release/src/router/dnscrypt/src/plugins/example-ldns-forward-after-nxdomain/example-ldns-forward-after-nxdomain.c

   1
   2 #include <dnscrypt/plugin.h>
   3 #include <ldns/ldns.h>
   4
   5 DCPLUGIN_MAIN(__FILE__);
   6
   7 typedef struct Forwarder_ {
   8     ldns_resolver *resolver;
   9 } Forwarder;
  10
  11 const char *
  12 dcplugin_description(DCPlugin * const dcplugin)
  13 {
  14     return "Resolve a name without dnscrypt after an NXDOMAIN response";
  15 }
  16
  17 const char *
  18 dcplugin_long_description(DCPlugin * const dcplugin)
  19 {
  20     return
  21         "Example usage:\n"
  22         "\n"
  23         "# dnscrypt-proxy --plugin \\\n"
  24         "  libdcplugin_example_ldns_forward_after_nxdomain.la,/etc/resolv.conf";
  25 }
  26
  27 int
  28 dcplugin_init(DCPlugin * const dcplugin, int argc, char *argv[])
  29 {
  30     Forwarder  *forwarder;
  31     const char *resolver_conf = NULL;
  32
  33     forwarder = calloc(1U, sizeof *forwarder);
  34     dcplugin_set_user_data(dcplugin, forwarder);
  35     if (forwarder == NULL) {
  36         return -1;
  37     }
  38     if (argc > 1) {
  39         resolver_conf = argv[1];
  40     }
  41     if (ldns_resolver_new_frm_file(&forwarder->resolver, resolver_conf)
  42         != LDNS_STATUS_OK) {
  43         return -1;
  44     }
  45     ldns_resolver_set_retry(forwarder->resolver, 1);
  46     ldns_resolver_set_timeout(forwarder->resolver, (struct timeval) {
  47         .tv_sec = 2, .tv_usec = 0
  48     });
  49     return 0;
  50 }
  51
  52 int
  53 dcplugin_destroy(DCPlugin *dcplugin)
  54 {
  55     Forwarder *forwarder = dcplugin_get_user_data(dcplugin);
  56
  57     if (forwarder == NULL) {
  58         return 0;
  59     }
  60     ldns_resolver_deep_free(forwarder->resolver);
  61     free(forwarder);
  62
  63     return 0;
  64 }
  65
  66 DCPluginSyncFilterResult
  67 dcplugin_sync_post_filter(DCPlugin *dcplugin, DCPluginDNSPacket *dcp_packet)
  68 {
  69     Forwarder *forwarder = dcplugin_get_user_data(dcplugin);
  70     ldns_pkt  *query = NULL;
  71     ldns_pkt  *response = NULL;
  72     uint8_t   *query_wire = dcplugin_get_wire_data(dcp_packet);
  73     uint8_t   *response_wire = NULL;
  74     size_t     response_wire_len;
  75
  76     if (LDNS_RCODE_WIRE(query_wire) != LDNS_RCODE_NXDOMAIN) {
  77         return DCP_SYNC_FILTER_RESULT_OK;
  78     }
  79     LDNS_AA_CLR(query_wire);
  80     LDNS_QR_CLR(query_wire);
  81     LDNS_TC_CLR(query_wire);
  82     ldns_wire2pkt(&query, query_wire, dcplugin_get_wire_data_len(dcp_packet));
  83     ldns_pkt_set_edns_data(query, ldns_rdf_new_frm_str(LDNS_RDF_TYPE_HEX, ""));
  84     ldns_send(&response, forwarder->resolver, query);
  85     ldns_pkt_free(query);
  86     ldns_pkt2wire(&response_wire, response, &response_wire_len);
  87     ldns_pkt_free(response);
  88     if (response_wire_len > dcplugin_get_wire_data_max_len(dcp_packet)) {
  89         free(response_wire);
  90         return DCP_SYNC_FILTER_RESULT_ERROR;
  91     }
  92     dcplugin_set_wire_data(dcp_packet, response_wire, response_wire_len);
  93     free(response_wire);
  94
  95     return DCP_SYNC_FILTER_RESULT_OK;
  96 }