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     const char *name;
  24     int port;
  25     struct comm_if *comm;
  26     resolve_answer_fn *answer;
  27     adns_query query;
  28 };
  29
  30 static resolve_request_fn resolve_request;
  31 static bool_t resolve_request(void *sst, cstring_t name,
  32                               int port, struct comm_if *comm,
  33                               resolve_answer_fn *cb, void *cst)
  34 {
  35     struct adns *st=sst;
  36     struct query *q;
  37     int rv;
  38     const int maxlitlen=
  39 #ifdef CONFIG_IPV6
  40         ADNS_ADDR2TEXT_BUFLEN*2
  41 #else
  42         50
  43 #endif
  44         ;
  45     ssize_t l=strlen(name);
  46     if (name[0]=='[' && l<maxlitlen && l>2 && name[l-1]==']') {
  47         char trimmed[maxlitlen+1];
  48         memcpy(trimmed,name+1,l-2);
  49         trimmed[l-2]=0;
  50         struct comm_addr ca;
  51         ca.comm=comm;
  52         ca.ix=-1;
  53 #ifdef CONFIG_IPV6
  54         socklen_t salen=sizeof(ca.ia);
  55         rv=adns_text2addr(trimmed, port, adns_qf_addrlit_ipv4_quadonly,
  56                           &ca.ia.sa, &salen);
  57         assert(rv!=ENOSPC);
  58         if (rv) {
  59             char msg[250];
  60             snprintf(msg,sizeof(msg),"invalid address literal: %s",
  61                      strerror(rv));
  62             msg[sizeof(msg)-1]=0;
  63             cb(cst,0,0,0,name,msg);
  64         } else {
  65             cb(cst,&ca,1,1,name,0);
  66         }
  67 #else
  68         ca.ia.sin.sin_family=AF_INET;
  69         ca.ia.sin.sin_port=htons(port);
  70         if (inet_aton(trimmed,&ca.ia.sin.sin_addr))
  71             cb(cst,&ca,1,1,name,0);
  72         else
  73             cb(cst,0,0,0,name,"invalid IP address");
  74 #endif
  75         return True;
  76     }
  77
  78     NEW(q);
  79     q->cst=cst;
  80     q->comm=comm;
  81     q->port=port;
  82     q->name=name;
  83     q->answer=cb;
  84
  85     rv=adns_submit(st->ast, name, adns_r_addr, 0, q, &q->query);
  86     if (rv) {
  87         Message(M_WARNING,
  88                 "resolver: failed to submit lookup for %s: %s",name,
  89                 adns_strerror(rv));
  90         free(q);
  91         return False;
  92     }
  93
  94     return True;
  95 }
  96
  97 static int resolver_beforepoll(void *sst, struct pollfd *fds, int *nfds_io,
  98                                int *timeout_io)
  99 {
 100     struct adns *st=sst;
 101     return adns_beforepoll(st->ast, fds, nfds_io, timeout_io, tv_now);
 102 }
 103
 104 static void resolver_afterpoll(void *sst, struct pollfd *fds, int nfds)
 105 {
 106     struct adns *st=sst;
 107     adns_query aq;
 108     adns_answer *ans;
 109     void *qp;
 110     struct query *q;
 111     int rv;
 112
 113     adns_afterpoll(st->ast, fds, nfds, tv_now);
 114
 115     while (True) {
 116         aq=NULL;
 117         rv=adns_check(st->ast, &aq, &ans, &qp);
 118         if (rv==0) {
 119             q=qp;
 120             if (ans->status!=adns_s_ok) {
 121                 q->answer(q->cst,NULL,0,0,q->name,adns_strerror(ans->status));
 122                 free(q);
 123                 free(ans);
 124             } else {
 125                 int rslot, wslot, total;
 126                 int ca_len=MIN(ans->nrrs,MAX_PEER_ADDRS);
 127                 struct comm_addr ca_buf[ca_len];
 128                 for (rslot=0, wslot=0, total=0;
 129                      rslot<ans->nrrs;
 130                      rslot++) {
 131                     total++;
 132                     if (!(wslot<ca_len)) continue;
 133                     adns_rr_addr *ra=&ans->rrs.addr[rslot];
 134                     struct comm_addr *ca=&ca_buf[wslot];
 135                     ca->comm=q->comm;
 136                     ca->ix=-1;
 137                     assert(ra->len <= (int)sizeof(ca->ia));
 138                     memcpy(&ca->ia,&ra->addr,ra->len);
 139                     switch (ra->addr.sa.sa_family) {
 140                     case AF_INET:
 141                         assert(ra->len == sizeof(ca->ia.sin));
 142                         ca->ia.sin.sin_port=htons(q->port);
 143                         break;
 144 #ifdef CONFIG_IPV6
 145                     case AF_INET6:
 146                         assert(ra->len == sizeof(ca->ia.sin6));
 147                         ca->ia.sin6.sin6_port=htons(q->port);
 148                         break;
 149 #endif /*CONFIG_IPV6*/
 150                     default:
 151                         /* silently skip unexpected AFs from adns */
 152                         continue;
 153                     }
 154                     wslot++;
 155                 }
 156                 q->answer(q->cst,ca_buf,wslot,total,q->name,0);
 157                 free(q);
 158                 free(ans);
 159             }
 160         } else if (rv==EAGAIN || rv==ESRCH) {
 161             break;
 162         } else {
 163             fatal("resolver_afterpoll: adns_check() returned %d",rv);
 164         }
 165     }
 166
 167     return;
 168 }
 169
 170 /* Initialise adns, using parameters supplied */
 171 static list_t *adnsresolver_apply(closure_t *self, struct cloc loc,
 172                                   dict_t *context, list_t *args)
 173 {
 174     struct adns *st;
 175     dict_t *d;
 176     item_t *i;
 177     string_t conf;
 178
 179     NEW(st);
 180     st->cl.description="adns";
 181     st->cl.type=CL_RESOLVER;
 182     st->cl.apply=NULL;
 183     st->cl.interface=&st->ops;
 184     st->loc=loc;
 185     st->ops.st=st;
 186     st->ops.request=resolve_request;
 187
 188     i=list_elem(args,0);
 189     if (!i || i->type!=t_dict) {
 190         cfgfatal(st->loc,"adns","first argument must be a dictionary\n");
 191     }
 192     d=i->data.dict;
 193     conf=dict_read_string(d,"config",False,"adns",loc);
 194
 195     if (conf) {
 196         if (adns_init_strcfg(&st->ast, 0, 0, conf)) {
 197             fatal_perror("Failed to initialise ADNS");
 198         }
 199     } else {
 200         if (adns_init(&st->ast, 0, 0)) {
 201             fatal_perror("Failed to initialise ADNS");
 202         }
 203     }
 204
 205     register_for_poll(st, resolver_beforepoll, resolver_afterpoll,
 206                       "resolver");
 207
 208     return new_closure(&st->cl);
 209 }
 210
 211 void resolver_module(dict_t *dict)
 212 {
 213     add_closure(dict,"adns",adnsresolver_apply);
 214 }