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 char *hostname = NULL;
  72 static char *sdudp =  "_services._dns-sd._udp.local";
  73 static char *sdtcp =  "_services._dns-sd._tcp.local";
  74
  75 char *
  76 service_name(const char *domain)
  77 {
  78         static char buffer[256];
  79
  80         snprintf(buffer, sizeof(buffer), "%s.%s", hostname, domain);
  81
  82         return buffer;
  83 }
  84
  85 static void
  86 service_add_ptr(struct service *s)
  87 {
  88         unsigned char buffer[MAX_NAME_LEN];
  89         const char *host = service_name(s->service);
  90         int len = dn_comp(host, buffer, MAX_NAME_LEN, NULL, NULL);
  91
  92         if (len < 1)
  93                 return;
  94
  95         dns_add_answer(TYPE_PTR, buffer, len);
  96 }
  97
  98 static void
  99 service_add_ptr_c(const char *host)
 100 {
 101         unsigned char buffer[MAX_NAME_LEN];
 102         int len = dn_comp(host, buffer, MAX_NAME_LEN, NULL, NULL);
 103
 104         if (len < 1)
 105                 return;
 106
 107         dns_add_answer(TYPE_PTR, buffer, len);
 108 }
 109
 110 static void
 111 service_send_a(struct interface *iface)
 112 {
 113         unsigned char buffer[MAX_NAME_LEN];
 114         char *host = service_name("local");
 115         int len = dn_comp(host, buffer, MAX_NAME_LEN, NULL, NULL);
 116
 117         if (len < 1)
 118                 return;
 119
 120         dns_add_answer(TYPE_A, (uint8_t *) &iface->v4_addr.s_addr, 4);
 121 }
 122
 123 static void
 124 service_add_srv(struct service *s)
 125 {
 126         unsigned char buffer[MAX_NAME_LEN];
 127         struct dns_srv_data *sd;
 128         char *host = service_name("local");
 129         int len = dn_comp(host, buffer, MAX_NAME_LEN, NULL, NULL);
 130
 131         if (len < 1)
 132                 return;
 133
 134         sd = calloc(1, len + sizeof(struct dns_srv_data));
 135         if (!sd)
 136                 return;
 137
 138         sd->port = cpu_to_be16(s->port);
 139         memcpy(&sd[1], buffer, len);
 140         host = service_name(s->service);
 141         dns_add_answer(TYPE_SRV, (uint8_t *) sd, len + sizeof(struct dns_srv_data));
 142         free(sd);
 143 }
 144
 145 #define TOUT_LOOKUP     60
 146
 147 static int
 148 service_timeout(struct service *s)
 149 {
 150         time_t t = time(NULL);
 151
 152         if (t - s->t <= TOUT_LOOKUP)
 153                 return 0;
 154
 155         s->t = t;
 156
 157         return 1;
 158 }
 159
 160 void
 161 service_reply_a(struct interface *iface, int type)
 162 {
 163         if (type != TYPE_A)
 164                 return;
 165
 166         dns_init_answer();
 167         service_send_a(iface);
 168         dns_send_answer(iface, service_name("local"));
 169 }
 170
 171 void
 172 service_reply(struct interface *iface, const char *match)
 173 {
 174         struct service *s;
 175
 176         vlist_for_each_element(&services, s, node) {
 177                 char *host = service_name(s->service);
 178                 char *service = strstr(host, "._");
 179
 180                 if (!s->active || !service || !service_timeout(s))
 181                         continue;
 182
 183                 service++;
 184
 185                 if (match && strcmp(match, s->service))
 186                         continue;
 187
 188                 dns_init_answer();
 189                 service_add_ptr(s);
 190                 dns_send_answer(iface, service);
 191
 192                 dns_init_answer();
 193                 service_add_srv(s);
 194                 if (s->txt && s->txt_len)
 195                         dns_add_answer(TYPE_TXT, (uint8_t *) s->txt, s->txt_len);
 196                 dns_send_answer(iface, host);
 197         }
 198
 199         if (match)
 200                 return;
 201
 202         dns_init_answer();
 203         service_send_a(iface);
 204         dns_send_answer(iface, service_name("local"));
 205 }
 206
 207 void
 208 service_announce_services(struct interface *iface, const char *service)
 209 {
 210         struct service *s;
 211         int tcp = 1;
 212
 213         if (!strcmp(service, sdudp))
 214                 tcp = 0;
 215         else if (strcmp(service, sdtcp))
 216                 return;
 217
 218         vlist_for_each_element(&services, s, node) {
 219                 if (!strstr(s->service, "._tcp") && tcp)
 220                         continue;
 221                 if (!strstr(s->service, "._udp") && !tcp)
 222                         continue;
 223                 s->t = 0;
 224                 dns_init_answer();
 225                 service_add_ptr_c(s->service);
 226                 if (tcp)
 227                         dns_send_answer(iface, sdtcp);
 228                 else
 229                         dns_send_answer(iface, sdudp);
 230                 service_reply(iface, s->service);
 231         }
 232 }
 233
 234 void
 235 service_announce(struct interface *iface)
 236 {
 237         service_announce_services(iface, sdudp);
 238         service_announce_services(iface, sdtcp);
 239 }
 240
 241 static void
 242 service_update(struct vlist_tree *tree, struct vlist_node *node_new,
 243                struct vlist_node *node_old)
 244 {
 245         struct service *s;
 246
 247         if (!node_old)
 248                 return;
 249
 250         s = container_of(node_old, struct service, node);
 251         free(s);
 252 }
 253
 254 static void
 255 service_load(char *path)
 256 {
 257         struct blob_attr *txt, *cur, *_tb[__SERVICE_MAX];
 258         int rem, i;
 259         glob_t gl;
 260
 261         if (glob(path, GLOB_NOESCAPE | GLOB_MARK, NULL, &gl))
 262                 return;
 263
 264         for (i = 0; i < gl.gl_pathc; i++) {
 265                 blob_buf_init(&b, 0);
 266
 267                 if (!blobmsg_add_json_from_file(&b, gl.gl_pathv[i]))
 268                         continue;
 269                 blob_for_each_attr(cur, b.head, rem) {
 270                         struct service *s;
 271                         char *d_service, *d_daemon;
 272                         uint8_t *d_txt;
 273                         int rem2;
 274                         int txt_len = 0;
 275
 276                         blobmsg_parse(service_policy, ARRAY_SIZE(service_policy),
 277                                 _tb, blobmsg_data(cur), blobmsg_data_len(cur));
 278                         if (!_tb[SERVICE_PORT] || !_tb[SERVICE_TXT])
 279                                 continue;
 280
 281                         blobmsg_for_each_attr(txt, _tb[SERVICE_TXT], rem2)
 282                                 txt_len += 1 + strlen(blobmsg_get_string(txt));
 283
 284                         s = calloc_a(sizeof(*s),
 285                                 &d_daemon, strlen(gl.gl_pathv[i]) + 1,
 286                                 &d_service, strlen(blobmsg_name(cur)) + 1,
 287                                 &d_txt, txt_len);
 288                         if (!s)
 289                                 continue;
 290
 291                         s->port = blobmsg_get_u32(_tb[SERVICE_PORT]);
 292                         s->service = strcpy(d_service, blobmsg_name(cur));
 293                         s->daemon = strcpy(d_daemon, gl.gl_pathv[i]);
 294                         s->active = 1;
 295                         s->t = 0;
 296                         s->txt_len = txt_len;
 297                         s->txt = d_txt;
 298
 299                         blobmsg_for_each_attr(txt, _tb[SERVICE_TXT], rem2) {
 300                                 int len = strlen(blobmsg_get_string(txt));
 301                                 if (!len)
 302                                         continue;
 303                                 if (len > 0xff)
 304                                         len = 0xff;
 305                                 *d_txt = len;
 306                                 d_txt++;
 307                                 memcpy(d_txt, blobmsg_get_string(txt), len);
 308                                 d_txt += len;
 309                         }
 310
 311                         vlist_add(&services, &s->node, s->service);
 312                 }
 313         }
 314 }
 315
 316 void
 317 service_init(void)
 318 {
 319         if (!hostname)
 320                 hostname = get_hostname();
 321
 322         vlist_update(&services);
 323         service_load("/tmp/run/mdnsd/*");
 324         vlist_flush(&services);
 325 }
 326
 327 void
 328 service_cleanup(void)
 329 {
 330         vlist_flush(&services);
 331 }