/** * Destiny TCP header compression * * Copyright (C) 2013 INRIA. * * This file is subject to the terms and conditions of the GNU Lesser General * Public License. See the file LICENSE in the top level directory for more * details. * * @ingroup destiny * @{ * @file tcp_hc.c * @brief TCP HC * @author Oliver Gesch * @} */ #include #include #include #include "ipv6.h" #include "net_help.h" #include "socket.h" #include "tcp.h" #include "tcp_hc.h" #ifdef TCP_HC socket_internal_t *get_tcp_socket_by_context(ipv6_hdr_t *current_ipv6_header, uint16_t current_context) { socket_internal_t *temp_socket; for (int i = 1; i < MAX_SOCKETS + 1; i++) { temp_socket = get_socket(i); if ((temp_socket != NULL) && ipv6_addr_is_equal(&temp_socket->socket_values.foreign_address.sin6_addr, ¤t_ipv6_header->srcaddr) && ipv6_addr_is_equal(&temp_socket->socket_values.local_address.sin6_addr, ¤t_ipv6_header->destaddr) && (temp_socket->socket_values.tcp_control.tcp_context.context_id == current_context)) { return temp_socket; } } return NULL; } void update_tcp_hc_context(bool incoming, socket_internal_t *current_socket, tcp_hdr_t *current_tcp_packet) { tcp_hc_context_t *current_context = ¤t_socket->socket_values.tcp_control.tcp_context; if (incoming) { current_context->ack_rcv = current_tcp_packet->ack_nr; current_context->seq_rcv = current_tcp_packet->seq_nr; current_context->wnd_rcv = current_tcp_packet->window; } else { current_context->ack_snd = current_tcp_packet->ack_nr; current_context->seq_snd = current_tcp_packet->seq_nr; current_context->wnd_snd = current_tcp_packet->window; } } 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)->dataOffset_reserved) * 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))->dataOffset_reserved) * 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; } socket_internal_t *decompress_tcp_packet(ipv6_hdr_t *temp_ipv6_header) { uint8_t *packet_buffer = ((uint8_t *)temp_ipv6_header) + IPV6_HDR_LEN; uint16_t tcp_hc_header; socket_internal_t *current_socket = NULL; uint16_t packet_size = 0; /* Full header TCP segment */ if (*(((uint8_t *)temp_ipv6_header) + IPV6_HDR_LEN) == 0x01) { switch_tcp_packet_byte_order(((tcp_hdr_t *)(((uint8_t *)temp_ipv6_header) + IPV6_HDR_LEN + 3))); current_socket = get_tcp_socket(temp_ipv6_header, ((tcp_hdr_t *)(((uint8_t *)temp_ipv6_header) + IPV6_HDR_LEN + 3))); if (current_socket != NULL) { if (current_socket->socket_values.tcp_control.state == LISTEN) { memcpy(¤t_socket->socket_values.tcp_control.tcp_context.context_id, ((uint8_t *)temp_ipv6_header) + IPV6_HDR_LEN + 1, 2); current_socket->socket_values.tcp_control.tcp_context.context_id = NTOHS(current_socket->socket_values.tcp_control.tcp_context.context_id); } memmove(((uint8_t *)temp_ipv6_header) + IPV6_HDR_LEN, (((uint8_t *)temp_ipv6_header) + IPV6_HDR_LEN + 3), temp_ipv6_header->length - 3); temp_ipv6_header->length -= 3; return current_socket; } else { printf("Socket Null!\n"); /* Found no matching socket for this packet -> Drop it */ return NULL; } } /* Compressed header TCP segment */ else { /* Temporary TCP Header */ tcp_hdr_t full_tcp_header; memset(&full_tcp_header, 0, sizeof(tcp_hdr_t)); /* Current context ID */ uint16_t current_context; memcpy(¤t_context, (packet_buffer + 2), 2); current_context = NTOHS(current_context); /* Copy TCP_HC header into local variable * (1,0,0,1|SEQ,SEQ,0)(1,0,0,1|0,0,0,0) */ memcpy(&tcp_hc_header, packet_buffer, 2); tcp_hc_header = NTOHS(tcp_hc_header); uint8_t header_type = UNDEFINED; if (BITSET(tcp_hc_header, 15) && !BITSET(tcp_hc_header, 14) && !BITSET(tcp_hc_header, 13)) { header_type = MOSTLY_COMPRESSED_HEADER; } else if (BITSET(tcp_hc_header, 15) && BITSET(tcp_hc_header, 14) && !BITSET(tcp_hc_header, 13)) { header_type = COMPRESSED_HEADER; } /* Setting pointer to first tcp_hc field */ packet_buffer += 4; packet_size += 4; /* Current socket */ socket_internal_t *current_socket = get_tcp_socket_by_context(temp_ipv6_header, current_context); if (current_socket == NULL) { printf("Current Socket == NULL!\n"); return NULL; } /* Current TCP Context values */ tcp_hc_context_t *current_tcp_context = ¤t_socket->socket_values.tcp_control.tcp_context; /*----------------------------------*/ /*| Sequence number handling |*/ /*----------------------------------*/ if (!BITSET(tcp_hc_header, 11) && !BITSET(tcp_hc_header, 10)) { /* Seq = (0|0), sequence number didn't change, copy old value */ memcpy(&full_tcp_header.seq_nr, ¤t_tcp_context->seq_rcv, 4); } /* The 24 most significant bits haven't changed from previous packet */ else if (!BITSET(tcp_hc_header, 11) && BITSET(tcp_hc_header, 10)) { /* Seq = (0|1), copy 1 byte of tcp_hc packet and 3 bytes from * previous packet */ full_tcp_header.seq_nr |= *packet_buffer; full_tcp_header.seq_nr |= ((current_tcp_context->seq_rcv) & 0xFFFFFF00); packet_buffer += 1; packet_size += 1; } /* If the 16 most significant bits haven't changed from previous packet */ else if (BITSET(tcp_hc_header, 11) && !BITSET(tcp_hc_header, 10)) { /* Seq = (1|0), copy 2 bytes of tcp_hc packet and 2 bytes from * previous packet */ full_tcp_header.seq_nr |= NTOHS(*((uint16_t *)packet_buffer)); full_tcp_header.seq_nr |= ((current_tcp_context->seq_rcv) & 0xFFFF0000); packet_buffer += 2; packet_size += 2; } /* Sending uncompressed sequence number */ else { /* Seq = (1|1), copy 4 bytes of tcp_hc packet */ memcpy(&full_tcp_header.seq_nr, packet_buffer, 4); full_tcp_header.seq_nr = NTOHL(full_tcp_header.seq_nr); packet_buffer += 4; packet_size += 4; } /*----------------------------------*/ /*| Acknowledgment number handling |*/ /*----------------------------------*/ if (!BITSET(tcp_hc_header, 9) && !BITSET(tcp_hc_header, 8)) { /* Ack = (0|0), acknowledgment number didn't change, copy old value */ memcpy(&full_tcp_header.ack_nr, ¤t_tcp_context->ack_rcv, 4); } /* The 24 most significant bits haven't changed from previous packet */ else if (!BITSET(tcp_hc_header, 9) && BITSET(tcp_hc_header, 8)) { /* Ack = (0|1), copy 1 byte of tcp_hc packet and 3 bytes from * previous packet */ full_tcp_header.ack_nr |= *packet_buffer; full_tcp_header.ack_nr |= ((current_tcp_context->ack_rcv) & 0xFFFFFF00); packet_buffer += 1; packet_size += 1; SET_TCP_ACK(full_tcp_header.reserved_flags); } /* If the 16 most significant bits haven't changed from previous packet */ else if (BITSET(tcp_hc_header, 9) && !BITSET(tcp_hc_header, 8)) { /* Ack = (1|0), copy 2 bytes of tcp_hc packet and 2 bytes from * previous packet */ full_tcp_header.ack_nr |= NTOHS(*((uint16_t *)packet_buffer)); full_tcp_header.ack_nr |= ((current_tcp_context->ack_rcv) & 0xFFFF0000); packet_buffer += 2; packet_size += 2; SET_TCP_ACK(full_tcp_header.reserved_flags); } /* Sending uncompressed acknowledgment number */ else { /* Ack = (1|1), copy 4 bytes of tcp_hc packet */ memcpy(&full_tcp_header.ack_nr, packet_buffer, 4); full_tcp_header.ack_nr = NTOHL(full_tcp_header.ack_nr); packet_buffer += 4; packet_size += 4; if (header_type == COMPRESSED_HEADER) { SET_TCP_ACK(full_tcp_header.reserved_flags); } } /*----------------------------------*/ /*| Window handling |*/ /*----------------------------------*/ if (!BITSET(tcp_hc_header, 7) && !BITSET(tcp_hc_header, 6)) { /* Wnd = (0|0), copy old value */ memcpy(&full_tcp_header.window, ¤t_tcp_context->wnd_rcv, 2); } /* The 8 most significant bits haven't changed from previous packet */ else if (!BITSET(tcp_hc_header, 7) && BITSET(tcp_hc_header, 6)) { /* Wnd = (0|1), copy 1 byte of tcp_hc packet and 1 byte from * previous packet */ full_tcp_header.window |= *packet_buffer; full_tcp_header.window |= ((current_tcp_context->wnd_rcv) & 0xFF00); packet_buffer += 1; packet_size += 1; } /* If the 8 less significant bits haven't changed from previous packet */ else if (BITSET(tcp_hc_header, 7) && !BITSET(tcp_hc_header, 6)) { /* Wnd = (1|0), copy 1 byte of tcp_hc packet and 1 byte from previous packet */ full_tcp_header.window |= ((*((uint16_t *)packet_buffer)) & 0xFF00); full_tcp_header.window |= ((current_tcp_context->wnd_rcv) & 0x00FF); packet_buffer += 1; packet_size += 1; } /* Sending uncompressed window size */ else { /* Wnd = (1|1), copy 2 bytes of tcp_hc packet */ memcpy(&full_tcp_header.window, packet_buffer, 2); full_tcp_header.window = NTOHS(full_tcp_header.window); packet_buffer += 2; packet_size += 2; } /* FIN flag */ if (BITSET(tcp_hc_header, 3)) { /* F = (1) */ if (IS_TCP_ACK(full_tcp_header.reserved_flags)) { SET_TCP_FIN_ACK(full_tcp_header.reserved_flags); } else { SET_TCP_FIN(full_tcp_header.reserved_flags); } } /* Copy checksum into into tcp header */ memcpy(&full_tcp_header.checksum, packet_buffer, 2); full_tcp_header.checksum = NTOHS(full_tcp_header.checksum); packet_buffer += 2; packet_size += 2; /* Copy dest. and src. port into tcp header */ memcpy(&full_tcp_header.dst_port, ¤t_socket->socket_values.local_address.sin6_port, 2); memcpy(&full_tcp_header.src_port, ¤t_socket->socket_values.foreign_address.sin6_port, 2); /* Ordinary TCP header length */ full_tcp_header.dataOffset_reserved = TCP_HDR_LEN / 4; /* Move payload to end of tcp header */ memmove(((uint8_t *)temp_ipv6_header) + IPV6_HDR_LEN + TCP_HDR_LEN, packet_buffer, temp_ipv6_header->length - packet_size); /* Copy TCP uncompressed header in front of payload */ memcpy(((uint8_t *)temp_ipv6_header) + IPV6_HDR_LEN, &full_tcp_header, TCP_HDR_LEN); /* Set IPV6 header length */ temp_ipv6_header->length = temp_ipv6_header->length - packet_size + TCP_HDR_LEN; return current_socket; } } #endif