void handle_tcp_syn_packet(ipv6_hdr_t *ipv6_header, tcp_hdr_t *tcp_header,
socket_internal_t *tcp_socket)
{
msg_t m_send_tcp;
if (tcp_socket->socket_values.tcp_control.state == TCP_LISTEN) {
socket_internal_t *new_socket = new_tcp_queued_socket(ipv6_header,
tcp_header);
if (new_socket != NULL) {
#ifdef TCP_HC
update_tcp_hc_context(true, new_socket, tcp_header);
#endif
/* notify socket function destiny_socket_accept(..) that a new
* connection request has arrived. No need to wait for an answer
* because the server destiny_socket_accept() function isnt reading
* from anything other than the queued sockets */
net_msg_send(&m_send_tcp, tcp_socket->recv_pid, 0, TCP_SYN);
}
else {
printf("Dropped TCP SYN Message because an error occured while "\
"requesting a new queued socket!\n");
}
}
else {
printf("Dropped TCP SYN Message because socket was not in state TCP_LISTEN!");
}
}
void tcp_packet_handler(void)
{
msg_t m_recv_ip, m_send_ip;
ipv6_hdr_t *ipv6_header;
tcp_hdr_t *tcp_header;
uint8_t *payload;
socket_internal_t *tcp_socket = NULL;
uint16_t chksum;
while (1) {
msg_receive(&m_recv_ip);
ipv6_header = ((ipv6_hdr_t *)m_recv_ip.content.ptr);
tcp_header = ((tcp_hdr_t *)(m_recv_ip.content.ptr + IPV6_HDR_LEN));
#ifdef TCP_HC
tcp_socket = decompress_tcp_packet(ipv6_header);
#else
switch_tcp_packet_byte_order(tcp_header);
tcp_socket = get_tcp_socket(ipv6_header, tcp_header);
#endif
chksum = tcp_csum(ipv6_header, tcp_header);
payload = (uint8_t *)(m_recv_ip.content.ptr + IPV6_HDR_LEN + tcp_header->data_offset * 4);
if ((chksum == 0xffff) && (tcp_socket != NULL)) {
#ifdef TCP_HC
update_tcp_hc_context(true, tcp_socket, tcp_header);
#endif
/* Remove reserved bits from tcp flags field */
uint8_t tcp_flags = tcp_header->reserved_flags;
switch (tcp_flags) {
case TCP_ACK: {
/* only ACK Bit set */
uint8_t tcp_payload_len = NTOHS(ipv6_header->length) - TCP_HDR_LEN;
uint8_t state = tcp_socket->socket_values.tcp_control.state;
if ((tcp_payload_len > 0) && (state == TCP_ESTABLISHED)) {
/* handle data segments only when the connection was established successfully */
handle_tcp_no_flags_packet(ipv6_header, tcp_header, tcp_socket, payload, tcp_payload_len);
}
else if (tcp_payload_len == 0
&& (state == TCP_ESTABLISHED || state == TCP_SYN_RCVD
|| state == TCP_CLOSING || state == TCP_LAST_ACK)) {
/* no payload, acknowledging data only */
handle_tcp_ack_packet(ipv6_header, tcp_header, tcp_socket);
}
break;
}
case TCP_RST: {
printf("RST Bit set!\n");
/* only RST Bit set */
handle_tcp_rst_packet(ipv6_header, tcp_header, tcp_socket);
break;
}
case TCP_SYN: {
/* only SYN Bit set, look for matching, listening socket
* and request new queued socket */
printf("SYN Bit set!\n");
handle_tcp_syn_packet(ipv6_header, tcp_header, tcp_socket);
break;
}
case TCP_SYN_ACK: {
/* only SYN and ACK Bit set, complete three way handshake
* when socket in state TCP_SYN_SENT */
handle_tcp_syn_ack_packet(ipv6_header, tcp_header, tcp_socket);
break;
}
case TCP_FIN_ACK: {
if (tcp_socket->socket_values.tcp_control.state == TCP_ESTABLISHED) {
/* this is the first FIN */
printf("FIN ACK Bit set!\n");
handle_tcp_fin_packet(ipv6_header, tcp_header, tcp_socket);
}
else {
/* this is the response to FIN */
handle_tcp_fin_ack_packet(ipv6_header, tcp_header, tcp_socket);
}
break;
}
default: {
printf("Unable to process the incoming segment!\n");
}
}
}
else {
printf("Wrong checksum (%x) or no corresponding socket found!\n",
chksum);
printArrayRange(((uint8_t *)ipv6_header), IPV6_HDR_LEN +
NTOHS(ipv6_header->length), "Incoming");
print_tcp_status(INC_PACKET, ipv6_header, tcp_header,
&tcp_socket->socket_values);
}
msg_reply(&m_recv_ip, &m_send_ip);
}
}
uint16_t compress_tcp_packet(socket_internal_t *current_socket,
uint8_t *current_tcp_packet,
ipv6_hdr_t *temp_ipv6_header,
uint8_t flags,
uint8_t payload_length)
{
socket_t *current_tcp_socket = ¤t_socket->socket_values;
tcp_hc_context_t *tcp_context = ¤t_tcp_socket->tcp_control.tcp_context;
tcp_cb_t *tcp_cb = ¤t_tcp_socket->tcp_control;
tcp_hdr_t full_tcp_header;
uint16_t packet_size = 0;
/* Connection establisment phase, use FULL_HEADER TCP */
if (tcp_context->hc_type == FULL_HEADER) {
/* draft-aayadi-6lowpan-tcphc-01: 5.1 Full header TCP segment.
* Establishing Connection */
/* Move tcp packet 3 bytes to add padding and Context ID */
memmove(current_tcp_packet + 3, current_tcp_packet,
((((tcp_hdr_t *)current_tcp_packet)->data_offset) * 4) +
payload_length);
/* 1 padding byte with value 0x01 to introduce full header TCP_HC
* segment */
memset(current_tcp_packet, 0x01, 1);
/* Adding Context ID */
uint16_t current_context = HTONS(tcp_context->context_id);
memcpy(current_tcp_packet + 1, ¤t_context, 2);
/* Return correct header length (+3) */
packet_size = ((((tcp_hdr_t *)(current_tcp_packet + 3))->data_offset) * 4) + 3 +
payload_length;
/* Update the tcp context fields */
update_tcp_hc_context(false, current_socket, (tcp_hdr_t *)(current_tcp_packet + 3));
/* Convert TCP packet to network byte order */
switch_tcp_packet_byte_order((tcp_hdr_t *)(current_tcp_packet + 3));
return packet_size;
}
/* Check for header compression type: COMPRESSED_HEADER */
else if (tcp_context->hc_type == COMPRESSED_HEADER) {
/* draft-aayadi-6lowpan-tcphc-01: 5.1 Compressed header TCP segment. */
/* Temporary variable for TCP_HC_Header Bytes */
uint16_t tcp_hc_header = 0x0000;
/* Save TCP_Header to refresh TCP Context values after compressing the
* packet */
memcpy(&full_tcp_header, current_tcp_packet, TCP_HDR_LEN);
/* Temporary variable for storing TCP header beginning */
uint8_t *tcp_packet_begin = current_tcp_packet;
/* Position for first TCP header value, TCP_HC_Header and Context ID */
current_tcp_packet += 4;
/* Packet size value */
packet_size += 4;
/* 5.2. LOWPAN_TCPHC Format */
/* First 3 bits of TCP_HC_Header are not exactly specified. In this
* implementation they are (1|1|0) * for compressed headers and the
* CID is always 16 bits (1) */
/* (1|1|0|1) = D */
tcp_hc_header |= 0xD000;
/*----------------------------------*/
/*| Sequence number handling |*/
/*----------------------------------*/
if (full_tcp_header.seq_nr == tcp_context->seq_snd) {
/* Nothing to do, Seq = (0|0) */
}
/* If the 24 most significant bits haven't changed from previous
* packet, don't transmit them */
else if ((full_tcp_header.seq_nr & 0xFFFFFF00) == (tcp_context->seq_snd &
0xFFFFFF00)) {
/* Seq = (0|1) */
tcp_hc_header |= 0x0400;
/* Copy first 8 less significant bits of sequence number into
* buffer */
*current_tcp_packet = (uint8_t)(full_tcp_header.seq_nr & 0x000000FF);
current_tcp_packet += 1;
packet_size += 1;
}
/* If the 16 most significant bits haven't changed from previous packet,
* don't transmit them */
else if ((full_tcp_header.seq_nr & 0xFFFF0000) == (tcp_context->seq_snd & 0xFFFF0000)) {
/* Seq = (1|0) */
tcp_hc_header |= 0x0800;
/* Copy first 16 less significant bits of sequence number into buffer */
*((uint16_t *)current_tcp_packet) =
HTONS((uint16_t)(full_tcp_header.seq_nr & 0x0000FFFF));
current_tcp_packet += 2;
packet_size += 2;
}
/* Sending uncompressed sequence number */
else {
/* Seq = (1|1) */
tcp_hc_header |= 0x0C00;
/* Copy all bits of sequence number into buffer */
uint32_t cur_seq_no = HTONL(full_tcp_header.seq_nr);
memcpy(current_tcp_packet, &cur_seq_no, 4);
current_tcp_packet += 4;
packet_size += 4;
}
/*----------------------------------*/
/*| Acknowledgment number handling |*/
/*----------------------------------*/
if ((IS_TCP_ACK(full_tcp_header.reserved_flags) &&
(tcp_cb->tcp_context.ack_snd == full_tcp_header.ack_nr))) {
tcp_context->ack_snd = tcp_context->seq_rcv;
}
if (full_tcp_header.ack_nr == tcp_context->ack_snd) {
/* Nothing to do, Ack = (0|0) */
}
/* If the 24 most significant bits haven't changed from previous packet,
* don't transmit them */
else if ((full_tcp_header.ack_nr & 0xFFFFFF00) == (tcp_context->ack_snd &
0xFFFFFF00)) {
/* Ack = (0|1) */
tcp_hc_header |= 0x0100;
/* Copy first 8 less significant bits of acknowledgment number into
* buffer */
*current_tcp_packet = (uint8_t)(full_tcp_header.ack_nr & 0x000000FF);
current_tcp_packet += 1;
packet_size += 1;
}
/* If the 16 most significant bits haven't changed from previous packet,
* don't transmit them */
else if ((full_tcp_header.ack_nr & 0xFFFF0000) == (tcp_context->ack_snd &
0xFFFF0000)) {
/* Ack = (1|0) */
tcp_hc_header |= 0x0200;
/* Copy first 16 less significant bits of acknowledgment number
* into buffer */
*((uint16_t *)current_tcp_packet) =
HTONS((uint16_t)(full_tcp_header.ack_nr & 0x0000FFFF));
current_tcp_packet += 2;
packet_size += 2;
}
/* Sending uncompressed acknowledgment number */
else {
/* Ack = (1|1) */
tcp_hc_header |= 0x0300;
/* Copy all bits of acknowledgment number into buffer */
uint32_t cur_ack_nr = HTONL(full_tcp_header.ack_nr);
memcpy(current_tcp_packet, &cur_ack_nr, 4);
current_tcp_packet += 4;
packet_size += 4;
}
/*----------------------------------*/
/*| Window handling |*/
/*----------------------------------*/
if (full_tcp_header.window == tcp_context->wnd_snd) {
/* Nothing to do, Wnd = (0|0) */
}
/* If the 8 most significant bits haven't changed from previous packet,
* don't transmit them */
else if ((full_tcp_header.window & 0xFF00) == (tcp_context->wnd_snd & 0xFF00)) {
/* Wnd = (0|1) */
tcp_hc_header |= 0x0040;
/* Copy first 8 less significant bits of window size into buffer */
*current_tcp_packet = (uint8_t)(full_tcp_header.window & 0x00FF);
current_tcp_packet += 1;
packet_size += 1;
}
/* If the 8 less significant bits haven't changed from previous packet,
* don't transmit them */
else if ((full_tcp_header.window & 0x00FF) == (tcp_context->wnd_snd &
0x00FF)) {
/* Wnd = (1|0) */
tcp_hc_header |= 0x0080;
/* Copy first 8 most significant bits of window size into buffer */
*current_tcp_packet = (uint8_t)(full_tcp_header.window & 0xFF00);
current_tcp_packet += 1;
packet_size += 1;
}
/* Sending uncompressed window */
else {
/* Wnd = (1|1) */
tcp_hc_header |= 0x00C0;
/* Copy all bits of window size into buffer */
uint16_t cur_window = HTONS(full_tcp_header.window);
memcpy(current_tcp_packet, &cur_window, 2);
current_tcp_packet += 2;
packet_size += 2;
}
/* FIN flag */
if (IS_TCP_FIN(full_tcp_header.reserved_flags)) {
/* F = (1) */
tcp_hc_header |= 0x0008;
}
/* Copy checksum into buffer */
uint16_t cur_chk_sum = HTONS(full_tcp_header.checksum);
memcpy(current_tcp_packet, &cur_chk_sum, 2);
current_tcp_packet += 2;
packet_size += 2;
/* Copy TCP_HC Bytes into buffer */
uint16_t cur_tcp_hc_header = HTONS(tcp_hc_header);
memcpy(tcp_packet_begin, &cur_tcp_hc_header, 2);
/* Copy TCP_HC Context ID into buffer */
uint16_t cur_context_id = HTONS(tcp_context->context_id);
memcpy(tcp_packet_begin + 2, &cur_context_id, 2);
/* Move payload to end of tcp header */
memmove(current_tcp_packet, tcp_packet_begin + TCP_HDR_LEN,
payload_length);
/* Adding TCP payload length to TCP_HC header length */
packet_size += payload_length;
update_tcp_hc_context(false, current_socket, &full_tcp_header);
return packet_size;
}
/* Check for header compression type: MOSTLY_COMPRESSED_HEADER */
else if (tcp_context->hc_type == MOSTLY_COMPRESSED_HEADER) {
/* draft-aayadi-6lowpan-tcphc-01: 5.1 Compressed header TCP segment. */
/* Temporary variable for TCP_HC_Header Bytes */
uint16_t tcp_hc_header = 0x0000;
/* Save TCP_Header to refresh TCP Context values after compressing the
* packet */
memcpy(&full_tcp_header, current_tcp_packet, TCP_HDR_LEN);
/* Temporary variable for storing TCP header beginning */
uint8_t *tcp_packet_begin = current_tcp_packet;
/* Position for first TCP header value, TCP_HC_Header and Context ID */
current_tcp_packet += 4;
/* Packet size value */
packet_size += 4;
/* 5.2. LOWPAN_TCPHC Format */
/* First 3 bits of TCP_HC_Header are not exactly specified. In this
* implementation they are (1|0|0) for mostly compressed headers and
* the CID is always 16 bits (1) */
/* (1|0|0|1) = 9 */
tcp_hc_header |= 0x9000;
/*----------------------------------*/
/*| Sequence number handling |*/
/*----------------------------------*/
/* Sending uncompressed sequence number */
/* Seq = (1|1) */
tcp_hc_header |= 0x0C00;
/* Copy all bits of sequence number into buffer */
uint32_t cur_seq_no = HTONL(full_tcp_header.seq_nr);
memcpy(current_tcp_packet, &cur_seq_no, 4);
current_tcp_packet += 4;
packet_size += 4;
/*----------------------------------*/
/*| Acknowledgment number handling |*/
/*----------------------------------*/
/* Ack = (1|1) */
tcp_hc_header |= 0x0300;
/* Copy all bits of acknowledgment number into buffer */
uint32_t cur_ack_nr = HTONL(full_tcp_header.ack_nr);
memcpy(current_tcp_packet, &cur_ack_nr, 4);
current_tcp_packet += 4;
packet_size += 4;
/*----------------------------------*/
/*| Window handling |*/
/*----------------------------------*/
/* Wnd = (1|1) */
tcp_hc_header |= 0x00C0;
/* Copy all bits of window size into buffer */
uint16_t cur_window = HTONS(full_tcp_header.window);
memcpy(current_tcp_packet, &cur_window, 2);
current_tcp_packet += 2;
packet_size += 2;
/* FIN flag */
if (IS_TCP_FIN(full_tcp_header.reserved_flags)) {
/* F = (1) */
tcp_hc_header |= 0x0008;
}
/* Copy checksum into buffer */
uint16_t cur_chk_sum = HTONS(full_tcp_header.checksum);
memcpy(current_tcp_packet, &cur_chk_sum, 2);
current_tcp_packet += 2;
packet_size += 2;
/* Copy TCP_HC Bytes into buffer */
uint16_t cur_tcp_hc_header = HTONS(tcp_hc_header);
memcpy(tcp_packet_begin, &cur_tcp_hc_header, 2);
/* Copy TCP_HC Context ID into buffer */
uint16_t cur_context_id = HTONS(tcp_context->context_id);
memcpy(tcp_packet_begin + 2, &cur_context_id, 2);
/* Move payload to end of tcp header */
memmove(current_tcp_packet, tcp_packet_begin + TCP_HDR_LEN,
payload_length);
/* Adding TCP payload length to TCP_HC header length */
packet_size += payload_length;
update_tcp_hc_context(false, current_socket, &full_tcp_header);
return packet_size;
}
return 0;
}
void tcp_packet_handler(void)
{
msg_t m_recv_ip, m_send_ip;
ipv6_hdr_t *ipv6_header;
tcp_hdr_t *tcp_header;
uint8_t *payload;
socket_internal_t *tcp_socket = NULL;
uint16_t chksum;
while (1) {
msg_receive(&m_recv_ip);
ipv6_header = ((ipv6_hdr_t *)m_recv_ip.content.ptr);
tcp_header = ((tcp_hdr_t *)(m_recv_ip.content.ptr + IPV6_HDR_LEN));
#ifdef TCP_HC
tcp_socket = decompress_tcp_packet(ipv6_header);
#else
switch_tcp_packet_byte_order(tcp_header);
tcp_socket = get_tcp_socket(ipv6_header, tcp_header);
#endif
chksum = tcp_csum(ipv6_header, tcp_header);
payload = (uint8_t *)(m_recv_ip.content.ptr + IPV6_HDR_LEN +
tcp_header->dataOffset_reserved * 4);
if ((chksum == 0xffff) && (tcp_socket != NULL)) {
#ifdef TCP_HC
update_tcp_hc_context(true, tcp_socket, tcp_header);
#endif
/* Remove reserved bits from tcp flags field */
uint8_t tcp_flags = tcp_header->reserved_flags & REMOVE_RESERVED;
switch(tcp_flags) {
case TCP_ACK: {
/* only ACK Bit set */
handle_tcp_ack_packet(ipv6_header, tcp_header, tcp_socket);
break;
}
case TCP_RST: {
printf("RST Bit set!\n");
/* only RST Bit set */
handle_tcp_rst_packet(ipv6_header, tcp_header, tcp_socket);
break;
}
case TCP_SYN: {
/* only SYN Bit set, look for matching, listening socket
* and request new queued socket */
printf("SYN Bit set!\n");
handle_tcp_syn_packet(ipv6_header, tcp_header, tcp_socket);
break;
}
case TCP_SYN_ACK: {
/* only SYN and ACK Bit set, complete three way handshake
* when socket in state SYN_SENT */
handle_tcp_syn_ack_packet(ipv6_header, tcp_header, tcp_socket);
break;
}
case TCP_FIN: {
printf("FIN Bit set!\n");
/* only FIN Bit set */
handle_tcp_fin_packet(ipv6_header, tcp_header, tcp_socket);
break;
}
case TCP_FIN_ACK: {
printf("FIN ACK Bit set!\n");
/* only FIN and ACK Bit set */
handle_tcp_fin_ack_packet(ipv6_header, tcp_header, tcp_socket);
break;
}
default: {
handle_tcp_no_flags_packet(ipv6_header, tcp_header,
tcp_socket, payload);
}
}
}
else {
printf("Wrong checksum (%x) or no corresponding socket found!\n",
chksum);
printArrayRange(((uint8_t *)ipv6_header), IPV6_HDR_LEN +
ipv6_header->length, "Incoming");
print_tcp_status(INC_PACKET, ipv6_header, tcp_header,
&tcp_socket->socket_values);
}
msg_reply(&m_recv_ip, &m_send_ip);
}
}
