libcli/dns: Simplify dns over tcp requests, save 39 lines :-)

tstream_readv_pdu_send() is overkill here, tstream_read_packet_send()
is sufficient. The only downside is that dns_tcp_request_recv() does
not return a talloc context on its own in reply anymore, but as the
reply is immediately ndr-parsed, so we keep that around only a tiny
bit longer.

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Pavel Filipenský <pfilipensky@samba.org>

diff --git a/libcli/dns/dns.c b/libcli/dns/dns.c
index 81144601bb89bccd16bcd55e74ec8adc766eb3e2..4539a7713ba86cc3258366447a9f8c550bfb2a76 100644 (file)
--- a/libcli/dns/dns.c
+++ b/libcli/dns/dns.c
@@ -23,6 +23,7 @@
 #include "system/network.h"
 #include <tevent.h>
 #include "lib/tsocket/tsocket.h"
+#include "source3/lib/util_tsock.h"
 #include "libcli/dns/libdns.h"
 #include "lib/util/tevent_unix.h"
 #include "lib/util/samba_util.h"
@@ -193,11 +194,9 @@ struct dns_tcp_request_state {
 
 static void dns_tcp_request_connected(struct tevent_req *subreq);
 static void dns_tcp_request_sent(struct tevent_req *subreq);
-static int dns_tcp_request_next_vector(struct tstream_context *stream,
-                                      void *private_data,
-                                      TALLOC_CTX *mem_ctx,
-                                      struct iovec **_vector,
-                                      size_t *_count);
+static ssize_t dns_tcp_request_more(uint8_t *buf,
+                                   size_t buflen,
+                                   void *private_data);
 static void dns_tcp_request_received(struct tevent_req *subreq);
 
 static struct tevent_req *dns_tcp_request_send(TALLOC_CTX *mem_ctx,
@@ -297,76 +296,37 @@ static void dns_tcp_request_sent(struct tevent_req *subreq)
                return;
        }
 
-       subreq = tstream_readv_pdu_send(state, state->ev, state->stream,
-                                       dns_tcp_request_next_vector, state);
+       subreq = tstream_read_packet_send(state,
+                                         state->ev,
+                                         state->stream,
+                                         2,
+                                         dns_tcp_request_more,
+                                         NULL);
        if (tevent_req_nomem(subreq, req)) {
                return;
        }
        tevent_req_set_callback(subreq, dns_tcp_request_received, req);
 }
 
-static int dns_tcp_request_next_vector(struct tstream_context *stream,
-                                      void *private_data,
-                                      TALLOC_CTX *mem_ctx,
-                                      struct iovec **_vector,
-                                      size_t *_count)
+static ssize_t dns_tcp_request_more(uint8_t *buf,
+                                   size_t buflen,
+                                   void *private_data)
 {
-       struct dns_tcp_request_state *state = talloc_get_type_abort(
-               private_data, struct dns_tcp_request_state);
-       struct iovec *vector;
-       uint16_t msglen;
-
-       if (state->nread == 0) {
-               vector = talloc_array(mem_ctx, struct iovec, 1);
-               if (vector == NULL) {
-                       return -1;
-               }
-               vector[0] = (struct iovec) {
-                       .iov_base = state->dns_msglen_hdr,
-                       .iov_len = sizeof(state->dns_msglen_hdr)
-               };
-               state->nread = sizeof(state->dns_msglen_hdr);
-
-               *_vector = vector;
-               *_count = 1;
-               return 0;
-       }
-
-       if (state->nread == sizeof(state->dns_msglen_hdr)) {
-               msglen = RSVAL(state->dns_msglen_hdr, 0);
-
-               state->reply = talloc_array(state, uint8_t, msglen);
-               if (state->reply == NULL) {
-                       return -1;
-               }
-
-               vector = talloc_array(mem_ctx, struct iovec, 1);
-               if (vector == NULL) {
-                       return -1;
-               }
-               vector[0] = (struct iovec) {
-                       .iov_base = state->reply,
-                       .iov_len = msglen
-               };
-               state->nread += msglen;
-
-               *_vector = vector;
-               *_count = 1;
-               return 0;
+       if (buflen > 2) {
+               return 0; /* We've been here, we're done */
        }
-
-       *_vector = NULL;
-       *_count = 0;
-       return 0;
+       return PULL_BE_U16(buf, 0);
 }
 
 static void dns_tcp_request_received(struct tevent_req *subreq)
 {
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
+       struct dns_tcp_request_state *state = tevent_req_data(
+               req, struct dns_tcp_request_state);
        int ret, err;
 
-       ret = tstream_readv_pdu_recv(subreq, &err);
+       ret = tstream_read_packet_recv(subreq, state, &state->reply, &err);
        TALLOC_FREE(subreq);
        if (ret == -1) {
                tevent_req_error(req, err);
@@ -390,8 +350,14 @@ static int dns_tcp_request_recv(struct tevent_req *req,
                return err;
        }
 
-       *reply_len = talloc_array_length(state->reply);
-       *reply = talloc_move(mem_ctx, &state->reply);
+       /*
+        * DNS over TCP prefixes each message with a 2-byte length
+        * header, skip it.
+        */
+       *reply_len = talloc_array_length(state->reply) - 2;
+       *reply = state->reply + 2;
+       talloc_steal(mem_ctx, state->reply);
+
        tevent_req_received(req);
 
        return 0;
@@ -568,7 +534,6 @@ static void dns_cli_request_tcp_done(struct tevent_req *subreq)
                tevent_req_error(req, ndr_map_error2errno(ndr_err));
                return;
        }
-       TALLOC_FREE(reply.data);
 
        if (state->reply->id != state->req_id) {
                DBG_DEBUG("Got id %"PRIu16", expected %"PRIu16"\n",

diff --git a/libcli/dns/wscript_build b/libcli/dns/wscript_build
index 2d90aa7ec0ffbe87babb60c42ae05e5817628fb7..e1e05429a96cb6bf110857e30a66075ba3469668 100644 (file)
--- a/libcli/dns/wscript_build
+++ b/libcli/dns/wscript_build
@@ -2,7 +2,7 @@
 
 bld.SAMBA_LIBRARY('clidns',
         source='dns.c resolvconf.c',
-        public_deps='LIBTSOCKET tevent-util ndr-standard',
+        public_deps='LIBTSOCKET util_tsock tevent-util ndr-standard',
         private_library=True)
 
 bld.SAMBA_BINARY('resolvconftest',