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 #include <arpa/inet.h>
  10 #include <string.h>
  11
  12
  13 struct adns {
  14     closure_t cl;
  15     struct resolver_if ops;
  16     struct cloc loc;
  17     adns_state ast;
  18 };
  19
  20 struct query {
  21     void *cst;
  22     resolve_answer_fn *answer;
  23     adns_query query;
  24 };
  25
  26 static resolve_request_fn resolve_request;
  27 static bool_t resolve_request(void *sst, cstring_t name,
  28                               resolve_answer_fn *cb, void *cst)
  29 {
  30     struct adns *st=sst;
  31     struct query *q;
  32     int rv;
  33     const int maxlitlen=50;
  34
  35     ssize_t l=strlen(name);
  36     if (name[0]=='[' && l<maxlitlen && l>2 && name[l-1]==']') {
  37         char trimmed[maxlitlen+1];
  38         memcpy(trimmed,name+1,l-2);
  39         trimmed[l-2]=0;
  40         struct in_addr ia;
  41         if (inet_aton(trimmed,&ia))
  42             cb(cst,&ia);
  43         else
  44             cb(cst,0);
  45         return True;
  46     }
  47
  48     q=safe_malloc(sizeof *q,"resolve_request");
  49     q->cst=cst;
  50     q->answer=cb;
  51
  52     rv=adns_submit(st->ast, name, adns_r_a, 0, q, &q->query);
  53
  54     return rv==0;
  55 }
  56
  57 static int resolver_beforepoll(void *sst, struct pollfd *fds, int *nfds_io,
  58                                int *timeout_io)
  59 {
  60     struct adns *st=sst;
  61     return adns_beforepoll(st->ast, fds, nfds_io, timeout_io, tv_now);
  62 }
  63
  64 static void resolver_afterpoll(void *sst, struct pollfd *fds, int nfds)
  65 {
  66     struct adns *st=sst;
  67     adns_query aq;
  68     adns_answer *ans;
  69     void *qp;
  70     struct query *q;
  71     int rv;
  72
  73     adns_afterpoll(st->ast, fds, nfds, tv_now);
  74
  75     while (True) {
  76         aq=NULL;
  77         rv=adns_check(st->ast, &aq, &ans, &qp);
  78         if (rv==0) {
  79             q=qp;
  80             if (ans->status!=adns_s_ok) {
  81                 q->answer(q->cst,NULL); /* Failure */
  82                 free(q);
  83                 free(ans);
  84             } else {
  85                 q->answer(q->cst,ans->rrs.inaddr);
  86                 free(q);
  87                 free(ans);
  88             }
  89         } else if (rv==EAGAIN || rv==ESRCH) {
  90             break;
  91         } else {
  92             fatal("resolver_afterpoll: adns_check() returned %d",rv);
  93         }
  94     }
  95
  96     return;
  97 }
  98
  99 /* Initialise adns, using parameters supplied */
 100 static list_t *adnsresolver_apply(closure_t *self, struct cloc loc,
 101                                   dict_t *context, list_t *args)
 102 {
 103     struct adns *st;
 104     dict_t *d;
 105     item_t *i;
 106     string_t conf;
 107
 108     st=safe_malloc(sizeof(*st),"adnsresolver_apply");
 109     st->cl.description="adns";
 110     st->cl.type=CL_RESOLVER;
 111     st->cl.apply=NULL;
 112     st->cl.interface=&st->ops;
 113     st->loc=loc;
 114     st->ops.st=st;
 115     st->ops.request=resolve_request;
 116
 117     i=list_elem(args,0);
 118     if (!i || i->type!=t_dict) {
 119         cfgfatal(st->loc,"adns","first argument must be a dictionary\n");
 120     }
 121     d=i->data.dict;
 122     conf=dict_read_string(d,"config",False,"adns",loc);
 123
 124     if (conf) {
 125         if (adns_init_strcfg(&st->ast, 0, 0, conf)) {
 126             fatal_perror("Failed to initialise ADNS");
 127         }
 128     } else {
 129         if (adns_init(&st->ast, 0, 0)) {
 130             fatal_perror("Failed to initialise ADNS");
 131         }
 132     }
 133
 134     register_for_poll(st, resolver_beforepoll, resolver_afterpoll,
 135                       ADNS_POLLFDS_RECOMMENDED+5,"resolver");
 136
 137     return new_closure(&st->cl);
 138 }
 139
 140 void resolver_module(dict_t *dict)
 141 {
 142     add_closure(dict,"adns",adnsresolver_apply);
 143 }