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