#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include <byteswap.h>
#include <latch.h>
#include <errno.h>
#include <gpxe/process.h>
#include <gpxe/init.h>
#include <gpxe/netdevice.h>
#include <gpxe/pkbuff.h>
#include <gpxe/ip.h>
#include <gpxe/tcp.h>
#include <gpxe/tcpip.h>
#include <gpxe/retry.h>
#include "uip/uip.h"
/** @file
*
* TCP protocol
*
* The gPXE TCP stack is currently implemented on top of the uIP
* protocol stack. This file provides wrappers around uIP so that
* higher-level protocol implementations do not need to talk directly
* to uIP (which has a somewhat baroque API).
*
* Basic operation is to create a #tcp_connection structure, call
* tcp_connect() and then call run_tcpip() in a loop until the
* operation has completed. The TCP stack will call the various
* methods defined in the #tcp_operations structure in order to send
* and receive data.
*
* See hello.c for a trivial example of a TCP protocol using this
* API.
*
*/
#if USE_UIP
/**
* TCP transmit buffer
*
* When a tcp_operations::senddata() method is called, it is
* guaranteed to be able to use this buffer as temporary space for
* constructing the data to be sent. For example, code such as
*
* @code
*
* static void my_senddata ( struct tcp_connection *conn, void *buf,
* size_t len ) {
* len = snprintf ( buf, len, "FETCH %s\r\n", filename );
* tcp_send ( conn, buf + already_sent, len - already_sent );
* }
*
* @endcode
*
* is allowed, and is probably the best way to deal with
* variably-sized data.
*
* Note that you cannot use this simple mechanism if you want to be
* able to construct single data blocks of more than #len bytes.
*/
static void *tcp_buffer = uip_buf + ( 40 + UIP_LLH_LEN );
/** Size of #tcp_buffer */
static size_t tcp_buflen = UIP_BUFSIZE - ( 40 + UIP_LLH_LEN );
/**
* Open a TCP connection
*
* @v conn TCP connection
*
* This sets up a new TCP connection to the remote host specified in
* tcp_connection::sin.
*/
void tcp_connect ( struct tcp_connection *conn ) {
struct uip_conn *uip_conn;
u16_t ipaddr[2];
assert ( conn->sin.sin_addr.s_addr != 0 );
assert ( conn->sin.sin_port != 0 );
assert ( conn->tcp_op != NULL );
assert ( sizeof ( uip_conn->appstate ) == sizeof ( conn ) );
* ( ( uint32_t * ) ipaddr ) = conn->sin.sin_addr.s_addr;
uip_conn = uip_connect ( ipaddr, conn->sin.sin_port );
#warning "Use linked lists so that uip_connect() cannot fail"
assert ( uip_conn != NULL );
*( ( void ** ) uip_conn->appstate ) = conn;
}
/**
* Send data via a TCP connection
*
* @v conn TCP connection
* @v data Data to send
* @v len Length of data
*
* Data will be automatically limited to the current TCP window size.
*
* If retransmission is required, the connection's
* tcp_operations::senddata() method will be called again in order to
* regenerate the data.
*/
void tcp_send ( struct tcp_connection *conn __unused,
const void *data, size_t len ) {
assert ( conn = *( ( void ** ) uip_conn->appstate ) );
if ( len > tcp_buflen )
len = tcp_buflen;
memmove ( tcp_buffer, data, len );
uip_send ( tcp_buffer, len );
}
/**
* Close a TCP connection
*
* @v conn TCP connection
*/
void tcp_close ( struct tcp_connection *conn __unused ) {
assert ( conn = *( ( void ** ) uip_conn->appstate ) );
uip_close();
}
/**
* uIP TCP application call interface
*
* This is the entry point of gPXE from the point of view of the uIP
* protocol stack. This function calls the appropriate methods from
* the connection's @tcp_operations table in order to process received
* data, transmit new data etc.
*/
void uip_tcp_appcall ( void ) {
struct tcp_connection *conn = *( ( void ** ) uip_conn->appstate );
struct tcp_operations *op = conn->tcp_op;
if ( op->closed ) {
if ( uip_aborted() )
op->closed ( conn, -ECONNABORTED );
if ( uip_timedout() )
op->closed ( conn, -ETIMEDOUT );
if ( uip_closed() )
op->closed ( conn, 0 );
}
if ( uip_connected() && op->connected )
op->connected ( conn );
if ( uip_acked() && op->acked )
op->acked ( conn, uip_conn->len );
if ( uip_newdata() && op->newdata )
op->newdata ( conn, ( void * ) uip_appdata, uip_len );
if ( ( uip_rexmit() || uip_newdata() || uip_acked() ||
uip_connected() || uip_poll() ) && op->senddata )
op->senddata ( conn, tcp_buffer, tcp_buflen );
}
/* Present here to allow everything to link. Will go into separate
* udp.c file
*/
void uip_udp_appcall ( void ) {
}
/**
* Perform periodic processing of all TCP connections
*
* This allows TCP connections to retransmit data if necessary.
*/
static void tcp_periodic ( void ) {
struct pk_buff *pkb;
int i;
for ( i = 0 ; i < UIP_CONNS ; i++ ) {
uip_periodic ( i );
if ( uip_len > 0 ) {
pkb = alloc_pkb ( uip_len + MAX_LL_HEADER_LEN);
if ( ! pkb )
continue;
pkb_reserve ( pkb, MAX_LL_HEADER_LEN );
pkb_put ( pkb, uip_len );
memcpy ( pkb->data, uip_buf, uip_len );
ipv4_uip_tx ( pkb );
}
}
}
/**
* Kick a connection into life
*
* @v conn TCP connection
*
* Call this function when you have new data to send and are not
* already being called as part of TCP processing.
*/
void tcp_kick ( struct tcp_connection *conn __unused ) {
/* Just kick all the connections; this will work for now */
tcp_periodic();
}
/**
* Single-step the TCP stack
*
* @v process TCP process
*
* This calls tcp_periodic() at regular intervals.
*/
static void tcp_step ( struct process *process ) {
static unsigned long timeout = 0;
if ( currticks() > timeout ) {
timeout = currticks() + ( TICKS_PER_SEC / 10 );
tcp_periodic ();
}
schedule ( process );
}
/** TCP stack process */
static struct process tcp_process = {
.step = tcp_step,
};
/** Initialise the TCP stack */
static void init_tcp ( void ) {
schedule ( &tcp_process );
}
INIT_FN ( INIT_PROCESS, init_tcp, NULL, NULL );
#else
/**
* List of registered TCP connections
*/
static LIST_HEAD ( tcp_conns );
/**
* List of TCP states
*/
static const char *tcp_states[] = {
"CLOSED",
"LISTEN",
"SYN_SENT",
"SYN_RCVD",
"ESTABLISHED",
"FIN_WAIT_1",
"FIN_WAIT_2",
"CLOSING",
"TIME_WAIT",
"CLOSE_WAIT",
"LAST_ACK",
"INVALID" };
/**
* TCP state transition function
*
* @v conn TCP connection
* @v nxt_state Next TCP state
*/
void tcp_set_flags ( struct tcp_connection *conn ) {
/* Set the TCP flags */
switch ( conn->tcp_state ) {
case TCP_CLOSED:
if ( conn->tcp_lstate == TCP_SYN_RCVD ) {
conn->tcp_flags |= TCP_RST;
}
break;
case TCP_LISTEN:
break;
case TCP_SYN_SENT:
if ( conn->tcp_lstate == TCP_LISTEN ||
conn->tcp_lstate == TCP_CLOSED ) {
conn->tcp_flags |= TCP_SYN;
}
break;
case TCP_SYN_RCVD:
if ( conn->tcp_lstate == TCP_LISTEN ||
conn->tcp_lstate == TCP_SYN_SENT ) {
conn->tcp_flags |= ( TCP_SYN | TCP_ACK );
}
break;
case TCP_ESTABLISHED:
if ( conn->tcp_lstate == TCP_SYN_SENT ) {
conn->tcp_flags |= TCP_ACK;
}
break;
case TCP_FIN_WAIT_1:
if ( conn->tcp_lstate == TCP_SYN_RCVD ||
conn->tcp_lstate == TCP_ESTABLISHED ) {
conn->tcp_flags |= TCP_FIN;
}
break;
case TCP_FIN_WAIT_2:
break;
case TCP_CLOSING:
if ( conn->tcp_lstate == TCP_FIN_WAIT_1 ) {
conn->tcp_flags |= TCP_ACK;
}
break;
case TCP_TIME_WAIT:
if ( conn->tcp_lstate == TCP_FIN_WAIT_1 ||
conn->tcp_lstate == TCP_FIN_WAIT_2 ) {
conn->tcp_flags |= TCP_ACK;
}
break;
case TCP_CLOSE_WAIT:
if ( conn->tcp_lstate == TCP_ESTABLISHED ) {
conn->tcp_flags |= TCP_ACK;
}
break;
case TCP_LAST_ACK:
if ( conn->tcp_lstate == TCP_CLOSE_WAIT ) {
conn->tcp_flags |= TCP_FIN;
}
break;
default:
DBG ( "TCP_INVALID state %d\n", conn->tcp_state );
return;
}
}
void tcp_trans ( struct tcp_connection *conn, int nxt_state ) {
/* Remember the last state */
conn->tcp_lstate = conn->tcp_state;
conn->tcp_state = nxt_state;
/* TODO: Check if this check is required */
if ( conn->tcp_lstate == conn->tcp_state ||
conn->tcp_state == TCP_INVALID ) {
conn->tcp_flags = 0;
return;
}
tcp_set_flags ( conn );
}
/**
* Dump TCP header
*
* @v tcphdr TCP header
*/
void tcp_dump ( struct tcp_header *tcphdr ) {
DBG ( "TCP %p src:%d dest:%d seq:%lx ack:%lx hlen:%hd flags:%#hx\n",
tcphdr, ntohs ( tcphdr->src ), ntohs ( tcphdr->dest ), ntohl ( tcphdr->seq ),
ntohl ( tcphdr->ack ), ( ( tcphdr->hlen & TCP_MASK_HLEN ) / 16 ), ( tcphdr->flags & TCP_MASK_FLAGS ) );
}
/**
* Initialize a TCP connection
*
* @v conn TCP connection
*
* This function assigns initial values to some fields in the connection
* structure. The application should call tcp_init_conn after creating a new
* connection before calling any other "tcp_*" function.
*
* struct tcp_connection my_conn;
* tcp_init_conn ( &my_conn );
* ...
*/
void tcp_init_conn ( struct tcp_connection *conn ) {
conn->local_port = 0;
conn->tcp_state = TCP_CLOSED;
conn->tcp_lstate = TCP_INVALID;
conn->tx_pkb = NULL;
conn->tcp_op = NULL;
}
/** Retry timer
*
* @v timer Retry timer
* @v over Failure indicator
*/
void tcp_expired ( struct retry_timer *timer, int over ) {
struct tcp_connection *conn;
conn = ( struct tcp_connection * ) container_of ( timer,
struct tcp_connection, timer );
DBG ( "Timer expired in %s\n", tcp_states[conn->tcp_state] );
switch ( conn->tcp_state ) {
case TCP_SYN_SENT:
if ( over ) {
tcp_trans ( conn, TCP_CLOSED );
stop_timer ( &conn->timer );
DBG ( "Timeout! Connection closed\n" );
return;
}
goto send_tcp_nomsg;
case TCP_SYN_RCVD:
if ( over ) {
tcp_trans ( conn, TCP_CLOSED );
stop_timer ( &conn->timer );
goto send_tcp_nomsg;
}
goto send_tcp_nomsg;
case TCP_ESTABLISHED:
if ( conn->tcp_lstate == TCP_SYN_SENT ) {
goto send_tcp_nomsg;
}
break;
case TCP_CLOSE_WAIT:
if ( conn->tcp_lstate == TCP_ESTABLISHED ) {
goto send_tcp_nomsg;
}
break;
case TCP_FIN_WAIT_1:
case TCP_FIN_WAIT_2:
goto send_tcp_nomsg;
case TCP_CLOSING:
case TCP_LAST_ACK:
if ( conn->tcp_lstate == TCP_CLOSE_WAIT ) {
goto send_tcp_nomsg;
}
return;
case TCP_TIME_WAIT:
tcp_trans ( conn, TCP_CLOSED );
stop_timer ( &conn->timer );
return;
}
/* Retransmit the data */
tcp_set_flags ( conn );
tcp_senddata ( conn );
return;
send_tcp_nomsg:
free_pkb ( conn->tx_pkb );
conn->tx_pkb = alloc_pkb ( MIN_PKB_LEN );
pkb_reserve ( conn->tx_pkb, MAX_HDR_LEN );
tcp_set_flags ( conn );
int rc;
if ( ( rc = tcp_send ( conn, TCP_NOMSG, TCP_NOMSG_LEN ) ) != 0 ) {
DBG ( "Error sending TCP message (rc = %d)\n", rc );
}
return;
}
/**
* Connect to a remote server
*
* @v conn TCP connection
* @v peer Remote socket address
*
* This function initiates a TCP connection to the socket address specified in
* peer. It sends a SYN packet to peer. When the connection is established, the
* TCP stack calls the connected() callback function.
*/
int tcp_connectto ( struct tcp_connection *conn,
struct sockaddr_tcpip *peer ) {
int rc;
/* A connection can only be established from the CLOSED state */
if ( conn->tcp_state != TCP_CLOSED ) {
DBG ( "Error opening connection: Invalid state %s\n",
tcp_states[conn->tcp_state] );
return -EISCONN;
}
/* Add the connection to the set of listening connections */
if ( ( rc = tcp_listen ( conn, conn->local_port ) ) != 0 ) {
return rc;
}
memcpy ( &conn->peer, peer, sizeof ( conn->peer ) );
/* Initialize the TCP timer */
conn->timer.expired = tcp_expired;
/* Send a SYN packet and transition to TCP_SYN_SENT */
conn->snd_una = random();
tcp_trans ( conn, TCP_SYN_SENT );
/* Allocate space for the packet */
free_pkb ( conn->tx_pkb );
conn->tx_pkb = alloc_pkb ( MIN_PKB_LEN );
pkb_reserve ( conn->tx_pkb, MAX_HDR_LEN );
conn->rcv_win = MAX_PKB_LEN - MAX_HDR_LEN; /* TODO: Is this OK? */
return tcp_send ( conn, TCP_NOMSG, TCP_NOMSG_LEN );
}
int tcp_connect ( struct tcp_connection *conn ) {
return tcp_connectto ( conn, &conn->peer );
}
/**
* Close the connection
*
* @v conn
*
* This function sends a FIN packet to the remote end of the connection. When
* the remote end of the connection ACKs the FIN (FIN consumes one byte on the
* snd stream), the stack invokes the closed() callback function.
*/
int tcp_close ( struct tcp_connection *conn ) {
/* A connection can only be closed if it is a connected state */
switch ( conn->tcp_state ) {
case TCP_SYN_RCVD:
case TCP_ESTABLISHED:
tcp_trans ( conn, TCP_FIN_WAIT_1 );
conn->tcp_op->closed ( conn, CONN_SNDCLOSE ); /* TODO: Check! */
/* FIN consumes one byte on the snd stream */
// conn->snd_una++;
goto send_tcp_nomsg;
case TCP_SYN_SENT:
case TCP_LISTEN:
/**
* Since the connection does not expect any packets from the
* remote end, it can be removed from the set of listening
* connections.
*/
list_del ( &conn->list );
tcp_trans ( conn, TCP_CLOSED );
conn->tcp_op->closed ( conn, CONN_SNDCLOSE );
return 0;
case TCP_CLOSE_WAIT:
tcp_trans ( conn, TCP_LAST_ACK );
conn->tcp_op->closed ( conn, CONN_SNDCLOSE ); /* TODO: Check! */
/* FIN consumes one byte on the snd stream */
// conn->snd_una++;
goto send_tcp_nomsg;
default:
DBG ( "tcp_close(): Invalid state %s\n",
tcp_states[conn->tcp_state] );
return -EPROTO;
}
send_tcp_nomsg:
free_pkb ( conn->tx_pkb );
conn->tx_pkb = alloc_pkb ( MIN_PKB_LEN );
conn->tcp_flags = TCP_FIN;
pkb_reserve ( conn->tx_pkb, MAX_HDR_LEN );
return tcp_send ( conn, TCP_NOMSG, TCP_NOMSG_LEN );
}
/**
* Bind TCP connection to local port
*
* @v conn TCP connection
* @v local_port Local port, in network byte order
* @ret rc Return status code
*/
int tcp_bind ( struct tcp_connection *conn, uint16_t local_port ) {
struct tcp_connection *existing;
list_for_each_entry ( existing, &tcp_conns, list ) {
if ( existing->local_port == local_port )
return -EADDRINUSE;
}
conn->local_port = local_port;
return 0;
}
/**
* Listen for a packet
*
* @v conn TCP connection
* @v local_port Local port, in network byte order
*
* This function adds the connection to a list of registered tcp
* connections. If the local port is 0, the connection is assigned an
* available port between MIN_TCP_PORT and 65535.
*/
int tcp_listen ( struct tcp_connection *conn, uint16_t local_port ) {
static uint16_t try_port = 1024;
int rc;
/* If no port specified, find the first available port */
if ( ! local_port ) {
for ( ; try_port ; try_port++ ) {
if ( try_port < 1024 )
continue;
if ( tcp_listen ( conn, htons ( try_port ) ) == 0 )
return 0;
}
return -EADDRINUSE;
}
/* Attempt bind to local port */
if ( ( rc = tcp_bind ( conn, local_port ) ) != 0 )
return rc;
/* Add to TCP connection list */
list_add ( &conn->list, &tcp_conns );
DBG ( "TCP opened %p on port %d\n", conn, ntohs ( local_port ) );
return 0;
}
/**
* Send data
*
* @v conn TCP connection
*
* This function allocates space to the transmit buffer and invokes the
* senddata() callback function. It passes the allocated buffer to senddata().
* The applicaion may use this space to write it's data.
*/
int tcp_senddata ( struct tcp_connection *conn ) {
/* The connection must be in a state in which the user can send data */
switch ( conn->tcp_state ) {
case TCP_LISTEN:
tcp_trans ( conn, TCP_SYN_SENT );
conn->snd_una = random();
break;
case TCP_ESTABLISHED:
case TCP_CLOSE_WAIT:
break;
default:
DBG ( "tcp_senddata: Invalid state %s\n",
tcp_states[conn->tcp_state] );
return -EPROTO;
}
/* Allocate space to the TX buffer */
free_pkb ( conn->tx_pkb );
conn->tx_pkb = alloc_pkb ( MAX_PKB_LEN );
if ( !conn->tx_pkb ) {
DBG ( "Insufficient memory\n" );
return -ENOMEM;
}
pkb_reserve ( conn->tx_pkb, MAX_HDR_LEN );
/* Set the advertised window */
conn->rcv_win = pkb_available ( conn->tx_pkb );
/* Call the senddata() call back function */
conn->tcp_op->senddata ( conn, conn->tx_pkb->data,
pkb_available ( conn->tx_pkb ) );
return 0;
}
/**
* Transmit data
*
* @v conn TCP connection
* @v data Data to be sent
* @v len Length of the data
*
* This function sends data to the peer socket address
*/
int tcp_send ( struct tcp_connection *conn, const void *data, size_t len ) {
struct sockaddr_tcpip *peer = &conn->peer;
struct pk_buff *pkb = conn->tx_pkb;
int slen;
/* Determine the amount of data to be sent */
slen = len < conn->snd_win ? len : conn->snd_win;
/* Copy payload */
memmove ( pkb_put ( pkb, slen ), data, slen );
/* Fill up the TCP header */
struct tcp_header *tcphdr = pkb_push ( pkb, sizeof ( *tcphdr ) );
/* Source port, assumed to be in network byte order in conn */
tcphdr->src = conn->local_port;
/* Destination port, assumed to be in network byte order in peer */
tcphdr->dest = peer->st_port;
tcphdr->seq = htonl ( conn->snd_una );
tcphdr->ack = htonl ( conn->rcv_nxt );
/* Header length, = 0x50 (without TCP options) */
tcphdr->hlen = ( uint8_t ) ( ( sizeof ( *tcphdr ) / 4 ) << 4 );
/* Copy TCP flags, and then reset the variable */
tcphdr->flags = conn->tcp_flags;
conn->tcp_flags = 0;
/* Advertised window, in network byte order */
tcphdr->win = htons ( conn->rcv_win );
/* Set urgent pointer to 0 */
tcphdr->urg = 0;
/* Calculate and store partial checksum, in host byte order */
tcphdr->csum = 0;
tcphdr->csum = tcpip_chksum ( pkb->data, pkb_len ( pkb ) );
/* Dump the TCP header */
/* Start the timer */
if ( ( conn->tcp_state == TCP_ESTABLISHED && conn->tcp_lstate == TCP_SYN_SENT ) ||
( conn->tcp_state == TCP_LISTEN && conn->tcp_lstate == TCP_SYN_RCVD ) ||
( conn->tcp_state == TCP_CLOSED && conn->tcp_lstate == TCP_SYN_RCVD ) ) {
// Don't start the timer
} else {
start_timer ( &conn->timer );
}
/* Transmit packet */
return tcpip_tx ( pkb, &tcp_protocol, peer );
}
/**
* Process received packet
*
* @v pkb Packet buffer
* @v partial Partial checksum
*/
static int tcp_rx ( struct pk_buff *pkb,
struct sockaddr_tcpip *st_src __unused,
struct sockaddr_tcpip *st_dest __unused ) {
struct tcp_connection *conn;
struct tcp_header *tcphdr;
uint32_t acked, toack;
int hlen;
/* Sanity check */
if ( pkb_len ( pkb ) < sizeof ( *tcphdr ) ) {
DBG ( "Packet too short (%d bytes)\n", pkb_len ( pkb ) );
return -EINVAL;
}
/* Process TCP header */
tcphdr = pkb->data;
tcp_dump ( tcphdr );
/* Verify header length */
hlen = ( ( tcphdr->hlen & TCP_MASK_HLEN ) / 16 ) * 4;
if ( hlen != sizeof ( *tcphdr ) ) {
if ( hlen == sizeof ( *tcphdr ) + 4 ) {
DBG ( "TCP options sent\n" );
} else {
DBG ( "Bad header length (%d bytes)\n", hlen );
return -EINVAL;
}
}
/* TODO: Verify checksum */
/* Demux TCP connection */
list_for_each_entry ( conn, &tcp_conns, list ) {
if ( tcphdr->dest == conn->local_port ) {
goto found_conn;
}
}
DBG ( "No connection found on port %d\n", ntohs ( tcphdr->dest ) );
return 0;
found_conn:
/* Stop the timer */
stop_timer ( &conn->timer );
/* Set the advertised window */
conn->snd_win = tcphdr->win;
/* TCP State Machine */
conn->tcp_lstate = conn->tcp_state;
switch ( conn->tcp_state ) {
case TCP_CLOSED:
DBG ( "tcp_rx(): Invalid state %s\n",
tcp_states[conn->tcp_state] );
return -EINVAL;
case TCP_LISTEN:
if ( tcphdr->flags & TCP_SYN ) {
tcp_trans ( conn, TCP_SYN_RCVD );
/* Synchronize the sequence numbers */
conn->rcv_nxt = ntohl ( tcphdr->seq ) + 1;
conn->tcp_flags |= TCP_ACK;
/* Set the sequence number for the snd stream */
conn->snd_una = random();
conn->tcp_flags |= TCP_SYN;
/* Send a SYN,ACK packet */
goto send_tcp_nomsg;
}
/* Unexpected packet */
goto unexpected;
case TCP_SYN_SENT:
if ( tcphdr->flags & TCP_SYN ) {
/* Synchronize the sequence number in rcv stream */
conn->rcv_nxt = ntohl ( tcphdr->seq ) + 1;
conn->tcp_flags |= TCP_ACK;
if ( tcphdr->flags & TCP_ACK ) {
tcp_trans ( conn, TCP_ESTABLISHED );
/**
* Process ACK of SYN. This does not invoke the
* acked() callback function.
*/
conn->snd_una = ntohl ( tcphdr->ack );
conn->tcp_op->connected ( conn );
conn->tcp_flags |= TCP_ACK;
tcp_senddata ( conn );
return;
} else {
tcp_trans ( conn, TCP_SYN_RCVD );
conn->tcp_flags |= TCP_SYN;
goto send_tcp_nomsg;
}
}
/* Unexpected packet */
goto unexpected;
case TCP_SYN_RCVD:
if ( tcphdr->flags & TCP_RST ) {
tcp_trans ( conn, TCP_LISTEN );
conn->tcp_op->closed ( conn, CONN_RESTART );
return 0;
}
if ( tcphdr->flags & TCP_ACK ) {
tcp_trans ( conn, TCP_ESTABLISHED );
/**
* Process ACK of SYN. It neither invokes the callback
* function nor does it send an ACK.
*/
conn->snd_una = tcphdr->ack - 1;
conn->tcp_op->connected ( conn );
return 0;
}
/* Unexpected packet */
goto unexpected;
case TCP_ESTABLISHED:
#if 0
if ( tcphdr->flags & TCP_FIN ) {
tcp_trans ( conn, TCP_CLOSE_WAIT );
/* FIN consumes one byte */
conn->rcv_nxt++;
conn->tcp_flags |= TCP_ACK;
/* Send an acknowledgement */
goto send_tcp_nomsg;
}
#endif
/* Packet might contain data */
break;
case TCP_FIN_WAIT_1:
if ( tcphdr->flags & TCP_FIN ) {
conn->rcv_nxt++;
conn->tcp_flags |= TCP_ACK;
conn->tcp_op->closed ( conn, CONN_SNDCLOSE );
if ( tcphdr->flags & TCP_ACK ) {
tcp_trans ( conn, TCP_TIME_WAIT );
} else {
tcp_trans ( conn, TCP_CLOSING );
}
/* Send an acknowledgement */
goto send_tcp_nomsg;
}
if ( tcphdr->flags & TCP_ACK ) {
tcp_trans ( conn, TCP_FIN_WAIT_2 );
}
/* Packet might contain data */
break;
case TCP_FIN_WAIT_2:
if ( tcphdr->flags & TCP_FIN ) {
tcp_trans ( conn, TCP_TIME_WAIT );
/* FIN consumes one byte */
conn->rcv_nxt++;
conn->tcp_flags |= TCP_ACK;
goto send_tcp_nomsg;
}
/* Packet might contain data */
break;
case TCP_CLOSING:
if ( tcphdr->flags & TCP_ACK ) {
tcp_trans ( conn, TCP_TIME_WAIT );
start_timer ( &conn->timer );
return 0;
}
/* Unexpected packet */
goto unexpected;
case TCP_TIME_WAIT:
/* Unexpected packet */
goto unexpected;
case TCP_CLOSE_WAIT:
/* Packet could acknowledge data */
break;
case TCP_LAST_ACK:
if ( tcphdr->flags & TCP_ACK ) {
tcp_trans ( conn, TCP_CLOSED );
return 0;
}
/* Unexpected packet */
goto unexpected;
}
/**
* Any packet reaching this point either contains new data or
* acknowledges previously transmitted data.
*/
assert ( ( tcphdr->flags & TCP_ACK ) ||
pkb_len ( pkb ) > sizeof ( *tcphdr ) );
/* Check for new data */
toack = pkb_len ( pkb ) - hlen;
if ( toack > 0 ) {
/* Check if expected sequence number */
if ( conn->rcv_nxt == ntohl ( tcphdr->seq ) ) {
conn->rcv_nxt += toack;
conn->tcp_op->newdata ( conn, pkb->data + hlen,
toack );
} else {
DBG ( "Unexpected sequence number %lx (wanted %lx)\n",
ntohl ( tcphdr->seq ), conn->rcv_nxt );
}
/* Acknowledge new data */
conn->tcp_flags |= TCP_ACK;
if ( !( tcphdr->flags & TCP_ACK ) ) {
goto send_tcp_nomsg;
}
}
/* Process ACK */
if ( tcphdr->flags & TCP_ACK ) {
acked = ntohl ( tcphdr->ack ) - conn->snd_una;
if ( acked < 0 ) { /* TODO: Replace all uint32_t arith */
DBG ( "Previously ACKed (%d)\n", tcphdr->ack );
return 0;
}
/* Advance snd stream */
conn->snd_una += acked;
/* Invoke the acked() callback function */
conn->tcp_op->acked ( conn, acked );
/* Invoke the senddata() callback function */
tcp_senddata ( conn );
}
/* If the connection is in ESTABLISHED and it receives a FIN */
if ( conn->tcp_state == ESTABLISHED && ( tcphdr->flags & TCP_FIN ) ) {
tcp_trans ( conn, TCP_CLOSE_WAIT );
conn->tcp_op->closed ( conn, CONN_SNDCLOSE );
conn->rcv_nxt++;
if ( ! ( tcphdr->flags & TCP_ACK ) ) {
conn->tcp_flags |= TCP_ACK;
/* Send an acknowledgement */
goto send_tcp_nomsg;
}
/* Otherwise, the packet has been ACKed already */
}
return 0;
send_tcp_nomsg:
free_pkb ( conn->tx_pkb );
conn->tx_pkb = alloc_pkb ( MIN_PKB_LEN );
pkb_reserve ( conn->tx_pkb, MAX_HDR_LEN );
int rc;
if ( ( rc = tcp_send ( conn, TCP_NOMSG, TCP_NOMSG_LEN ) ) != 0 ) {
DBG ( "Error sending TCP message (rc = %d)\n", rc );
}
return 0;
unexpected:
DBG ( "Unexpected packet received in %s with flags = %#hx\n",
tcp_states[conn->tcp_state], tcphdr->flags & TCP_MASK_FLAGS );
tcp_close ( conn );
free_pkb ( conn->tx_pkb );
return -EINVAL;
}
/** TCP protocol */
struct tcpip_protocol tcp_protocol __tcpip_protocol = {
.name = "TCP",
.rx = tcp_rx,
.tcpip_proto = IP_TCP,
.csum_offset = 16,
};
#endif /* USE_UIP */
