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 * The supported protocols are:
36 * slip transfer IP packets using the SLIP protocol
37 * debug simply print debugging info and exit
38 * counted our own "counted packet" protocol, see below
40 * <local-addr> is address of the interface to be created on the
41 * local system; <peer-addr> is the address of the point-to-point
42 * peer. They must be actual addresses (not hostnames).
44 * <prefix>/<mask>,<prefix>/<mask>,...
46 * List of additional routes to add for this interface. routes will
47 * be set up on the local system arranging for packets for those
48 * networks to be sent via the created interface. <prefix> must be an
49 * IPv4 address, and mask must be an integer (dotted-quad masks are
50 * not supported). If no additional routes are to be set up, use `-'
51 * or supply an empty argument.
53 * Each <config> item - whether a line in a file such as
54 * /etc/userv/ipif-networks, or the single trusted argument supplied
55 * on the service program command line - is one of:
58 * ./<config-file-name>
59 * ../<config-file-name>
61 * Reads a file which contains lines which are each <config>
64 * <gid>,[=][-|+]<prefix>/<len>(-|+<prefix>/<len>...)[,<junk>]
66 * Indicates that <gid> may allocate addresses in the relevant address
67 * range (<junk> is ignored). <gid> must be numeric. To specify a
68 * single host address, you must specify a mask of /32. If `=' is
69 * specified then the specific subrange is only allowed for the local
70 * endpoint address, but not for remote addresses.
72 * More than one range may be given, with each range prefixed
73 * by + or -. In this case each address range in the rule will
74 * scanned in order, and the first range in the rule that matches
75 * any desired rule will count: if that first matching range is
76 * prefixed by `+' (or nothing) then the rule applies, if it
77 * is prefixed by `-' (or nothing matches), the rule does not.
80 * Means that anything is to be permitted. This should not appear in
81 * /etc/userv/ipif-networks, as that would permit any user on the
82 * system to create any interfaces with any addresses and routes
83 * attached. It is provided so that root can usefully invoke the ipif
84 * service program directly (not via userv), without needing to set up
85 * permissions in /etc/userv/ipif-networks.
89 * Comment. Blank lines are also ignored.
91 * NB: Permission is granted if _any_ config entry matches the request.
93 * The service program should be run from userv with no-disconnect-hup.
96 * Counted packet protocol:
98 * In each direction a bytestream is sent, containing a series
102 * 32 bits in network byte order length L
103 * 8 bits message flags F
104 * 24 bits in network byte order sub-opcode O
107 * Where the flags F are as follows:
108 * 0x01 first 4 bytes of payload are a command tag
109 * allocated by caller and to be returned by service in response
110 * 0x02 response message indicates an error; opcode is an error code
111 * and remainder of response depends on error code
113 * And the flags and opcode (F | O) combinations are
114 * 0x00 | 0x000000 message is an IPv4 or IPv6 datagram
115 * 0x01 | 0x000001 add local address; payload is tag + V4 or V6 address
116 * 0x01 | 0x000002 remove local address
117 * command payload: tag + V4 or V6 address
118 * successful response payload: tag only
119 * 0x01 | 0x000003 add route
120 * command payload: tag + 1 byte prefix len + addr
123 * Copyright (C) 1999-2000,2003 Ian Jackson
124 * This file is part of ipif, part of userv-utils
126 * This is free software; you can redistribute it and/or modify it
127 * under the terms of the GNU General Public License as published by
128 * the Free Software Foundation; either version 2 of the License, or
129 * (at your option) any later version.
131 * This program is distributed in the hope that it will be useful, but
132 * WITHOUT ANY WARRANTY; without even the implied warranty of
133 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
134 * General Public License for more details.
136 * You should have received a copy of the GNU General Public License
137 * along with userv-utils; if not, write to the Free Software
138 * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
156 #include <sys/types.h>
157 #include <sys/wait.h>
158 #include <sys/stat.h>
160 #include <sys/types.h>
161 #include <sys/ioctl.h>
162 #include <sys/socket.h>
164 #include <sys/stat.h>
167 #include <linux/if.h>
168 #include <linux/if_tun.h>
171 #define MAXEXROUTES 50
174 static const unsigned long gidmaxval= (unsigned long)((gid_t)-2);
175 static const char *const protos_ok[]= { "slip", 0 };
176 static const int signals[]= { SIGHUP, SIGINT, SIGTERM, 0 };
178 static const char *configstr, *proto;
179 static unsigned long localaddr, peeraddr, mtu;
180 static int localpming, peerpming;
181 static int localallow, peerallow, allallow;
182 static int nexroutes;
183 static struct exroute {
184 unsigned long prefix, mask;
186 char prefixtxt[ATXTLEN], masktxt[ATXTLEN];
187 } exroutes[MAXEXROUTES];
189 static char localtxt[ATXTLEN];
190 static char peertxt[ATXTLEN];
192 static struct pplace {
193 struct pplace *parent;
194 const char *filename;
203 static void terminate(int estatus) {
208 static void fatal(const char *fmt, ...)
209 __attribute__((format(printf,1,2)));
210 static void fatal(const char *fmt, ...) {
214 fputs("userv-ipif service: fatal error: ",stderr);
215 vfprintf(stderr, fmt, al);
220 static void sysfatal(const char *fmt, ...)
221 __attribute__((format(printf,1,2)));
222 static void sysfatal(const char *fmt, ...) {
229 fputs("userv-ipif service: fatal system error: ",stderr);
230 vfprintf(stderr, fmt, al);
231 fprintf(stderr,": %s\n", strerror(e));
236 static void badusage(const char *fmt, ...)
237 __attribute__((format(printf,1,2)));
238 static void badusage(const char *fmt, ...) {
244 "userv-ipif service: %s:%d: ",
245 cpplace->filename, cpplace->lineno);
247 fputs("userv-ipif service: invalid usage: ",stderr);
250 vfprintf(stderr, fmt, al);
254 for (cpp=cpplace->parent; cpp; cpp=cpp->parent) {
256 "userv-ipif service: %s:%d: ... in file included from here\n",
257 cpp->filename, cpp->lineno);
263 static char *ip2txt(unsigned long addr, char *buf) {
264 sprintf(buf, "%lu.%lu.%lu.%lu",
272 static unsigned long eat_number(const char **argp, const char *what,
273 unsigned long min, unsigned long max,
274 const char *endchars, int *endchar_r) {
275 /* If !endchars then the endchar must be a nul, otherwise it may be
276 * a nul (resulting in *argp set to 0) or something else (*argp set
277 * to point to after delim, *endchar_r set to delim).
278 * *endchar_r may be 0.
284 if (!*argp) { badusage("missing number %s",what); }
285 rv= strtoul(*argp,&ep,0);
286 if ((endchar= *ep)) {
287 if (!endchars) badusage("junk after number %s",what);
288 if (!strchr(endchars,endchar))
289 badusage("invalid character or delimiter `%c' in or after number, %s:"
290 " expected %s (or none?)", endchar,what,endchars);
295 if (endchar_r) *endchar_r= endchar;
296 if (rv < min || rv > max) badusage("number %s value %lu out of range %lu..%lu",
301 static int addrnet_overlap(unsigned long p1, unsigned long m1,
302 unsigned long p2, unsigned long m2) {
306 return (p1 & mask) == (p2 & mask);
309 static void addrnet_mustdiffer(const char *w1, unsigned long p1, unsigned long m1,
310 const char *w2, unsigned long p2, unsigned long m2) {
311 if (!addrnet_overlap(p1,m1,p2,m2)) return;
312 badusage("%s %08lx/%08lx overlaps/clashes with %s %08lx/%08lx",
316 static unsigned long eat_addr(const char **argp, const char *what,
317 const char *endchars, int *endchar_r) {
326 sprintf(whatbuf,"%s byte #%d",what,i);
327 rv |= eat_number(argp,whatbuf, 0,255, i<3 ? "." : endchars, endchar_r);
333 static void eat_prefixmask(const char **argp, const char *what,
334 const char *endchars, int *endchar_r,
335 unsigned long *prefix_r, unsigned long *mask_r, int *len_r) {
336 /* mask_r and len_r may be 0 */
339 unsigned long prefix, mask;
341 prefix= eat_addr(argp,what, "/",0);
342 sprintf(whatbuf,"%s length",what);
343 len= eat_number(argp,whatbuf, 0,32, endchars,endchar_r);
345 mask= len ? (~0UL << (32-len)) : 0UL;
346 if (prefix & ~mask) badusage("%s prefix %08lx not fully contained in mask %08lx",
349 if (mask_r) *mask_r= mask;
350 if (len_r) *len_r= len;
353 static int addrnet_isin(unsigned long prefix, unsigned long mask,
354 unsigned long mprefix, unsigned long mmask) {
355 return !(~mask & mmask) && (prefix & mmask) == mprefix;
358 /* Totally hideous algorithm for parsing the config file lines.
359 * For each config file line, we first see if its gid applies. If not
360 * we skip it. Otherwise, we do
362 * which sets <foo>pming to 1
363 * for each range. <foo>pming may be 0 if we've determined that
364 * this line does not apply to <foo>.
366 * which calls permit_range_thing for each <foo>
367 * which checks to see if <foo> is inside the relevant
368 * range (for +) or overlaps it (for -) and updates
369 * <foo>allow and <foo>pming.
372 static void permit_begin(void) {
375 localpming= peerpming= 1;
376 for (i=0; i<nexroutes; i++) exroutes[i].pming= 1;
379 static void permit_range_thing(unsigned long tprefix, unsigned long tmask,
380 const char *what, int *tallow, int *tpming,
381 unsigned long pprefix, unsigned long pmask,
382 int plus, int *any) {
384 if (!addrnet_isin(tprefix,tmask, pprefix,pmask)) return;
385 if (*tpming) *tallow= 1;
387 if (!addrnet_overlap(tprefix,tmask, pprefix,pmask)) return;
390 if (!proto) printf(" %c%s", plus?'+':'-', what);
394 static void permit_range(unsigned long prefix, unsigned long mask,
395 int plus, int localonly) {
399 assert(!(prefix & ~mask));
402 permit_range_thing(localaddr,~0UL,"local", &localallow,&localpming,
403 prefix,mask, plus,&any);
406 permit_range_thing(peeraddr,~0UL, "peer-addr", &peerallow,&peerpming,
407 prefix,mask, plus,&any);
408 for (i=0; i<nexroutes; i++) {
409 sprintf(idbuf,"route#%d",i);
410 permit_range_thing(exroutes[i].prefix,exroutes[i].mask, idbuf,
411 &exroutes[i].allow,&exroutes[i].pming,
412 prefix,mask, plus,&any);
416 if (!any) fputs(" nothing",stdout);
419 static void pconfig(const char *configstr, int truncated);
421 static void pfile(const char *filename) {
425 struct pplace npp, *cpp;
427 for (cpp=cpplace; cpp; cpp=cpp->parent) {
428 if (!strcmp(cpp->filename,filename))
429 badusage("recursive configuration file `%s'",filename);
432 file= fopen(filename,"r");
434 badusage("cannot open configuration file `%s': %s", filename, strerror(errno));
436 if (!proto) printf("config file `%s':\n",filename);
439 npp.filename= filename;
443 while (fgets(buf, sizeof(buf), file)) {
448 truncated= (buf[l-1] != '\n');
449 while (l>0 && isspace((unsigned char) buf[l-1])) l--;
454 while ((c= getc(file)) != EOF && c != '\n');
458 pconfig(buf,truncated);
461 badusage("failed while reading configuration file: %s", strerror(errno));
466 static void pconfig(const char *configstr, int truncated) {
467 unsigned long fgid, tgid, pprefix, pmask;
468 int plen, localonly, plus, rangeix, delim;
473 switch (configstr[0]) {
476 permit_range(0UL,0UL,1,0);
483 if (truncated) badusage("filename too long (`%.100s...')",configstr);
488 if (!isdigit((unsigned char)configstr[0]))
489 badusage("unknown configuration directive");
491 fgid= eat_number(&configstr,"gid", 0,gidmaxval, ",",0);
493 if (!proto) printf(" %5lu", fgid);
495 gidlist= getenv("USERV_GID");
496 if (!gidlist) fatal("USERV_GID not set");
499 if (!proto) printf(" no matching gid\n");
502 tgid= eat_number(&gidlist,"userv-gid", 0,gidmaxval, " ",0);
503 if (tgid == fgid) break;
506 if (configstr[0] == '=') {
517 switch (configstr[0]) {
518 case '-': plus= 0; /* fall through */
519 case '+': configstr++;
524 sprintf(whattxt, "%s-prefix#%d",
525 plus ? "permitted" : "notpermitted",
527 eat_prefixmask(&configstr,whattxt, ",+-",&delim,
528 &pprefix,&pmask,&plen);
529 if (!configstr && truncated)
530 badusage("gid,prefix/len,... spec too long");
533 printf(" %c%s/%d:", plus?'+':'-',ip2txt(pprefix,ptxt), plen);
535 permit_range(pprefix,pmask,plus,localonly);
536 if (delim==',') break;
538 plus= delim=='-' ? 0 : 1;
547 static void checkallow(int allow, const char *what,
548 const char *prefixtxt, const char *masktxt) {
550 fprintf(stderr,"userv-ipif service: access denied for %s, %s/%s\n",
551 what, prefixtxt, masktxt);
555 static void parseargs(int argc, const char *const *argv) {
556 unsigned long routeaddr, routemask;
558 const char *const *cprotop;
560 char erwhatbuf[100], erwhatbuf2[100];
562 if (argc < NARGS+1) { badusage("too few arguments"); }
563 if (argc > NARGS+1) { badusage("too many arguments"); }
568 if (strcmp(carg,"--")) badusage("separator argument `--' not found, got `%s'",carg);
571 localaddr= eat_addr(&carg,"local-addr", ",",0);
572 peeraddr= eat_addr(&carg,"peer-addr", ",",0);
573 mtu= eat_number(&carg,"mtu", 576,65536, ",",0);
574 localallow= peerallow= 0;
576 if (!strcmp(carg,"debug")) {
579 for (cprotop= protos_ok;
580 (proto= *cprotop) && strcmp(proto,carg);
582 if (!proto) fatal("invalid protocol");
585 addrnet_mustdiffer("local-addr",localaddr,~0UL, "peer-addr",peeraddr,~0UL);
588 if (strcmp(carg,"-")) {
592 if (nexroutes == MAXEXROUTES)
593 fatal("too many extra routes (only %d allowed)",MAXEXROUTES);
594 sprintf(erwhatbuf,"route#%d",nexroutes);
596 eat_prefixmask(&carg,erwhatbuf, ",",0, &routeaddr,&routemask,0);
597 if (routemask == ~0UL) {
598 addrnet_mustdiffer(erwhatbuf,routeaddr,routemask, "local-addr",localaddr,~0UL);
599 addrnet_mustdiffer(erwhatbuf,routeaddr,routemask, "peer-addr",peeraddr,~0UL);
601 for (i=0; i<nexroutes; i++) {
602 sprintf(erwhatbuf2,"route#%d",i);
603 addrnet_mustdiffer(erwhatbuf,routeaddr,routemask,
604 erwhatbuf2,exroutes[i].prefix,exroutes[i].mask);
606 exroutes[nexroutes].prefix= routeaddr;
607 exroutes[nexroutes].mask= routemask;
608 exroutes[nexroutes].allow= 0;
609 ip2txt(routeaddr,exroutes[nexroutes].prefixtxt);
610 ip2txt(routemask,exroutes[nexroutes].masktxt);
614 ip2txt(localaddr,localtxt);
615 ip2txt(peeraddr,peertxt);
618 static void checkpermit(void) {
623 checkallow(localallow,"local-addr", localtxt,"32");
624 checkallow(peerallow,"peer-addr", peertxt,"32");
625 for (i=0; i<nexroutes; i++) {
626 sprintf(erwhatbuf, "route#%d", i);
627 checkallow(exroutes[i].allow, erwhatbuf, exroutes[i].prefixtxt, exroutes[i].masktxt);
629 if (!allallow) fatal("access denied");
632 static void dumpdebug(void) __attribute__((noreturn));
633 static void dumpdebug(void) {
637 printf("protocol: debug\n"
638 "local: %08lx == %s\n"
639 "peer: %08lx == %s\n"
646 for (i=0; i<nexroutes; i++) {
647 sprintf(erwhatbuf, "route#%d:", i);
648 printf("%-9s %08lx/%08lx == %s/%s\n",
650 exroutes[i].prefix, exroutes[i].mask,
651 exroutes[i].prefixtxt, exroutes[i].masktxt);
653 if (ferror(stdout) || fclose(stdout)) sysfatal("flush stdout");
658 static int task(const char *desc) {
663 if (pid == (pid_t)-1) sysfatal("fork for task");
667 pidr= waitpid(pid,&status,0);
668 if (pidr!=(pid_t)-1) break;
669 if (errno==EINTR) continue;
670 sysfatal("waitpid for task");
674 if (WIFEXITED(status)) {
675 if (WEXITSTATUS(status))
676 fatal("userv-ipif service: %s exited with error exit status %d\n",
677 desc, WEXITSTATUS(status));
678 } else if (WIFSIGNALED(status)) {
679 fatal("userv-ipif service: %s died due to signal %s%s\n",
680 desc, strsignal(WTERMSIG(status)),
681 WCOREDUMP(status) ? " (core dumped)" : "");
683 fatal("userv-ipif service: %s unexpectedly terminated"
684 " with unknown status code %d\n", desc, status);
690 static void createif(void) {
691 static const char ifnamepat[]= "userv%d";
695 memset(&ifr,0,sizeof(ifr));
696 ifr.ifr_flags= IFF_TUN | IFF_NO_PI;
698 assert(sizeof(ifr.ifr_name) >= sizeof(ifnamepat));
699 strcpy(ifr.ifr_name, ifnamepat);
701 tunfd= open("/dev/net/tun", O_RDWR);
702 if (!tunfd) sysfatal("open /dev/net/tun");
704 r= fcntl(tunfd, F_GETFD);
705 if (r==-1) sysfatal("fcntl(tunfd,F_GETFD)");
706 r= fcntl(tunfd, F_SETFD, r|FD_CLOEXEC);
707 if (r==-1) sysfatal("fcntl(tunfd,F_SETFD,|FD_CLOEXEC)");
709 r= ioctl(tunfd, TUNSETIFF, (void*)&ifr);
710 if (r) sysfatal("ioctl TUNSETIFF");
712 /* ifr.ifr_name might not be null-terminated. crazy abi. */
713 ifname= malloc(sizeof(ifr.ifr_name)+1);
714 if (!ifname) sysfatal("malloc for interface name");
715 memcpy(ifname, ifr.ifr_name, sizeof(ifr.ifr_name));
716 ifname[sizeof(ifr.ifr_name)]= 0;
719 static void netconfigure(void) {
723 if (task("ifconfig")) {
724 sprintf(mtutxt,"%lu",mtu);
726 execlp("ifconfig", "ifconfig", ifname, localtxt,
727 "netmask","255.255.255.255", "pointopoint",peertxt, "-broadcast",
728 "mtu",mtutxt, "up", (char*)0);
729 sysfatal("cannot exec ifconfig");
732 for (i=0; i<nexroutes; i++) {
734 execlp("route","route", "add", "-net",exroutes[i].prefixtxt,
735 "netmask",exroutes[i].masktxt,
736 "gw",peertxt, "dev",ifname, (char*)0);
737 sysfatal("cannot exec route (for route)");
742 static void setnonblock(int fd) {
744 r= fcntl(fd,F_GETFL);
745 if (r==-1) sysfatal("fcntl F_GETFL");
746 r= fcntl(fd,F_SETFL, r|O_NONBLOCK);
747 if (r==-1) sysfatal("fcntl F_SETFL O_NONBLOCK");
750 static void rx_packet(const uint8_t *packet, int len) {
752 int r= write(tunfd, packet, len);
754 if (errno==EINTR) continue;
755 if (errno==EAGAIN) return; /* oh well */
756 sysfatal("error writing packet to tun (transmitting)");
763 static int output_waiting, input_waiting;
765 #define SLIP_END 0300
766 #define SLIP_ESC 0333
767 #define SLIP_ESC_END 0334
768 #define SLIP_ESC_ESC 0335
770 static void more_rx_data(uint8_t *input_buf, uint8_t *output_buf) {
771 /* we make slip_data never contain continuation of a packet */
772 /* input_buf is passed as a parameter since it's in copydata's stack frame */
774 static int output_len;
776 uint8_t *op= output_buf + output_len;
777 const uint8_t *ip= input_buf + scanned;
778 const uint8_t *ip_end= input_buf + input_waiting;
782 if (ip>=ip_end) break;
785 rx_packet(output_buf, op-output_buf);
787 eaten= ip - input_buf;
791 if (ip>=ip_end) { /* rescan this when there's more */ ip--; break; }
793 if (c==SLIP_ESC_END) c=SLIP_END;
794 else if (c==SLIP_ESC_ESC) c=SLIP_ESC;
795 else fatal("unexpected byte 0%o after SLIP_ESC",c);
797 if (op == output_buf+mtu)
798 fatal("SLIP packet exceeds mtu");
802 output_len= op - output_buf;
803 scanned= ip - input_buf;
805 input_waiting -= eaten;
806 memmove(input_buf, input_buf+eaten, input_waiting);
810 static void tx_packet(uint8_t *output_buf, const uint8_t *ip, int inlen) {
811 /* output_buf is passed as a parameter since it's in copydata's stack frame */
812 assert(!output_waiting);
813 uint8_t *op= output_buf;
818 if (c==SLIP_END) { *op++= SLIP_ESC; *op++= SLIP_ESC_END; }
819 else if (c==SLIP_ESC) { *op++= SLIP_ESC; *op++= SLIP_ESC_ESC; }
823 assert(op <= output_buf + mtu*2+2);
825 output_waiting= op - output_buf;
828 static void copydata(void) __attribute__((noreturn));
829 static void copydata(void) {
830 uint8_t output_buf[mtu*2+2];
831 uint8_t input_buf[mtu*2+2];
832 uint8_t rx_packet_buf[mtu];
836 struct pollfd polls[3];
837 memset(polls, 0, sizeof(polls));
839 polls[0].fd= 0; polls[0].events= POLLIN;
843 /* We don't do flow control on input packets; instead, we just throw
844 * away ones which the kernel doesn't accept. So we always poll for
847 * Output packets we buffer, so we poll only as appropriate for those.
850 /* Start by transmitting one END byte to say we're ready. */
851 output_buf[0]= SLIP_END;
855 if (output_waiting) {
856 r= write(1, output_buf, output_waiting);
858 if (errno==EINTR) continue;
860 sysfatal("error writing SLIP output (packets being received)");
864 memmove(output_buf, output_buf+r, output_waiting);
867 if (output_waiting) {
868 polls[1].events |= POLLOUT;
869 polls[2].events &= ~POLLIN;
871 polls[1].events &= ~POLLOUT;
872 polls[2].events |= POLLIN;
877 if (errno==EINTR) continue;
878 sysfatal("poll() failed");
880 assert(r>0); /* we used an infinite timeout */
882 for (i=0; i<sizeof(polls)/sizeof(polls[0]); i++)
883 if (polls[i].revents & ~polls[i].events)
884 fatal("unexpected revents 0x%x for fd=%d",
885 polls[i].revents, polls[i].fd);
887 if (polls[0].events & POLLIN) {
888 int want= sizeof(input_buf) - input_waiting;
889 if (want<0) fatal("incoming packet necessarily exceeds MTU");
890 r= read(0, input_buf + input_waiting, want);
893 assert(r < sizeof(input_buf));
894 more_rx_data(input_buf, rx_packet_buf);
898 if (!(errno==EINTR || errno==EAGAIN))
899 sysfatal("error reading input SLIP data (packets to transmit)");
903 /* We handle what would be (polls[1].events & POLLOUT) above,
904 * unconditionally. That eliminates the need to poll in the usual case */
906 if (polls[2].events & POLLIN) {
907 uint8_t packet_buf[mtu];
908 r= read(tunfd, packet_buf, mtu);
910 tx_packet(output_buf, packet_buf, r);
913 if (!(errno==EAGAIN || errno==EWOULDBLOCK))
914 sysfatal("error reading packet (being transmitted) from tun");
920 int main(int argc, const char *const *argv) {
921 parseargs(argc,argv);
922 pconfig(configstr,0);
924 if (!proto) dumpdebug();