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 resolve_request_fn resolve_request;
  25 static bool_t resolve_request(void *sst, cstring_t name,
  26                               resolve_answer_fn *cb, void *cst)
  27 {
  28     struct adns *st=sst;
  29     struct query *q;
  30     int rv;
  31
  32     q=safe_malloc(sizeof *q,"resolve_request");
  33     q->cst=cst;
  34     q->answer=cb;
  35
  36     rv=adns_submit(st->ast, name, adns_r_a, 0, q, &q->query);
  37
  38     return rv==0;
  39 }
  40
  41 static int resolver_beforepoll(void *sst, struct pollfd *fds, int *nfds_io,
  42                                int *timeout_io)
  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 {
  50     struct adns *st=sst;
  51     adns_query aq;
  52     adns_answer *ans;
  53     void *qp;
  54     struct query *q;
  55     int rv;
  56
  57     adns_afterpoll(st->ast, fds, nfds, tv_now);
  58
  59     while (True) {
  60         aq=NULL;
  61         rv=adns_check(st->ast, &aq, &ans, &qp);
  62         if (rv==0) {
  63             q=qp;
  64             if (ans->status!=adns_s_ok) {
  65                 q->answer(q->cst,NULL); /* Failure */
  66                 free(q);
  67                 free(ans);
  68             } else {
  69                 q->answer(q->cst,ans->rrs.inaddr);
  70                 free(q);
  71                 free(ans);
  72             }
  73         } else if (rv==EAGAIN || rv==ESRCH) {
  74             break;
  75         } else {
  76             fatal("resolver_afterpoll: adns_check() returned %d",rv);
  77         }
  78     }
  79
  80     return;
  81 }
  82
  83 /* Initialise adns, using parameters supplied */
  84 static list_t *adnsresolver_apply(closure_t *self, struct cloc loc,
  85                                   dict_t *context, list_t *args)
  86 {
  87     struct adns *st;
  88     dict_t *d;
  89     item_t *i;
  90     string_t conf;
  91
  92     st=safe_malloc(sizeof(*st),"adnsresolver_apply");
  93     st->cl.description="adns";
  94     st->cl.type=CL_RESOLVER;
  95     st->cl.apply=NULL;
  96     st->cl.interface=&st->ops;
  97     st->loc=loc;
  98     st->ops.st=st;
  99     st->ops.request=resolve_request;
 100
 101     i=list_elem(args,0);
 102     if (!i || i->type!=t_dict) {
 103         cfgfatal(st->loc,"adns","first argument must be a dictionary\n");
 104     }
 105     d=i->data.dict;
 106     conf=dict_read_string(d,"config",False,"adns",loc);
 107
 108     if (conf) {
 109         if (adns_init_strcfg(&st->ast, 0, 0, conf)) {
 110             fatal_perror("Failed to initialise ADNS");
 111         }
 112     } else {
 113         if (adns_init(&st->ast, 0, 0)) {
 114             fatal_perror("Failed to initialise ADNS");
 115         }
 116     }
 117
 118     register_for_poll(st, resolver_beforepoll, resolver_afterpoll,
 119                       ADNS_POLLFDS_RECOMMENDED+5,"resolver");
 120
 121     return new_closure(&st->cl);
 122 }
 123
 124 void resolver_module(dict_t *dict)
 125 {
 126     add_closure(dict,"adns",adnsresolver_apply);
 127 }