rpc: Add tstream_u32_read

In npa_tstream.c we have two next_vector functions reading a big
endian uin32_t length and then the blob described by the length. This
factors that next_vector out into a central routine.

Why? I'll add another NPA protocol in the future, and this would add
yet another two copies of that next_vector code

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>

libcli/named_pipe_auth/tstream_u32_read.c

@@ -0,0 +1,159 @@
+/*
+ * Unix SMB/CIFS implementation.
+ *
+ * Copyright (C) Volker Lendecke 2019
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "replace.h"
+#include "system/filesys.h"
+#include "tstream_u32_read.h"
+#include "lib/util/byteorder.h"
+#include "lib/util/tevent_unix.h"
+
+struct tstream_u32_read_state {
+	size_t max_msglen;
+	size_t buflen;
+	uint8_t *buf;
+};
+
+static int tstream_u32_read_next_vector(struct tstream_context *stream,
+					void *private_data,
+					TALLOC_CTX *mem_ctx,
+					struct iovec **_vector,
+					size_t *_count);
+static void tstream_u32_read_done(struct tevent_req *subreq);
+
+struct tevent_req *tstream_u32_read_send(
+	TALLOC_CTX *mem_ctx,
+	struct tevent_context *ev,
+	uint32_t max_msglen,
+	struct tstream_context *stream)
+{
+	struct tevent_req *req = NULL, *subreq = NULL;
+	struct tstream_u32_read_state *state = NULL;
+
+	req = tevent_req_create(
+		mem_ctx, &state, struct tstream_u32_read_state);
+	if (req == NULL) {
+		return NULL;
+	}
+	state->max_msglen = max_msglen;
+
+	subreq = tstream_readv_pdu_send(
+		state,
+		ev,
+		stream,
+		tstream_u32_read_next_vector,
+		state);
+	if (tevent_req_nomem(subreq, req)) {
+		return tevent_req_post(req, ev);
+	}
+	tevent_req_set_callback(subreq, tstream_u32_read_done, req);
+	return req;
+}
+
+static int tstream_u32_read_next_vector(struct tstream_context *stream,
+					void *private_data,
+					TALLOC_CTX *mem_ctx,
+					struct iovec **_vector,
+					size_t *_count)
+{
+	struct tstream_u32_read_state *state = talloc_get_type_abort(
+		private_data, struct tstream_u32_read_state);
+	size_t buflen = talloc_get_size(state->buf);
+	struct iovec *vector;
+	uint32_t msg_len;
+	size_t ofs = 0;
+	size_t count;
+
+	if (buflen == 0) {
+		msg_len = 4;
+		state->buf = talloc_array(state, uint8_t, msg_len);
+		if (state->buf == NULL) {
+			return -1;
+		}
+	} else if (buflen == 4) {
+
+		ofs = 4;
+
+		msg_len = RIVAL(state->buf, 0);
+		if ((msg_len == 0) || (msg_len > state->max_msglen)) {
+			errno = EMSGSIZE;
+			return -1;
+		}
+		msg_len += ofs;
+		if (msg_len < ofs) {
+			errno = EMSGSIZE;
+			return -1;
+		}
+
+		state->buf = talloc_realloc(
+			state, state->buf, uint8_t, msg_len);
+		if (state->buf == NULL) {
+			return -1;
+		}
+	} else {
+		*_vector = NULL;
+		*_count = 0;
+		return 0;
+	}
+
+	vector = talloc(mem_ctx, struct iovec);
+	if (vector == NULL) {
+		return -1;
+	}
+	*vector = (struct iovec) {
+		.iov_base = state->buf + ofs, .iov_len = msg_len - ofs,
+	};
+	count = 1;
+
+	*_vector = vector;
+	*_count = count;
+	return 0;
+}
+
+static void tstream_u32_read_done(struct tevent_req *subreq)
+{
+	struct tevent_req *req = tevent_req_callback_data(
+		subreq, struct tevent_req);
+	int ret, err;
+
+	ret = tstream_readv_pdu_recv(subreq, &err);
+	TALLOC_FREE(subreq);
+	if (ret == -1) {
+		tevent_req_error(req, err);
+		return;
+	}
+	tevent_req_done(req);
+}
+
+int tstream_u32_read_recv(
+	struct tevent_req *req,
+	TALLOC_CTX *mem_ctx,
+	uint8_t **buf,
+	size_t *buflen)
+{
+	struct tstream_u32_read_state *state = tevent_req_data(
+		req, struct tstream_u32_read_state);
+	int err;
+
+	if (tevent_req_is_unix_error(req, &err)) {
+		return err;
+	}
+	*buflen = talloc_get_size(state->buf);
+	*buf = talloc_move(mem_ctx, &state->buf);
+	return 0;
+}

libcli/named_pipe_auth/tstream_u32_read.h

@@ -0,0 +1,37 @@
+/*
+ * Unix SMB/CIFS implementation.
+ *
+ * Copyright (C) Volker Lendecke 2019
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef TSTREAM_U32_READ_H
+#define TSTREAM_U32_READ_H
+
+#include "replace.h"
+#include "tsocket.h"
+
+struct tevent_req *tstream_u32_read_send(
+	TALLOC_CTX *mem_ctx,
+	struct tevent_context *ev,
+	uint32_t max_msglen,
+	struct tstream_context *stream);
+int tstream_u32_read_recv(
+	struct tevent_req *req,
+	TALLOC_CTX *mem_ctx,
+	uint8_t **buf,
+	size_t *buflen);
+
+#endif

libcli/named_pipe_auth/wscript_build

@@ -2,7 +2,7 @@
 
 
 bld.SAMBA_LIBRARY('npa_tstream',
-                  source='npa_tstream.c',
+                  source='npa_tstream.c tstream_u32_read.c',
                   private_library=True,
                   public_deps='NDR_NAMED_PIPE_AUTH tevent LIBTSOCKET'
                   )