net: ICMP protocol

Packet format and common utilities for the Internet Control Message
Protocol.

Issue #2732

repos/os/include/net/icmp.h

@@ -0,0 +1,95 @@
+/*
+ * \brief  Internet Control Message Protocol
+ * \author Martin Stein
+ * \date   2018-03-23
+ */
+
+/*
+ * Copyright (C) 2018 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU Affero General Public License version 3.
+ */
+
+#ifndef _NET__ICMP_H_
+#define _NET__ICMP_H_
+
+/* Genode includes */
+#include <util/endian.h>
+#include <base/exception.h>
+
+namespace Genode { class Output; }
+
+namespace Net { class Icmp_packet; }
+
+
+class Net::Icmp_packet
+{
+	private:
+
+		Genode::uint8_t  _type;
+		Genode::uint8_t  _code;
+		Genode::uint16_t _checksum;
+		union {
+			Genode::uint32_t _rest_of_header_u32[1];
+			Genode::uint16_t _rest_of_header_u16[2];
+			Genode::uint8_t  _rest_of_header_u8[4];
+		};
+		Genode::uint8_t _data[0];
+
+	public:
+
+		struct Bad_data_type : Genode::Exception { };
+
+		enum class Type
+		{
+			ECHO_REPLY      = 0,
+			DST_UNREACHABLE = 3,
+			ECHO_REQUEST    = 8,
+		};
+
+		enum class Code
+		{
+			DST_NET_UNREACHABLE = 0,
+			ECHO_REQUEST        = 0,
+			ECHO_REPLY          = 0,
+		};
+
+		Genode::uint16_t calc_checksum(Genode::size_t data_sz) const;
+
+
+		/***************
+		 ** Accessors **
+		 ***************/
+
+		Type              type()           const { return (Type)_type; }
+		Code              code()           const { return (Code)_code; }
+		Genode::uint16_t  checksum()       const { return host_to_big_endian(_checksum); }
+		Genode::uint16_t  query_id()       const { return host_to_big_endian(_rest_of_header_u16[0]); }
+		Genode::uint16_t  query_seq()      const { return host_to_big_endian(_rest_of_header_u16[1]); }
+		Genode::uint32_t  rest_of_header() const { return host_to_big_endian(_rest_of_header_u32[0]); }
+
+		template <typename T> T &data(Genode::size_t data_size)
+		{
+			if (data_size < sizeof(T)) {
+				throw Bad_data_type();
+			}
+			return *(T *)(_data);
+		}
+
+		void type(Type v)                       { _type = (Genode::uint8_t)v; }
+		void code(Code v)                       { _code = (Genode::uint8_t)v; }
+		void checksum(Genode::uint16_t v)       { _checksum = host_to_big_endian(v); }
+		void rest_of_header(Genode::uint32_t v) { _rest_of_header_u32[0] = host_to_big_endian(v); }
+		void query_id(Genode::uint16_t v)       { _rest_of_header_u16[0] = host_to_big_endian(v); }
+		void query_seq(Genode::uint16_t v)      { _rest_of_header_u16[1] = host_to_big_endian(v); }
+
+
+		/*********
+		 ** log **
+		 *********/
+
+		void print(Genode::Output &output) const;
+};
+
+#endif /* _NET__ICMP_H_ */

repos/os/include/net/ipv4.h

@@ -117,8 +117,9 @@ class Net::Ipv4_packet
 
 		enum class Protocol : Genode::uint8_t
 		{
-			TCP = 6,
-			UDP = 17,
+			ICMP = 1,
+			TCP  = 6,
+			UDP  = 17,
 		};
 
 		struct Bad_data_type : Genode::Exception { };

repos/os/lib/mk/net.mk

@@ -1,3 +1,4 @@
-SRC_CC = ethernet.cc ipv4.cc dhcp.cc arp.cc udp.cc tcp.cc mac_address.cc
+SRC_CC += ethernet.cc ipv4.cc dhcp.cc arp.cc udp.cc tcp.cc mac_address.cc
+SRC_CC += icmp.cc
 
 vpath %.cc $(REP_DIR)/src/lib/net

repos/os/src/lib/net/icmp.cc

@@ -0,0 +1,54 @@
+/*
+ * \brief  Internet Control Message Protocol
+ * \author Martin Stein
+ * \date   2018-03-23
+ */
+
+/*
+ * Copyright (C) 2018 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU Affero General Public License version 3.
+ */
+
+/* Genode includes */
+#include <net/icmp.h>
+#include <base/output.h>
+
+using namespace Net;
+using namespace Genode;
+
+
+void Net::Icmp_packet::print(Output &output) const
+{
+	Genode::print(output, "\033[32mICMP\033[0m ", (unsigned)type(), " ",
+	                      (unsigned)code());
+}
+
+
+uint16_t Icmp_packet::calc_checksum(size_t data_sz) const
+{
+	/* do not sum-up checksum itself */
+	register long sum   = _type + _code;
+	addr_t        addr  = (addr_t)&_rest_of_header_u32;
+	size_t        count = sizeof(Icmp_packet) + data_sz - sizeof(_type) -
+	                      sizeof(_code) - sizeof(_checksum);
+
+	/* sum-up rest of header and data */
+	while (count > 1) {
+		sum   += *(uint16_t *)addr;
+		addr  += sizeof(uint16_t);
+		count -= sizeof(uint16_t);
+	}
+	/* add left-over byte, if any */
+	if (count) {
+		sum += *(uint8_t *)addr;
+	}
+	/*  fold 32-bit sum to 16 bits */
+	while (sum >> 16) {
+		sum = (sum & 0xffff) + (sum >> 16);
+	}
+	/* write to header */
+	uint16_t sum16 = ~sum;
+	return host_to_big_endian(sum16);
+}

repos/os/src/lib/net/ipv4.cc

@@ -16,6 +16,7 @@
 
 #include <net/udp.h>
 #include <net/tcp.h>
+#include <net/icmp.h>
 #include <net/ipv4.h>
 
 using namespace Genode;
@@ -32,6 +33,9 @@ void Net::Ipv4_packet::print(Genode::Output &output) const
 	case Protocol::UDP:
 		Genode::print(output, *reinterpret_cast<Udp_packet const *>(_data));
 		break;
+	case Protocol::ICMP:
+		Genode::print(output, *reinterpret_cast<Icmp_packet const *>(_data));
+		break;
 	default: ; }
 }