src/resolve/resolved-manager.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2014 Tom Gundersen <teg@jklm.no>
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20  ***/
  21
  22 #include <arpa/inet.h>
  23 #include <resolv.h>
  24 #include <linux/if.h>
  25
  26 #include "resolved.h"
  27 #include "event-util.h"
  28 #include "network-util.h"
  29 #include "sd-dhcp-lease.h"
  30 #include "dhcp-lease-internal.h"
  31 #include "network-internal.h"
  32 #include "conf-parser.h"
  33
  34 static int set_fallback_dns(Manager *m, const char *string) {
  35         char *word, *state;
  36         size_t length;
  37         int r;
  38
  39         assert(m);
  40         assert(string);
  41
  42         FOREACH_WORD_QUOTED(word, length, string, state) {
  43                 _cleanup_free_ Address *address = NULL;
  44                 Address *tail;
  45                 _cleanup_free_ char *addrstr = NULL;
  46
  47                 address = new0(Address, 1);
  48                 if (!address)
  49                         return -ENOMEM;
  50
  51                 addrstr = strndup(word, length);
  52                 if (!addrstr)
  53                         return -ENOMEM;
  54
  55                 r = net_parse_inaddr(addrstr, &address->family, &address->in_addr);
  56                 if (r < 0) {
  57                         log_debug("Ignoring invalid DNS address '%s'", addrstr);
  58                         continue;
  59                 }
  60
  61                 LIST_FIND_TAIL(addresses, m->fallback_dns, tail);
  62                 LIST_INSERT_AFTER(addresses, m->fallback_dns, tail, address);
  63                 address = NULL;
  64         }
  65
  66         return 0;
  67 }
  68
  69 int config_parse_dnsv(
  70                 const char *unit,
  71                 const char *filename,
  72                 unsigned line,
  73                 const char *section,
  74                 unsigned section_line,
  75                 const char *lvalue,
  76                 int ltype,
  77                 const char *rvalue,
  78                 void *data,
  79                 void *userdata) {
  80
  81         Manager *m = userdata;
  82         Address *address;
  83
  84         assert(filename);
  85         assert(lvalue);
  86         assert(rvalue);
  87         assert(m);
  88
  89         while ((address = m->fallback_dns)) {
  90                 LIST_REMOVE(addresses, m->fallback_dns, address);
  91                 free(address);
  92         }
  93
  94         set_fallback_dns(m, rvalue);
  95
  96         return 0;
  97 }
  98
  99 static int manager_parse_config_file(Manager *m) {
 100         int r;
 101
 102         assert(m);
 103
 104         r = config_parse(NULL, "/etc/systemd/resolved.conf", NULL,
 105                          "Resolve\0", config_item_perf_lookup, (void*) resolved_gperf_lookup,
 106                          false, false, m);
 107         if (r < 0)
 108                 log_warning("Failed to parse configuration file: %s", strerror(-r));
 109
 110         return r;
 111 }
 112
 113 int manager_new(Manager **ret) {
 114         _cleanup_manager_free_ Manager *m = NULL;
 115         int r;
 116
 117         m = new0(Manager, 1);
 118         if (!m)
 119                 return -ENOMEM;
 120
 121         r = set_fallback_dns(m, DNS_SERVERS);
 122         if (r < 0)
 123                 return r;
 124
 125         r = manager_parse_config_file(m);
 126         if (r < 0)
 127                 return r;
 128
 129         r = sd_event_default(&m->event);
 130         if (r < 0)
 131                 return r;
 132
 133         sd_event_add_signal(m->event, NULL, SIGTERM, NULL,  NULL);
 134         sd_event_add_signal(m->event, NULL, SIGINT, NULL, NULL);
 135
 136         sd_event_set_watchdog(m->event, true);
 137
 138         *ret = m;
 139         m = NULL;
 140
 141         return 0;
 142 }
 143
 144 void manager_free(Manager *m) {
 145         Address *address;
 146
 147         if (!m)
 148                 return;
 149
 150         sd_event_unref(m->event);
 151
 152         while ((address = m->fallback_dns)) {
 153                 LIST_REMOVE(addresses, m->fallback_dns, address);
 154                 free(address);
 155         }
 156
 157         free(m);
 158 }
 159
 160 static void append_dns(FILE *f, void *dns, unsigned char family, unsigned *count) {
 161         char buf[INET6_ADDRSTRLEN];
 162         const char *address;
 163
 164         assert(f);
 165         assert(dns);
 166         assert(count);
 167
 168         address = inet_ntop(family, dns, buf, INET6_ADDRSTRLEN);
 169         if (!address) {
 170                 log_warning("Invalid DNS address. Ignoring.");
 171                 return;
 172         }
 173
 174         if (*count == MAXNS)
 175                 fputs("# Too many DNS servers configured, the following entries "
 176                       "may be ignored\n", f);
 177
 178         fprintf(f, "nameserver %s\n", address);
 179
 180         (*count) ++;
 181 }
 182
 183 int manager_update_resolv_conf(Manager *m) {
 184         const char *path = "/run/systemd/resolve/resolv.conf";
 185         _cleanup_free_ char *temp_path = NULL;
 186         _cleanup_fclose_ FILE *f = NULL;
 187          _cleanup_free_ unsigned *indices = NULL;
 188         Address *address;
 189         unsigned count = 0;
 190         int n, r, i;
 191
 192         assert(m);
 193
 194         r = fopen_temporary(path, &f, &temp_path);
 195         if (r < 0)
 196                 return r;
 197
 198         fchmod(fileno(f), 0644);
 199
 200         fputs("# This file is managed by systemd-resolved(8). Do not edit.\n#\n"
 201               "# Third party programs must not access this file directly, but\n"
 202               "# only through the symlink at /etc/resolv.conf. To manage\n"
 203               "# resolv.conf(5) in a different way, replace the symlink by a\n"
 204               "# static file or a different symlink.\n\n", f);
 205
 206         n = sd_network_get_ifindices(&indices);
 207         if (n < 0)
 208                 n = 0;
 209
 210         for (i = 0; i < n; i++) {
 211                 _cleanup_dhcp_lease_unref_ sd_dhcp_lease *lease = NULL;
 212                 struct in_addr *nameservers;
 213                 struct in6_addr *nameservers6;
 214                 size_t nameservers_size;
 215
 216                 r = sd_network_dhcp_use_dns(indices[i]);
 217                 if (r > 0) {
 218                         r = sd_network_get_dhcp_lease(indices[i], &lease);
 219                         if (r >= 0) {
 220                                 r = sd_dhcp_lease_get_dns(lease, &nameservers, &nameservers_size);
 221                                 if (r >= 0) {
 222                                         unsigned j;
 223
 224                                         for (j = 0; j < nameservers_size; j++)
 225                                                 append_dns(f, &nameservers[j], AF_INET, &count);
 226                                 }
 227                         }
 228                 }
 229
 230                 r = sd_network_get_dns(indices[i], &nameservers, &nameservers_size);
 231                 if (r >= 0) {
 232                         unsigned j;
 233
 234                         for (j = 0; j < nameservers_size; j++)
 235                                 append_dns(f, &nameservers[j], AF_INET, &count);
 236
 237                         free(nameservers);
 238                 }
 239
 240                 r = sd_network_get_dns6(indices[i], &nameservers6, &nameservers_size);
 241                 if (r >= 0) {
 242                         unsigned j;
 243
 244                         for (j = 0; j < nameservers_size; j++)
 245                                 append_dns(f, &nameservers6[j], AF_INET6, &count);
 246
 247                         free(nameservers6);
 248                 }
 249         }
 250
 251         LIST_FOREACH(addresses, address, m->fallback_dns)
 252                 append_dns(f, &address->in_addr, address->family, &count);
 253
 254         fflush(f);
 255
 256         if (ferror(f) || rename(temp_path, path) < 0) {
 257                 r = -errno;
 258                 unlink(path);
 259                 unlink(temp_path);
 260                 return r;
 261         }
 262
 263         return 0;
 264 }
 265
 266 static int manager_network_event_handler(sd_event_source *s, int fd, uint32_t revents,
 267                                          void *userdata) {
 268         Manager *m = userdata;
 269         int r;
 270
 271         assert(m);
 272
 273         r = manager_update_resolv_conf(m);
 274         if (r < 0)
 275                 log_warning("Could not update resolv.conf: %s", strerror(-r));
 276
 277         sd_network_monitor_flush(m->network_monitor);
 278
 279         return 0;
 280 }
 281
 282 int manager_network_monitor_listen(Manager *m) {
 283         _cleanup_event_source_unref_ sd_event_source *event_source = NULL;
 284         _cleanup_network_monitor_unref_ sd_network_monitor *monitor = NULL;
 285         int r, fd, events;
 286
 287         r = sd_network_monitor_new(NULL, &monitor);
 288         if (r < 0)
 289                 return r;
 290
 291         fd = sd_network_monitor_get_fd(monitor);
 292         if (fd < 0)
 293                 return fd;
 294
 295         events = sd_network_monitor_get_events(monitor);
 296         if (events < 0)
 297                 return events;
 298
 299         r = sd_event_add_io(m->event, &event_source, fd, events,
 300                             &manager_network_event_handler, m);
 301         if (r < 0)
 302                 return r;
 303
 304         m->network_monitor = monitor;
 305         m->network_event_source = event_source;
 306         monitor = NULL;
 307         event_source = NULL;
 308
 309         return 0;
 310 }