resolver.c

   1 /* Name resolution using adns */
   2
   3 #include <errno.h>
   4 #include "secnet.h"
   5 #ifndef HAVE_LIBADNS
   6 #error secnet requires ADNS version 1.0 or above
   7 #endif
   8 #include <adns.h>
   9
  10
  11 struct adns {
  12     closure_t cl;
  13     struct resolver_if ops;
  14     struct cloc loc;
  15     adns_state ast;
  16 };
  17
  18 struct query {
  19     void *cst;
  20     resolve_answer_fn *answer;
  21     adns_query query;
  22 };
  23
  24 static bool_t resolve_request(void *sst, string_t name,
  25                               resolve_answer_fn *cb, void *cst)
  26 {
  27     struct adns *st=sst;
  28     struct query *q;
  29     int rv;
  30
  31     q=safe_malloc(sizeof *q,"resolve_request");
  32     q->cst=cst;
  33     q->answer=cb;
  34
  35     rv=adns_submit(st->ast, name, adns_r_a, 0, q, &q->query);
  36
  37     return rv==0;
  38 }
  39
  40 static int resolver_beforepoll(void *sst, struct pollfd *fds, int *nfds_io,
  41                                int *timeout_io, const struct timeval *tv_now,
  42                                uint64_t *now)
  43 {
  44     struct adns *st=sst;
  45     return adns_beforepoll(st->ast, fds, nfds_io, timeout_io, tv_now);
  46 }
  47
  48 static void resolver_afterpoll(void *sst, struct pollfd *fds, int nfds,
  49                                const struct timeval *tv_now, uint64_t *now)
  50 {
  51     struct adns *st=sst;
  52     adns_query aq;
  53     adns_answer *ans;
  54     void *qp;
  55     struct query *q;
  56     int rv;
  57
  58     adns_afterpoll(st->ast, fds, nfds, tv_now);
  59
  60     while (True) {
  61         aq=NULL;
  62         rv=adns_check(st->ast, &aq, &ans, &qp);
  63         if (rv==0) {
  64             q=qp;
  65             if (ans->status!=adns_s_ok) {
  66                 q->answer(q->cst,NULL); /* Failure */
  67                 free(q);
  68                 free(ans);
  69             } else {
  70                 q->answer(q->cst,ans->rrs.inaddr);
  71                 free(q);
  72                 free(ans);
  73             }
  74         } else if (rv==EAGAIN || rv==ESRCH) {
  75             break;
  76         } else {
  77             fatal("resolver_afterpoll: adns_check() returned %d\n",rv);
  78         }
  79     }
  80
  81     return;
  82 }
  83
  84 /* Initialise adns, using parameters supplied */
  85 static list_t *adnsresolver_apply(closure_t *self, struct cloc loc,
  86                                   dict_t *context, list_t *args)
  87 {
  88     struct adns *st;
  89     dict_t *d;
  90     item_t *i;
  91     string_t conf;
  92
  93     st=safe_malloc(sizeof(*st),"adnsresolver_apply");
  94     st->cl.description="adns";
  95     st->cl.type=CL_RESOLVER;
  96     st->cl.apply=NULL;
  97     st->cl.interface=&st->ops;
  98     st->loc=loc;
  99     st->ops.st=st;
 100     st->ops.request=resolve_request;
 101
 102     i=list_elem(args,0);
 103     if (!i || i->type!=t_dict) {
 104         cfgfatal(st->loc,"adns","first argument must be a dictionary\n");
 105     }
 106     d=i->data.dict;
 107     conf=dict_read_string(d,"config",False,"adns",loc);
 108
 109     if (conf) {
 110         if (adns_init_strcfg(&st->ast, 0, 0, conf)) {
 111             fatal_perror("Failed to initialise ADNS");
 112         }
 113     } else {
 114         if (adns_init(&st->ast, 0, 0)) {
 115             fatal_perror("Failed to initialise ADNS");
 116         }
 117     }
 118
 119     register_for_poll(st, resolver_beforepoll, resolver_afterpoll,
 120                       ADNS_POLLFDS_RECOMMENDED+5,"resolver");
 121
 122     return new_closure(&st->cl);
 123 }
 124
 125 init_module resolver_module;
 126 void resolver_module(dict_t *dict)
 127 {
 128     add_closure(dict,"adns",adnsresolver_apply);
 129 }