add some programs for playing with DoS attacks on TCP

CMakeLists.txt

@@ -34,6 +34,7 @@ else ()
     build_switch(NCD "build badvpn-ncd" OFF)
     build_switch(TUNCTL "build badvpn-tunctl" OFF)
 endif ()
+build_switch(DOSTEST "build dostest-server and dostest-attacker" OFF)
 
 if (BUILD_NCD AND NOT (CMAKE_SYSTEM_NAME STREQUAL "Linux"))
     message(FATAL_ERROR "NCD is only available on Linux")
@@ -296,6 +297,11 @@ if (BUILD_NCD)
     add_subdirectory(ncd-request)
 endif ()
 
+# dostest
+if (BUILD_DOSTEST)
+    add_subdirectory(dostest)
+endif ()
+
 message(STATUS "Building components:")
 
 # print what we're building and what not

blog_channels.txt

@@ -128,3 +128,5 @@ ncd_net_ipv6_addr 4
 ncd_net_ipv6_route 4
 ncd_net_ipv4_addr_in_network 4
 ncd_net_ipv6_addr_in_network 4
+dostest_server 4
+dostest_attacker 4

dostest/CMakeLists.txt

@@ -0,0 +1,10 @@
+add_executable(dostest-server
+    dostest-server.c
+    StreamBuffer.c
+)
+target_link_libraries(dostest-server base system)
+
+add_executable(dostest-attacker
+    dostest-attacker.c
+)
+target_link_libraries(dostest-attacker base system)

dostest/StreamBuffer.c

@@ -0,0 +1,147 @@
+/**
+ * @file StreamBuffer.c
+ * @author Ambroz Bizjak <[email protected]>
+ * 
+ * @section LICENSE
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the author nor the
+ *    names of its contributors may be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <misc/balloc.h>
+#include <misc/minmax.h>
+
+#include "StreamBuffer.h"
+
+// called when receive operation is complete
+static void input_handler_done (void *vo, int data_len)
+{
+    StreamBuffer *o = (StreamBuffer *)vo;
+    ASSERT(data_len > 0)
+    ASSERT(data_len <= o->buf_size - (o->buf_start + o->buf_used))
+
+    // remember if buffer was empty
+    int was_empty = (o->buf_used == 0);
+
+    // increment buf_used by the amount that was received
+    o->buf_used += data_len;
+
+    // start another receive operation unless buffer is full
+    if (o->buf_used < o->buf_size - o->buf_start) {
+        int end = o->buf_start + o->buf_used;
+        StreamRecvInterface_Receiver_Recv(o->input, o->buf + end, o->buf_size - end);
+    }
+    else if (o->buf_used < o->buf_size) {
+        // wrap around
+        StreamRecvInterface_Receiver_Recv(o->input, o->buf, o->buf_start);
+    }
+
+    // if buffer was empty before, start send operation
+    if (was_empty) {
+        StreamPassInterface_Sender_Send(o->output, o->buf + o->buf_start, o->buf_used);
+    }
+}
+
+// called when send operation is complete
+static void output_handler_done (void *vo, int data_len)
+{
+    StreamBuffer *o = (StreamBuffer *)vo;
+    ASSERT(data_len > 0)
+    ASSERT(data_len <= o->buf_used)
+    ASSERT(data_len <= o->buf_size - o->buf_start)
+
+    // remember if buffer was full
+    int was_full = (o->buf_used == o->buf_size);
+
+    // increment buf_start and decrement buf_used by the
+    // amount that was sent
+    o->buf_start += data_len;
+    o->buf_used -= data_len;
+
+    // wrap around buf_start
+    if (o->buf_start == o->buf_size) {
+        o->buf_start = 0;
+    }
+
+    // start receive operation if buffer was full
+    if (was_full) {
+        int end;
+        int avail;
+        if (o->buf_used >= o->buf_size - o->buf_start) {
+            end = o->buf_used - (o->buf_size - o->buf_start);
+            avail = o->buf_start - end;
+        } else {
+            end = o->buf_start + o->buf_used;
+            avail = o->buf_size - end;
+        }
+        StreamRecvInterface_Receiver_Recv(o->input, o->buf + end, avail);
+    }
+
+    // start another receive send unless buffer is empty
+    if (o->buf_used > 0) {
+        int to_send = bmin_int(o->buf_used, o->buf_size - o->buf_start);
+        StreamPassInterface_Sender_Send(o->output, o->buf + o->buf_start, to_send);
+    }
+}
+
+int StreamBuffer_Init (StreamBuffer *o, int buf_size, StreamRecvInterface *input, StreamPassInterface *output)
+{
+    ASSERT(buf_size > 0)
+    ASSERT(input)
+    ASSERT(output)
+
+    // remember arguments
+    o->buf_size = buf_size;
+    o->input = input;
+    o->output = output;
+
+    // allocate buffer memory
+    o->buf = (uint8_t *)BAllocSize(bsize_fromint(o->buf_size));
+    if (!o->buf) {
+        goto fail0;
+    }
+
+    // set initial buffer state
+    o->buf_start = 0;
+    o->buf_used = 0;
+
+    // set receive and send done callbacks
+    StreamRecvInterface_Receiver_Init(o->input, input_handler_done, o);
+    StreamPassInterface_Sender_Init(o->output, output_handler_done, o);
+
+    // start receive operation
+    StreamRecvInterface_Receiver_Recv(o->input, o->buf, o->buf_size);
+
+    DebugObject_Init(&o->d_obj);
+    return 1;
+
+fail0:
+    return 0;
+}
+
+void StreamBuffer_Free (StreamBuffer *o)
+{
+    DebugObject_Free(&o->d_obj);
+
+    // free buffer memory
+    BFree(o->buf);
+}

dostest/StreamBuffer.h

@@ -0,0 +1,70 @@
+/**
+ * @file StreamBuffer.h
+ * @author Ambroz Bizjak <[email protected]>
+ * 
+ * @section LICENSE
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the author nor the
+ *    names of its contributors may be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef BADVPN_STREAMBUFFER_H
+#define BADVPN_STREAMBUFFER_H
+
+#include <misc/debug.h>
+#include <base/DebugObject.h>
+#include <flow/StreamRecvInterface.h>
+#include <flow/StreamPassInterface.h>
+
+/**
+ * Buffer object which reads data from a \link StreamRecvInterface and writes
+ * it to a \link StreamPassInterface.
+ */
+typedef struct {
+    int buf_size;
+    StreamRecvInterface *input;
+    StreamPassInterface *output;
+    uint8_t *buf;
+    int buf_start;
+    int buf_used;
+    DebugObject d_obj;
+} StreamBuffer;
+
+/**
+ * Initializes the buffer object.
+ * 
+ * @param o object to initialize
+ * @param buf_size size of the buffer. Must be >0.
+ * @param input input interface
+ * @param outout output interface
+ * @return 1 on success, 0 on failure
+ */
+int StreamBuffer_Init (StreamBuffer *o, int buf_size, StreamRecvInterface *input, StreamPassInterface *output) WARN_UNUSED;
+
+/**
+ * Frees the buffer object.
+ * 
+ * @param o object to free
+ */
+void StreamBuffer_Free (StreamBuffer *o);
+
+#endif