resolver.c

   1 /* Name resolution using adns */
   2
   3 #include <errno.h>
   4 #include "secnet.h"
   5 #include "util.h"
   6 #ifndef HAVE_LIBADNS
   7 #error secnet requires ADNS version 1.0 or above
   8 #endif
   9 #include <adns.h>
  10 #include <arpa/inet.h>
  11 #include <string.h>
  12
  13
  14 struct adns {
  15     closure_t cl;
  16     struct resolver_if ops;
  17     struct cloc loc;
  18     adns_state ast;
  19 };
  20
  21 struct query {
  22     void *cst;
  23     int port;
  24     struct comm_if *comm;
  25     resolve_answer_fn *answer;
  26     adns_query query;
  27 };
  28
  29 static resolve_request_fn resolve_request;
  30 static bool_t resolve_request(void *sst, cstring_t name,
  31                               int port, struct comm_if *comm,
  32                               resolve_answer_fn *cb, void *cst)
  33 {
  34     struct adns *st=sst;
  35     struct query *q;
  36     int rv;
  37     const int maxlitlen=50;
  38
  39     ssize_t l=strlen(name);
  40     if (name[0]=='[' && l<maxlitlen && l>2 && name[l-1]==']') {
  41         char trimmed[maxlitlen+1];
  42         memcpy(trimmed,name+1,l-2);
  43         trimmed[l-2]=0;
  44         struct comm_addr ca;
  45         ca.comm=comm;
  46         ca.ia.sin.sin_family=AF_INET;
  47         ca.ia.sin.sin_port=htons(port);
  48         if (inet_aton(trimmed,&ca.ia.sin.sin_addr))
  49             cb(cst,&ca,1,1);
  50         else
  51             cb(cst,0,0,0);
  52         return True;
  53     }
  54
  55     q=safe_malloc(sizeof *q,"resolve_request");
  56     q->cst=cst;
  57     q->comm=comm;
  58     q->port=port;
  59     q->answer=cb;
  60
  61     rv=adns_submit(st->ast, name, adns_r_addr, 0, q, &q->query);
  62     if (rv) {
  63         Message(M_WARNING,
  64                 "resolver: failed to submit lookup for %s: %s",name,
  65                 adns_strerror(rv));
  66         free(q);
  67         return False;
  68     }
  69
  70     return True;
  71 }
  72
  73 static int resolver_beforepoll(void *sst, struct pollfd *fds, int *nfds_io,
  74                                int *timeout_io)
  75 {
  76     struct adns *st=sst;
  77     return adns_beforepoll(st->ast, fds, nfds_io, timeout_io, tv_now);
  78 }
  79
  80 static void resolver_afterpoll(void *sst, struct pollfd *fds, int nfds)
  81 {
  82     struct adns *st=sst;
  83     adns_query aq;
  84     adns_answer *ans;
  85     void *qp;
  86     struct query *q;
  87     int rv;
  88
  89     adns_afterpoll(st->ast, fds, nfds, tv_now);
  90
  91     while (True) {
  92         aq=NULL;
  93         rv=adns_check(st->ast, &aq, &ans, &qp);
  94         if (rv==0) {
  95             q=qp;
  96             if (ans->status!=adns_s_ok) {
  97                 q->answer(q->cst,NULL,0,0); /* Failure */
  98                 free(q);
  99                 free(ans);
 100             } else {
 101                 int rslot, wslot, total;
 102                 int ca_len=MIN(ans->nrrs,MAX_PEER_ADDRS);
 103                 struct comm_addr ca_buf[ca_len];
 104                 for (rslot=0, wslot=0, total=0;
 105                      rslot<ans->nrrs;
 106                      rslot++) {
 107                     total++;
 108                     if (!(wslot<ca_len)) continue;
 109                     adns_rr_addr *ra=&ans->rrs.addr[rslot];
 110                     struct comm_addr *ca=&ca_buf[wslot];
 111                     ca->comm=q->comm;
 112                     switch (ra->addr.sa.sa_family) {
 113                     case AF_INET:
 114                         assert(ra->len == sizeof(ca->ia.sin));
 115                         break;
 116                     default:
 117                         /* silently skip unexpected AFs from adns */
 118                         continue;
 119                     }
 120                     memcpy(&ca->ia,&ra->addr,ra->len);
 121                     wslot++;
 122                 }
 123                 q->answer(q->cst,ca_buf,wslot,total);
 124                 free(q);
 125                 free(ans);
 126             }
 127         } else if (rv==EAGAIN || rv==ESRCH) {
 128             break;
 129         } else {
 130             fatal("resolver_afterpoll: adns_check() returned %d",rv);
 131         }
 132     }
 133
 134     return;
 135 }
 136
 137 /* Initialise adns, using parameters supplied */
 138 static list_t *adnsresolver_apply(closure_t *self, struct cloc loc,
 139                                   dict_t *context, list_t *args)
 140 {
 141     struct adns *st;
 142     dict_t *d;
 143     item_t *i;
 144     string_t conf;
 145
 146     st=safe_malloc(sizeof(*st),"adnsresolver_apply");
 147     st->cl.description="adns";
 148     st->cl.type=CL_RESOLVER;
 149     st->cl.apply=NULL;
 150     st->cl.interface=&st->ops;
 151     st->loc=loc;
 152     st->ops.st=st;
 153     st->ops.request=resolve_request;
 154
 155     i=list_elem(args,0);
 156     if (!i || i->type!=t_dict) {
 157         cfgfatal(st->loc,"adns","first argument must be a dictionary\n");
 158     }
 159     d=i->data.dict;
 160     conf=dict_read_string(d,"config",False,"adns",loc);
 161
 162     if (conf) {
 163         if (adns_init_strcfg(&st->ast, 0, 0, conf)) {
 164             fatal_perror("Failed to initialise ADNS");
 165         }
 166     } else {
 167         if (adns_init(&st->ast, 0, 0)) {
 168             fatal_perror("Failed to initialise ADNS");
 169         }
 170     }
 171
 172     register_for_poll(st, resolver_beforepoll, resolver_afterpoll,
 173                       ADNS_POLLFDS_RECOMMENDED+5,"resolver");
 174
 175     return new_closure(&st->cl);
 176 }
 177
 178 void resolver_module(dict_t *dict)
 179 {
 180     add_closure(dict,"adns",adnsresolver_apply);
 181 }