Move checksum utils into their own file

src/utils/checksum_utils.cpp

@@ -0,0 +1,131 @@
+/*
+ * Copyright (c) 2017, Matias Fontanini
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ * 
+ * * Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * * 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.
+ * 
+ * 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 COPYRIGHT
+ * OWNER OR CONTRIBUTORS 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 "utils/checksum_utils.h"
+#include <cstring>
+#include "ip_address.h"
+#include "ipv6_address.h"
+#include "endianness.h"
+#include "memory_helpers.h"
+
+using std::memcpy;
+
+using Tins::Memory::InputMemoryStream;
+using Tins::Memory::OutputMemoryStream;
+
+namespace Tins {
+namespace Utils {
+
+uint32_t do_checksum(const uint8_t* start, const uint8_t* end) {
+    return Endian::host_to_be<uint32_t>(sum_range(start, end));
+}
+
+uint16_t sum_range(const uint8_t* start, const uint8_t* end) {
+    uint32_t checksum(0);
+    const uint8_t* last = end;
+    uint16_t buffer = 0;
+    uint16_t padding = 0;
+    const uint8_t* ptr = start;
+
+    if (((end - start) & 1) == 1) {
+        last = end - 1;
+        padding = Endian::host_to_le<uint16_t>(*(end - 1));
+    }
+
+    while (ptr < last) {
+        memcpy(&buffer, ptr, sizeof(uint16_t));
+        checksum += buffer;
+        ptr += sizeof(uint16_t);
+    }
+
+    checksum += padding;
+    while (checksum >> 16) {
+        checksum = (checksum & 0xffff) + (checksum >> 16);
+    }
+    return checksum;  
+}
+
+template <size_t buffer_size, typename AddressType>
+uint32_t generic_pseudoheader_checksum(const AddressType& source_ip, 
+                                       const AddressType& dest_ip,
+                                       uint16_t len,
+                                       uint16_t flag) {
+    uint8_t buffer[buffer_size];
+    OutputMemoryStream stream(buffer, sizeof(buffer));
+    stream.write(source_ip);
+    stream.write(dest_ip);
+    stream.write(Endian::host_to_be(flag));
+    stream.write(Endian::host_to_be(len));
+
+    InputMemoryStream input_stream(buffer, sizeof(buffer));
+    uint32_t checksum = 0;
+    while (input_stream) {
+        checksum += input_stream.read<uint16_t>();
+    }
+    return checksum;
+}
+
+uint32_t pseudoheader_checksum(IPv4Address source_ip, 
+                               IPv4Address dest_ip,
+                               uint16_t len,
+                               uint16_t flag) {
+    return generic_pseudoheader_checksum<sizeof(uint32_t) * 3>(
+        source_ip, dest_ip, len, flag
+    );
+}
+
+uint32_t pseudoheader_checksum(IPv6Address source_ip,
+                               IPv6Address dest_ip,
+                               uint16_t len,
+                               uint16_t flag) {
+    return generic_pseudoheader_checksum<IPv6Address::address_size * 2 + sizeof(uint16_t) * 2>(
+        source_ip, dest_ip, len, flag
+    );
+}
+
+uint32_t crc32(const uint8_t* data, uint32_t data_size) {
+    uint32_t i, crc = 0;
+    static uint32_t crc_table[] = {
+        0x4DBDF21C, 0x500AE278, 0x76D3D2D4, 0x6B64C2B0,
+        0x3B61B38C, 0x26D6A3E8, 0x000F9344, 0x1DB88320,
+        0xA005713C, 0xBDB26158, 0x9B6B51F4, 0x86DC4190,
+        0xD6D930AC, 0xCB6E20C8, 0xEDB71064, 0xF0000000
+    };
+
+    for (i = 0; i < data_size; ++i) {
+        crc = (crc >> 4) ^ crc_table[(crc ^ data[i]) & 0x0F];
+        crc = (crc >> 4) ^ crc_table[(crc ^ (data[i] >> 4)) & 0x0F];
+    }
+
+    return crc;
+}
+
+
+} // Utils
+} // Tins