *op
++= SLIP_ESC
; *op
++= SLIP_ESC_END
; }
794 else if (c
==SLIP_ESC
) { *op
++= SLIP_ESC
; *op
++= SLIP_ESC_ESC
; }
798 assert(op
<= output_buf
+ mtu
*2+2);
800 output_waiting
= op
- output_buf
;
803 static void copydata(void) __attribute__((noreturn
));
804 static void copydata(void) {
805 uint8_t output_buf
[mtu
*2+2];
806 uint8_t input_buf
[mtu
*2+2];
807 uint8_t rx_packet_buf
[mtu
];
811 struct pollfd polls
[3];
812 memset(polls
, 0, sizeof(polls
));
814 polls
[0].fd
= 0; polls
[0].events
= POLLIN
;
818 /* We don't do flow control on input packets; instead, we just throw
819 * away ones which the kernel doesn't accept. So we always poll for
822 * Output packets we buffer, so we poll only as appropriate for those.
825 /* Start by transmitting one END byte to say we're ready. */
826 output_buf
[0]= SLIP_END
;
830 if (output_waiting
) {
831 r
= write(1, output_buf
, output_waiting
);
833 if (errno
==EINTR
) continue;
835 sysfatal("error writing SLIP output (packets being received)");
839 memmove(output_buf
, output_buf
+r
, output_waiting
);
842 if (output_waiting
) {
843 polls
[1].events
|= POLLOUT
;
844 polls
[2].events
&= ~POLLIN
;
846 polls
[1].events
&= ~POLLOUT
;
847 polls
[2].events
|= POLLIN
;
852 if (errno
==EINTR
) continue;
853 sysfatal("poll() failed");
855 assert(r
>0); /* we used an infinite timeout */
857 for (i
=0; i
<sizeof(polls
)/sizeof(polls
[0]); i
++)
858 if (polls
[i
].revents
& ~polls
[i
].events
)
859 fatal("unexpected revents 0x%x for fd=%d",
860 polls
[i
].revents
, polls
[i
].fd
);
862 if (polls
[0].events
& POLLIN
) {
863 int want
= sizeof(input_buf
) - input_waiting
;
864 if (want
<0) fatal("incoming packet necessarily exceeds MTU");
865 r
= read(0, input_buf
+ input_waiting
, want
);
868 assert(input_waiting
<= sizeof(input_buf
));
869 more_rx_data(input_buf
, rx_packet_buf
);
873 if (!(errno
==EINTR
|| errno
==EAGAIN
))
874 sysfatal("error reading input SLIP data (packets to transmit)");
878 /* We handle what would be (polls[1].events & POLLOUT) above,
879 * unconditionally. That eliminates the need to poll in the usual case */
881 if (polls
[2].events
& POLLIN
) {
882 uint8_t packet_buf
[mtu
];
883 r
= read(tunfd
, packet_buf
, mtu
);
885 tx_packet(output_buf
, packet_buf
, r
);
888 if (!(errno
==EAGAIN
|| errno
==EWOULDBLOCK
))
889 sysfatal("error reading packet (being transmitted) from tun");
895 int main(int argc
, const char *const *argv
) {
896 parseargs(argc
,argv
);
897 pconfig(configstr
,0);
899 if (!proto
) dumpdebug();