flow: add PacketRouter

flow/CMakeLists.txt

@@ -34,5 +34,6 @@ add_library(flow
     StreamRecvInterface.c
     FlowError.c
     RouteBuffer.c
+    PacketRouter.c
 )
 target_link_libraries(flow system security)

flow/PacketRouter.c

@@ -0,0 +1,128 @@
+/**
+ * @file PacketRouter.c
+ * @author Ambroz Bizjak <ambrop7@gmail.com>
+ * 
+ * @section LICENSE
+ * 
+ * This file is part of BadVPN.
+ * 
+ * BadVPN is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ * 
+ * BadVPN 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.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <flow/PacketRouter.h>
+
+static void input_handler_done (PacketRouter *o, int data_len)
+{
+    ASSERT(data_len >= 0)
+    ASSERT(data_len <= o->mtu - o->recv_offset)
+    ASSERT(!BPending_IsSet(&o->next_job))
+    DebugObject_Access(&o->d_obj);
+    
+    // set next job
+    BPending_Set(&o->next_job);
+    
+    // call handler
+    o->handler(o->user, RouteBufferSource_Pointer(&o->rbs), data_len);
+    return;
+}
+
+static void next_job_handler (PacketRouter *o)
+{
+    DebugObject_Access(&o->d_obj);
+    
+    // receive
+    PacketRecvInterface_Receiver_Recv(o->input, RouteBufferSource_Pointer(&o->rbs) + o->recv_offset);
+}
+
+int PacketRouter_Init (PacketRouter *o, int mtu, int recv_offset, PacketRecvInterface *input, PacketRouter_handler handler, void *user, BPendingGroup *pg)
+{
+    ASSERT(mtu >= 0)
+    ASSERT(recv_offset >= 0)
+    ASSERT(recv_offset <= mtu)
+    ASSERT(PacketRecvInterface_GetMTU(input) <= mtu - recv_offset)
+    
+    // init arguments
+    o->mtu = mtu;
+    o->recv_offset = recv_offset;
+    o->input = input;
+    o->handler = handler;
+    o->user = user;
+    
+    // init input
+    PacketRecvInterface_Receiver_Init(o->input, (PacketRecvInterface_handler_done)input_handler_done, o);
+    
+    // init RouteBufferSource
+    if (!RouteBufferSource_Init(&o->rbs, mtu)) {
+        goto fail0;
+    }
+    
+    // init next job
+    BPending_Init(&o->next_job, pg, (BPending_handler)next_job_handler, o);
+    
+    // receive
+    PacketRecvInterface_Receiver_Recv(o->input, RouteBufferSource_Pointer(&o->rbs) + o->recv_offset);
+    
+    DebugObject_Init(&o->d_obj);
+    
+    return 1;
+    
+fail0:
+    return 0;
+}
+
+void PacketRouter_Free (PacketRouter *o)
+{
+    DebugObject_Free(&o->d_obj);
+    
+    // free next job
+    BPending_Free(&o->next_job);
+    
+    // free RouteBufferSource
+    RouteBufferSource_Free(&o->rbs);
+}
+
+int PacketRouter_Route (PacketRouter *o, int len, RouteBuffer *output, uint8_t **next_buf, int copy_offset, int copy_len)
+{
+    ASSERT(len >= 0)
+    ASSERT(len <= o->mtu)
+    ASSERT(RouteBuffer_GetMTU(output) == o->mtu)
+    ASSERT(copy_offset >= 0)
+    ASSERT(copy_offset <= o->mtu)
+    ASSERT(copy_len >= 0)
+    ASSERT(copy_len <= o->mtu - copy_offset)
+    ASSERT(BPending_IsSet(&o->next_job))
+    DebugObject_Access(&o->d_obj);
+    
+    if (!RouteBufferSource_Route(&o->rbs, len, output, copy_offset, copy_len)) {
+        return 0;
+    }
+    
+    if (next_buf) {
+        *next_buf = RouteBufferSource_Pointer(&o->rbs);
+    } else {
+        // unset next job
+        BPending_Unset(&o->next_job);
+        
+        // receive
+        PacketRecvInterface_Receiver_Recv(o->input, RouteBufferSource_Pointer(&o->rbs) + o->recv_offset);
+    }
+    
+    return 1;
+}
+
+void PacketRouter_AssertRoute (PacketRouter *o)
+{
+    ASSERT(BPending_IsSet(&o->next_job))
+    DebugObject_Access(&o->d_obj);
+}

flow/PacketRouter.h

@@ -0,0 +1,121 @@
+/**
+ * @file PacketRouter.h
+ * @author Ambroz Bizjak <ambrop7@gmail.com>
+ * 
+ * @section LICENSE
+ * 
+ * This file is part of BadVPN.
+ * 
+ * BadVPN is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ * 
+ * BadVPN 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.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ * 
+ * @section DESCRIPTION
+ * 
+ * Object which simplifies routing packets to {@link RouteBuffer}'s from a
+ * {@link PacketRecvInterface} input.
+ */
+
+#ifndef BADVPN_FLOW_PACKETROUTER_H
+#define BADVPN_FLOW_PACKETROUTER_H
+
+#include <system/DebugObject.h>
+#include <system/BPending.h>
+#include <flow/PacketRecvInterface.h>
+#include <flow/RouteBuffer.h>
+
+/**
+ * Handler called when a packet is received, allowing the user to route it
+ * to one or more buffers using {@link PacketRouter_Route}.
+ * 
+ * @param user as in {@link PacketRouter_Init}
+ * @param buf the buffer for the packet. May be modified by the user.
+ *            Will have space for mtu bytes. Only valid in the job context of
+ *            this handler, until {@link PacketRouter_Route} is called successfully 
+ * @param recv_len length of the input packet (located at recv_offset bytes offset)
+ */
+typedef void (*PacketRouter_handler) (void *user, uint8_t *buf, int recv_len);
+
+/**
+ * Object which simplifies routing packets to {@link RouteBuffer}'s from a
+ * {@link PacketRecvInterface} input.
+ * 
+ * Packets are routed by calling {@link PacketRouter_Route} (possibly multiple times)
+ * from the job context of the {@link PacketRouter_handler} handler.
+ */
+typedef struct {
+    int mtu;
+    int recv_offset;
+    PacketRecvInterface *input;
+    PacketRouter_handler handler;
+    void *user;
+    RouteBufferSource rbs;
+    BPending next_job;
+    DebugObject d_obj;
+} PacketRouter;
+
+/**
+ * Initializes the object.
+ * 
+ * @param o the object
+ * @param mtu maximum packet size. Must be >=0. It will only be possible to route packets to
+ *            {@link RouteBuffer}'s with the same MTU.
+ * @param recv_offset offset from the beginning for receiving input packets.
+ *                    Must be >=0 and <=mtu. The leading space should be initialized
+ *                    by the user before routing a packet.
+ * @param input input interface. Its MTU must be <= mtu - recv_offset.
+ * @param handler handler called when a packet is received to allow the user to route it
+ * @param user value passed to handler
+ * @param pg pending group
+ * @return 1 on success, 0 on failure
+ */
+int PacketRouter_Init (PacketRouter *o, int mtu, int recv_offset, PacketRecvInterface *input, PacketRouter_handler handler, void *user, BPendingGroup *pg) WARN_UNUSED;
+
+/**
+ * Frees the object.
+ * 
+ * @param o the object
+ */
+void PacketRouter_Free (PacketRouter *o);
+
+/**
+ * Routes the current packet to the given buffer.
+ * Must be called from the job context of the {@link PacketRouter_handler} handler.
+ * This function must not have been called successfully with a NULL next_buf in this
+ * handler.
+ * On success, copies part of the current packet to next one (regardless if next_buf
+ * is provided or not; if not, copies before receiving another packet).
+ * 
+ * @param o the object
+ * @param len total packet length (e.g. recv_offset + (recv_len from handler)).
+ *            Must be >=0 and <=mtu.
+ * @param output buffer to route to. Its MTU must be the same as of this object.
+ * @param next_buf if not NULL, on success, will be set to the address of a new current
+ *                 packet. In this case, this function can be called again to route the packet
+ *                 to another buffer. The returned pointer will be valid within the job context
+ *                 of the calling {@link PacketRouter_handler} handler, like the previous one.
+ * @param copy_offset Offset from the beginning for copying to the next packet.
+ *                    Must be >=0 and <=mtu.
+ * @param copy_len Number of bytes to copy from the old current
+ *                 packet to the next one. Must be >=0 and <= mtu - copy_offset.
+ * @return 1 on success, 0 on failure (buffer full)
+ */
+int PacketRouter_Route (PacketRouter *o, int len, RouteBuffer *output, uint8_t **next_buf, int copy_offset, int copy_len);
+
+/**
+ * Asserts that {@link PacketRouter_Route} can be called.
+ * 
+ * @param o the object
+ */
+void PacketRouter_AssertRoute (PacketRouter *o);
+
+#endif