service.c

   1 /*
   2  * Copyright (C) 2014 John Crispin <blogic@openwrt.org>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU Lesser General Public License version 2.1
   6  * as published by the Free Software Foundation
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  */
  13
  14 #include <sys/types.h>
  15 #include <arpa/nameser.h>
  16 #include <sys/socket.h>
  17
  18 #include <resolv.h>
  19 #include <glob.h>
  20 #include <stdio.h>
  21 #include <time.h>
  22
  23 #include <uci.h>
  24 #include <uci_blob.h>
  25
  26 #include <libubox/vlist.h>
  27 #include <libubox/uloop.h>
  28 #include <libubox/avl-cmp.h>
  29 #include <libubox/blobmsg_json.h>
  30
  31 #include "dns.h"
  32 #include "service.h"
  33 #include "util.h"
  34 #include "interface.h"
  35
  36 enum {
  37         SERVICE_PORT,
  38         SERVICE_TXT,
  39         __SERVICE_MAX,
  40 };
  41
  42 struct service {
  43         struct vlist_node node;
  44
  45         time_t t;
  46
  47         const char *service;
  48         const char *daemon;
  49         const uint8_t *txt;
  50         int txt_len;
  51         int port;
  52         int active;
  53 };
  54
  55 static const struct blobmsg_policy service_policy[__SERVICE_MAX] = {
  56         [SERVICE_PORT] = { .name = "port", .type = BLOBMSG_TYPE_INT32 },
  57         [SERVICE_TXT] = { .name = "txt", .type = BLOBMSG_TYPE_ARRAY },
  58 };
  59
  60 static void
  61 service_update(struct vlist_tree *tree, struct vlist_node *node_new,
  62                struct vlist_node *node_old);
  63
  64 static struct blob_buf b;
  65 static VLIST_TREE(services, avl_strcmp, service_update, false, false);
  66 static char *sdudp =  "_services._dns-sd._udp.local";
  67 static char *sdtcp =  "_services._dns-sd._tcp.local";
  68
  69 static const char *
  70 service_name(const char *domain)
  71 {
  72         static char buffer[256];
  73
  74         snprintf(buffer, sizeof(buffer), "%s.%s", mdns_hostname, domain);
  75
  76         return buffer;
  77 }
  78
  79 static void
  80 service_add_ptr(const char *host)
  81 {
  82         int len = dn_comp(host, mdns_buf, sizeof(mdns_buf), NULL, NULL);
  83
  84         if (len < 1)
  85                 return;
  86
  87         dns_add_answer(TYPE_PTR, mdns_buf, len);
  88 }
  89
  90 static void
  91 service_add_srv(struct service *s)
  92 {
  93         struct dns_srv_data *sd = (struct dns_srv_data *) mdns_buf;
  94         int len = sizeof(*sd);
  95
  96         len += dn_comp(mdns_hostname_local, mdns_buf + len, sizeof(mdns_buf) - len, NULL, NULL);
  97         if (len <= sizeof(*sd))
  98                 return;
  99
 100         sd->port = cpu_to_be16(s->port);
 101         dns_add_answer(TYPE_SRV, mdns_buf, len);
 102 }
 103
 104 #define TOUT_LOOKUP     60
 105
 106 static int
 107 service_timeout(struct service *s)
 108 {
 109         time_t t = time(NULL);
 110
 111         if (t - s->t <= TOUT_LOOKUP)
 112                 return 0;
 113
 114         s->t = t;
 115
 116         return 1;
 117 }
 118
 119 void
 120 service_reply_a(struct interface *iface, int type)
 121 {
 122         if (type != TYPE_A)
 123                 return;
 124
 125         dns_init_answer();
 126         dns_add_answer(TYPE_A, (uint8_t *) &iface->v4_addr.s_addr, 4);
 127         dns_send_answer(iface, mdns_hostname_local);
 128 }
 129
 130 void
 131 service_reply(struct interface *iface, const char *match)
 132 {
 133         struct service *s;
 134
 135         vlist_for_each_element(&services, s, node) {
 136                 const char *host = service_name(s->service);
 137                 char *service = strstr(host, "._");
 138
 139                 if (!s->active || !service || !service_timeout(s))
 140                         continue;
 141
 142                 service++;
 143
 144                 if (match && strcmp(match, s->service))
 145                         continue;
 146
 147                 dns_init_answer();
 148                 service_add_ptr(service_name(s->service));
 149                 dns_send_answer(iface, service);
 150
 151                 dns_init_answer();
 152                 service_add_srv(s);
 153                 if (s->txt && s->txt_len)
 154                         dns_add_answer(TYPE_TXT, (uint8_t *) s->txt, s->txt_len);
 155                 dns_send_answer(iface, host);
 156         }
 157
 158         if (match)
 159                 return;
 160
 161         service_reply_a(iface, TYPE_A);
 162 }
 163
 164 void
 165 service_announce_services(struct interface *iface, const char *service)
 166 {
 167         struct service *s;
 168         int tcp = 1;
 169
 170         if (!strcmp(service, sdudp))
 171                 tcp = 0;
 172         else if (strcmp(service, sdtcp))
 173                 return;
 174
 175         vlist_for_each_element(&services, s, node) {
 176                 if (!strstr(s->service, "._tcp") && tcp)
 177                         continue;
 178                 if (!strstr(s->service, "._udp") && !tcp)
 179                         continue;
 180                 s->t = 0;
 181                 dns_init_answer();
 182                 service_add_ptr(s->service);
 183                 if (tcp)
 184                         dns_send_answer(iface, sdtcp);
 185                 else
 186                         dns_send_answer(iface, sdudp);
 187                 service_reply(iface, s->service);
 188         }
 189 }
 190
 191 void
 192 service_announce(struct interface *iface)
 193 {
 194         service_announce_services(iface, sdudp);
 195         service_announce_services(iface, sdtcp);
 196 }
 197
 198 static void
 199 service_update(struct vlist_tree *tree, struct vlist_node *node_new,
 200                struct vlist_node *node_old)
 201 {
 202         struct service *s;
 203
 204         if (!node_old)
 205                 return;
 206
 207         s = container_of(node_old, struct service, node);
 208         free(s);
 209 }
 210
 211 static void
 212 service_load(char *path)
 213 {
 214         struct blob_attr *txt, *cur, *_tb[__SERVICE_MAX];
 215         int rem, i;
 216         glob_t gl;
 217
 218         if (glob(path, GLOB_NOESCAPE | GLOB_MARK, NULL, &gl))
 219                 return;
 220
 221         for (i = 0; i < gl.gl_pathc; i++) {
 222                 blob_buf_init(&b, 0);
 223
 224                 if (!blobmsg_add_json_from_file(&b, gl.gl_pathv[i]))
 225                         continue;
 226                 blob_for_each_attr(cur, b.head, rem) {
 227                         struct service *s;
 228                         char *d_service, *d_daemon;
 229                         uint8_t *d_txt;
 230                         int rem2;
 231                         int txt_len = 0;
 232
 233                         blobmsg_parse(service_policy, ARRAY_SIZE(service_policy),
 234                                 _tb, blobmsg_data(cur), blobmsg_data_len(cur));
 235                         if (!_tb[SERVICE_PORT] || !_tb[SERVICE_TXT])
 236                                 continue;
 237
 238                         blobmsg_for_each_attr(txt, _tb[SERVICE_TXT], rem2)
 239                                 txt_len += 1 + strlen(blobmsg_get_string(txt));
 240
 241                         s = calloc_a(sizeof(*s),
 242                                 &d_daemon, strlen(gl.gl_pathv[i]) + 1,
 243                                 &d_service, strlen(blobmsg_name(cur)) + 1,
 244                                 &d_txt, txt_len);
 245                         if (!s)
 246                                 continue;
 247
 248                         s->port = blobmsg_get_u32(_tb[SERVICE_PORT]);
 249                         s->service = strcpy(d_service, blobmsg_name(cur));
 250                         s->daemon = strcpy(d_daemon, gl.gl_pathv[i]);
 251                         s->active = 1;
 252                         s->t = 0;
 253                         s->txt_len = txt_len;
 254                         s->txt = d_txt;
 255
 256                         blobmsg_for_each_attr(txt, _tb[SERVICE_TXT], rem2) {
 257                                 int len = strlen(blobmsg_get_string(txt));
 258                                 if (!len)
 259                                         continue;
 260                                 if (len > 0xff)
 261                                         len = 0xff;
 262                                 *d_txt = len;
 263                                 d_txt++;
 264                                 memcpy(d_txt, blobmsg_get_string(txt), len);
 265                                 d_txt += len;
 266                         }
 267
 268                         vlist_add(&services, &s->node, s->service);
 269                 }
 270         }
 271 }
 272
 273 void
 274 service_init(void)
 275 {
 276         get_hostname();
 277
 278         vlist_update(&services);
 279         service_load("/tmp/run/mdnsd/*");
 280         vlist_flush(&services);
 281 }
 282
 283 void
 284 service_cleanup(void)
 285 {
 286         vlist_flush(&services);
 287         blob_buf_free(&b);
 288 }