#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <assert.h>
#include <errno.h>
#include <byteswap.h>
#include <timer.h>
#include <gpxe/iobuf.h>
#include <gpxe/malloc.h>
#include <gpxe/retry.h>
#include <gpxe/stream.h>
#include <gpxe/tcpip.h>
#include <gpxe/tcp.h>
/** @file
*
* TCP protocol
*
*/
struct tcp_connection;
static void tcp_expired ( struct retry_timer *timer, int over );
static int tcp_senddata_conn ( struct tcp_connection *tcp, int force_send );
static struct stream_connection_operations tcp_op;
/**
* A TCP connection
*
* This data structure represents the internal state of a TCP
* connection.
*/
struct tcp_connection {
/** The stream connection */
struct stream_connection stream;
/** List of TCP connections */
struct list_head list;
/** Remote socket address */
struct sockaddr_tcpip peer;
/** Local port, in network byte order */
uint16_t local_port;
/** Current TCP state */
unsigned int tcp_state;
/** Previous TCP state
*
* Maintained only for debug messages
*/
unsigned int prev_tcp_state;
/** Current sequence number
*
* Equivalent to SND.UNA in RFC 793 terminology.
*/
uint32_t snd_seq;
/** Unacknowledged sequence count
*
* Equivalent to (SND.NXT-SND.UNA) in RFC 793 terminology.
*/
uint32_t snd_sent;
/** Send window
*
* Equivalent to SND.WND in RFC 793 terminology
*/
uint32_t snd_win;
/** Current acknowledgement number
*
* Equivalent to RCV.NXT in RFC 793 terminology.
*/
uint32_t rcv_ack;
/** Transmit I/O buffer
*
* This buffer is allocated prior to calling the application's
* senddata() method, to provide temporary storage space.
*/
struct io_buffer *tx_iob;
/** Retransmission timer */
struct retry_timer timer;
};
/**
* List of registered TCP connections
*/
static LIST_HEAD ( tcp_conns );
/**
* Name TCP state
*
* @v state TCP state
* @ret name Name of TCP state
*/
static inline __attribute__ (( always_inline )) const char *
tcp_state ( int state ) {
switch ( state ) {
case TCP_CLOSED: return "CLOSED";
case TCP_LISTEN: return "LISTEN";
case TCP_SYN_SENT: return "SYN_SENT";
case TCP_SYN_RCVD: return "SYN_RCVD";
case TCP_ESTABLISHED: return "ESTABLISHED";
case TCP_FIN_WAIT_1: return "FIN_WAIT_1";
case TCP_FIN_WAIT_2: return "FIN_WAIT_2";
case TCP_CLOSING_OR_LAST_ACK: return "CLOSING/LAST_ACK";
case TCP_TIME_WAIT: return "TIME_WAIT";
case TCP_CLOSE_WAIT: return "CLOSE_WAIT";
default: return "INVALID";
}
}
/**
* Dump TCP state transition
*
* @v tcp TCP connection
*/
static inline __attribute__ (( always_inline )) void
tcp_dump_state ( struct tcp_connection *tcp ) {
if ( tcp->tcp_state != tcp->prev_tcp_state ) {
DBGC ( tcp, "TCP %p transitioned from %s to %s\n", tcp,
tcp_state ( tcp->prev_tcp_state ),
tcp_state ( tcp->tcp_state ) );
}
tcp->prev_tcp_state = tcp->tcp_state;
}
/**
* Dump TCP flags
*
* @v flags TCP flags
*/
static inline __attribute__ (( always_inline )) void
tcp_dump_flags ( struct tcp_connection *tcp, unsigned int flags ) {
if ( flags & TCP_RST )
DBGC ( tcp, " RST" );
if ( flags & TCP_SYN )
DBGC ( tcp, " SYN" );
if ( flags & TCP_PSH )
DBGC ( tcp, " PSH" );
if ( flags & TCP_FIN )
DBGC ( tcp, " FIN" );
if ( flags & TCP_ACK )
DBGC ( tcp, " ACK" );
}
/**
* Allocate TCP connection
*
* @ret conn TCP connection, or NULL
*
* Allocates TCP connection and adds it to the TCP connection list.
*/
static struct tcp_connection * alloc_tcp ( void ) {
struct tcp_connection *tcp;
tcp = malloc ( sizeof ( *tcp ) );
if ( tcp ) {
DBGC ( tcp, "TCP %p allocated\n", tcp );
memset ( tcp, 0, sizeof ( *tcp ) );
tcp->tcp_state = tcp->prev_tcp_state = TCP_CLOSED;
tcp->snd_seq = random();
tcp->timer.expired = tcp_expired;
tcp->stream.op = &tcp_op;
list_add ( &tcp->list, &tcp_conns );
}
return tcp;
}
/**
* Free TCP connection
*
* @v tcp TCP connection
*
* Removes connection from TCP connection list and frees the data
* structure.
*/
static void free_tcp ( struct tcp_connection *tcp ) {
assert ( tcp );
assert ( tcp->tcp_state == TCP_CLOSED );
stop_timer ( &tcp->timer );
list_del ( &tcp->list );
free ( tcp );
DBGC ( tcp, "TCP %p freed\n", tcp );
}
/**
* Abort TCP connection
*
* @v tcp TCP connection
* @v send_rst Send a RST after closing
* @v rc Reason code
*/
static void tcp_abort ( struct tcp_connection *tcp, int send_rst, int rc ) {
/* Transition to CLOSED */
tcp->tcp_state = TCP_CLOSED;
tcp_dump_state ( tcp );
/* Send RST if requested to do so */
if ( send_rst )
tcp_senddata_conn ( tcp, 1 );
/* Close stream */
stream_closed ( &tcp->stream, rc );
/* Free the connection */
free_tcp ( tcp );
}
/**
* Transmit any outstanding data
*
* @v tcp TCP connection
* @v force_send Force sending of packet
*
* Transmits any outstanding data on the connection. If the
* connection is in a connected state, the application's senddata()
* method will be called to generate the data payload, if any.
*
* Note that even if an error is returned, the retransmission timer
* will have been started if necessary, and so the stack will
* eventually attempt to retransmit the failed packet.
*/
static int tcp_senddata_conn ( struct tcp_connection *tcp, int force_send ) {
struct io_buffer *iobuf;
struct tcp_header *tcphdr;
struct tcp_mss_option *mssopt;
void *payload;
unsigned int flags;
size_t len;
size_t seq_len;
size_t window;
int rc;
/* Allocate space to the TX buffer */
iobuf = alloc_iob ( MAX_IOB_LEN );
if ( ! iobuf ) {
DBGC ( tcp, "TCP %p could not allocate data buffer\n", tcp );
/* Start the retry timer so that we attempt to
* retransmit this packet later. (Start it
* unconditionally, since without a I/O buffer we
* can't call the senddata() callback, and so may not
* be able to tell whether or not we have something
* that actually needs to be retransmitted).
*/
start_timer ( &tcp->timer );
return -ENOMEM;
}
iob_reserve ( iobuf, MAX_HDR_LEN );
/* If we are connected, call the senddata() method, which may
* call tcp_send() to queue up a data payload.
*/
if ( TCP_CAN_SEND_DATA ( tcp->tcp_state ) ) {
tcp->tx_iob = iobuf;
stream_senddata ( &tcp->stream, iobuf->data,
iob_tailroom ( iobuf ) );
tcp->tx_iob = NULL;
}
/* Truncate payload length to fit transmit window */
len = iob_len ( iobuf );
if ( len > tcp->snd_win )
len = tcp->snd_win;
/* Calculate amount of sequence space that this transmission
* consumes. (SYN or FIN consume one byte, and we can never
* send both at once).
*/
seq_len = len;
flags = TCP_FLAGS_SENDING ( tcp->tcp_state );
assert ( ! ( ( flags & TCP_SYN ) && ( flags & TCP_FIN ) ) );
if ( flags & ( TCP_SYN | TCP_FIN ) )
seq_len++;
tcp->snd_sent = seq_len;
/* If we have nothing to transmit, drop the packet */
if ( ( seq_len == 0 ) && ! force_send ) {
free_iob ( iobuf );
return 0;
}
/* If we are transmitting anything that requires
* acknowledgement (i.e. consumes sequence space), start the
* retransmission timer.
*/
if ( seq_len )
start_timer ( &tcp->timer );
/* Estimate window size */
window = ( ( freemem * 3 ) / 4 );
if ( window > TCP_MAX_WINDOW_SIZE )
window = TCP_MAX_WINDOW_SIZE;
window &= ~0x03; /* Keep everything dword-aligned */
/* Fill up the TCP header */
payload = iobuf->data;
if ( flags & TCP_SYN ) {
mssopt = iob_push ( iobuf, sizeof ( *mssopt ) );
mssopt->kind = TCP_OPTION_MSS;
mssopt->length = sizeof ( *mssopt );
mssopt->mss = htons ( TCP_MSS );
}
tcphdr = iob_push ( iobuf, sizeof ( *tcphdr ) );
memset ( tcphdr, 0, sizeof ( *tcphdr ) );
tcphdr->src = tcp->local_port;
tcphdr->dest = tcp->peer.st_port;
tcphdr->seq = htonl ( tcp->snd_seq );
tcphdr->ack = htonl ( tcp->rcv_ack );
tcphdr->hlen = ( ( payload - iobuf->data ) << 2 );
tcphdr->flags = flags;
tcphdr->win = htons ( window );
tcphdr->csum = tcpip_chksum ( iobuf->data, iob_len ( iobuf ) );
/* Dump header */
DBGC ( tcp, "TCP %p TX %d->%d %08lx..%08lx %08lx %4zd",
tcp, ntohs ( tcphdr->src ), ntohs ( tcphdr->dest ),
ntohl ( tcphdr->seq ), ( ntohl ( tcphdr->seq ) + seq_len ),
ntohl ( tcphdr->ack ), len );
tcp_dump_flags ( tcp, tcphdr->flags );
DBGC ( tcp, "\n" );
/* Transmit packet */
rc = tcpip_tx ( iobuf, &tcp_protocol, &tcp->peer, NULL, &tcphdr->csum );
/* If we got -ENETUNREACH, kill the connection immediately
* because there is no point retrying. This isn't strictly
* necessary (since we will eventually time out anyway), but
* it avoids irritating needless delays. Don't do this for
* RST packets transmitted on connection abort, to avoid a
* potential infinite loop.
*/
if ( ( ! ( tcp->tcp_state & TCP_STATE_SENT ( TCP_RST ) ) ) &&
( rc == -ENETUNREACH ) ) {
DBGC ( tcp, "TCP %p aborting after TX failed: %s\n",
tcp, strerror ( rc ) );
tcp_abort ( tcp, 0, rc );
}
return rc;
}
/**
* Transmit any outstanding data
*
* @v stream TCP stream
*
* This function allocates space to the transmit buffer and invokes
* the senddata() callback function, to allow the application to
* transmit new data.
*/
static int tcp_kick ( struct stream_connection *stream ) {
struct tcp_connection *tcp =
container_of ( stream, struct tcp_connection, stream );
return tcp_senddata_conn ( tcp, 0 );
}
/**
* Transmit data
*
* @v stream TCP stream
* @v data Data to be sent
* @v len Length of the data
* @ret rc Return status code
*
* This function queues data to be sent via the TCP connection. It
* can be called only in the context of an application's senddata()
* method.
*/
static int tcp_send ( struct stream_connection *stream,
const void *data, size_t len ) {
struct tcp_connection *tcp =
container_of ( stream, struct tcp_connection, stream );
struct io_buffer *iobuf;
/* Check that we have a I/O buffer to fill */
iobuf = tcp->tx_iob;
if ( ! iobuf ) {
DBGC ( tcp, "TCP %p tried to send data outside of the "
"senddata() method\n", tcp );
return -EINVAL;
}
/* Truncate length to fit I/O buffer */
if ( len > iob_tailroom ( iobuf ) )
len = iob_tailroom ( iobuf );
/* Copy payload */
memmove ( iob_put ( iobuf, len ), data, len );
return 0;
}
/**
* Retransmission timer expired
*
* @v timer Retry timer
* @v over Failure indicator
*/
static void tcp_expired ( struct retry_timer *timer, int over ) {
struct tcp_connection *tcp =
container_of ( timer, struct tcp_connection, timer );
int graceful_close = TCP_CLOSED_GRACEFULLY ( tcp->tcp_state );
DBGC ( tcp, "TCP %p timer %s in %s\n", tcp,
( over ? "expired" : "fired" ), tcp_state ( tcp->tcp_state ) );
assert ( ( tcp->tcp_state == TCP_SYN_SENT ) ||
( tcp->tcp_state == TCP_SYN_RCVD ) ||
( tcp->tcp_state == TCP_ESTABLISHED ) ||
( tcp->tcp_state == TCP_FIN_WAIT_1 ) ||
( tcp->tcp_state == TCP_TIME_WAIT ) ||
( tcp->tcp_state == TCP_CLOSE_WAIT ) ||
( tcp->tcp_state == TCP_CLOSING_OR_LAST_ACK ) );
if ( over || graceful_close ) {
/* If we have finally timed out and given up, or if
* this is the result of a graceful close, terminate
* the connection
*/
tcp_abort ( tcp, 1, -ETIMEDOUT );
} else {
/* Otherwise, retransmit the packet */
tcp_senddata_conn ( tcp, 0 );
}
}
/**
* Send RST response to incoming packet
*
* @v in_tcphdr TCP header of incoming packet
* @ret rc Return status code
*/
static int tcp_send_reset ( struct tcp_connection *tcp,
struct tcp_header *in_tcphdr ) {
struct io_buffer *iobuf;
struct tcp_header *tcphdr;
/* Allocate space for dataless TX buffer */
iobuf = alloc_iob ( MAX_HDR_LEN );
if ( ! iobuf ) {
DBGC ( tcp, "TCP %p could not allocate data buffer\n", tcp );
return -ENOMEM;
}
iob_reserve ( iobuf, MAX_HDR_LEN );
/* Construct RST response */
tcphdr = iob_push ( iobuf, sizeof ( *tcphdr ) );
memset ( tcphdr, 0, sizeof ( *tcphdr ) );
tcphdr->src = in_tcphdr->dest;
tcphdr->dest = in_tcphdr->src;
tcphdr->seq = in_tcphdr->ack;
tcphdr->ack = in_tcphdr->seq;
tcphdr->hlen = ( ( sizeof ( *tcphdr ) / 4 ) << 4 );
tcphdr->flags = ( TCP_RST | TCP_ACK );
tcphdr->win = htons ( TCP_MAX_WINDOW_SIZE );
tcphdr->csum = tcpip_chksum ( iobuf->data, iob_len ( iobuf ) );
/* Dump header */
DBGC ( tcp, "TCP %p TX %d->%d %08lx..%08lx %08lx %4zd",
tcp, ntohs ( tcphdr->src ), ntohs ( tcphdr->dest ),
ntohl ( tcphdr->seq ), ( ntohl ( tcphdr->seq ) ),
ntohl ( tcphdr->ack ), 0 );
tcp_dump_flags ( tcp, tcphdr->flags );
DBGC ( tcp, "\n" );
/* Transmit packet */
return tcpip_tx ( iobuf, &tcp_protocol, &tcp->peer,
NULL, &tcphdr->csum );
}
/**
* Identify TCP connection by local port number
*
* @v local_port Local port (in network-endian order)
* @ret tcp TCP connection, or NULL
*/
static struct tcp_connection * tcp_demux ( uint16_t local_port ) {
struct tcp_connection *tcp;
list_for_each_entry ( tcp, &tcp_conns, list ) {
if ( tcp->local_port == local_port )
return tcp;
}
return NULL;
}
/**
* Handle TCP received SYN
*
* @v tcp TCP connection
* @v seq SEQ value (in host-endian order)
* @ret rc Return status code
*/
static int tcp_rx_syn ( struct tcp_connection *tcp, uint32_t seq ) {
/* Synchronise sequence numbers on first SYN */
if ( ! ( tcp->tcp_state & TCP_STATE_RCVD ( TCP_SYN ) ) )
tcp->rcv_ack = seq;
/* Ignore duplicate SYN */
if ( ( tcp->rcv_ack - seq ) > 0 )
return 0;
/* Mark SYN as received and start sending ACKs with each packet */
tcp->tcp_state |= ( TCP_STATE_SENT ( TCP_ACK ) |
TCP_STATE_RCVD ( TCP_SYN ) );
/* Acknowledge SYN */
tcp->rcv_ack++;
/* Notify application of established connection, if applicable */
if ( ( tcp->tcp_state & TCP_STATE_ACKED ( TCP_SYN ) ) )
stream_connected ( &tcp->stream );
return 0;
}
/**
* Handle TCP received ACK
*
* @v tcp TCP connection
* @v ack ACK value (in host-endian order)
* @v win WIN value (in host-endian order)
* @ret rc Return status code
*/
static int tcp_rx_ack ( struct tcp_connection *tcp, uint32_t ack,
uint32_t win ) {
size_t ack_len = ( ack - tcp->snd_seq );
size_t len;
unsigned int acked_flags = 0;
/* Ignore duplicate or out-of-range ACK */
if ( ack_len > tcp->snd_sent ) {
DBGC ( tcp, "TCP %p received ACK for [%08lx,%08lx), "
"sent only [%08lx,%08lx)\n", tcp, tcp->snd_seq,
( tcp->snd_seq + ack_len ), tcp->snd_seq,
( tcp->snd_seq + tcp->snd_sent ) );
return -EINVAL;
}
/* If we are sending flags and this ACK acknowledges all
* outstanding sequence points, then it acknowledges the
* flags. (This works since both SYN and FIN will always be
* the last outstanding sequence point.)
*/
len = ack_len;
if ( ack_len == tcp->snd_sent ) {
acked_flags = ( TCP_FLAGS_SENDING ( tcp->tcp_state ) &
( TCP_SYN | TCP_FIN ) );
if ( acked_flags )
len--;
}
/* Update SEQ and sent counters, and window size */
tcp->snd_seq = ack;
tcp->snd_sent = 0;
tcp->snd_win = win;
/* Stop the retransmission timer */
stop_timer ( &tcp->timer );
/* Notify application of acknowledged data, if any */
if ( len )
stream_acked ( &tcp->stream, len );
/* Mark SYN/FIN as acknowledged if applicable. */
if ( acked_flags )
tcp->tcp_state |= TCP_STATE_ACKED ( acked_flags );
/* Notify application of established connection, if applicable */
if ( ( acked_flags & TCP_SYN ) &&
( tcp->tcp_state & TCP_STATE_RCVD ( TCP_SYN ) ) ) {
stream_connected ( &tcp->stream );
}
return 0;
}
/**
* Handle TCP received data
*
* @v tcp TCP connection
* @v seq SEQ value (in host-endian order)
* @v data Data buffer
* @v len Length of data buffer
* @ret rc Return status code
*/
static int tcp_rx_data ( struct tcp_connection *tcp, uint32_t seq,
void *data, size_t len ) {
size_t already_rcvd;
/* Ignore duplicate data */
already_rcvd = ( tcp->rcv_ack - seq );
if ( already_rcvd >= len )
return 0;
data += already_rcvd;
len -= already_rcvd;
/* Acknowledge new data */
tcp->rcv_ack += len;
/* Notify application */
stream_newdata ( &tcp->stream, data, len );
return 0;
}
/**
* Handle TCP received FIN
*
* @v tcp TCP connection
* @v seq SEQ value (in host-endian order)
* @ret rc Return status code
*/
static int tcp_rx_fin ( struct tcp_connection *tcp, uint32_t seq ) {
/* Ignore duplicate FIN */
if ( ( tcp->rcv_ack - seq ) > 0 )
return 0;
/* Mark FIN as received, acknowledge it, and send our own FIN */
tcp->tcp_state |= ( TCP_STATE_RCVD ( TCP_FIN ) |
TCP_STATE_SENT ( TCP_FIN ) );
tcp->rcv_ack++;
/* Close stream */
stream_closed ( &tcp->stream, 0 );
return 0;
}
/**
* Handle TCP received RST
*
* @v tcp TCP connection
* @v seq SEQ value (in host-endian order)
* @ret rc Return status code
*/
static int tcp_rx_rst ( struct tcp_connection *tcp, uint32_t seq ) {
/* Accept RST only if it falls within the window. If we have
* not yet received a SYN, then we have no window to test
* against, so fall back to checking that our SYN has been
* ACKed.
*/
if ( tcp->tcp_state & TCP_STATE_RCVD ( TCP_SYN ) ) {
if ( ( tcp->rcv_ack - seq ) > 0 )
return 0;
} else {
if ( ! ( tcp->tcp_state & TCP_STATE_ACKED ( TCP_SYN ) ) )
return 0;
}
/* Abort connection without sending a RST */
tcp_abort ( tcp, 0, -ECONNRESET );
return -ECONNRESET;
}
/**
* Process received packet
*
* @v iobuf I/O buffer
* @v st_src Partially-filled source address
* @v st_dest Partially-filled destination address
* @v pshdr_csum Pseudo-header checksum
* @ret rc Return status code
*/
static int tcp_rx ( struct io_buffer *iobuf,
struct sockaddr_tcpip *st_src __unused,
struct sockaddr_tcpip *st_dest __unused,
uint16_t pshdr_csum ) {
struct tcp_header *tcphdr = iobuf->data;
struct tcp_connection *tcp;
unsigned int hlen;
uint16_t csum;
uint32_t start_seq;
uint32_t seq;
uint32_t ack;
uint32_t win;
unsigned int flags;
void *data;
size_t len;
int rc;
/* Sanity check packet */
if ( iob_len ( iobuf ) < sizeof ( *tcphdr ) ) {
DBG ( "TCP packet too short at %d bytes (min %d bytes)\n",
iob_len ( iobuf ), sizeof ( *tcphdr ) );
rc = -EINVAL;
goto done;
}
hlen = ( ( tcphdr->hlen & TCP_MASK_HLEN ) / 16 ) * 4;
if ( hlen < sizeof ( *tcphdr ) ) {
DBG ( "TCP header too short at %d bytes (min %d bytes)\n",
hlen, sizeof ( *tcphdr ) );
rc = -EINVAL;
goto done;
}
if ( hlen > iob_len ( iobuf ) ) {
DBG ( "TCP header too long at %d bytes (max %d bytes)\n",
hlen, iob_len ( iobuf ) );
rc = -EINVAL;
goto done;
}
csum = tcpip_continue_chksum ( pshdr_csum, iobuf->data, iob_len ( iobuf ));
if ( csum != 0 ) {
DBG ( "TCP checksum incorrect (is %04x including checksum "
"field, should be 0000)\n", csum );
rc = -EINVAL;
goto done;
}
/* Parse parameters from header and strip header */
tcp = tcp_demux ( tcphdr->dest );
start_seq = seq = ntohl ( tcphdr->seq );
ack = ntohl ( tcphdr->ack );
win = ntohs ( tcphdr->win );
flags = tcphdr->flags;
data = iob_pull ( iobuf, hlen );
len = iob_len ( iobuf );
/* Dump header */
DBGC ( tcp, "TCP %p RX %d<-%d %08lx %08lx..%08lx %4zd",
tcp, ntohs ( tcphdr->dest ), ntohs ( tcphdr->src ),
ntohl ( tcphdr->ack ), ntohl ( tcphdr->seq ),
( ntohl ( tcphdr->seq ) + len +
( ( tcphdr->flags & ( TCP_SYN | TCP_FIN ) ) ? 1 : 0 ) ), len);
tcp_dump_flags ( tcp, tcphdr->flags );
DBGC ( tcp, "\n" );
/* If no connection was found, send RST */
if ( ! tcp ) {
tcp_send_reset ( tcp, tcphdr );
rc = -ENOTCONN;
goto done;
}
/* Handle ACK, if present */
if ( flags & TCP_ACK ) {
if ( ( rc = tcp_rx_ack ( tcp, ack, win ) ) != 0 ) {
tcp_send_reset ( tcp, tcphdr );
goto done;
}
}
/* Handle SYN, if present */
if ( flags & TCP_SYN ) {
tcp_rx_syn ( tcp, seq );
seq++;
}
/* Handle RST, if present */
if ( flags & TCP_RST ) {
if ( ( rc = tcp_rx_rst ( tcp, seq ) ) != 0 )
goto done;
}
/* Handle new data, if any */
tcp_rx_data ( tcp, seq, data, len );
seq += len;
/* Handle FIN, if present */
if ( flags & TCP_FIN ) {
tcp_rx_fin ( tcp, seq );
seq++;
}
/* Dump out any state change as a result of the received packet */
tcp_dump_state ( tcp );
/* Send out any pending data. If peer is expecting an ACK for
* this packet then force sending a reply.
*/
tcp_senddata_conn ( tcp, ( start_seq != seq ) );
/* If this packet was the last we expect to receive, set up
* timer to expire and cause the connection to be freed.
*/
if ( TCP_CLOSED_GRACEFULLY ( tcp->tcp_state ) ) {
tcp->timer.timeout = ( 2 * TCP_MSL );
start_timer ( &tcp->timer );
}
rc = 0;
done:
/* Free received packet */
free_iob ( iobuf );
return rc;
}
/**
* Bind TCP connection to local port
*
* @v stream TCP stream
* @v local Local address
* @ret rc Return status code
*
* Only the port portion of the local address is used. If the local
* port is 0, the connection is assigned an available port between
* 1024 and 65535.
*/
static int tcp_bind ( struct stream_connection *stream,
struct sockaddr *local ) {
struct tcp_connection *tcp =
container_of ( stream, struct tcp_connection, stream );
struct sockaddr_tcpip *st = ( ( struct sockaddr_tcpip * ) local );
struct tcp_connection *existing;
struct sockaddr_tcpip try;
static uint16_t try_port = 1024;
uint16_t local_port = st->st_port;
/* If no port specified, find the first available port */
if ( ! local_port ) {
for ( ; try_port ; try_port++ ) {
if ( try_port < 1024 )
continue;
try.st_port = htons ( try_port );
if ( tcp_bind ( stream,
( struct sockaddr * ) &try ) == 0 ) {
return 0;
}
}
DBGC ( tcp, "TCP %p could not bind: no free ports\n", tcp );
return -EADDRINUSE;
}
/* Attempt bind to local port */
list_for_each_entry ( existing, &tcp_conns, list ) {
if ( existing->local_port == local_port ) {
DBGC ( tcp, "TCP %p could not bind: port %d in use\n",
tcp, ntohs ( local_port ) );
return -EADDRINUSE;
}
}
tcp->local_port = local_port;
DBGC ( tcp, "TCP %p bound to port %d\n", tcp, ntohs ( local_port ) );
return 0;
}
/**
* Connect to a remote server
*
* @v stream TCP stream
* @v peer Remote socket address
* @ret rc Return status code
*
* 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.
*/
static int tcp_connect ( struct stream_connection *stream,
struct sockaddr *peer ) {
struct tcp_connection *tcp =
container_of ( stream, struct tcp_connection, stream );
struct sockaddr_tcpip *st = ( ( struct sockaddr_tcpip * ) peer );
struct sockaddr_tcpip local;
int rc;
/* Bind to local port if not already bound */
if ( ! tcp->local_port ) {
local.st_port = 0;
if ( ( rc = tcp_bind ( stream,
( struct sockaddr * ) &local ) ) != 0 ){
return rc;
}
}
/* Bind to peer */
memcpy ( &tcp->peer, st, sizeof ( tcp->peer ) );
/* Transition to TCP_SYN_SENT and send the SYN */
tcp->tcp_state = TCP_SYN_SENT;
tcp_dump_state ( tcp );
tcp_senddata_conn ( tcp, 0 );
return 0;
}
/**
* Close the connection
*
* @v stream TCP stream
*
* The TCP connection will persist until the state machine has
* returned to the TCP_CLOSED state.
*/
static void tcp_close ( struct stream_connection *stream ) {
struct tcp_connection *tcp =
container_of ( stream, struct tcp_connection, stream );
/* If we have not yet received a SYN (i.e. we are in CLOSED,
* LISTEN or SYN_SENT), just delete the connection
*/
if ( ! ( tcp->tcp_state & TCP_STATE_RCVD ( TCP_SYN ) ) ) {
tcp->tcp_state = TCP_CLOSED;
tcp_dump_state ( tcp );
free_tcp ( tcp );
return;
}
/* If we have not had our SYN acknowledged (i.e. we are in
* SYN_RCVD), pretend that it has been acknowledged so that we
* can send a FIN without breaking things.
*/
if ( ! ( tcp->tcp_state & TCP_STATE_ACKED ( TCP_SYN ) ) )
tcp_rx_ack ( tcp, ( tcp->snd_seq + 1 ), 0 );
/* Send a FIN to initiate the close */
tcp->tcp_state |= TCP_STATE_SENT ( TCP_FIN );
tcp_dump_state ( tcp );
tcp_senddata_conn ( tcp, 0 );
}
/**
* Open TCP connection
*
* @v app Stream application
* @ret rc Return status code
*/
int tcp_open ( struct stream_application *app ) {
struct tcp_connection *tcp;
/* Application must not already have an open connection */
if ( app->conn ) {
DBG ( "TCP app %p already open on %p\n", app, app->conn );
return -EISCONN;
}
/* Allocate connection state storage and add to connection list */
tcp = alloc_tcp();
if ( ! tcp ) {
DBG ( "TCP app %p could not allocate connection\n", app );
return -ENOMEM;
}
/* Associate application with connection */
stream_associate ( app, &tcp->stream );
return 0;
}
/** TCP stream operations */
static struct stream_connection_operations tcp_op = {
.bind = tcp_bind,
.connect = tcp_connect,
.close = tcp_close,
.send = tcp_send,
.kick = tcp_kick,
};
/** TCP protocol */
struct tcpip_protocol tcp_protocol __tcpip_protocol = {
.name = "TCP",
.rx = tcp_rx,
.tcpip_proto = IP_TCP,
};
