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