1 | /* |
1 | /* |
2 | vpn.C -- handle the protocol, encryption, handshaking etc. |
2 | vpn.C -- handle the protocol, encryption, handshaking etc. |
3 | Copyright (C) 2003-2008 Marc Lehmann <gvpe@schmorp.de> |
3 | Copyright (C) 2003-2008,2010,2011,2013 Marc Lehmann <gvpe@schmorp.de> |
4 | |
4 | |
5 | This file is part of GVPE. |
5 | This file is part of GVPE. |
6 | |
6 | |
7 | GVPE is free software; you can redistribute it and/or modify it |
7 | GVPE is free software; you can redistribute it and/or modify it |
8 | under the terms of the GNU General Public License as published by the |
8 | under the terms of the GNU General Public License as published by the |
… | |
… | |
38 | #include <cstdlib> |
38 | #include <cstdlib> |
39 | |
39 | |
40 | #include <sys/types.h> |
40 | #include <sys/types.h> |
41 | #include <sys/socket.h> |
41 | #include <sys/socket.h> |
42 | #include <sys/wait.h> |
42 | #include <sys/wait.h> |
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43 | #include <sys/stat.h> |
43 | #include <errno.h> |
44 | #include <errno.h> |
44 | #include <time.h> |
45 | #include <time.h> |
45 | #include <unistd.h> |
46 | #include <unistd.h> |
46 | #include <fcntl.h> |
47 | #include <fcntl.h> |
47 | #include <sys/socket.h> |
48 | #include <sys/socket.h> |
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52 | |
53 | |
53 | #include "connection.h" |
54 | #include "connection.h" |
54 | #include "util.h" |
55 | #include "util.h" |
55 | #include "vpn.h" |
56 | #include "vpn.h" |
56 | |
57 | |
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58 | using namespace std; |
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59 | |
57 | vpn network; // THE vpn (bad design...) |
60 | vpn network; // THE vpn (bad design...) |
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61 | |
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62 | ///////////////////////////////////////////////////////////////////////////// |
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63 | |
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64 | // hopefully temporary workaround for rare buffer full conditions |
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65 | // if it happens, usually instantly retrying or retrying ~5ms later |
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66 | // is good enough with current network technologies/kernels |
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67 | |
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68 | static ssize_t |
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69 | xsendto (int fd, const void *buf, size_t len, int flags, |
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70 | const struct sockaddr *sa, socklen_t salen) |
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71 | { |
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72 | ssize_t res; |
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73 | |
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74 | for (int retry = 0; retry <= 13; ++retry) // ~100ms |
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75 | { |
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76 | res = sendto (fd, buf, len, flags, sa, salen); |
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77 | |
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78 | if (res >= 0 || errno != ENOBUFS) |
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79 | break; |
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80 | |
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81 | struct timespec ts = { 0, 1000 * retry }; |
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82 | nanosleep (&ts, 0); |
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83 | } |
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84 | |
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85 | return res; |
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86 | } |
58 | |
87 | |
59 | ///////////////////////////////////////////////////////////////////////////// |
88 | ///////////////////////////////////////////////////////////////////////////// |
60 | |
89 | |
61 | static void inline |
90 | static void inline |
62 | set_tos (int fd, int &tos_prev, int tos) |
91 | set_tos (int fd, int &tos_prev, int tos) |
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75 | { |
104 | { |
76 | // the tunnel device mtu should be the physical mtu - overhead |
105 | // the tunnel device mtu should be the physical mtu - overhead |
77 | // the tricky part is rounding to the cipher key blocksize |
106 | // the tricky part is rounding to the cipher key blocksize |
78 | int mtu = conf.mtu - ETH_OVERHEAD - VPE_OVERHEAD - MAX_OVERHEAD; |
107 | int mtu = conf.mtu - ETH_OVERHEAD - VPE_OVERHEAD - MAX_OVERHEAD; |
79 | mtu += ETH_OVERHEAD - 6 - 6; // now we have the data portion |
108 | mtu += ETH_OVERHEAD - 6 - 6; // now we have the data portion |
80 | mtu -= mtu % EVP_CIPHER_block_size (CIPHER); // round |
109 | mtu -= mtu % BLOCK_SIZE (CIPHER); // round |
81 | mtu -= ETH_OVERHEAD - 6 - 6; // and get interface mtu again |
110 | mtu -= ETH_OVERHEAD - 6 - 6; // and get interface mtu again |
82 | |
111 | |
83 | char *env; |
112 | char *env; |
84 | asprintf (&env, "CONFBASE=%s", confbase); putenv (env); |
113 | asprintf (&env, "CONFBASE=%s", confbase); putenv (env); |
85 | asprintf (&env, "IFNAME=%s", tap->interface ()); putenv (env); |
114 | asprintf (&env, "IFNAME=%s", tap->interface ()); putenv (env); |
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110 | inline const char * |
139 | inline const char * |
111 | vpn::script_if_up () |
140 | vpn::script_if_up () |
112 | { |
141 | { |
113 | script_init_env (); |
142 | script_init_env (); |
114 | |
143 | |
115 | char *filename; |
144 | return conf.config_filename (::conf.script_if_up, "if-up"); |
116 | asprintf (&filename, |
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117 | "%s/%s", |
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118 | confbase, |
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119 | ::conf.script_if_up ? ::conf.script_if_up : "if-up"); |
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120 | |
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121 | return filename; |
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122 | } |
145 | } |
123 | |
146 | |
124 | int |
147 | int |
125 | vpn::setup_socket (u8 prot, int family, int type, int proto) |
148 | vpn::setup_socket (u8 prot, int family, int type, int proto) |
126 | { |
149 | { |
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232 | icmpv4_fd = setup_socket (PROT_ICMPv4, PF_INET, SOCK_RAW, IPPROTO_ICMP); |
255 | icmpv4_fd = setup_socket (PROT_ICMPv4, PF_INET, SOCK_RAW, IPPROTO_ICMP); |
233 | |
256 | |
234 | if (icmpv4_fd < 0) |
257 | if (icmpv4_fd < 0) |
235 | return -1; |
258 | return -1; |
236 | |
259 | |
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260 | // no clue where trhis is actually defined |
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261 | #if !defined(ICMP_FILTER) && defined(__linux) |
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262 | #define ICMP_FILTER 1 |
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263 | #endif |
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264 | |
237 | #ifdef ICMP_FILTER |
265 | #ifdef ICMP_FILTER |
238 | { |
266 | { |
239 | icmp_filter oval; |
267 | uint32_t oval; |
240 | oval.data = 0xffffffff; |
268 | oval = 0; |
241 | if (::conf.icmp_type < 32) |
269 | if (::conf.icmp_type < 32) |
242 | oval.data &= ~(1 << ::conf.icmp_type); |
270 | oval |= 1 << ::conf.icmp_type; |
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271 | oval = ~oval; |
243 | |
272 | |
244 | setsockopt (icmpv4_fd, SOL_RAW, ICMP_FILTER, &oval, sizeof oval); |
273 | setsockopt (icmpv4_fd, SOL_RAW, ICMP_FILTER, &oval, sizeof oval); |
245 | } |
274 | } |
246 | #endif |
275 | #endif |
247 | |
276 | |
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392 | |
421 | |
393 | return 0; |
422 | return 0; |
394 | } |
423 | } |
395 | |
424 | |
396 | bool |
425 | bool |
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426 | vpn::drop_privileges () |
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427 | { |
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428 | if (::conf.change_root) |
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429 | { |
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430 | if (!strcmp (::conf.change_root, "/")) |
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431 | { |
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432 | char dir [L_tmpnam]; |
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433 | if (!tmpnam (dir)) |
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434 | { |
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435 | slog (L_CRIT, _("unable to create anonymous root path.")); |
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436 | return false; |
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437 | } |
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438 | |
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439 | if (mkdir (dir, 0700)) |
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440 | { |
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441 | slog (L_CRIT, _("unable to create anonymous root directory.")); |
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442 | return false; |
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443 | } |
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444 | |
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445 | if (chdir (dir)) |
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446 | { |
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447 | slog (L_CRIT, _("unable to change to anonymous root directory.")); |
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448 | return false; |
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449 | } |
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450 | |
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451 | if (rmdir (dir)) |
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452 | slog (L_ERR, _("unable to remove anonymous root directory, continuing.")); |
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453 | } |
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454 | else |
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455 | { |
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456 | if (chdir (::conf.change_root)) |
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457 | { |
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458 | slog (L_CRIT, _("%s: unable to change to specified root directory."), ::conf.change_root); |
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459 | return false; |
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460 | } |
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461 | } |
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462 | |
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463 | if (chroot (".")) |
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464 | { |
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465 | slog (L_CRIT, _("unable to set new root directory.")); |
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466 | return false; |
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467 | } |
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468 | |
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469 | if (chdir ("/")) |
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470 | { |
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471 | slog (L_CRIT, _("unable to set cwd to new root directory.")); |
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472 | return false; |
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473 | } |
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474 | } |
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475 | |
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476 | if (::conf.change_gid) |
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477 | if (setgid (::conf.change_gid)) |
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478 | { |
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479 | slog (L_CRIT, _("unable to change group id to %d."), ::conf.change_gid); |
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480 | return false; |
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481 | } |
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482 | |
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483 | if (::conf.change_uid) |
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484 | if (setuid (::conf.change_uid)) |
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485 | { |
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486 | slog (L_CRIT, _("unable to change user id to %d."), ::conf.change_uid); |
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487 | return false; |
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488 | } |
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489 | |
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490 | return true; |
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491 | } |
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492 | |
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493 | bool |
397 | vpn::send_ipv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) |
494 | vpn::send_ipv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) |
398 | { |
495 | { |
399 | set_tos (ipv4_fd, ipv4_tos, tos); |
496 | set_tos (ipv4_fd, ipv4_tos, tos); |
400 | sendto (ipv4_fd, &((*pkt)[0]), pkt->len, 0, si.sav4 (), si.salenv4 ()); |
497 | xsendto (ipv4_fd, &((*pkt)[0]), pkt->len, 0, si.sav4 (), si.salenv4 ()); |
401 | |
498 | |
402 | return true; |
499 | return true; |
403 | } |
500 | } |
404 | |
501 | |
405 | static u16 |
502 | static u16 |
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436 | hdr->code = 255; |
533 | hdr->code = 255; |
437 | hdr->checksum = 0; |
534 | hdr->checksum = 0; |
438 | hdr->checksum = ipv4_checksum ((u16 *)hdr, pkt->len); |
535 | hdr->checksum = ipv4_checksum ((u16 *)hdr, pkt->len); |
439 | |
536 | |
440 | set_tos (icmpv4_fd, icmpv4_tos, tos); |
537 | set_tos (icmpv4_fd, icmpv4_tos, tos); |
441 | sendto (icmpv4_fd, &((*pkt)[0]), pkt->len, 0, si.sav4 (), si.salenv4 ()); |
538 | xsendto (icmpv4_fd, &((*pkt)[0]), pkt->len, 0, si.sav4 (), si.salenv4 ()); |
442 | |
539 | |
443 | return true; |
540 | return true; |
444 | } |
541 | } |
445 | #endif |
542 | #endif |
446 | |
543 | |
447 | bool |
544 | bool |
448 | vpn::send_udpv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) |
545 | vpn::send_udpv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) |
449 | { |
546 | { |
450 | set_tos (udpv4_fd, udpv4_tos, tos); |
547 | set_tos (udpv4_fd, udpv4_tos, tos); |
451 | sendto (udpv4_fd, &((*pkt)[0]), pkt->len, 0, si.sav4 (), si.salenv4 ()); |
548 | xsendto (udpv4_fd, &((*pkt)[0]), pkt->len, 0, si.sav4 (), si.salenv4 ()); |
452 | |
549 | |
453 | return true; |
550 | return true; |
454 | } |
551 | } |
455 | |
552 | |
456 | void |
553 | void |
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482 | (const char *)rsi, pkt->typ (), pkt->src (), pkt->dst (), pkt->len); |
579 | (const char *)rsi, pkt->typ (), pkt->src (), pkt->dst (), pkt->len); |
483 | |
580 | |
484 | if (src == 0 || src > conns.size () |
581 | if (src == 0 || src > conns.size () |
485 | || dst > conns.size () |
582 | || dst > conns.size () |
486 | || pkt->typ () >= vpn_packet::PT_MAX) |
583 | || pkt->typ () >= vpn_packet::PT_MAX) |
487 | slog (L_WARN, _("(%s): received corrupted packet type %d (src %d, dst %d)."), |
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488 | (const char *)rsi, pkt->typ (), pkt->src (), pkt->dst ()); |
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489 | else if (dst > conns.size ()) |
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490 | slog (L_WARN, _("(%s): received corrupted packet type %d (src %d, dst %d)."), |
584 | slog (L_WARN, _("(%s): received corrupted packet type %d (src %d, dst %d)."), |
491 | (const char *)rsi, pkt->typ (), pkt->src (), pkt->dst ()); |
585 | (const char *)rsi, pkt->typ (), pkt->src (), pkt->dst ()); |
492 | else |
586 | else |
493 | { |
587 | { |
494 | connection *c = conns[src - 1]; |
588 | connection *c = conns[src - 1]; |
… | |
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516 | vpn::send_vpn_packet (vpn_packet *pkt, const sockinfo &si, int tos) |
610 | vpn::send_vpn_packet (vpn_packet *pkt, const sockinfo &si, int tos) |
517 | { |
611 | { |
518 | switch (si.prot) |
612 | switch (si.prot) |
519 | { |
613 | { |
520 | case PROT_IPv4: |
614 | case PROT_IPv4: |
521 | return send_ipv4_packet (pkt, si, tos); |
615 | return send_ipv4_packet (pkt, si, tos); |
522 | |
616 | |
523 | case PROT_UDPv4: |
617 | case PROT_UDPv4: |
524 | return send_udpv4_packet (pkt, si, tos); |
618 | return send_udpv4_packet (pkt, si, tos); |
525 | |
619 | |
526 | #if ENABLE_TCP |
620 | #if ENABLE_TCP |
527 | case PROT_TCPv4: |
621 | case PROT_TCPv4: |
528 | return send_tcpv4_packet (pkt, si, tos); |
622 | return send_tcpv4_packet (pkt, si, tos); |
529 | #endif |
623 | #endif |
530 | #if ENABLE_ICMP |
624 | #if ENABLE_ICMP |
531 | case PROT_ICMPv4: |
625 | case PROT_ICMPv4: |
532 | return send_icmpv4_packet (pkt, si, tos); |
626 | return send_icmpv4_packet (pkt, si, tos); |
533 | #endif |
627 | #endif |
534 | #if ENABLE_DNS |
628 | #if ENABLE_DNS |
535 | case PROT_DNSv4: |
629 | case PROT_DNSv4: |
536 | return send_dnsv4_packet (pkt, si, tos); |
630 | return send_dnsv4_packet (pkt, si, tos); |
537 | #endif |
631 | #endif |
538 | default: |
632 | default: |
539 | slog (L_CRIT, _("%s: FATAL: trying to send packet with unsupported protocol."), (const char *)si); |
633 | slog (L_CRIT, _("%s: FATAL: trying to send packet with unsupported protocol."), (const char *)si); |
540 | } |
634 | } |
541 | |
635 | |
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559 | if (len > 0) |
653 | if (len > 0) |
560 | { |
654 | { |
561 | pkt->len = len; |
655 | pkt->len = len; |
562 | |
656 | |
563 | // raw sockets deliver the ipv4 header, but don't expect it on sends |
657 | // raw sockets deliver the ipv4 header, but don't expect it on sends |
564 | pkt->skip_hdr (IP_OVERHEAD); |
658 | pkt->skip_hdr (pkt->ipv4_hdr_len ()); |
565 | |
659 | |
566 | recv_vpn_packet (pkt, si); |
660 | recv_vpn_packet (pkt, si); |
567 | } |
661 | } |
568 | else |
662 | else |
569 | { |
663 | { |
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606 | if (hdr->type == ::conf.icmp_type |
700 | if (hdr->type == ::conf.icmp_type |
607 | && hdr->code == 255) |
701 | && hdr->code == 255) |
608 | { |
702 | { |
609 | // raw sockets deliver the ipv4, but don't expect it on sends |
703 | // raw sockets deliver the ipv4, but don't expect it on sends |
610 | // this is slow, but... |
704 | // this is slow, but... |
611 | pkt->skip_hdr (ICMP_OVERHEAD); |
705 | pkt->skip_hdr (pkt->ipv4_hdr_len () + (ICMP_OVERHEAD - IP_OVERHEAD)); |
612 | |
706 | |
613 | recv_vpn_packet (pkt, si); |
707 | recv_vpn_packet (pkt, si); |
614 | } |
708 | } |
615 | } |
709 | } |
616 | else |
710 | else |
… | |
… | |
827 | { |
921 | { |
828 | for (conns_vector::iterator i = conns.begin (); i != conns.end (); ++i) |
922 | for (conns_vector::iterator i = conns.begin (); i != conns.end (); ++i) |
829 | { |
923 | { |
830 | connection *o = *i; |
924 | connection *o = *i; |
831 | |
925 | |
832 | if (!o->is_direct |
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833 | && o->si.valid () |
926 | if (o->si.valid () |
834 | && c->si != o->si |
927 | && c->si != o->si |
835 | && c == find_router_for (o)) |
928 | && c == find_router_for (o) |
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929 | && !can_direct (THISNODE, o->conf)) |
836 | { |
930 | { |
837 | slog (L_DEBUG, _("%s: can now route packets via %s, re-keying connection."), |
931 | slog (L_DEBUG, _("%s: can now route packets via %s, re-keying connection."), |
838 | o->conf->nodename, c->conf->nodename); |
932 | o->conf->nodename, c->conf->nodename); |
839 | o->rekey (); |
933 | o->rekey (); |
840 | } |
934 | } |