r11595: added a helper layer to parse streams into individual packets. This is

something that Andrew Bartlett has been asking for for a while, and
when I started having to re-invent this packet parsing code yet again
for SMB2 I decided it was time to do it generically

you use it by providing a "is this a full packet yet?" helper function
to the packet_*() functions, which then handle all the logic of
partial packet buffering.

This also goes to great lengths to operate efficiently, minimising the
number of recv system calls.
(This used to be commit e6c47b954a6f09c53ea419800ce873295fcd0be9)

3 files changed, 368 insertions, 0 deletions

diff --git a/source4/lib/stream/config.mk b/source4/lib/stream/config.mk
new file mode 100644
index 0000000000..1ec650ab10
--- /dev/null
+++ b/source4/lib/stream/config.mk
@@ -0,0 +1,9 @@
+
+################################################
+# Start SUBSYSTEM LIBPACKET
+[SUBSYSTEM::LIBPACKET]
+INIT_OBJ_FILES = \
+		packet.o
+NOPROTO=YES
+# End SUBSYSTEM LIBPACKET
+################################################
diff --git a/source4/lib/stream/packet.c b/source4/lib/stream/packet.c
new file mode 100644
index 0000000000..971135ff9b
--- /dev/null
+++ b/source4/lib/stream/packet.c
@@ -0,0 +1,312 @@
+/* 
+   Unix SMB/CIFS mplementation.
+
+   helper layer for breaking up streams into discrete requests
+   
+   Copyright (C) Andrew Tridgell  2005
+    
+   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 2 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, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+   
+*/
+
+#include "includes.h"
+#include "dlinklist.h"
+#include "lib/events/events.h"
+#include "lib/socket/socket.h"
+#include "lib/tls/tls.h"
+#include "lib/stream/packet.h"
+
+
+struct packet_context {
+	packet_callback_fn_t callback;
+	packet_full_request_fn_t full_request;
+	packet_error_handler_fn_t error_handler;
+	DATA_BLOB partial;
+	uint32_t initial_read_size;
+	uint32_t num_read;
+	struct tls_context *tls;
+	struct socket_context *sock;
+	struct event_context *ev;
+	size_t packet_size;
+	void *private;
+};
+
+/*
+  initialise a packet receiver
+*/
+struct packet_context *packet_init(TALLOC_CTX *mem_ctx)
+{
+	return talloc_zero(mem_ctx, struct packet_context);
+}
+
+
+/*
+  set the request callback, called when a full request is ready
+*/
+void packet_set_callback(struct packet_context *pc, packet_callback_fn_t callback)
+{
+	pc->callback = callback;
+}
+
+/*
+  set the error handler
+*/
+void packet_set_error_handler(struct packet_context *pc, packet_error_handler_fn_t handler)
+{
+	pc->error_handler = handler;
+}
+
+/*
+  set the private pointer passed to the callback functions
+*/
+void packet_set_private(struct packet_context *pc, void *private)
+{
+	pc->private = private;
+}
+
+/*
+  set the full request callback. Should return as follows:
+     NT_STATUS_OK == blob is a full request.
+     STATUS_MORE_ENTRIES == blob is not complete yet
+     any error == blob is not a valid 
+*/
+void packet_set_full_request(struct packet_context *pc, packet_full_request_fn_t callback)
+{
+	pc->full_request = callback;
+}
+
+/*
+  set a tls context to use. You must either set a tls_context or a socket_context
+*/
+void packet_set_tls(struct packet_context *pc, struct tls_context *tls)
+{
+	pc->tls = tls;
+}
+
+/*
+  set a socket context to use. You must either set a tls_context or a socket_context
+*/
+void packet_set_socket(struct packet_context *pc, struct socket_context *sock)
+{
+	pc->sock = sock;
+}
+
+/*
+  set an event context. If this is set then the code will ensure that
+  packets arrive with separate events, by creating a immediate event
+  for any secondary packets when more than one packet is read at one
+  time on a socket. This can matter for code that relies on not
+  getting more than one packet per event
+*/
+void packet_set_event_context(struct packet_context *pc, struct event_context *ev)
+{
+	pc->ev = ev;
+}
+
+
+/*
+  tell the caller we have an error
+*/
+static void packet_error(struct packet_context *pc, NTSTATUS status)
+{
+	pc->tls = NULL;
+	pc->sock = NULL;
+	if (pc->error_handler) {
+		pc->error_handler(pc->private, status);
+		return;
+	}
+	/* default error handler is to free the callers private pointer */
+	if (!NT_STATUS_EQUAL(status, NT_STATUS_END_OF_FILE)) {
+		DEBUG(0,("packet_error on %s - %s\n", 
+			 talloc_get_name(pc->private), nt_errstr(status)));
+	}
+	talloc_free(pc->private);
+	return;
+}
+
+
+/*
+  tell the caller we have EOF
+*/
+static void packet_eof(struct packet_context *pc)
+{
+	packet_error(pc, NT_STATUS_END_OF_FILE);
+}
+
+
+/*
+  used to put packets on event boundaries
+*/
+static void packet_next_event(struct event_context *ev, struct timed_event *te, 
+			      struct timeval t, void *private)
+{
+	struct packet_context *pc = talloc_get_type(private, struct packet_context);
+	packet_recv(pc);
+}
+
+/*
+  call this when the socket becomes readable to kick off the whole
+  stream parsing process
+*/
+void packet_recv(struct packet_context *pc)
+{
+	size_t npending;
+	NTSTATUS status;
+	size_t nread;
+	DATA_BLOB blob;
+
+	if (pc->packet_size != 0 && pc->num_read >= pc->packet_size) {
+		goto next_partial;
+	}
+
+	if (pc->packet_size != 0) {
+		/* we've already worked out how long this next packet is, so skip the
+		   socket_pending() call */
+		npending = pc->packet_size - pc->num_read;
+	} else {
+		if (pc->tls) {
+			status = tls_socket_pending(pc->tls, &npending);
+		} else if (pc->sock) {
+			status = socket_pending(pc->sock, &npending);
+		} else {
+			status = NT_STATUS_CONNECTION_DISCONNECTED;
+		}
+		if (!NT_STATUS_IS_OK(status)) {
+			packet_error(pc, status);
+			return;
+		}
+	}
+
+	if (npending == 0) {
+		packet_eof(pc);
+		return;
+	}
+
+	/* possibly expand the partial packet buffer */
+	if (npending + pc->num_read > pc->partial.length) {
+		status = data_blob_realloc(pc, &pc->partial, npending+pc->num_read);
+		if (!NT_STATUS_IS_OK(status)) {
+			packet_error(pc, status);
+			return;
+		}
+	}
+
+	if (pc->tls) {
+		status = tls_socket_recv(pc->tls, pc->partial.data + pc->num_read, 
+					 npending, &nread);
+	} else {
+		status = socket_recv(pc->sock, pc->partial.data + pc->num_read, 
+				     npending, &nread, 0);
+	}
+	if (NT_STATUS_IS_ERR(status)) {
+		packet_error(pc, status);
+		return;
+	}
+	if (!NT_STATUS_IS_OK(status)) {
+		return;
+	}
+
+	if (nread == 0) {
+		packet_eof(pc);
+		return;
+	}
+
+	pc->num_read += nread;
+
+	/* see if its a full request */
+next_partial:
+	blob = pc->partial;
+	blob.length = pc->num_read;
+	status = pc->full_request(pc->private, blob, &pc->packet_size);
+	if (NT_STATUS_IS_ERR(status)) {
+		packet_error(pc, status);
+		return;
+	}
+	if (!NT_STATUS_IS_OK(status)) {
+		return;
+	}
+
+	if (pc->packet_size > pc->num_read) {
+		/* the caller made an error */
+		DEBUG(0,("Invalid packet_size %u greater than num_read %u\n",
+			 pc->packet_size, pc->num_read));
+		packet_error(pc, NT_STATUS_INVALID_PARAMETER);
+		return;
+	}
+
+	/* it is a full request - give it to the caller */
+	blob = pc->partial;
+
+	if (pc->packet_size < pc->num_read) {
+		pc->partial = data_blob_talloc(pc, blob.data + pc->packet_size, 
+					       pc->num_read - pc->packet_size);
+		if (pc->partial.data == NULL) {
+			packet_error(pc, NT_STATUS_NO_MEMORY);
+			return;
+		}
+		data_blob_realloc(pc, &blob, pc->packet_size);
+	} else {
+		pc->partial = data_blob(NULL, 0);
+	}
+	pc->num_read -= pc->packet_size;
+	pc->packet_size = 0;
+
+	status = pc->callback(pc->private, blob);
+	if (!NT_STATUS_IS_OK(status)) {
+		packet_error(pc, status);
+		return;
+	}
+
+	if (pc->partial.length == 0) {
+		return;
+	}
+	
+	/* we got multiple packets in one tcp read */
+	if (pc->ev == NULL) {
+		goto next_partial;
+	}
+
+	blob = pc->partial;
+	blob.length = pc->num_read;
+
+	status = pc->full_request(pc->private, blob, &pc->packet_size);
+	if (NT_STATUS_IS_ERR(status)) {
+		packet_error(pc, status);
+		return;
+	}
+
+	if (!NT_STATUS_IS_OK(status)) {
+		return;
+	}
+
+	event_add_timed(pc->ev, pc, timeval_zero(), packet_next_event, pc);
+}
+
+
+
+/*
+  a full request checker for NBT formatted packets (first 3 bytes are length)
+*/
+NTSTATUS packet_full_request_nbt(void *private, DATA_BLOB blob, size_t *packet_size)
+{
+	if (blob.length < 4) {
+		return STATUS_MORE_ENTRIES;
+	}
+	*packet_size = 4 + smb_len(blob.data);
+	if (*packet_size > blob.length) {
+		return STATUS_MORE_ENTRIES;
+	}
+	return NT_STATUS_OK;
+}
diff --git a/source4/lib/stream/packet.h b/source4/lib/stream/packet.h
new file mode 100644
index 0000000000..6d29264a28
--- /dev/null
+++ b/source4/lib/stream/packet.h
@@ -0,0 +1,47 @@
+/* 
+   Unix SMB/CIFS mplementation.
+
+   helper layer for breaking up streams into discrete requests
+   
+   Copyright (C) Andrew Tridgell  2005
+    
+   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 2 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, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+   
+*/
+
+#include "lib/tls/tls.h"
+
+typedef NTSTATUS (*packet_full_request_fn_t)(void *private, 
+					     DATA_BLOB blob, size_t *packet_size);
+typedef NTSTATUS (*packet_callback_fn_t)(void *private, DATA_BLOB blob);
+typedef void (*packet_error_handler_fn_t)(void *private, NTSTATUS status);
+
+
+
+struct packet_context *packet_init(TALLOC_CTX *mem_ctx);
+void packet_set_callback(struct packet_context *pc, packet_callback_fn_t callback);
+void packet_set_error_handler(struct packet_context *pc, packet_error_handler_fn_t handler);
+void packet_set_private(struct packet_context *pc, void *private);
+void packet_set_full_request(struct packet_context *pc, packet_full_request_fn_t callback);
+void packet_set_tls(struct packet_context *pc, struct tls_context *tls);
+void packet_set_socket(struct packet_context *pc, struct socket_context *sock);
+void packet_set_event_context(struct packet_context *pc, struct event_context *ev);
+void packet_recv(struct packet_context *pc);
+
+/*
+  pre-canned handlers
+*/
+NTSTATUS packet_full_request_nbt(void *private, DATA_BLOB blob, size_t *packet_size);
+