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/.
130 #include <sys/types.h>
131 #include <sys/wait.h>
132 #include <sys/stat.h>
134 #include <sys/types.h>
135 #include <sys/ioctl.h>
136 #include <sys/socket.h>
138 #include <sys/stat.h>
141 #include <linux/if.h>
142 #include <linux/if_tun.h>
145 #define MAXEXROUTES 50
148 static const unsigned long gidmaxval= (unsigned long)((gid_t)-2);
149 static const char *const protos_ok[]= { "slip", 0 };
150 static const int signals[]= { SIGHUP, SIGINT, SIGTERM, 0 };
152 static const char *configstr, *proto;
153 static unsigned long localaddr, peeraddr, mtu;
154 static int localpming, peerpming;
155 static int localallow, peerallow, allallow;
156 static int nexroutes;
157 static struct exroute {
158 unsigned long prefix, mask;
160 char prefixtxt[ATXTLEN], masktxt[ATXTLEN];
161 } exroutes[MAXEXROUTES];
163 static char localtxt[ATXTLEN];
164 static char peertxt[ATXTLEN];
166 static struct pplace {
167 struct pplace *parent;
168 const char *filename;
177 static void terminate(int estatus) {
182 static void fatal(const char *fmt, ...)
183 __attribute__((format(printf,1,2)));
184 static void fatal(const char *fmt, ...) {
188 fputs("userv-ipif service: fatal error: ",stderr);
189 vfprintf(stderr, fmt, al);
194 static void sysfatal(const char *fmt, ...)
195 __attribute__((format(printf,1,2)));
196 static void sysfatal(const char *fmt, ...) {
203 fputs("userv-ipif service: fatal system error: ",stderr);
204 vfprintf(stderr, fmt, al);
205 fprintf(stderr,": %s\n", strerror(e));
210 static void badusage(const char *fmt, ...)
211 __attribute__((format(printf,1,2)));
212 static void badusage(const char *fmt, ...) {
218 "userv-ipif service: %s:%d: ",
219 cpplace->filename, cpplace->lineno);
221 fputs("userv-ipif service: invalid usage: ",stderr);
224 vfprintf(stderr, fmt, al);
228 for (cpp=cpplace->parent; cpp; cpp=cpp->parent) {
230 "userv-ipif service: %s:%d: ... in file included from here\n",
231 cpp->filename, cpp->lineno);
237 static char *ip2txt(unsigned long addr, char *buf) {
238 sprintf(buf, "%lu.%lu.%lu.%lu",
246 static unsigned long eat_number(const char **argp, const char *what,
247 unsigned long min, unsigned long max,
248 const char *endchars, int *endchar_r) {
249 /* If !endchars then the endchar must be a nul, otherwise it may be
250 * a nul (resulting in *argp set to 0) or something else (*argp set
251 * to point to after delim, *endchar_r set to delim).
252 * *endchar_r may be 0.
258 if (!*argp) { badusage("missing number %s",what); }
259 rv= strtoul(*argp,&ep,0);
260 if ((endchar= *ep)) {
261 if (!endchars) badusage("junk after number %s",what);
262 if (!strchr(endchars,endchar))
263 badusage("invalid character or delimiter `%c' in or after number, %s:"
264 " expected %s (or none?)", endchar,what,endchars);
269 if (endchar_r) *endchar_r= endchar;
270 if (rv < min || rv > max) badusage("number %s value %lu out of range %lu..%lu",
275 static int addrnet_overlap(unsigned long p1, unsigned long m1,
276 unsigned long p2, unsigned long m2) {
280 return (p1 & mask) == (p2 & mask);
283 static void addrnet_mustdiffer(const char *w1, unsigned long p1, unsigned long m1,
284 const char *w2, unsigned long p2, unsigned long m2) {
285 if (!addrnet_overlap(p1,m1,p2,m2)) return;
286 badusage("%s %08lx/%08lx overlaps/clashes with %s %08lx/%08lx",
290 static unsigned long eat_addr(const char **argp, const char *what,
291 const char *endchars, int *endchar_r) {
300 sprintf(whatbuf,"%s byte #%d",what,i);
301 rv |= eat_number(argp,whatbuf, 0,255, i<3 ? "." : endchars, endchar_r);
307 static void eat_prefixmask(const char **argp, const char *what,
308 const char *endchars, int *endchar_r,
309 unsigned long *prefix_r, unsigned long *mask_r, int *len_r) {
310 /* mask_r and len_r may be 0 */
313 unsigned long prefix, mask;
315 prefix= eat_addr(argp,what, "/",0);
316 sprintf(whatbuf,"%s length",what);
317 len= eat_number(argp,whatbuf, 0,32, endchars,endchar_r);
319 mask= len ? (~0UL << (32-len)) : 0UL;
320 if (prefix & ~mask) badusage("%s prefix %08lx not fully contained in mask %08lx",
323 if (mask_r) *mask_r= mask;
324 if (len_r) *len_r= len;
327 static char *eat_optionalstr(const char **argp,
331 const char *start= *argp;
332 const char *comma= strchr(start, ',');
344 char *r = malloc(len+1);
345 if (!r) sysfatal("malloc for command line string");
351 static int addrnet_isin(unsigned long prefix, unsigned long mask,
352 unsigned long mprefix, unsigned long mmask) {
353 return !(~mask & mmask) && (prefix & mmask) == mprefix;
356 /* Totally hideous algorithm for parsing the config file lines.
357 * For each config file line, we first see if its gid applies. If not
358 * we skip it. Otherwise, we do
360 * which sets <foo>pming to 1
361 * for each range. <foo>pming may be 0 if we've determined that
362 * this line does not apply to <foo>.
364 * which calls permit_range_thing for each <foo>
365 * which checks to see if <foo> is inside the relevant
366 * range (for +) or overlaps it (for -) and updates
367 * <foo>allow and <foo>pming.
370 static void permit_begin(void) {
373 localpming= peerpming= 1;
374 for (i=0; i<nexroutes; i++) exroutes[i].pming= 1;
377 static void permit_range_thing(unsigned long tprefix, unsigned long tmask,
378 const char *what, int *tallow, int *tpming,
379 unsigned long pprefix, unsigned long pmask,
380 int plus, int *any) {
382 if (!addrnet_isin(tprefix,tmask, pprefix,pmask)) return;
383 if (*tpming) *tallow= 1;
385 if (!addrnet_overlap(tprefix,tmask, pprefix,pmask)) return;
388 if (!proto) printf(" %c%s", plus?'+':'-', what);
392 static void permit_range(unsigned long prefix, unsigned long mask,
393 int plus, int localonly) {
397 assert(!(prefix & ~mask));
400 permit_range_thing(localaddr,~0UL,"local", &localallow,&localpming,
401 prefix,mask, plus,&any);
404 permit_range_thing(peeraddr,~0UL, "peer-addr", &peerallow,&peerpming,
405 prefix,mask, plus,&any);
406 for (i=0; i<nexroutes; i++) {
407 sprintf(idbuf,"route#%d",i);
408 permit_range_thing(exroutes[i].prefix,exroutes[i].mask, idbuf,
409 &exroutes[i].allow,&exroutes[i].pming,
410 prefix,mask, plus,&any);
414 if (!any) fputs(" nothing",stdout);
417 static void pconfig(const char *configstr, int truncated);
419 static void pfile(const char *filename) {
423 struct pplace npp, *cpp;
425 for (cpp=cpplace; cpp; cpp=cpp->parent) {
426 if (!strcmp(cpp->filename,filename))
427 badusage("recursive configuration file `%s'",filename);
430 file= fopen(filename,"r");
432 badusage("cannot open configuration file `%s': %s", filename, strerror(errno));
434 if (!proto) printf("config file `%s':\n",filename);
437 npp.filename= filename;
441 while (fgets(buf, sizeof(buf), file)) {
446 truncated= (buf[l-1] != '\n');
447 while (l>0 && isspace((unsigned char) buf[l-1])) l--;
452 while ((c= getc(file)) != EOF && c != '\n');
456 pconfig(buf,truncated);
459 badusage("failed while reading configuration file: %s", strerror(errno));
464 static void pconfig(const char *configstr, int truncated) {
465 unsigned long fgid, tgid, pprefix, pmask;
466 int plen, localonly, plus, rangeix, delim;
471 switch (configstr[0]) {
474 permit_range(0UL,0UL,1,0);
481 if (truncated) badusage("filename too long (`%.100s...')",configstr);
486 if (!isdigit((unsigned char)configstr[0]))
487 badusage("unknown configuration directive");
489 fgid= eat_number(&configstr,"gid", 0,gidmaxval, ",",0);
491 if (!proto) printf(" %5lu", fgid);
493 gidlist= getenv("USERV_GID");
494 if (!gidlist) fatal("USERV_GID not set");
497 if (!proto) printf(" no matching gid\n");
500 tgid= eat_number(&gidlist,"userv-gid", 0,gidmaxval, " ",0);
501 if (tgid == fgid) break;
504 if (configstr[0] == '=') {
515 switch (configstr[0]) {
516 case '-': plus= 0; /* fall through */
517 case '+': configstr++;
522 sprintf(whattxt, "%s-prefix#%d",
523 plus ? "permitted" : "notpermitted",
525 eat_prefixmask(&configstr,whattxt, ",+-",&delim,
526 &pprefix,&pmask,&plen);
527 if (!configstr && truncated)
528 badusage("gid,prefix/len,... spec too long");
531 printf(" %c%s/%d:", plus?'+':'-',ip2txt(pprefix,ptxt), plen);
533 permit_range(pprefix,pmask,plus,localonly);
534 if (delim==',') break;
536 plus= delim=='-' ? 0 : 1;
545 static void checkallow(int allow, const char *what,
546 const char *prefixtxt, const char *masktxt) {
548 fprintf(stderr,"userv-ipif service: access denied for %s, %s/%s\n",
549 what, prefixtxt, masktxt);
553 static void parseargs(int argc, const char *const *argv) {
554 unsigned long routeaddr, routemask;
556 const char *const *cprotop;
558 char erwhatbuf[100], erwhatbuf2[100];
560 if (argc < NARGS+1) { badusage("too few arguments"); }
561 if (argc > NARGS+1) { badusage("too many arguments"); }
566 if (strcmp(carg,"--")) badusage("separator argument `--' not found, got `%s'",carg);
569 localaddr= eat_addr(&carg,"local-addr", ",",0);
570 peeraddr= eat_addr(&carg,"peer-addr", ",",0);
571 mtu= eat_number(&carg,"mtu", 576,65536, ",",0);
572 localallow= peerallow= 0;
574 char *protostr = eat_optionalstr(&carg,"protocol","slip");
575 if (!strcmp(protostr,"debug")) {
578 for (cprotop= protos_ok;
579 (proto= *cprotop) && strcmp(proto,protostr);
581 if (!proto) fatal("invalid protocol");
584 addrnet_mustdiffer("local-addr",localaddr,~0UL, "peer-addr",peeraddr,~0UL);
587 if (strcmp(carg,"-")) {
591 if (nexroutes == MAXEXROUTES)
592 fatal("too many extra routes (only %d allowed)",MAXEXROUTES);
593 sprintf(erwhatbuf,"route#%d",nexroutes);
595 eat_prefixmask(&carg,erwhatbuf, ",",0, &routeaddr,&routemask,0);
596 if (routemask == ~0UL) {
597 addrnet_mustdiffer(erwhatbuf,routeaddr,routemask, "local-addr",localaddr,~0UL);
598 addrnet_mustdiffer(erwhatbuf,routeaddr,routemask, "peer-addr",peeraddr,~0UL);
600 for (i=0; i<nexroutes; i++) {
601 sprintf(erwhatbuf2,"route#%d",i);
602 addrnet_mustdiffer(erwhatbuf,routeaddr,routemask,
603 erwhatbuf2,exroutes[i].prefix,exroutes[i].mask);
605 exroutes[nexroutes].prefix= routeaddr;
606 exroutes[nexroutes].mask= routemask;
607 exroutes[nexroutes].allow= 0;
608 ip2txt(routeaddr,exroutes[nexroutes].prefixtxt);
609 ip2txt(routemask,exroutes[nexroutes].masktxt);
613 ip2txt(localaddr,localtxt);
614 ip2txt(peeraddr,peertxt);
617 static void checkpermit(void) {
622 checkallow(localallow,"local-addr", localtxt,"32");
623 checkallow(peerallow,"peer-addr", peertxt,"32");
624 for (i=0; i<nexroutes; i++) {
625 sprintf(erwhatbuf, "route#%d", i);
626 checkallow(exroutes[i].allow, erwhatbuf, exroutes[i].prefixtxt, exroutes[i].masktxt);
628 if (!allallow) fatal("access denied");
631 static void dumpdebug(void) __attribute__((noreturn));
632 static void dumpdebug(void) {
636 printf("protocol: debug\n"
637 "local: %08lx == %s\n"
638 "peer: %08lx == %s\n"
645 for (i=0; i<nexroutes; i++) {
646 sprintf(erwhatbuf, "route#%d:", i);
647 printf("%-9s %08lx/%08lx == %s/%s\n",
649 exroutes[i].prefix, exroutes[i].mask,
650 exroutes[i].prefixtxt, exroutes[i].masktxt);
652 if (ferror(stdout) || fclose(stdout)) sysfatal("flush stdout");
657 static int task(const char *desc) {
662 if (pid == (pid_t)-1) sysfatal("fork for task");
666 pidr= waitpid(pid,&status,0);
667 if (pidr!=(pid_t)-1) break;
668 if (errno==EINTR) continue;
669 sysfatal("waitpid for task");
673 if (WIFEXITED(status)) {
674 if (WEXITSTATUS(status))
675 fatal("userv-ipif service: %s exited with error exit status %d\n",
676 desc, WEXITSTATUS(status));
677 } else if (WIFSIGNALED(status)) {
678 fatal("userv-ipif service: %s died due to signal %s%s\n",
679 desc, strsignal(WTERMSIG(status)),
680 WCOREDUMP(status) ? " (core dumped)" : "");
682 fatal("userv-ipif service: %s unexpectedly terminated"
683 " with unknown status code %d\n", desc, status);
689 static void createif(void) {
690 static const char ifnamepat[]= "userv%d";
694 memset(&ifr,0,sizeof(ifr));
695 ifr.ifr_flags= IFF_TUN | IFF_NO_PI;
697 assert(sizeof(ifr.ifr_name) >= sizeof(ifnamepat));
698 strcpy(ifr.ifr_name, ifnamepat);
700 tunfd= open("/dev/net/tun", O_RDWR);
701 if (!tunfd) sysfatal("open /dev/net/tun");
703 r= fcntl(tunfd, F_GETFD);
704 if (r==-1) sysfatal("fcntl(tunfd,F_GETFD)");
705 r= fcntl(tunfd, F_SETFD, r|FD_CLOEXEC);
706 if (r==-1) sysfatal("fcntl(tunfd,F_SETFD,|FD_CLOEXEC)");
708 r= ioctl(tunfd, TUNSETIFF, (void*)&ifr);
709 if (r) sysfatal("ioctl TUNSETIFF");
711 /* ifr.ifr_name might not be null-terminated. crazy abi. */
712 ifname= malloc(sizeof(ifr.ifr_name)+1);
713 if (!ifname) sysfatal("malloc for interface name");
714 memcpy(ifname, ifr.ifr_name, sizeof(ifr.ifr_name));
715 ifname[sizeof(ifr.ifr_name)]= 0;
718 static void netconfigure(void) {
722 if (task("ifconfig")) {
723 sprintf(mtutxt,"%lu",mtu);
725 execlp("ifconfig", "ifconfig", ifname, localtxt,
726 "netmask","255.255.255.255", "pointopoint",peertxt, "-broadcast",
727 "mtu",mtutxt, "up", (char*)0);
728 sysfatal("cannot exec ifconfig");
731 for (i=0; i<nexroutes; i++) {
733 execlp("route","route", "add", "-net",exroutes[i].prefixtxt,
734 "netmask",exroutes[i].masktxt,
735 "gw",peertxt, "dev",ifname, (char*)0);
736 sysfatal("cannot exec route (for route)");
741 static void setnonblock(int fd) {
743 r= fcntl(fd,F_GETFL);
744 if (r==-1) sysfatal("fcntl F_GETFL");
745 r= fcntl(fd,F_SETFL, r|O_NONBLOCK);
746 if (r==-1) sysfatal("fcntl F_SETFL O_NONBLOCK");
749 static void rx_packet(const uint8_t *packet, int len) {
753 int r= write(tunfd, packet, len);
755 if (errno==EINTR) continue;
756 if (errno==EAGAIN || errno==ENOMEM) return; /* oh well */
757 sysfatal("error writing packet to tun (transmitting)");
764 static int output_waiting, input_waiting;
766 #define SLIP_END 0300
767 #define SLIP_ESC 0333
768 #define SLIP_ESC_END 0334
769 #define SLIP_ESC_ESC 0335
771 static void more_rx_data(uint8_t *input_buf, uint8_t *output_buf) {
772 /* we make slip_data never contain continuation of a packet */
773 /* input_buf is passed as a parameter since it's in copydata's stack frame */
775 static int output_len;
777 uint8_t *op= output_buf + output_len;
778 const uint8_t *ip= input_buf + scanned;
779 const uint8_t *ip_end= input_buf + input_waiting;
783 if (ip>=ip_end) break;
786 rx_packet(output_buf, op-output_buf);
788 eaten= ip - input_buf;
792 if (ip>=ip_end) { /* rescan this when there's more */ ip--; break; }
794 if (c==SLIP_ESC_END) c=SLIP_END;
795 else if (c==SLIP_ESC_ESC) c=SLIP_ESC;
796 else fatal("unexpected byte 0%o after SLIP_ESC",c);
798 if (op == output_buf+mtu)
799 fatal("SLIP packet exceeds mtu");
803 output_len= op - output_buf;
804 scanned= ip - input_buf;
806 input_waiting -= eaten;
807 memmove(input_buf, input_buf+eaten, input_waiting);
811 static void tx_packet(uint8_t *output_buf, const uint8_t *ip, int inlen) {
812 /* output_buf is passed as a parameter since it's in copydata's stack frame */
813 assert(!output_waiting);
814 uint8_t *op= output_buf;
819 if (c==SLIP_END) { *op++= SLIP_ESC; *op++= SLIP_ESC_END; }
820 else if (c==SLIP_ESC) { *op++= SLIP_ESC; *op++= SLIP_ESC_ESC; }
824 assert(op <= output_buf + mtu*2+2);
826 output_waiting= op - output_buf;
829 static void copydata(void) __attribute__((noreturn));
830 static void copydata(void) {
831 uint8_t output_buf[mtu*2+2];
832 uint8_t input_buf[mtu*2+2];
833 uint8_t rx_packet_buf[mtu];
837 struct pollfd polls[3];
838 memset(polls, 0, sizeof(polls));
840 polls[0].fd= 0; polls[0].events= POLLIN;
844 /* We don't do flow control on input packets; instead, we just throw
845 * away ones which the kernel doesn't accept. So we always poll for
848 * Output packets we buffer, so we poll only as appropriate for those.
851 /* Start by transmitting one END byte to say we're ready. */
852 output_buf[0]= SLIP_END;
856 if (output_waiting) {
857 r= write(1, output_buf, output_waiting);
859 if (errno==EINTR) continue;
861 sysfatal("error writing SLIP output (packets being received)");
865 memmove(output_buf, output_buf+r, output_waiting);
868 if (output_waiting) {
869 polls[1].events |= POLLOUT;
870 polls[2].events &= ~POLLIN;
872 polls[1].events &= ~POLLOUT;
873 polls[2].events |= POLLIN;
878 if (errno==EINTR) continue;
879 sysfatal("poll() failed");
881 assert(r>0); /* we used an infinite timeout */
883 for (i=0; i<sizeof(polls)/sizeof(polls[0]); i++)
884 if (polls[i].revents & ~polls[i].events)
885 fatal("unexpected revents 0x%x for fd=%d",
886 polls[i].revents, polls[i].fd);
888 if (polls[0].events & POLLIN) {
889 int want= sizeof(input_buf) - input_waiting;
890 if (want<0) fatal("incoming packet necessarily exceeds MTU");
891 r= read(0, input_buf + input_waiting, want);
894 assert(input_waiting <= sizeof(input_buf));
895 more_rx_data(input_buf, rx_packet_buf);
899 if (!(errno==EINTR || errno==EAGAIN))
900 sysfatal("error reading input SLIP data (packets to transmit)");
904 /* We handle what would be (polls[1].events & POLLOUT) above,
905 * unconditionally. That eliminates the need to poll in the usual case */
907 if (polls[2].events & POLLIN) {
908 uint8_t packet_buf[mtu];
909 r= read(tunfd, packet_buf, mtu);
911 tx_packet(output_buf, packet_buf, r);
914 if (!(errno==EAGAIN || errno==EWOULDBLOCK))
915 sysfatal("error reading packet (being transmitted) from tun");
921 int main(int argc, const char *const *argv) {
922 parseargs(argc,argv);
923 pconfig(configstr,0);
925 if (!proto) dumpdebug();