#include "internal.h"
-void adns__procdgram(adns_state ads, const byte *dgram, int len, int serv) {
- /* FIXME do something with incoming datagrams */
+typedef enum {
+ rcode_noerror,
+ rcode_formaterror,
+ rcode_servfail,
+ rcode_nxdomain,
+ rcode_notimp,
+ rcode_refused
+} dns_rcode;
+
+#define GETIL_B(cb) (dgram[*(cb)++])
+#define GET_B(cb,tv) ((tv)= GETIL_B((cb)))
+#define GET_W(cb,tv) ((tv)=0, (tv)|=(GETIL_B((cb))<<8), (tv)|=GETIL_B(cb), (tv))
+
+static void vbuf__append_quoted1035(vbuf *vb, const byte *buf, int len) {
+ char qbuf[10];
+ int i;
+
+ while (len) {
+ qbuf[0]= 0;
+ for (i=0; i<len; i++) {
+ ch= buf[i];
+ if (ch == '.' || ch == '"' || ch == '(' || ch == ')' ||
+ ch == '@' || ch == ';' || ch == '$') {
+ sprintf(qbuf,"\\%c",ch);
+ break;
+ } else if (ch <= ' ' || ch >= 127) {
+ sprintf(qbuf,"\\%03o",ch);
+ break;
+ }
+ }
+ if (!adns__vbuf_append(vb,buf,i) || !adns__vbuf_append(vb,qbuf,strlen(qbuf)))
+ return adns_s_nolocalmem;
+ buf+= i; len-= i;
+ }
+}
+
+static adns_status get_domain_perm(adns_state ads, adns_query qu, int serv,
+ const byte *dgram, int dglen,
+ int *cbyte_io, int max, char **domain_r) {
+ /* Returns 0 for OK (*domain_r set) or truncated (*domain_r null)
+ * or any other adns_s_* value.
+ */
+ int cbyte, sused, lablen;
+
+ /* If we follow a pointer we set cbyte_io to 0 to indicate that
+ * we've lost our original starting and ending points; we don't
+ * put the end of the pointed-to thing into the original *cbyte_io.
+ */
+ cbyte= *cbyte_io;
+ sused= qu->ans.used;
+ *domain_r= 0;
+ for (;;) {
+ if (cbyte>=max) goto x_truncated;
+ lablen= GET_B(cbyte);
+ if (!lablen) break;
+ if (lablen&0x0c000) {
+ if ((lablen&0x0c000) != 0x0c0000) return adns_s_unknownreply;
+ if (cbyte_io) { *cbyte_io= cbyte; cbyte_io= 0; }
+ cbyte= (lablen&0x3fff) + DNS_HDR_SIZE;
+ max= dglen;
+ continue;
+ }
+ if (cbyte+lablen>=max) bgoto x_truncated;
+ if (qu->ans.used != sused)
+ if (!adns__vbuf_append(&qu->ans,".",1)) return adns_s_nolocalmem;
+ if (qu->flags & adns_qf_anyquote) {
+ if (!vbuf__append_quoted1035(&qu->ans,dgram+cbyte,lablen))
+ return adns_s_nolocalmem;
+ } else {
+ if (!ctype_isalpha(dgram[cbyte])) return adns_s_invaliddomain;
+ for (i= cbyte+1; i<cbyte+lablen; i++) {
+ ch= dgram[cbyte];
+ if (ch != '-' && !ctype_isalpha(ch) && !ctype_isdigit(ch))
+ return adns_s_invaliddomain;
+ }
+ if (!adns__vbuf_append(&qu->ans,dgram+cbyte,lablen))
+ return adns_s_nolocalmem;
+ }
+ }
+ if (cbyte_io) *cbyte_io= cbyte;
+ if (!adns__vbuf_append(&qu->ans,"",1)) return adns_s_nolocalmem;
+ *domain_r= qu->ans.buf+sused;
+ return adns_s_ok;
+
+ x_truncated:
+ return cbyte_io ? -1 : adns_s_serverfaulty;
+}
+
+static adns_status get_domain_temp(adns_state ads, adns_query qu, int serv,
+ const byte *dgram, int dglen,
+ int *cbyte_io, int max, char **domain_r) {
+ int sused;
+ adns_status st;
+
+ sused= qu->ans.used;
+ st= get_domain_perm(ads,qu,serv,dgram,dglen,cbyte_io,max,domain_r);
+ qu->ans.used= sused;
+ return st;
+}
+
+/* fixme: sensible comparison of owners */
+
+static adns_status get_rr_temp(adns_state ads, adns_query qu, int serv,
+ const byte *dgram, int dglen,
+ int *cbyte_io,
+ int *type_r, int *class_r, int *rdlen_r, int *rdstart_r,
+ char **owner_r) {
+ int cbyte, tmp, rdlen;
+
+ cbyte= *cbyte_io;
+ st= get_domain_temp(ads,qu,serv,dgram,dglen,&cbyte,dglen,owner_r);
+ if (st) return st;
+
+ if (cbyte+10>len) goto x_truncated;
+ GET_W(cbyte,tmp); if (type_r) *type_r= tmp;
+ GET_W(cbyte,tmp); if (class_r) *class_r= tmp;
+ cbyte+= 4; /* we skip the TTL */
+ GET_W(cbyte,rdlen); if (rdlen_r) *rdlen_r= tmp;
+ if (rdstart_r) *rdstart_r= cbyte;
+ cbyte+= rdlen;
+ if (cbyte>dglen) goto x_truncated;
+ *cbyte_io= cbyte;
+ return adns_s_ok;
+
+ x_truncated:
+ *owner_r= 0; return 0;;
+}
+
+void adns__procdgram(adns_state ads, const byte *dgram, int dglen, int serv) {
+ int cbyte, anstart, rrstart, lablen, wantedrrs, get_t;
+
+ cbyte= 0;
+
+ if (dglen<DNS_HDR_SIZE) {
+ adns__diag(ads,serv,"received datagram too short for message header (%d)",len);
+ return;
+ }
+ GET_W(cbyte,id);
+ GET_B(cbyte,f1);
+ GET_B(cbyte,f2);
+ GET_W(cbyte,qdcount);
+ GET_W(cbyte,ancount);
+ GET_W(cbyte,nscount);
+ GET_W(cbyte,arcount);
+ assert(cbyte == DNS_HDR_SIZE);
+
+ if (f1&0x80) {
+ adns__diag(ads,serv,"server sent us a query, not a response");
+ return;
+ }
+ if (f1&0x70) {
+ adns__diag(ads,serv,"server sent us unknown opcode %d (wanted 0=QUERY)",
+ (f1>>4)&0x70);
+ return;
+ }
+ if (!qdcount) {
+ adns__diag(ads,serv,"server sent reply without quoting our question");
+ return;
+ } else if (qdcount>1) {
+ adns__diag(ads,serv,"server claimed to answer %d questions with one message",
+ qdcount);
+ return;
+ }
+ for (qu= ads->timew; qu= nqu; qu++) {
+ nqu= qu->next;
+ if (qu->id != id) continue;
+ if (len < qu->querylen) continue;
+ if (memcmp(qu->querymsg+DNSHDRSIZE,dgram+DNSHDRSIZE,qu->querylen-DNSHDRSIZE))
+ continue;
+ break;
+ }
+ anstart= qu->querylen;
+ if (!qu) {
+ adns__debug(ads,serv,"reply not found (id=%02x)",id);
+ return;
+ }
+ if (!(f1&0x01)) {
+ adns__diag(ads,serv,"server thinks we didn't ask for recursive lookup");
+ adns__query_fail(ads,qu,adns_s_serverfaulty);
+ return;
+ }
+
+ rcode= (f1&0x0f);
+ switch (rcode) {
+ case rcode_noerror:
+ case rcode_nxdomain:
+ break;
+ case rcode_formaterror:
+ adns__warn(ads,serv,"server cannot understand our query (Format Error)");
+ adns__query_fail(ads,qu,adns_s_serverfaulty);
+ return;
+ case rcode_servfail;
+ adns__query_fail(ads,qu,adns_s_serverfailure);
+ return;
+ case rcode_notimp:
+ adns__warn(ads,serv,"server claims not to implement our query");
+ adns__query_fail(ads,qu,adns_s_notimplemented);
+ return;
+ case rcode_refused:
+ adns__warn(ads,serv,"server refused our query");
+ adns__query_fail(ads,qu,adns_s_refused);
+ return;
+ default:
+ adns__warn(ads,serv,"server gave unknown response code %d",rcode);
+ adns__query_fail(ads,qu,adns_s_reasonunknown);
+ return;
+ }
+
+ /* Now, take a look at the answer section, and see if it is complete.
+ * If it has any CNAMEs we stuff them in the answer.
+ */
+ wantedrrs= 0;
+ for (rri= 0; rri<ancount; rri++) {
+ rrstart= cbyte;
+ st= get_rr_temp(ads,qu,serv,
+ dgram,dglen,
+ &cbyte,
+ &rrtype,&rrclass,&rdlength,&cowner);
+ if (st) adns__query_fail(ads,qu,st);
+ if (rrclass != DNS_CLASS_IN) {
+ adns__diag(ads,serv,"ignoring RR with wrong class %d (expected IN=%d)",
+ rrclass,DNS_CLASS_IN);
+ continue;
+ }
+ if (strcmp_quoted1035(cowner, qu->cname ? qu->cname : qu->owner)) {
+ adns__debug(ads,serv,"ignoring answer RR with irrelevant owner \"%s\"",cowner);
+ continue;
+ }
+ if (!qu->cname &&
+ (qu->type & adns__rrt_typemask) != adns_cname &&
+ rrtype == adns_cname) { /* Ignore second and subsequent CNAMEs */
+ qu->cname= get_domain_perm(ads,qu,dgram,len,rdstart,rdstart+rdlength);
+ /* If we find the answer section truncated after this point we restart
+ * the query at the CNAME; otherwise we can use it as-is.
+ */
+ } else if (rrtype == (qu->type & adns__rrt_typemask)) {
+ wantedrrs++;
+ } else {
+ adns__debug(ads,serv,"ignoring answer RR with irrelevant type %d",rrtype);
+ }
+ }
+
+ /* If we got here then the answer section is intact. */
+ nsstart= cbyte;
+
+ if (!wantedrrs) {
+ /* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */
+
+ if (rcode == rcode_nxdomain) {
+ adnns__query_finish(ads,qu,adns_s_nxdomain);
+ return;
+ }
+
+ /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */
+ for (rri= 0; rri<nscount; rri++) {
+
+ }
+ } else {
+
+
+ if (!(f2&0x80)) {
+ adns__diag(ads,serv,"server is not willing to do recursive lookups for us");
+ adns__query_fail(ads,qu,adns_s_norecurse);
+ return;
+ }
+
+
+ ) {
+ if (type
+ if (cbyte+lab
+ if (anstart > dgend) { truncated(ads,qu,f1); return; }
+ }
+ for
+
+ /* Look for CNAMEs in the answer section */
+
+ }
+
+
+ adns__diag(ads,serv,"server refused our query");
+
+ case rcode_
+
+ case 0: /* NOERROR
+ break;
+ case 1: /* Format error */
+ case 3: /* Name Error */
+
+ qr= f1&0x80;
+
+
adns__diag(ads,serv,"received datagram size %d",len);
+
}
~ianmdlvl / adns.git / blobdiff