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         FILLZERO(ca);
  46         ca.comm=comm;
  47         ca.ix=-1;
  48         ca.ia.sin.sin_family=AF_INET;
  49         ca.ia.sin.sin_port=htons(port);
  50         if (inet_aton(trimmed,&ca.ia.sin.sin_addr))
  51             cb(cst,&ca,1);
  52         else
  53             cb(cst,0,0);
  54         return True;
  55     }
  56
  57     q=safe_malloc(sizeof *q,"resolve_request");
  58     q->cst=cst;
  59     q->comm=comm;
  60     q->port=port;
  61     q->answer=cb;
  62
  63     rv=adns_submit(st->ast, name, adns_r_addr, 0, q, &q->query);
  64     if (rv) {
  65         Message(M_WARNING,
  66                 "resolver: failed to submit lookup for %s: %s",name,
  67                 adns_strerror(rv));
  68         free(q);
  69         return False;
  70     }
  71
  72     return True;
  73 }
  74
  75 static int resolver_beforepoll(void *sst, struct pollfd *fds, int *nfds_io,
  76                                int *timeout_io)
  77 {
  78     struct adns *st=sst;
  79     return adns_beforepoll(st->ast, fds, nfds_io, timeout_io, tv_now);
  80 }
  81
  82 static void resolver_afterpoll(void *sst, struct pollfd *fds, int nfds)
  83 {
  84     struct adns *st=sst;
  85     adns_query aq;
  86     adns_answer *ans;
  87     void *qp;
  88     struct query *q;
  89     int rv;
  90
  91     adns_afterpoll(st->ast, fds, nfds, tv_now);
  92
  93     while (True) {
  94         aq=NULL;
  95         rv=adns_check(st->ast, &aq, &ans, &qp);
  96         if (rv==0) {
  97             q=qp;
  98             if (ans->status!=adns_s_ok) {
  99                 q->answer(q->cst,NULL,0); /* Failure */
 100                 free(q);
 101                 free(ans);
 102             } else {
 103                 int rslot, wslot;
 104                 int ca_len=MIN(ans->nrrs,MAX_PEER_ADDRS);
 105                 struct comm_addr ca_buf[ca_len];
 106                 FILLZERO(ca_buf);
 107                 for (rslot=0, wslot=0;
 108                      rslot<ans->nrrs && wslot<ca_len;
 109                      rslot++) {
 110                     adns_rr_addr *ra=&ans->rrs.addr[rslot];
 111                     struct comm_addr *ca=&ca_buf[wslot];
 112                     ca->comm=q->comm;
 113                     /* copy fields individually so we leave holes zeroed: */
 114                     switch (ra->addr.sa.sa_family) {
 115                     case AF_INET:
 116                         assert(ra->len == sizeof(ca->ia.sin));
 117                         ca->ia.sin.sin_family=ra->addr.inet.sin_family;
 118                         ca->ia.sin.sin_addr=  ra->addr.inet.sin_addr;
 119                         ca->ia.sin.sin_port=  htons(q->port);
 120                         wslot++;
 121                         break;
 122                     default:
 123                         break;
 124                     }
 125                 }
 126                 q->answer(q->cst,ca_buf,wslot);
 127                 free(q);
 128                 free(ans);
 129             }
 130         } else if (rv==EAGAIN || rv==ESRCH) {
 131             break;
 132         } else {
 133             fatal("resolver_afterpoll: adns_check() returned %d",rv);
 134         }
 135     }
 136
 137     return;
 138 }
 139
 140 /* Initialise adns, using parameters supplied */
 141 static list_t *adnsresolver_apply(closure_t *self, struct cloc loc,
 142                                   dict_t *context, list_t *args)
 143 {
 144     struct adns *st;
 145     dict_t *d;
 146     item_t *i;
 147     string_t conf;
 148
 149     st=safe_malloc(sizeof(*st),"adnsresolver_apply");
 150     st->cl.description="adns";
 151     st->cl.type=CL_RESOLVER;
 152     st->cl.apply=NULL;
 153     st->cl.interface=&st->ops;
 154     st->loc=loc;
 155     st->ops.st=st;
 156     st->ops.request=resolve_request;
 157
 158     i=list_elem(args,0);
 159     if (!i || i->type!=t_dict) {
 160         cfgfatal(st->loc,"adns","first argument must be a dictionary\n");
 161     }
 162     d=i->data.dict;
 163     conf=dict_read_string(d,"config",False,"adns",loc);
 164
 165     if (conf) {
 166         if (adns_init_strcfg(&st->ast, 0, 0, conf)) {
 167             fatal_perror("Failed to initialise ADNS");
 168         }
 169     } else {
 170         if (adns_init(&st->ast, 0, 0)) {
 171             fatal_perror("Failed to initialise ADNS");
 172         }
 173     }
 174
 175     register_for_poll(st, resolver_beforepoll, resolver_afterpoll,
 176                       ADNS_POLLFDS_RECOMMENDED+5,"resolver");
 177
 178     return new_closure(&st->cl);
 179 }
 180
 181 void resolver_module(dict_t *dict)
 182 {
 183     add_closure(dict,"adns",adnsresolver_apply);
 184 }