Add ICMPExtension class

src/CMakeLists.txt

@@ -25,6 +25,7 @@ ADD_LIBRARY(
     dot1q.cpp
     eapol.cpp
     ethernetII.cpp
+    icmp_extension.cpp
     icmp.cpp
     icmpv6.cpp
     internals.cpp

src/icmp_extension.cpp

@@ -0,0 +1,54 @@
+#include <algorithm>
+#include "icmp_extension.h"
+#include "endianness.h"
+#include "exceptions.h"
+
+using std::runtime_error;
+
+namespace Tins {
+
+const uint32_t ICMPExtension::BASE_HEADER_SIZE = sizeof(uint16_t) + sizeof(uint8_t) * 2;
+
+ICMPExtension::ICMPExtension(const uint8_t* buffer, uint32_t total_sz) {
+    // Check for the base header (u16 length + u8 clss + u8 type)
+    if (total_sz < BASE_HEADER_SIZE) {
+        throw malformed_packet();
+    }
+
+    uint16_t length = Endian::be_to_host(*(const uint16_t*)buffer);
+    buffer += sizeof(uint16_t);
+    extension_class_ = *buffer++;
+    extension_type_ = *buffer++;
+    total_sz -= BASE_HEADER_SIZE;
+    // Length is BASE_HEADER_SIZE + payload size, make sure it's valid
+    if (length < BASE_HEADER_SIZE || length - BASE_HEADER_SIZE > total_sz) {
+        throw malformed_packet();
+    }
+    length -= BASE_HEADER_SIZE;
+    payload_.assign(buffer, buffer + length);
+}
+
+uint32_t ICMPExtension::extension_size() const {
+    return BASE_HEADER_SIZE + payload_.size();
+}
+
+void ICMPExtension::serialize(uint8_t* buffer, uint32_t buffer_size) const {
+    if (buffer_size < extension_size()) {
+        throw runtime_error("Serialization buffer is too small");
+    }
+    *(uint16_t*)buffer = Endian::host_to_be<uint16_t>(extension_size());
+    buffer += sizeof(uint16_t);
+    *buffer = extension_class_;
+    buffer += sizeof(uint8_t);
+    *buffer = extension_type_;
+    buffer += sizeof(uint8_t);
+    copy(payload_.begin(), payload_.end(), buffer);
+}
+
+ICMPExtension::serialization_type ICMPExtension::serialize() const {
+    serialization_type output(extension_size());
+    serialize(&output[0], output.size());
+    return output;
+}
+
+} // Tins