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 const struct uci_blob_param_list service_attr_list = {
  61         .n_params = __SERVICE_MAX,
  62         .params = service_policy,
  63 };
  64
  65 static void
  66 service_update(struct vlist_tree *tree, struct vlist_node *node_new,
  67                struct vlist_node *node_old);
  68
  69 static struct blob_buf b;
  70 static VLIST_TREE(services, avl_strcmp, service_update, false, false);
  71 static char *sdudp =  "_services._dns-sd._udp.local";
  72 static char *sdtcp =  "_services._dns-sd._tcp.local";
  73
  74 static const char *
  75 service_name(const char *domain)
  76 {
  77         static char buffer[256];
  78
  79         snprintf(buffer, sizeof(buffer), "%s.%s", mdns_hostname, domain);
  80
  81         return buffer;
  82 }
  83
  84 static void
  85 service_add_ptr(const char *host)
  86 {
  87         int len = dn_comp(host, mdns_buf, sizeof(mdns_buf), NULL, NULL);
  88
  89         if (len < 1)
  90                 return;
  91
  92         dns_add_answer(TYPE_PTR, mdns_buf, len);
  93 }
  94
  95 static void
  96 service_add_srv(struct service *s)
  97 {
  98         struct dns_srv_data *sd = (struct dns_srv_data *) mdns_buf;
  99         int len = sizeof(*sd);
 100
 101         len += dn_comp(mdns_hostname_local, mdns_buf + len, sizeof(mdns_buf) - len, NULL, NULL);
 102         if (len <= sizeof(*sd))
 103                 return;
 104
 105         sd->port = cpu_to_be16(s->port);
 106         dns_add_answer(TYPE_SRV, mdns_buf, len);
 107 }
 108
 109 #define TOUT_LOOKUP     60
 110
 111 static int
 112 service_timeout(struct service *s)
 113 {
 114         time_t t = time(NULL);
 115
 116         if (t - s->t <= TOUT_LOOKUP)
 117                 return 0;
 118
 119         s->t = t;
 120
 121         return 1;
 122 }
 123
 124 void
 125 service_reply_a(struct interface *iface, int type)
 126 {
 127         if (type != TYPE_A)
 128                 return;
 129
 130         dns_init_answer();
 131         dns_add_answer(TYPE_A, (uint8_t *) &iface->v4_addr.s_addr, 4);
 132         dns_send_answer(iface, mdns_hostname_local);
 133 }
 134
 135 void
 136 service_reply(struct interface *iface, const char *match)
 137 {
 138         struct service *s;
 139
 140         vlist_for_each_element(&services, s, node) {
 141                 const char *host = service_name(s->service);
 142                 char *service = strstr(host, "._");
 143
 144                 if (!s->active || !service || !service_timeout(s))
 145                         continue;
 146
 147                 service++;
 148
 149                 if (match && strcmp(match, s->service))
 150                         continue;
 151
 152                 dns_init_answer();
 153                 service_add_ptr(service_name(s->service));
 154                 dns_send_answer(iface, service);
 155
 156                 dns_init_answer();
 157                 service_add_srv(s);
 158                 if (s->txt && s->txt_len)
 159                         dns_add_answer(TYPE_TXT, (uint8_t *) s->txt, s->txt_len);
 160                 dns_send_answer(iface, host);
 161         }
 162
 163         if (match)
 164                 return;
 165
 166         service_reply_a(iface, TYPE_A);
 167 }
 168
 169 void
 170 service_announce_services(struct interface *iface, const char *service)
 171 {
 172         struct service *s;
 173         int tcp = 1;
 174
 175         if (!strcmp(service, sdudp))
 176                 tcp = 0;
 177         else if (strcmp(service, sdtcp))
 178                 return;
 179
 180         vlist_for_each_element(&services, s, node) {
 181                 if (!strstr(s->service, "._tcp") && tcp)
 182                         continue;
 183                 if (!strstr(s->service, "._udp") && !tcp)
 184                         continue;
 185                 s->t = 0;
 186                 dns_init_answer();
 187                 service_add_ptr(s->service);
 188                 if (tcp)
 189                         dns_send_answer(iface, sdtcp);
 190                 else
 191                         dns_send_answer(iface, sdudp);
 192                 service_reply(iface, s->service);
 193         }
 194 }
 195
 196 void
 197 service_announce(struct interface *iface)
 198 {
 199         service_announce_services(iface, sdudp);
 200         service_announce_services(iface, sdtcp);
 201 }
 202
 203 static void
 204 service_update(struct vlist_tree *tree, struct vlist_node *node_new,
 205                struct vlist_node *node_old)
 206 {
 207         struct service *s;
 208
 209         if (!node_old)
 210                 return;
 211
 212         s = container_of(node_old, struct service, node);
 213         free(s);
 214 }
 215
 216 static void
 217 service_load(char *path)
 218 {
 219         struct blob_attr *txt, *cur, *_tb[__SERVICE_MAX];
 220         int rem, i;
 221         glob_t gl;
 222
 223         if (glob(path, GLOB_NOESCAPE | GLOB_MARK, NULL, &gl))
 224                 return;
 225
 226         for (i = 0; i < gl.gl_pathc; i++) {
 227                 blob_buf_init(&b, 0);
 228
 229                 if (!blobmsg_add_json_from_file(&b, gl.gl_pathv[i]))
 230                         continue;
 231                 blob_for_each_attr(cur, b.head, rem) {
 232                         struct service *s;
 233                         char *d_service, *d_daemon;
 234                         uint8_t *d_txt;
 235                         int rem2;
 236                         int txt_len = 0;
 237
 238                         blobmsg_parse(service_policy, ARRAY_SIZE(service_policy),
 239                                 _tb, blobmsg_data(cur), blobmsg_data_len(cur));
 240                         if (!_tb[SERVICE_PORT] || !_tb[SERVICE_TXT])
 241                                 continue;
 242
 243                         blobmsg_for_each_attr(txt, _tb[SERVICE_TXT], rem2)
 244                                 txt_len += 1 + strlen(blobmsg_get_string(txt));
 245
 246                         s = calloc_a(sizeof(*s),
 247                                 &d_daemon, strlen(gl.gl_pathv[i]) + 1,
 248                                 &d_service, strlen(blobmsg_name(cur)) + 1,
 249                                 &d_txt, txt_len);
 250                         if (!s)
 251                                 continue;
 252
 253                         s->port = blobmsg_get_u32(_tb[SERVICE_PORT]);
 254                         s->service = strcpy(d_service, blobmsg_name(cur));
 255                         s->daemon = strcpy(d_daemon, gl.gl_pathv[i]);
 256                         s->active = 1;
 257                         s->t = 0;
 258                         s->txt_len = txt_len;
 259                         s->txt = d_txt;
 260
 261                         blobmsg_for_each_attr(txt, _tb[SERVICE_TXT], rem2) {
 262                                 int len = strlen(blobmsg_get_string(txt));
 263                                 if (!len)
 264                                         continue;
 265                                 if (len > 0xff)
 266                                         len = 0xff;
 267                                 *d_txt = len;
 268                                 d_txt++;
 269                                 memcpy(d_txt, blobmsg_get_string(txt), len);
 270                                 d_txt += len;
 271                         }
 272
 273                         vlist_add(&services, &s->node, s->service);
 274                 }
 275         }
 276 }
 277
 278 void
 279 service_init(void)
 280 {
 281         get_hostname();
 282
 283         vlist_update(&services);
 284         service_load("/tmp/run/mdnsd/*");
 285         vlist_flush(&services);
 286 }
 287
 288 void
 289 service_cleanup(void)
 290 {
 291         vlist_flush(&services);
 292         blob_buf_free(&b);
 293 }