chiark - git - mdw - secnet/blob - 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     if (rv) {
  54         Message(M_WARNING,
  55                 "resolver: failed to submit lookup for %s: %s",name,
  56                 adns_strerror(rv));
  57         free(q);
  58         return False;
  59     }
  60
  61     return True;
  62 }
  63
  64 static int resolver_beforepoll(void *sst, struct pollfd *fds, int *nfds_io,
  65                                int *timeout_io)
  66 {
  67     struct adns *st=sst;
  68     return adns_beforepoll(st->ast, fds, nfds_io, timeout_io, tv_now);
  69 }
  70
  71 static void resolver_afterpoll(void *sst, struct pollfd *fds, int nfds)
  72 {
  73     struct adns *st=sst;
  74     adns_query aq;
  75     adns_answer *ans;
  76     void *qp;
  77     struct query *q;
  78     int rv;
  79
  80     adns_afterpoll(st->ast, fds, nfds, tv_now);
  81
  82     while (True) {
  83         aq=NULL;
  84         rv=adns_check(st->ast, &aq, &ans, &qp);
  85         if (rv==0) {
  86             q=qp;
  87             if (ans->status!=adns_s_ok) {
  88                 q->answer(q->cst,NULL); /* Failure */
  89                 free(q);
  90                 free(ans);
  91             } else {
  92                 q->answer(q->cst,ans->rrs.inaddr);
  93                 free(q);
  94                 free(ans);
  95             }
  96         } else if (rv==EAGAIN || rv==ESRCH) {
  97             break;
  98         } else {
  99             fatal("resolver_afterpoll: adns_check() returned %d",rv);
 100         }
 101     }
 102
 103     return;
 104 }
 105
 106 /* Initialise adns, using parameters supplied */
 107 static list_t *adnsresolver_apply(closure_t *self, struct cloc loc,
 108                                   dict_t *context, list_t *args)
 109 {
 110     struct adns *st;
 111     dict_t *d;
 112     item_t *i;
 113     string_t conf;
 114
 115     st=safe_malloc(sizeof(*st),"adnsresolver_apply");
 116     st->cl.description="adns";
 117     st->cl.type=CL_RESOLVER;
 118     st->cl.apply=NULL;
 119     st->cl.interface=&st->ops;
 120     st->loc=loc;
 121     st->ops.st=st;
 122     st->ops.request=resolve_request;
 123
 124     i=list_elem(args,0);
 125     if (!i || i->type!=t_dict) {
 126         cfgfatal(st->loc,"adns","first argument must be a dictionary\n");
 127     }
 128     d=i->data.dict;
 129     conf=dict_read_string(d,"config",False,"adns",loc);
 130
 131     if (conf) {
 132         if (adns_init_strcfg(&st->ast, 0, 0, conf)) {
 133             fatal_perror("Failed to initialise ADNS");
 134         }
 135     } else {
 136         if (adns_init(&st->ast, 0, 0)) {
 137             fatal_perror("Failed to initialise ADNS");
 138         }
 139     }
 140
 141     register_for_poll(st, resolver_beforepoll, resolver_afterpoll,
 142                       ADNS_POLLFDS_RECOMMENDED+5,"resolver");
 143
 144     return new_closure(&st->cl);
 145 }
 146
 147 void resolver_module(dict_t *dict)
 148 {
 149     add_closure(dict,"adns",adnsresolver_apply);
 150 }