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tcp.c File Reference

TCP (Transmition Control Protocol) layer. More...

#include <const.h>
#include <arch/mem.h>
#include <kernel/clock.h>
#include <kernel/console.h>
#include <kernel/speaker.h>
#include <kernel/kmalloc.h>
#include <kernel/semaphore.h>
#include <net/ip.h>
#include <net/network.h>
#include <net/tcp.h>

Go to the source code of this file.

Functions
uint16_t	tcp_checksum (const void *buff, size_t len, in_addr_t src_addr, in_addr_t dest_addr)
	Calculate the TCP checksum. Parameters: buff  The TCP packet. len  The size of the TCP packet. src_addr  The IP source address (in network format). dest_addr  The IP destination address (in network format). Returns: The result of the checksum.
void	connect_sound ()
void	disconnect_sound ()
void	to_tcp_layer (tcp_t *packet, size_t len, in_addr_t ip_src, in_addr_t ip_dst)
int	tcp_module_init ()
int	tcp_module_close ()
Variables
tcp_state_t *	tcp_conn = NULL
semaphore_t	tcp_mutex

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Detailed Description

TCP (Transmition Control Protocol) layer.

Author:

Andrea Righi <drizzt@inwind.it>

Date:

Last update:
2003-01-21 Andrea Righi: Suppressed deferencing type-punned pointer warning.

Note:

Copyright (©) 2003 Andrea Righi

Todo:

Complete the states machine for the TCP connections.

Definition in file tcp.c.

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Function Documentation

void connect_sound (    )

Definition at line 72 of file tcp.c. { // Beeps when a TCP connection is opened // sound(0x580); delay(20); nosound(); }

void disconnect_sound (    )

Definition at line 81 of file tcp.c. { // Beeps when a TCP connection is closed // sound(0x420); delay(20); nosound(); }

uint16_t tcp_checksum (  const void *    buff, size_t    len, in_addr_t    src_addr, in_addr_t    dest_addr )

Calculate the TCP checksum. Parameters: buff  The TCP packet. len  The size of the TCP packet. src_addr  The IP source address (in network format). dest_addr  The IP destination address (in network format). Returns: The result of the checksum. Definition at line 35 of file tcp.c. { const uint16_t *buf=buff; uint16_t *ip_src=(void *)&src_addr, *ip_dst=(void *)&dest_addr; uint32_t sum; size_t length=len; // Calculate the sum // sum = 0; while (len > 1) { sum += *buf++; if (sum & 0x80000000) sum = (sum & 0xFFFF) + (sum >> 16); len -= 2; } if ( len & 1 ) // Add the padding if the packet lenght is odd // sum += *((uint8_t *)buf); // Add the pseudo-header // sum += *(ip_src++); sum += *ip_src; sum += *(ip_dst++); sum += *ip_dst; sum += htons(IPPROTO_TCP); sum += htons(length); // Add the carries // while (sum >> 16) sum = (sum & 0xFFFF) + (sum >> 16); // Return the one's complement of sum // return ( (uint16_t)(~sum) ); }

int tcp_module_close (    )

Definition at line 309 of file tcp.c. { return(0); }

int tcp_module_init (    )

Definition at line 303 of file tcp.c. { INIT_MUTEX(&tcp_mutex); return(0); }

void to_tcp_layer (  tcp_t *    packet, size_t    len, in_addr_t    ip_src, in_addr_t    ip_dst )

Definition at line 93 of file tcp.c. { // Process a TCP packet from the IP layer // int i; uint8_t *data_buf = ((uint8_t *)packet) + (packet->tcp_hdr_len * sizeof(dword)); bool chk; // Calculate the checksum // chk = tcp_checksum( packet, len, ip_src, ip_dst ); if ( chk ) { kprintf("\n\rTCP checksum error! %04X", chk); return; } DOWN(&tcp_mutex); // Dump the UDP packet // kprintf( "\n\rTCP packet received: %u(%u) bytes" "\n\rsender = %u.%u.%u.%u:%u" "\n\rreceiver= %u.%u.%u.%u:%u" "\n\rseq=%u, ack=%u, win=%u", len - (packet->tcp_hdr_len)*sizeof(dword), len, IP_A(ntohl(ip_src)), IP_B(ntohl(ip_src)), IP_C(ntohl(ip_src)), IP_D(ntohl(ip_src)), ntohs(packet->tcp_src), IP_A(ntohl(ip_dst)), IP_B(ntohl(ip_dst)), IP_C(ntohl(ip_dst)), IP_D(ntohl(ip_dst)), ntohs(packet->tcp_dst), ntohl(packet->tcp_seq_num), ntohl(packet->tcp_ack_num), ntohs(packet->tcp_win_size) ); // Dump the flags // kprintf("\n\rURG:%u ACK:%u PSH:%u RST:%u SYN:%u FIN:%u", packet->tcp_urg, packet->tcp_ack, packet->tcp_psh, packet->tcp_rst, packet->tcp_syn, packet->tcp_fin ); kprintf("\n\rData:\n\r"); for(i=0; i<(len-packet->tcp_hdr_len*4); i++) kputchar( data_buf[i] ); if ( (packet->tcp_syn) && (tcp_conn!=NULL)) { // For now only one connection is allowed :-( // kprintf("\n\rOnly one TCP connection is allowed!"); // Send an RST // packet->tcp_ack_num = htonl(ntohl(packet->tcp_seq_num) + len - packet->tcp_hdr_len*4 + 1); packet->tcp_seq_num = tcp_conn->seq_num; packet->tcp_hdr_len = 5; len = sizeof(tcp_t); packet->tcp_ack = 1; packet->tcp_rst = 1; packet->tcp_syn = 0; packet->tcp_chk = 0; packet->tcp_chk = tcp_checksum(packet, len, ip_dst, ip_src); send_ip_packet(ip_src, packet, len, 255, IPPROTO_TCP); UP(&tcp_mutex); return; } if ( (packet->tcp_syn) && !(packet->tcp_ack) && (tcp_conn==NULL) ) { // SYN received! // // Open a new connection using sockets // tcp_conn = kmalloc(sizeof(tcp_state_t)); memset(tcp_conn, 0, sizeof(tcp_state_t)); tcp_conn->socket.ip_src = ip_src; tcp_conn->socket.port_src = packet->tcp_src; tcp_conn->socket.ip_dst = ip_dst; tcp_conn->socket.port_dst = packet->tcp_dst; tcp_conn->state = TCP_SYN_RCVD; // Send SYN + ACK (seq+1) // // Swap source and destination ports // packet->tcp_dst ^= packet->tcp_src; packet->tcp_src ^= packet->tcp_dst; packet->tcp_dst ^= packet->tcp_src; packet->tcp_ack_num = htonl(ntohl(packet->tcp_seq_num) + 1); packet->tcp_seq_num = tcp_conn->seq_num = htonl(36363636); tcp_conn->seq_num = htonl(ntohl(tcp_conn->seq_num) + 1); packet->tcp_ack = 1; packet->tcp_chk = 0; packet->tcp_chk = tcp_checksum(packet, len, ip_dst, ip_src); send_ip_packet(ip_src, packet, len, 255, IPPROTO_TCP); UP(&tcp_mutex); return; } if ( (packet->tcp_rst) && (tcp_conn!=NULL) ) { // Free the TCP connection structure // kfree(tcp_conn); tcp_conn = NULL; disconnect_sound(); kprintf("\n\rTCP connection closed!\n\r"); UP(&tcp_mutex); return; } if ( (packet->tcp_fin) && (tcp_conn!=NULL) ) { if ( tcp_conn->state != TCP_ESTABLISHED ) return; // FIN received! // // Close the connection // // Send ACK (seq+1) and close also our connection // // setting the FIN flag on // // Swap source and destination ports // packet->tcp_dst ^= packet->tcp_src; packet->tcp_src ^= packet->tcp_dst; packet->tcp_dst ^= packet->tcp_src; packet->tcp_ack_num = htonl(ntohl(packet->tcp_seq_num) + len - packet->tcp_hdr_len*4 + 1); packet->tcp_seq_num = tcp_conn->seq_num; packet->tcp_hdr_len = 5; len = sizeof(tcp_t); packet->tcp_ack = 1; packet->tcp_chk = 0; packet->tcp_chk = tcp_checksum(packet, len, ip_dst, ip_src); send_ip_packet(ip_src, packet, len, 255, IPPROTO_TCP); // Go into the CLOSING state (wait for ACK) // tcp_conn->state = TCP_CLOSING; UP(&tcp_mutex); return; } if ( (packet->tcp_ack) && (tcp_conn->state==TCP_SYN_RCVD) ) { // Connection established! // kprintf("\n\rTCP connection established!"); connect_sound(); tcp_conn->state = TCP_ESTABLISHED; UP(&tcp_mutex); return; } if ( tcp_conn != NULL ) { // In the other cases ack every packet // if ( (tcp_conn->state == TCP_ESTABLISHED) ) { if ( (packet->tcp_ack) && ((len - packet->tcp_hdr_len*4)==0) ) { // Empty packet with ack! Do not reply // UP(&tcp_mutex); return; } // Swap source and destination ports // packet->tcp_dst ^= packet->tcp_src; packet->tcp_src ^= packet->tcp_dst; packet->tcp_dst ^= packet->tcp_src; // Send an echo packet to acknowledge // packet->tcp_ack_num = htonl(ntohl(packet->tcp_seq_num) + len - packet->tcp_hdr_len*4); // tcp_conn->seq_num = htonl(ntohl(tcp_conn->seq_num) + 1); packet->tcp_seq_num = tcp_conn->seq_num; tcp_conn->seq_num = htonl(ntohl(tcp_conn->seq_num) + len - packet->tcp_hdr_len*4); // packet->tcp_hdr_len = 5; // len = sizeof(tcp_t); packet->tcp_ack = 1; packet->tcp_chk = 0; packet->tcp_chk = tcp_checksum(packet, len, ip_dst, ip_src); send_ip_packet(ip_src, packet, len, 255, IPPROTO_TCP); UP(&tcp_mutex); return; } if ( (tcp_conn->state == TCP_CLOSING) ) { // ACK received! // // Free the TCP connection structure // kfree(tcp_conn); tcp_conn = NULL; disconnect_sound(); kprintf("\n\rTCP connection closed!\n\r"); UP(&tcp_mutex); return; } } UP(&tcp_mutex); }

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Variable Documentation

tcp_state_t* tcp_conn = NULL

Definition at line 90 of file tcp.c.

semaphore_t tcp_mutex

Definition at line 91 of file tcp.c.

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