mdw@git.distorted.org.uk Git - secnet/blob - polypath.c

   1 /* polypath
   2  * send/receive module for secnet
   3  * for multi-route setups */
   4
   5 #include "secnet.h"
   6 #include "util.h"
   7 #include "unaligned.h"
   8 #include "comm-common.h"
   9
  10 #include <adns.h>
  11 #include <ctype.h>
  12
  13 #ifdef CONFIG_IPV6
  14
  15 static comm_sendmsg_fn polypath_sendmsg;
  16
  17 struct interf {
  18     char *name; /* from malloc */
  19     struct udpsocks socks;
  20     bool_t experienced_xmit_noaf[MAX_AF+1];
  21     LIST_ENTRY(interf) entry;
  22 };
  23
  24 struct polypath {
  25     struct udpcommon uc;
  26     int max_interfs;
  27     const char *const *ifname_pats;
  28     const char *const *monitor_command;
  29     bool_t permit_loopback;
  30     LIST_HEAD(,interf) interfs;
  31     struct buffer_if lbuf;
  32     int monitor_fd;
  33     pid_t monitor_pid;
  34 };
  35
  36 #define LG 0, st->uc.cc.cl.description, &st->uc.cc.loc
  37
  38 static const char *const default_loopback_ifname_pats[] = {
  39     "!lo", 0
  40 };
  41 static const char *const default_ifname_pats[] = {
  42     "!tun*","!tap*","!sl*","!userv*", "*", 0
  43 };
  44
  45 static const char *const default_monitor_command[] = {
  46 #if __linux__
  47     DATAROOTDIR "/secnet/" "polypath-interface-monitor-linux", 0
  48 #else
  49     0
  50 #endif
  51 };
  52
  53 static const char *polypath_addr_to_string(void *commst,
  54                                            const struct comm_addr *ca)
  55 {
  56     static char sbuf[100];
  57
  58     snprintf(sbuf, sizeof(sbuf), "polypath:%s",
  59              iaddr_to_string(&ca->ia));
  60     return sbuf;
  61 }
  62
  63 static bool_t ifname_search_pats(struct polypath *st, struct cloc loc,
  64                                  const char *ifname, bool_t *want_io,
  65                                  const char *const *pats) {
  66     /* Returns True iff we found a list entry, in which case *want_io
  67      * is set to the sense of that entry.  Otherwise *want_io is set
  68      * to the sense of the last entry, or unchanged if there were no pats. */
  69     if (!pats)
  70         return False;
  71     const char *const *pati;
  72     for (pati=pats; *pati; pati++) {
  73         const char *pat=*pati;
  74         if (*pat=='!') { *want_io=False; pat++; }
  75         else if (*pat=='+') { *want_io=True; pat++; }
  76         else if (*pat=='*' || isalnum((unsigned char)*pat)) { *want_io=True; }
  77         else cfgfatal(loc,"polypath","invalid interface name pattern `%s'",pat);
  78         int match=fnmatch(pat,ifname,0);
  79         if (match==0) return True;
  80         if (match!=FNM_NOMATCH)
  81             cfgfatal(loc,"polypath","fnmatch failed! (pattern `%s')",pat);
  82     }
  83     return False;
  84 }
  85
  86 static bool_t ifname_wanted(struct polypath *st, struct cloc loc,
  87                             const char *ifname) {
  88     bool_t want=False; /* pretend an empty cfg ends with !<doesn'tmatch> */
  89     if (ifname_search_pats(st,loc,ifname,&want, st->ifname_pats))
  90         return want;
  91     if (want) /* last pattern was positive, do not search default */
  92         return False;
  93     if (!st->permit_loopback &&
  94         ifname_search_pats(st,loc,ifname,&want, default_loopback_ifname_pats))
  95         return want;
  96     if (ifname_search_pats(st,loc,ifname,&want, default_ifname_pats))
  97         return want;
  98     abort();
  99 }
 100
 101 static int polypath_beforepoll(void *state, struct pollfd *fds, int *nfds_io,
 102                                int *timeout_io)
 103 {
 104     struct polypath *st=state;
 105     BEFOREPOLL_WANT_FDS(1);
 106     fds[0].fd=st->monitor_fd;
 107     fds[0].events=POLLIN;
 108     return 0;
 109 }
 110
 111 static inline bool_t matches32(uint32_t word, uint32_t prefix, int prefixlen)
 112 {
 113     assert(prefixlen>0);
 114     assert(prefixlen<=32);
 115     uint32_t mask = ~(((uint32_t)1 << (32-prefixlen)) - 1);
 116     assert(!(prefix & ~mask));
 117     return (word & mask) == prefix;
 118 }
 119
 120 /* These macros expect
 121  *    bad_fn_type *const bad;
 122  *    void *badctx;
 123  * and
 124  *   out:
 125  */
 126 #define BAD(m)     do{ bad(st,badctx,m,0);  goto out; }while(0)
 127 #define BADE(m,ev) do{ bad(st,badctx,m,ev); goto out; }while(0)
 128 typedef void bad_fn_type(struct polypath *st, void *badctx,
 129                          const char* m, int ev);
 130
 131 typedef void polypath_ppml_callback_type(struct polypath *st,
 132           bad_fn_type *bad, void *badctx,
 133           bool_t add, const char *ifname, const char *ifaddr,
 134           const union iaddr *ia, int fd /* -1 if none yet */);
 135
 136 struct ppml_bad_ctx {
 137     const char *orgl;
 138     char *undospace;
 139 };
 140
 141 static void ppml_bad(struct polypath *st, void *badctx, const char *m, int ev)
 142 {
 143     struct ppml_bad_ctx *bc=badctx;
 144     if (bc->undospace)
 145         *(bc->undospace)=' ';
 146     lg_perror(LG,M_WARNING,ev,
 147               "error processing polypath state change: %s"
 148               " (while processing `%s')",
 149               m,bc->orgl);
 150 }
 151
 152 static void polypath_process_monitor_line(struct polypath *st, char *orgl,
 153                                       polypath_ppml_callback_type *callback)
 154     /* always calls callback with fd==-1 */
 155 {
 156     struct udpcommon *uc=&st->uc;
 157     char *l=orgl;
 158     bad_fn_type (*const bad)=ppml_bad;
 159     struct ppml_bad_ctx badctx[1]={{
 160             .orgl=orgl,
 161             .undospace=0
 162         }};
 163
 164     bool_t add;
 165     int c=*l++;
 166     if (c=='+') add=True;
 167     else if (c=='-') add=False;
 168     else BAD("bad +/-");
 169
 170     int proto;
 171     c=*l++;
 172     if (c=='4') proto=AF_INET;
 173     else if (c=='6') proto=AF_INET6;
 174     else BAD("bad proto");
 175
 176     char *space=strchr(l,' ');
 177     if (!space) BAD("no first space");
 178     const char *ifname=space+1;
 179
 180     space=strchr(ifname,' ');
 181     if (!space) BAD("no second space");
 182     const char *ifaddr=space+1;
 183     *space=0;
 184     badctx->undospace=space;
 185
 186     union iaddr ia;
 187     FILLZERO(ia);
 188     socklen_t salen=sizeof(ia);
 189     int r=adns_text2addr(ifaddr,uc->port, adns_qf_addrlit_ipv4_quadonly,
 190                          &ia.sa, &salen);
 191     assert(r!=ENOSPC);
 192     if (r) BADE("adns_text2addr",r);
 193     if (ia.sa.sa_family!=proto) BAD("address family mismatch");
 194
 195 #define DONT(m) do{                                                     \
 196         if (add)                                                        \
 197             lg_perror(LG,M_INFO,0,"ignoring %s [%s]: %s",ifname,ifaddr,m); \
 198         goto out;                                                       \
 199     }while(0)
 200
 201     if (!ifname_wanted(st,st->uc.cc.loc,ifname))
 202         DONT("unwanted interface name");
 203
 204     switch (ia.sa.sa_family) {
 205     case AF_INET6: {
 206         const struct in6_addr *i6=&ia.sin6.sin6_addr;
 207 #define DONTKIND(X,m) \
 208         if (IN6_IS_ADDR_##X(i6)) DONT("IPv6 address is " m)
 209         DONTKIND(UNSPECIFIED, "unspecified");
 210         DONTKIND(MULTICAST  , "multicast"  );
 211         DONTKIND(LINKLOCAL  , "link local" );
 212         DONTKIND(SITELOCAL  , "site local" );
 213         DONTKIND(V4MAPPED   , "v4-mapped"  );
 214         if (!st->permit_loopback)
 215             DONTKIND(LOOPBACK   , "loopback"   );
 216 #undef DONTKIND
 217 #define DONTMASK(w7x,w6x,prefixlen,m)                                   \
 218         if (matches32(get_uint32(i6->s6_addr),                          \
 219                       ((uint32_t)0x##w7x << 16) | (uint32_t)0x##w6x,    \
 220                       prefixlen))                                       \
 221             DONT("IPv6 address is " m)
 222         DONTMASK( 100,   0,  8, "Discard-Only (RFC6666)");
 223         DONTMASK(2001,   0, 23, "in IETF protocol block (RFC2928)");
 224 #undef DONTMASK
 225         break;
 226     }
 227     case AF_INET: {
 228         const uint32_t i4=htonl(ia.sin.sin_addr.s_addr);
 229         if (i4==INADDR_ANY) DONT("IPv4 address is any/unspecified");
 230         if (i4==INADDR_BROADCAST) DONT("IPv4 address is all hosts broadcast");
 231 #define DONTMASK(b3,b2,b1,b0,prefixlen,m) do{                           \
 232             const uint8_t prefixbytes[4] = { (b3),(b2),(b1),(b0) };     \
 233             if (matches32(i4,get_uint32(prefixbytes),prefixlen))        \
 234                 DONT("IPv4 address is " m);                             \
 235         }while(0)
 236         DONTMASK(169,254,0,0, 16, "link local");
 237         DONTMASK(224,  0,0,0,  4, "multicast");
 238         DONTMASK(192,  0,0,0, 24, "in IETF protocol block (RFC6890)");
 239         DONTMASK(240,  0,0,0,  4, "in reserved addressing block (RFC1112)");
 240         if (!st->permit_loopback)
 241             DONTMASK(127,  0,0,0,  8, "loopback");
 242 #undef DONTMASK
 243         break;
 244     }
 245     default:
 246         abort();
 247     }
 248
 249 #undef DONT
 250
 251     /* OK, process it */
 252     callback(st, bad,badctx, add,ifname,ifaddr,&ia,-1);
 253
 254  out:;
 255 }
 256
 257 static void dump_pria(struct polypath *st, const char *ifname)
 258 {
 259 #ifdef POLYPATH_DEBUG
 260     struct interf *interf;
 261     if (ifname)
 262         lg_perror(LG,M_DEBUG,0, "polypath record ifaddr `%s'",ifname);
 263     LIST_FOREACH(interf, &st->interfs, entry) {
 264         lg_perror(LG,M_DEBUG,0, "  polypath interface `%s', nsocks=%d",
 265                   interf->name, interf->socks.n_socks);
 266         int i;
 267         for (i=0; i<interf->socks.n_socks; i++) {
 268             struct udpsock *us=&interf->socks.socks[i];
 269             lg_perror(LG,M_DEBUG,0, "    polypath sock fd=%d addr=%s",
 270                       us->fd, iaddr_to_string(&us->addr));
 271         }
 272     }
 273 #endif
 274 }
 275
 276 static bool_t polypath_make_socket(struct polypath *st,
 277                                    bad_fn_type *bad, void *badctx,
 278                                    struct udpsock *us, const char *ifname)
 279     /* on error exit has called bad; might leave us->fd as -1 */
 280 {
 281     assert(us->fd==-1);
 282
 283     bool_t ok=udp_make_socket(&st->uc,us,M_WARNING);
 284     if (!ok) BAD("unable to set up socket");
 285     int r=setsockopt(us->fd,SOL_SOCKET,SO_BINDTODEVICE,
 286                      ifname,strlen(ifname)+1);
 287     if (r) BADE("setsockopt(,,SO_BINDTODEVICE,)",errno);
 288     return True;
 289
 290  out:
 291     return False;
 292 }
 293
 294 static void polypath_record_ifaddr(struct polypath *st,
 295                                    bad_fn_type *bad, void *badctx,
 296                                    bool_t add, const char *ifname,
 297                                    const char *ifaddr,
 298                                    const union iaddr *ia, int fd)
 299 {
 300     struct udpcommon *uc=&st->uc;
 301     struct interf *interf=0;
 302     struct udpsock *us=0;
 303
 304     dump_pria(st,ifname);
 305
 306     int n_ifs=0;
 307     LIST_FOREACH(interf,&st->interfs,entry) {
 308         if (!strcmp(interf->name,ifname))
 309             goto found_interf;
 310         n_ifs++;
 311     }
 312     /* not found */
 313     if (n_ifs==st->max_interfs) BAD("too many interfaces");
 314     interf=malloc(sizeof(*interf));
 315     if (!interf) BADE("malloc for new interface",errno);
 316     interf->name=0;
 317     interf->socks.n_socks=0;
 318     FILLZERO(interf->experienced_xmit_noaf);
 319     LIST_INSERT_HEAD(&st->interfs,interf,entry);
 320     udp_socks_register(&st->uc,&interf->socks);
 321     interf->name=strdup(ifname);
 322     if (!interf->name) BADE("strdup interface name",errno);
 323  found_interf:
 324
 325     if (add) {
 326         if (interf->socks.n_socks == UDP_MAX_SOCKETS)
 327             BAD("too many addresses on this interface");
 328         struct udpsock *us=&interf->socks.socks[interf->socks.n_socks];
 329         us->fd=-1;
 330         COPY_OBJ(us->addr,*ia);
 331         if (fd<0) {
 332             bool_t ok=polypath_make_socket(st,bad,badctx, us,ifname);
 333             if (!ok) goto out;
 334         } else {
 335             FILLZERO(us->experienced);
 336             us->fd=fd;
 337             fd=-1;
 338         }
 339         interf->socks.n_socks++;
 340         us=0; /* do not destroy this socket during `out' */
 341         lg_perror(LG,M_INFO,0,"using %s %s",ifname,ifaddr);
 342     } else {
 343         int i;
 344         for (i=0; i<interf->socks.n_socks; i++)
 345             if (!memcmp(&interf->socks.socks[i].addr,ia,sizeof(*ia)))
 346                 goto address_remove_found;
 347         BAD("address to remove not found");
 348     address_remove_found:
 349         lg_perror(LG,M_INFO,0,"removed %s %s",ifname,ifaddr);
 350         udp_destroy_socket(&st->uc,&interf->socks.socks[i]);
 351         interf->socks.socks[i]=
 352             interf->socks.socks[--interf->socks.n_socks];
 353     }
 354
 355  out:
 356     if (us)
 357         udp_destroy_socket(uc,us);
 358     if (fd>=0)
 359         close(fd);
 360     if (interf && !interf->socks.n_socks) {
 361         udp_socks_deregister(&st->uc,&interf->socks);
 362         LIST_REMOVE(interf,entry);
 363         free(interf->name);
 364         free(interf);
 365     }
 366
 367     dump_pria(st,0);
 368 }
 369
 370 static void subproc_problem(struct polypath *st,
 371                             enum async_linebuf_result alr, const char *emsg)
 372 {
 373     int status;
 374     assert(st->monitor_pid);
 375
 376     pid_t gotpid=waitpid(st->monitor_pid,&status,WNOHANG);
 377     if (gotpid==st->monitor_pid) {
 378         st->monitor_pid=0;
 379         lg_exitstatus(LG,M_FATAL,status,"interface monitor");
 380     } else if (gotpid<0)
 381         lg_perror(LG,M_ERR,errno,"unable to reap interface monitor");
 382     else
 383         assert(gotpid==0);
 384
 385     if (alr==async_linebuf_eof)
 386         lg_perror(LG,M_FATAL,0,"unexpected EOF from interface monitor");
 387     else
 388         lg_perror(LG,M_FATAL,0,"bad output from interface monitor: %s",emsg);
 389     assert(!"not reached");
 390 }
 391
 392 static void afterpoll_monitor(struct polypath *st, struct pollfd *fd,
 393                               polypath_ppml_callback_type *callback)
 394 {
 395     enum async_linebuf_result alr;
 396     const char *emsg;
 397
 398     while ((alr=async_linebuf_read(fd,&st->lbuf,&emsg)) == async_linebuf_ok)
 399         polypath_process_monitor_line(st,st->lbuf.base,callback);
 400
 401     if (alr==async_linebuf_nothing)
 402         return;
 403
 404     subproc_problem(st,alr,emsg);
 405 }
 406
 407 static void polypath_afterpoll_monitor(void *state, struct pollfd *fds,
 408                                        int nfds)
 409 {
 410     struct polypath *st=state;
 411     if (nfds<1) return;
 412     afterpoll_monitor(st,fds,polypath_record_ifaddr);
 413 }
 414
 415 /* Actual udp packet sending work */
 416 static bool_t polypath_sendmsg(void *commst, struct buffer_if *buf,
 417                           const struct comm_addr *dest)
 418 {
 419     struct polypath *st=commst;
 420     struct interf *interf;
 421     bool_t allreasonable=True;
 422     int af=dest->ia.sa.sa_family;
 423
 424     LIST_FOREACH(interf,&st->interfs,entry) {
 425         int i;
 426         bool_t attempted=False, reasonable=False;
 427         for (i=0; i<interf->socks.n_socks; i++) {
 428             struct udpsock *us=&interf->socks.socks[i];
 429             if (af != us->addr.sa.sa_family)
 430                 continue;
 431             attempted=True;
 432             int r=sendto(us->fd,buf->start,buf->size,
 433                          0,&dest->ia.sa,iaddr_socklen(&dest->ia));
 434             udp_sock_experienced(0,&st->uc, interf->name,us,
 435                                  1,af, r,errno);
 436             if (r>=0) {
 437                 reasonable=True;
 438                 break;
 439             }
 440             if (!(errno==EAFNOSUPPORT || errno==ENETUNREACH))
 441                 reasonable=True;
 442             lg_perror(LG,M_DEBUG,errno,"%s [%s] xmit %"PRIu32" bytes to %s",
 443                       interf->name,iaddr_to_string(&us->addr),
 444                       buf->size,iaddr_to_string(&dest->ia));
 445         }
 446         if (!attempted)
 447             if (!interf->experienced_xmit_noaf[af]++)
 448                 lg_perror(LG,M_WARNING,0,
 449                           "%s has no suitable address to transmit %s",
 450                           interf->name, af_name(af));
 451         allreasonable *= reasonable;
 452     }
 453     return allreasonable;
 454 }
 455
 456 static void child_monitor(struct polypath *st, int childfd)
 457 {
 458     dup2(childfd,1);
 459     execvp(st->monitor_command[0],(char**)st->monitor_command);
 460     fprintf(stderr,"secnet: cannot execute %s: %s\n",
 461             st->monitor_command[0], strerror(errno));
 462     exit(-1);
 463 }
 464
 465 static void start_subproc(struct polypath *st, void (*make_fdpair)(int[2]),
 466                           void (*child)(struct polypath *st, int childfd))
 467 {
 468     int pfds[2];
 469
 470     assert(!st->monitor_pid);
 471     assert(st->monitor_fd<0);
 472
 473     make_fdpair(pfds);
 474
 475     pid_t pid=fork();
 476     if (!pid) {
 477         afterfork();
 478         child(st,pfds[1]);
 479         abort();
 480     }
 481     if (pid<0)
 482         fatal_perror("%s: failed to fork for interface monitoring",
 483                      st->uc.cc.cl.description);
 484
 485     close(pfds[1]);
 486     st->monitor_pid=pid;
 487     st->monitor_fd=pfds[0];
 488     setnonblock(st->monitor_fd);
 489 }
 490
 491 static void polypath_phase_startmonitor(void *sst, uint32_t newphase)
 492 {
 493     struct polypath *st=sst;
 494     start_subproc(st,pipe_cloexec,child_monitor);
 495     register_for_poll(st,polypath_beforepoll,
 496                       polypath_afterpoll_monitor,"polypath");
 497 }
 498
 499 static void polypath_phase_shutdown(void *sst, uint32_t newphase)
 500 {
 501     struct polypath *st=sst;
 502     if (st->monitor_pid) {
 503         assert(st->monitor_pid>0);
 504         kill(st->monitor_pid,SIGTERM);
 505     }
 506 }
 507
 508 #undef BAD
 509 #undef BADE
 510
 511 static list_t *polypath_apply(closure_t *self, struct cloc loc,
 512                               dict_t *context, list_t *args)
 513 {
 514     struct polypath *st;
 515
 516     COMM_APPLY(st,&st->uc.cc,polypath_,"polypath",loc);
 517     COMM_APPLY_STANDARD(st,&st->uc.cc,"polypath",args);
 518     UDP_APPLY_STANDARD(st,&st->uc,"polypath");
 519
 520     struct udpcommon *uc=&st->uc;
 521     struct commcommon *cc=&uc->cc;
 522
 523     st->max_interfs=dict_read_number(d,"max-interfaces",False,"polypath",loc,3);
 524
 525     st->ifname_pats=dict_read_string_array(d,"interfaces",False,"polypath",
 526                                            cc->loc,0);
 527     st->permit_loopback=0; /* ifname_wanted reads this */
 528     ifname_wanted(st,st->uc.cc.loc," "); /* try to check each pattern */
 529
 530     st->monitor_command=dict_read_string_array(d,"monitor-command",False,
 531                                "polypath",cc->loc, default_monitor_command);
 532     if (!st->monitor_command[0])
 533         cfgfatal(loc,"polypath","no polypath interface monitor-command"
 534                  " (polypath unsupported on this platform?)\n");
 535
 536     st->permit_loopback=dict_read_bool(d,"permit-loopback",False,
 537                                        "polypath",cc->loc,False);
 538
 539     LIST_INIT(&st->interfs);
 540     buffer_new(&st->lbuf,ADNS_ADDR2TEXT_BUFLEN+100);
 541     BUF_ALLOC(&st->lbuf,"polypath lbuf");
 542
 543     st->monitor_fd=-1;
 544     st->monitor_pid=0;
 545
 546     add_hook(PHASE_RUN,         polypath_phase_startmonitor,st);
 547     add_hook(PHASE_SHUTDOWN,    polypath_phase_shutdown,    st);
 548
 549     return new_closure(&cc->cl);
 550 }
 551
 552 #endif /* CONFIG_IPV6 */
 553
 554 void polypath_module(dict_t *dict)
 555 {
 556 #ifdef CONFIG_IPV6
 557     add_closure(dict,"polypath",polypath_apply);
 558 #endif /* CONFIG_IPV6 */
 559 }