diff --git a/CMakeLists.txt b/CMakeLists.txt
index ba8d1d90bdb54de37a3e23de29fce1b859fd62d6..011e57cb1c192fc3146abaa79d528e43980b65ae 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -54,6 +54,7 @@ set(AES67_INCLUDES
${AES67_DIR}/src/include/aes67/rtp-avp.h
${AES67_DIR}/src/include/aes67/rtp.h
${AES67_DIR}/src/include/aes67/audio.h
+ ${AES67_DIR}/src/include/aes67/eth.h
${AES67_DIR}/src/include/aes67/host/time.h
${AES67_DIR}/src/include/aes67/host/timer.h
@@ -69,6 +70,7 @@ set(AES67_SOURCE_FILES
${AES67_DIR}/src/core/sdp.c
${AES67_DIR}/src/core/sap.c
${AES67_DIR}/src/core/rtp.c
+ ${AES67_DIR}/src/core/eth.c
)
diff --git a/README.md b/README.md
index 63b46a4a4ed283f1c80eb6d75ad5737ea6a6d343..02f76c8b434daee7e5bdd77f2200be3f44b4424d 100644
--- a/README.md
+++ b/README.md
@@ -33,7 +33,8 @@ https://github.com/tschiemer/aes67
- Stream
- - [ ] RTP/RTCP
+ - [ ] RTP
+ - [ ] RTCP
- Command line / developer utilities
diff --git a/src/core/eth.c b/src/core/eth.c
new file mode 100644
index 0000000000000000000000000000000000000000..2a3ac496ff101d9a9d8f97894020da8c8428af11
--- /dev/null
+++ b/src/core/eth.c
@@ -0,0 +1,37 @@
+/**
+ * AES67 Framework
+ * Copyright (C) 2021 Philip Tschiemer, https://github.com/tschiemer/aes67
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "aes67/eth.h"
+
+u16_t aes67_ipv4_header_checksum(u8_t * header)
+{
+ int len = (header[AES67_IPV4_HEADER_IHL_OFFSET] & AES67_IPV4_HEADER_IHL_MASK) << 1;
+
+ u32_t sum = 0;
+ while(len--){
+ sum += *(header++) << 8;
+ sum += *(header++);
+ }
+
+ sum = (sum & 0xffff) + (sum >> 16);
+ sum = (sum & 0xffff) + (sum >> 16);
+
+ sum = (~sum) & 0xffff;
+
+ return sum;
+}
\ No newline at end of file
diff --git a/src/include/aes67/def.h b/src/include/aes67/def.h
index 21859f199a5176b834b15130b34a1314a82e98b2..ab9f0f91bdc69fc44d494ed9740d7f239543092b 100644
--- a/src/include/aes67/def.h
+++ b/src/include/aes67/def.h
@@ -161,6 +161,7 @@ s32_t aes67_atoi(u8_t * str, size_t len, s32_t base, u16_t * readlen);
u8_t aes67_xor8(u8_t * buf, size_t count);
#ifndef aes67_crc32
+#define AES67_CRC32_VERIFY_VALUE 0x2144DF1C
u32_t aes67_crc32(u8_t * buf, size_t count);
#endif
diff --git a/src/include/aes67/eth.h b/src/include/aes67/eth.h
new file mode 100644
index 0000000000000000000000000000000000000000..8f6fc1ccf4781b3a33560a975a78f612abfe3e49
--- /dev/null
+++ b/src/include/aes67/eth.h
@@ -0,0 +1,157 @@
+/**
+ * @file eth.h
+ * Lower level networking utilities, ethernet, ip, udp.
+ *
+ * References:
+ * AES67-2018 https://www.aes.org/publications/standards/search.cfm?docID=96
+ */
+
+/**
+ * AES67 Framework
+ * Copyright (C) 2021 Philip Tschiemer, https://github.com/tschiemer/aes67
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef AES67_ETH_H
+#define AES67_ETH_H
+
+#include "aes67/arch.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+//#define AES67_ETH_HEADER_DST 0
+//#define AES67_ETH_HEADER_SRC 6
+//#define
+
+#define AES67_ETH_ETHERTYPE_IPv4 0x0800
+#define AES67_ETH_ETHERTYPE_ARP 0x0806 // address resolution protocol
+#define AES67_ETH_ETHERTYPE_AVTP 0x22f0 // audio video transport protocol
+#define AES67_ETH_ETHERTYPE_SRP 0x22ea // stream reservation protocol
+#define AES67_ETH_ETHERTYPE_IPv6 0x86dd
+#define AES67_ETH_ETHERTYPE_VLAN_TAG 0x8100
+#define AES67_ETH_ETHERTYPE_IPv6 0x86dd
+#define AES67_ETH_ETHERTYPE_CobraNet 0x8819
+
+//#define AES67_ETH_CRC32_POLY 0x04c11db7
+//#define AES67_ETH_CRC32_INITIAL 0xffffffff
+
+#define AES67_IPV4_HEADER_MINSIZE 20
+
+#define AES67_IPV4_HEADER_VERSION_OFFSET 0
+#define AES67_IPV4_HEADER_VERSION_MASK 0xf0
+#define AES67_IPV4_HEADER_IHL_OFFSET 0
+#define AES67_IPV4_HEADER_IHL_MASK 0x0f
+#define AES67_IPV4_HEADER_DSCP_OFFSET 1 // Differentiated Services Code Point (DiffServ)
+#define AES67_IPV4_HEADER_DSCP_MASK 0b11111100
+#define AES67_IPV4_HEADER_ECN_OFFSET 1 // Explicit Congestion Notification
+#define AES67_IPV4_HEADER_ECN_MASK 0b11
+#define AES67_IPV4_HEADER_LENGTH_OFFSET 2
+#define AES67_IPV4_HEADER_IDENTIFICATION_OFFSET 4
+#define AES67_IPV4_HEADER_FRAGMENTATION_OFFSET 6
+#define AES67_IPV4_HEADER_FRAGMENTATION_FLAGS_MASK 0b1110000000000000
+#define AES67_IPV4_HEADER_FRAGMENTATION_FOFFSET_MASK 0b000111111111111
+#define AES67_IPV4_HEADER_TTL_OFFSET 8
+#define AES67_IPV4_HEADER_PROTOCOL_OFFSET 9
+#define AES67_IPV4_HEADER_HEADER_CHECKSUM_OFFSET 10
+#define AES67_IPV4_HEADER_SOURCE_OFFSET 12
+#define AES67_IPV4_HEADER_DESTINATION_OFFSET 16
+#define AES67_IPV4_HEADER_DATA_OFFSET 20 // assuming IHL == 5 (ie no extra headers)
+
+#define AES67_IPV4_HEADER_VERSION_4 0x40
+#define AES67_IPV4_HEADER_IHL_BASIC 0x05
+
+#define AES67_IPV4_HEADER_DSCP_DEFAULT 0
+#define AES67_IPV4_HEADER_DSCP_DEFAULT_CLOCK (46<<2) // Class EF
+#define AES67_IPV4_HEADER_DSCP_DEFAULT_MEDIA (34<<2) // Class AF41
+
+#define AES67_IPV4_HEADER_ECN_NON_ECT 0 // Non ECN capable transport
+#define AES67_IPV4_HEADER_ECN_ECT0 1 // ECN capable transport 0
+#define AES67_IPV4_HEADER_ECN_ECT1 2 // ECN capable transport 1
+#define AES67_IPV4_HEADER_ECN_CE 3 // Congestion encountered
+
+
+#define AES67_IPV4_HEADER_FRAGMENTATION_FLAGS_DF 0b0100000000000000 // don't fragment
+#define AES67_IPV4_HEADER_FRAGMENTATION_FLAGS_MF 0b0010000000000000 // more fragments
+
+#define AES67_IPV4_HEADER_PROTOCOL_ICMP 0x01
+#define AES67_IPV4_HEADER_PROTOCOL_IGMP 0x02
+#define AES67_IPV4_HEADER_PROTOCOL_TCP 0x06
+#define AES67_IPV4_HEADER_PROTOCOL_UDP 0x11
+#define AES67_IPV4_HEADER_PROTOCOL_RSVP 0x2e
+
+// No 802.1Q headers
+struct aes67_eth_frame {
+ u8_t destination[6];
+ u8_t source[6];
+ u8_t tpid[2];
+ u16_t length;
+ u8_t data[];
+} PACK_STRUCT;
+
+
+struct aes67_ipv4_packet {
+ u8_t byte0; // version + IHL
+ u8_t byte1; // DSCP + ECN
+ u16_t length; // total packet size (header + data, >= 20)
+ u16_t identification; // fragmentation identification
+ u16_t fragmentation; // flags + offset
+ u8_t ttl; // time to live
+ u8_t protocol; //
+ u16_t header_checksum; // The checksum field is the 16-bit ones' complement of the ones' complement sum of all
+ // 16-bit words in the header. For purposes of computing the checksum, the value of the
+ // checksum field is zero.
+ union {
+ u8_t bytes[4];
+ u32_t value;
+ } PACK_STRUCT source;
+ union {
+ u8_t bytes[4];
+ u32_t value;
+ } PACK_STRUCT destination;
+ u8_t data[];
+} PACK_STRUCT;
+
+struct aes67_udp_packet {
+ u16_t source_port;
+ u16_t destination_port;
+ u16_t length;
+ u16_t checksum;
+ u8_t data[];
+} PACK_STRUCT;
+
+struct aes67_udp_ipv4_pseudoheader {
+ union {
+ u8_t bytes[4];
+ u32_t value;
+ } PACK_STRUCT source;
+ union {
+ u8_t bytes[4];
+ u32_t value;
+ } PACK_STRUCT destination;
+ u8_t zeroes;
+ u8_t protocol;
+ u16_t udp_length;
+ struct aes67_udp_packet udp;
+};
+
+u16_t aes67_ipv4_header_checksum(u8_t * header);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif //AES67_ETH_H
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index fbf7bf4920bd7bb0b714375ca4cabd7bcdf65a80..8d0ecea2bc0314d7c2f8d595a3929eae2b9e3d41 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -30,6 +30,7 @@ set(TEST_UNIT_SOURCE_FILES
unit/sap.cpp
unit/sdp.cpp
unit/rtp.cpp
+ unit/eth.cpp
)
diff --git a/test/unit/eth.cpp b/test/unit/eth.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..bd198c52afca5e31a4eb7d0848f0549a7c68c6ad
--- /dev/null
+++ b/test/unit/eth.cpp
@@ -0,0 +1,57 @@
+/**
+ * AES67 Framework
+ * Copyright (C) 2021 Philip Tschiemer, https://github.com/tschiemer/aes67
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+#include "CppUTest/TestHarness.h"
+
+#include <string>
+
+#include "aes67/eth.h"
+
+TEST_GROUP(Eth_TestGroup){};
+
+TEST(Eth_TestGroup, eth_ipv4_header_checksum) {
+
+ // test value from https://en.wikipedia.org/wiki/IPv4_header_checksum
+
+ // without checksum
+ uint8_t ip1[] = {
+ 0x45, 0x00, 0x00, 0x73, 0x00, 0x00, 0x40, 0x00, 0x40, 0x11,
+ 0, 0, // checksum
+ 0xc0, 0xa8, 0x00, 0x01,
+ 0xc0, 0xa8, 0x00, 0xc7, // end of header
+ 0x00, 0x35, 0xe9, 0x7c, 0x00, 0x5f, 0x27, 0x9f, 0x1e, 0x4b, 0x81, 0x80
+ };
+
+ u16_t ck = aes67_ipv4_header_checksum(ip1);
+
+ CHECK_EQUAL(0xb861, ck);
+
+ // same WITH checksum
+ uint8_t ip2[] = {
+ 0x45, 0x00, 0x00, 0x73, 0x00, 0x00, 0x40, 0x00, 0x40,
+ 0x11, 0xb8, // checksum
+ 0x61, 0xc0, 0xa8, 0x00, 0x01,
+ 0xc0, 0xa8, 0x00, 0xc7, // end of header
+ 0x00, 0x35, 0xe9, 0x7c, 0x00, 0x5f, 0x27, 0x9f, 0x1e, 0x4b, 0x81, 0x80
+ };
+
+ ck = aes67_ipv4_header_checksum(ip2);
+
+ CHECK_EQUAL(0x0000, ck);
+}
\ No newline at end of file