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         FILLZERO(ca);
  52         ca.comm=comm;
  53         ca.ix=-1;
  54 #ifdef CONFIG_IPV6
  55         socklen_t salen=sizeof(ca.ia);
  56         rv=adns_text2addr(trimmed, port, adns_qf_addrlit_ipv4_quadonly,
  57                           &ca.ia.sa, &salen);
  58         assert(rv!=ENOSPC);
  59         if (rv) {
  60             char msg[250];
  61             snprintf(msg,sizeof(msg),"invalid address literal: %s",
  62                      strerror(rv));
  63             msg[sizeof(msg)-1]=0;
  64             cb(cst,0,0,name,msg);
  65         } else {
  66             cb(cst,&ca,1,name,0);
  67         }
  68 #else
  69         ca.ia.sin.sin_family=AF_INET;
  70         ca.ia.sin.sin_port=htons(port);
  71         if (inet_aton(trimmed,&ca.ia.sin.sin_addr))
  72             cb(cst,&ca,1,name,0);
  73         else
  74             cb(cst,0,0,name,"invalid IP address");
  75 #endif
  76         return True;
  77     }
  78
  79     q=safe_malloc(sizeof *q,"resolve_request");
  80     q->cst=cst;
  81     q->comm=comm;
  82     q->port=port;
  83     q->name=name;
  84     q->answer=cb;
  85
  86     rv=adns_submit(st->ast, name, adns_r_addr, 0, q, &q->query);
  87     if (rv) {
  88         Message(M_WARNING,
  89                 "resolver: failed to submit lookup for %s: %s",name,
  90                 adns_strerror(rv));
  91         free(q);
  92         return False;
  93     }
  94
  95     return True;
  96 }
  97
  98 static int resolver_beforepoll(void *sst, struct pollfd *fds, int *nfds_io,
  99                                int *timeout_io)
 100 {
 101     struct adns *st=sst;
 102     return adns_beforepoll(st->ast, fds, nfds_io, timeout_io, tv_now);
 103 }
 104
 105 static void resolver_afterpoll(void *sst, struct pollfd *fds, int nfds)
 106 {
 107     struct adns *st=sst;
 108     adns_query aq;
 109     adns_answer *ans;
 110     void *qp;
 111     struct query *q;
 112     int rv;
 113
 114     adns_afterpoll(st->ast, fds, nfds, tv_now);
 115
 116     while (True) {
 117         aq=NULL;
 118         rv=adns_check(st->ast, &aq, &ans, &qp);
 119         if (rv==0) {
 120             q=qp;
 121             if (ans->status!=adns_s_ok) {
 122                 q->answer(q->cst,NULL,0,q->name,adns_strerror(ans->status));
 123                 free(q);
 124                 free(ans);
 125             } else {
 126                 int rslot, wslot;
 127                 int ca_len=MIN(ans->nrrs,MAX_PEER_ADDRS);
 128                 struct comm_addr ca_buf[ca_len];
 129                 FILLZERO(ca_buf);
 130                 for (rslot=0, wslot=0;
 131                      rslot<ans->nrrs && wslot<ca_len;
 132                      rslot++) {
 133                     adns_rr_addr *ra=&ans->rrs.addr[rslot];
 134                     struct comm_addr *ca=&ca_buf[wslot];
 135                     ca->comm=q->comm;
 136                     /* copy fields individually so we leave holes zeroed: */
 137                     switch (ra->addr.sa.sa_family) {
 138                     case AF_INET:
 139                         assert(ra->len == sizeof(ca->ia.sin));
 140                         ca->ia.sin.sin_family=ra->addr.inet.sin_family;
 141                         ca->ia.sin.sin_addr=  ra->addr.inet.sin_addr;
 142                         ca->ia.sin.sin_port=  htons(q->port);
 143                         wslot++;
 144                         break;
 145 #ifdef CONFIG_IPV6
 146                     case AF_INET6:
 147                         assert(ra->len == sizeof(ca->ia.sin6));
 148                         ca->ia.sin6.sin6_family=ra->addr.inet6.sin6_family;
 149                         ca->ia.sin6.sin6_addr=  ra->addr.inet6.sin6_addr;
 150                         ca->ia.sin6.sin6_port=  htons(q->port);
 151                         wslot++;
 152                         break;
 153 #endif /*CONFIG_IPV6*/
 154                     default:
 155                         break;
 156                     }
 157                 }
 158                 q->answer(q->cst,ca_buf,wslot,q->name,0);
 159                 free(q);
 160                 free(ans);
 161             }
 162         } else if (rv==EAGAIN || rv==ESRCH) {
 163             break;
 164         } else {
 165             fatal("resolver_afterpoll: adns_check() returned %d",rv);
 166         }
 167     }
 168
 169     return;
 170 }
 171
 172 /* Initialise adns, using parameters supplied */
 173 static list_t *adnsresolver_apply(closure_t *self, struct cloc loc,
 174                                   dict_t *context, list_t *args)
 175 {
 176     struct adns *st;
 177     dict_t *d;
 178     item_t *i;
 179     string_t conf;
 180
 181     st=safe_malloc(sizeof(*st),"adnsresolver_apply");
 182     st->cl.description="adns";
 183     st->cl.type=CL_RESOLVER;
 184     st->cl.apply=NULL;
 185     st->cl.interface=&st->ops;
 186     st->loc=loc;
 187     st->ops.st=st;
 188     st->ops.request=resolve_request;
 189
 190     i=list_elem(args,0);
 191     if (!i || i->type!=t_dict) {
 192         cfgfatal(st->loc,"adns","first argument must be a dictionary\n");
 193     }
 194     d=i->data.dict;
 195     conf=dict_read_string(d,"config",False,"adns",loc);
 196
 197     if (conf) {
 198         if (adns_init_strcfg(&st->ast, 0, 0, conf)) {
 199             fatal_perror("Failed to initialise ADNS");
 200         }
 201     } else {
 202         if (adns_init(&st->ast, 0, 0)) {
 203             fatal_perror("Failed to initialise ADNS");
 204         }
 205     }
 206
 207     register_for_poll(st, resolver_beforepoll, resolver_afterpoll,
 208                       ADNS_POLLFDS_RECOMMENDED+5,"resolver");
 209
 210     return new_closure(&st->cl);
 211 }
 212
 213 void resolver_module(dict_t *dict)
 214 {
 215     add_closure(dict,"adns",adnsresolver_apply);
 216 }