s4 dns: Forward questions we can't answer to another server

This makes use of libdns and currently hardcodes the forward server, but
it works. :)

diff --git a/source4/dns_server/dns_query.c b/source4/dns_server/dns_query.c
index 4277659cf7e70348d3e92079427a8a9d4253bb5e..e57512c488307d4f669be83b7b019bc368642a4d 100644 (file)
--- a/source4/dns_server/dns_query.c
+++ b/source4/dns_server/dns_query.c
@@ -28,6 +28,7 @@
 #include "dsdb/samdb/samdb.h"
 #include "dsdb/common/util.h"
 #include "dns_server/dns_server.h"
+#include "libcli/dns/libdns.h"
 
 static WERROR create_response_rr(const struct dns_name_question *question,
                                 const struct dnsp_DnssrvRpcRecord *rec,
@@ -97,6 +98,73 @@ static WERROR create_response_rr(const struct dns_name_question *question,
        return WERR_OK;
 }
 
+static WERROR ask_forwarder(TALLOC_CTX *mem_ctx,
+                           struct dns_name_question *question,
+                           struct dns_res_rec **answers, uint16_t *ancount,
+                           struct dns_res_rec **nsrecs, uint16_t *nscount,
+                           struct dns_res_rec **additional, uint16_t *arcount)
+{
+       struct tevent_context *ev = tevent_context_init(mem_ctx);
+       struct dns_name_packet *out_packet, *in_packet;
+       uint16_t id = random();
+       DATA_BLOB out, in;
+       enum ndr_err_code ndr_err;
+       WERROR werr = WERR_OK;
+       struct tevent_req *req;
+
+       out_packet = talloc_zero(mem_ctx, struct dns_name_packet);
+       W_ERROR_HAVE_NO_MEMORY(out_packet);
+
+       out_packet->id = id;
+       out_packet->operation |= DNS_OPCODE_QUERY | DNS_FLAG_RECURSION_DESIRED;
+
+       out_packet->qdcount = 1;
+       out_packet->questions = question;
+
+       ndr_err = ndr_push_struct_blob(&out, mem_ctx, out_packet,
+                       (ndr_push_flags_fn_t)ndr_push_dns_name_packet);
+       if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+               return DNS_ERR(SERVER_FAILURE);
+       }
+
+       /* FIXME: Don't hardcode this, get that from a configuration somewhere */
+       req = dns_udp_request_send(mem_ctx, ev, "127.0.0.1", out.data, out.length);
+       W_ERROR_HAVE_NO_MEMORY(req);
+
+       if(!tevent_req_poll(req, ev)) {
+               return DNS_ERR(SERVER_FAILURE);
+       }
+
+       werr = dns_udp_request_recv(req, mem_ctx, &in.data, &in.length);
+       W_ERROR_NOT_OK_RETURN(werr);
+
+       in_packet = talloc_zero(mem_ctx, struct dns_name_packet);
+       W_ERROR_HAVE_NO_MEMORY(in_packet);
+
+       ndr_err = ndr_pull_struct_blob(&in, in_packet, in_packet,
+                       (ndr_pull_flags_fn_t)ndr_pull_dns_name_packet);
+       if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+               return DNS_ERR(SERVER_FAILURE);
+       }
+
+       if (in_packet->id != id) {
+               DEBUG(0, ("DNS packet id mismatch: 0x%0x, expected 0x%0x\n",
+                         in_packet->id, id));
+               return DNS_ERR(NAME_ERROR);
+       }
+
+       *ancount = in_packet->ancount;
+       *answers = talloc_move(mem_ctx, &in_packet->answers);
+
+       *nscount = in_packet->nscount;
+       *nsrecs = talloc_move(mem_ctx, &in_packet->nsrecs);
+
+       *arcount = in_packet->arcount;
+       *additional = talloc_move(mem_ctx, &in_packet->additional);
+
+       return werr;
+}
+
 static WERROR handle_question(struct dns_server *dns,
                              TALLOC_CTX *mem_ctx,
                              const struct dns_name_question *question,
@@ -145,8 +213,8 @@ WERROR dns_server_process_query(struct dns_server *dns,
                                struct dns_res_rec **nsrecs,     uint16_t *nscount,
                                struct dns_res_rec **additional, uint16_t *arcount)
 {
-       uint16_t num_answers=0;
-       struct dns_res_rec *ans=NULL;
+       uint16_t num_answers=0, num_nsrecs=0, num_additional=0;
+       struct dns_res_rec *ans=NULL, *ns=NULL, *adds=NULL;
        WERROR werror;
 
        if (in->qdcount != 1) {
@@ -159,17 +227,22 @@ WERROR dns_server_process_query(struct dns_server *dns,
        }
 
        werror = handle_question(dns, mem_ctx, &in->questions[0], &ans, &num_answers);
+       if(W_ERROR_EQUAL(DNS_ERR(NAME_ERROR), werror)) {
+               DEBUG(2, ("I don't feel responsible for '%s', forwarding\n", in->questions[0].name));
+               werror = ask_forwarder(mem_ctx, &in->questions[0], &ans, &num_answers,
+                                      &ns, &num_nsrecs, &adds, &num_additional);
+       }
        W_ERROR_NOT_OK_GOTO(werror, query_failed);
 
        *answers = ans;
        *ancount = num_answers;
 
        /*FIXME: Do something for these */
-       *nsrecs  = NULL;
-       *nscount = 0;
+       *nsrecs  = ns;
+       *nscount = num_nsrecs;
 
-       *additional = NULL;
-       *arcount    = 0;
+       *additional = adds;
+       *arcount    = num_additional;
 
        return WERR_OK;
 

diff --git a/source4/dns_server/wscript_build b/source4/dns_server/wscript_build
index 04c8188b37f7ac79c258b35a955bfe95b356a245..29895b2d185fd47ead82c23bc6891cd250edeaf8 100644 (file)
--- a/source4/dns_server/wscript_build
+++ b/source4/dns_server/wscript_build
@@ -4,7 +4,7 @@ bld.SAMBA_MODULE('service_dns',
         source='dns_server.c dns_query.c dns_update.c dns_utils.c',
         subsystem='service',
         init_function='server_service_dns_init',
-        deps='samba-hostconfig LIBTSOCKET LIBSAMBA_TSOCKET ldbsamba',
+        deps='samba-hostconfig LIBTSOCKET LIBSAMBA_TSOCKET ldbsamba LIBCLI_DNS',
         local_include=False,
         internal_module=False,
         )