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