diff options
Diffstat (limited to 'gpxe/src/net/tcp.c')
| -rw-r--r-- | gpxe/src/net/tcp.c | 1156 |
1 files changed, 0 insertions, 1156 deletions
diff --git a/gpxe/src/net/tcp.c b/gpxe/src/net/tcp.c deleted file mode 100644 index a0619622..00000000 --- a/gpxe/src/net/tcp.c +++ /dev/null @@ -1,1156 +0,0 @@ -#include <string.h> -#include <stdlib.h> -#include <stdio.h> -#include <assert.h> -#include <errno.h> -#include <byteswap.h> -#include <gpxe/timer.h> -#include <gpxe/iobuf.h> -#include <gpxe/malloc.h> -#include <gpxe/retry.h> -#include <gpxe/refcnt.h> -#include <gpxe/xfer.h> -#include <gpxe/open.h> -#include <gpxe/uri.h> -#include <gpxe/tcpip.h> -#include <gpxe/tcp.h> - -/** @file - * - * TCP protocol - * - */ - -FILE_LICENCE ( GPL2_OR_LATER ); - -/** A TCP connection */ -struct tcp_connection { - /** Reference counter */ - struct refcnt refcnt; - /** List of TCP connections */ - struct list_head list; - - /** Data transfer interface */ - struct xfer_interface xfer; - /** Data transfer interface closed flag */ - int xfer_closed; - - /** Remote socket address */ - struct sockaddr_tcpip peer; - /** Local port, in network byte order */ - unsigned int 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; - /** Receive window - * - * Equivalent to RCV.WND in RFC 793 terminology. - */ - uint32_t rcv_win; - /** Most recent received timestamp - * - * Equivalent to TS.Recent in RFC 1323 terminology. - */ - uint32_t ts_recent; - /** Timestamps enabled */ - int timestamps; - - /** Transmit queue */ - struct list_head queue; - /** Retransmission timer */ - struct retry_timer timer; -}; - -/** - * List of registered TCP connections - */ -static LIST_HEAD ( tcp_conns ); - -/* Forward declarations */ -static struct xfer_interface_operations tcp_xfer_operations; -static void tcp_expired ( struct retry_timer *timer, int over ); -static int tcp_rx_ack ( struct tcp_connection *tcp, uint32_t ack, - uint32_t win ); - -/** - * 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 ) - DBGC2 ( tcp, " RST" ); - if ( flags & TCP_SYN ) - DBGC2 ( tcp, " SYN" ); - if ( flags & TCP_PSH ) - DBGC2 ( tcp, " PSH" ); - if ( flags & TCP_FIN ) - DBGC2 ( tcp, " FIN" ); - if ( flags & TCP_ACK ) - DBGC2 ( tcp, " ACK" ); -} - -/*************************************************************************** - * - * Open and close - * - *************************************************************************** - */ - -/** - * Bind TCP connection to local port - * - * @v tcp TCP connection - * @v port Local port number, in network-endian order - * @ret rc Return status code - * - * If the port is 0, the connection is assigned an available port - * between 1024 and 65535. - */ -static int tcp_bind ( struct tcp_connection *tcp, unsigned int port ) { - struct tcp_connection *existing; - static uint16_t try_port = 1023; - - /* If no port specified, find the first available port */ - if ( ! port ) { - while ( try_port ) { - try_port++; - if ( try_port < 1024 ) - continue; - if ( tcp_bind ( tcp, htons ( try_port ) ) == 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 == port ) { - DBGC ( tcp, "TCP %p could not bind: port %d in use\n", - tcp, ntohs ( port ) ); - return -EADDRINUSE; - } - } - tcp->local_port = port; - - DBGC ( tcp, "TCP %p bound to port %d\n", tcp, ntohs ( port ) ); - return 0; -} - -/** - * Open a TCP connection - * - * @v xfer Data transfer interface - * @v peer Peer socket address - * @v local Local socket address, or NULL - * @ret rc Return status code - */ -static int tcp_open ( struct xfer_interface *xfer, struct sockaddr *peer, - struct sockaddr *local ) { - struct sockaddr_tcpip *st_peer = ( struct sockaddr_tcpip * ) peer; - struct sockaddr_tcpip *st_local = ( struct sockaddr_tcpip * ) local; - struct tcp_connection *tcp; - unsigned int bind_port; - int rc; - - /* Allocate and initialise structure */ - tcp = zalloc ( sizeof ( *tcp ) ); - if ( ! tcp ) - return -ENOMEM; - DBGC ( tcp, "TCP %p allocated\n", tcp ); - xfer_init ( &tcp->xfer, &tcp_xfer_operations, &tcp->refcnt ); - tcp->prev_tcp_state = TCP_CLOSED; - tcp->tcp_state = TCP_STATE_SENT ( TCP_SYN ); - tcp_dump_state ( tcp ); - tcp->snd_seq = random(); - INIT_LIST_HEAD ( &tcp->queue ); - tcp->timer.expired = tcp_expired; - memcpy ( &tcp->peer, st_peer, sizeof ( tcp->peer ) ); - - /* Bind to local port */ - bind_port = ( st_local ? st_local->st_port : 0 ); - if ( ( rc = tcp_bind ( tcp, bind_port ) ) != 0 ) - goto err; - - /* Start timer to initiate SYN */ - start_timer_nodelay ( &tcp->timer ); - - /* Attach parent interface, transfer reference to connection - * list and return - */ - xfer_plug_plug ( &tcp->xfer, xfer ); - list_add ( &tcp->list, &tcp_conns ); - return 0; - - err: - ref_put ( &tcp->refcnt ); - return rc; -} - -/** - * Close TCP connection - * - * @v tcp TCP connection - * @v rc Reason for close - * - * Closes the data transfer interface. If the TCP state machine is in - * a suitable state, the connection will be deleted. - */ -static void tcp_close ( struct tcp_connection *tcp, int rc ) { - struct io_buffer *iobuf; - struct io_buffer *tmp; - - /* Close data transfer interface */ - xfer_nullify ( &tcp->xfer ); - xfer_close ( &tcp->xfer, rc ); - tcp->xfer_closed = 1; - - /* If we are in CLOSED, or have otherwise not yet received a - * SYN (i.e. we are in LISTEN or SYN_SENT), just delete the - * connection. - */ - if ( ! ( tcp->tcp_state & TCP_STATE_RCVD ( TCP_SYN ) ) ) { - - /* Transition to CLOSED for the sake of debugging messages */ - tcp->tcp_state = TCP_CLOSED; - tcp_dump_state ( tcp ); - - /* Free any unsent I/O buffers */ - list_for_each_entry_safe ( iobuf, tmp, &tcp->queue, list ) { - list_del ( &iobuf->list ); - free_iob ( iobuf ); - } - - /* Remove from list and drop reference */ - stop_timer ( &tcp->timer ); - list_del ( &tcp->list ); - ref_put ( &tcp->refcnt ); - DBGC ( tcp, "TCP %p connection deleted\n", 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 ); - - /* If we have no data remaining to send, start sending FIN */ - if ( list_empty ( &tcp->queue ) ) { - tcp->tcp_state |= TCP_STATE_SENT ( TCP_FIN ); - tcp_dump_state ( tcp ); - } -} - -/*************************************************************************** - * - * Transmit data path - * - *************************************************************************** - */ - -/** - * Calculate transmission window - * - * @v tcp TCP connection - * @ret len Maximum length that can be sent in a single packet - */ -static size_t tcp_xmit_win ( struct tcp_connection *tcp ) { - size_t len; - - /* Not ready if we're not in a suitable connection state */ - if ( ! TCP_CAN_SEND_DATA ( tcp->tcp_state ) ) - return 0; - - /* Length is the minimum of the receiver's window and the path MTU */ - len = tcp->snd_win; - if ( len > TCP_PATH_MTU ) - len = TCP_PATH_MTU; - - return len; -} - -/** - * Process TCP transmit queue - * - * @v tcp TCP connection - * @v max_len Maximum length to process - * @v dest I/O buffer to fill with data, or NULL - * @v remove Remove data from queue - * @ret len Length of data processed - * - * This processes at most @c max_len bytes from the TCP connection's - * transmit queue. Data will be copied into the @c dest I/O buffer - * (if provided) and, if @c remove is true, removed from the transmit - * queue. - */ -static size_t tcp_process_queue ( struct tcp_connection *tcp, size_t max_len, - struct io_buffer *dest, int remove ) { - struct io_buffer *iobuf; - struct io_buffer *tmp; - size_t frag_len; - size_t len = 0; - - list_for_each_entry_safe ( iobuf, tmp, &tcp->queue, list ) { - frag_len = iob_len ( iobuf ); - if ( frag_len > max_len ) - frag_len = max_len; - if ( dest ) { - memcpy ( iob_put ( dest, frag_len ), iobuf->data, - frag_len ); - } - if ( remove ) { - iob_pull ( iobuf, frag_len ); - if ( ! iob_len ( iobuf ) ) { - list_del ( &iobuf->list ); - free_iob ( iobuf ); - } - } - len += frag_len; - max_len -= frag_len; - } - return len; -} - -/** - * Transmit any outstanding data - * - * @v tcp TCP connection - * @v force_send Force sending of packet - * - * Transmits any outstanding data on the connection. - * - * 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_xmit ( struct tcp_connection *tcp, int force_send ) { - struct io_buffer *iobuf; - struct tcp_header *tcphdr; - struct tcp_mss_option *mssopt; - struct tcp_timestamp_padded_option *tsopt; - void *payload; - unsigned int flags; - size_t len = 0; - uint32_t seq_len; - uint32_t app_win; - uint32_t max_rcv_win; - int rc; - - /* If retransmission timer is already running, do nothing */ - if ( timer_running ( &tcp->timer ) ) - return 0; - - /* Calculate both the actual (payload) and sequence space - * lengths that we wish to transmit. - */ - if ( TCP_CAN_SEND_DATA ( tcp->tcp_state ) ) { - len = tcp_process_queue ( tcp, tcp_xmit_win ( tcp ), - NULL, 0 ); - } - seq_len = len; - flags = TCP_FLAGS_SENDING ( tcp->tcp_state ); - if ( flags & ( TCP_SYN | TCP_FIN ) ) { - /* SYN or FIN consume one byte, and we can never send both */ - assert ( ! ( ( flags & TCP_SYN ) && ( flags & TCP_FIN ) ) ); - seq_len++; - } - tcp->snd_sent = seq_len; - - /* If we have nothing to transmit, stop now */ - if ( ( seq_len == 0 ) && ! force_send ) - return 0; - - /* If we are transmitting anything that requires - * acknowledgement (i.e. consumes sequence space), start the - * retransmission timer. Do this before attempting to - * allocate the I/O buffer, in case allocation itself fails. - */ - if ( seq_len ) - start_timer ( &tcp->timer ); - - /* Allocate I/O buffer */ - iobuf = alloc_iob ( len + MAX_HDR_LEN ); - if ( ! iobuf ) { - DBGC ( tcp, "TCP %p could not allocate iobuf for %08x..%08x " - "%08x\n", tcp, tcp->snd_seq, ( tcp->snd_seq + seq_len ), - tcp->rcv_ack ); - return -ENOMEM; - } - iob_reserve ( iobuf, MAX_HDR_LEN ); - - /* Fill data payload from transmit queue */ - tcp_process_queue ( tcp, len, iobuf, 0 ); - - /* Expand receive window if possible */ - max_rcv_win = ( ( freemem * 3 ) / 4 ); - if ( max_rcv_win > TCP_MAX_WINDOW_SIZE ) - max_rcv_win = TCP_MAX_WINDOW_SIZE; - app_win = xfer_window ( &tcp->xfer ); - if ( max_rcv_win > app_win ) - max_rcv_win = app_win; - max_rcv_win &= ~0x03; /* Keep everything dword-aligned */ - if ( tcp->rcv_win < max_rcv_win ) - tcp->rcv_win = max_rcv_win; - - /* 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 ); - } - if ( ( flags & TCP_SYN ) || tcp->timestamps ) { - tsopt = iob_push ( iobuf, sizeof ( *tsopt ) ); - memset ( tsopt->nop, TCP_OPTION_NOP, sizeof ( tsopt->nop ) ); - tsopt->tsopt.kind = TCP_OPTION_TS; - tsopt->tsopt.length = sizeof ( tsopt->tsopt ); - tsopt->tsopt.tsval = ntohl ( currticks() ); - tsopt->tsopt.tsecr = ntohl ( tcp->ts_recent ); - } - if ( ! ( flags & TCP_SYN ) ) - flags |= TCP_PSH; - 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 ( tcp->rcv_win ); - tcphdr->csum = tcpip_chksum ( iobuf->data, iob_len ( iobuf ) ); - - /* Dump header */ - DBGC2 ( tcp, "TCP %p TX %d->%d %08x..%08x %08x %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 ); - DBGC2 ( tcp, "\n" ); - - /* Transmit packet */ - if ( ( rc = tcpip_tx ( iobuf, &tcp_protocol, NULL, &tcp->peer, NULL, - &tcphdr->csum ) ) != 0 ) { - DBGC ( tcp, "TCP %p could not transmit %08x..%08x %08x: %s\n", - tcp, tcp->snd_seq, ( tcp->snd_seq + tcp->snd_sent ), - tcp->rcv_ack, strerror ( rc ) ); - return rc; - } - - 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 for %08x..%08x %08x\n", tcp, - ( over ? "expired" : "fired" ), tcp_state ( tcp->tcp_state ), - tcp->snd_seq, ( tcp->snd_seq + tcp->snd_sent ), tcp->rcv_ack ); - - 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->tcp_state = TCP_CLOSED; - tcp_dump_state ( tcp ); - tcp_close ( tcp, -ETIMEDOUT ); - } else { - /* Otherwise, retransmit the packet */ - tcp_xmit ( tcp, 0 ); - } -} - -/** - * Send RST response to incoming packet - * - * @v in_tcphdr TCP header of incoming packet - * @ret rc Return status code - */ -static int tcp_xmit_reset ( struct tcp_connection *tcp, - struct sockaddr_tcpip *st_dest, - struct tcp_header *in_tcphdr ) { - struct io_buffer *iobuf; - struct tcp_header *tcphdr; - int rc; - - /* Allocate space for dataless TX buffer */ - iobuf = alloc_iob ( MAX_HDR_LEN ); - if ( ! iobuf ) { - DBGC ( tcp, "TCP %p could not allocate iobuf for RST " - "%08x..%08x %08x\n", tcp, ntohl ( in_tcphdr->ack ), - ntohl ( in_tcphdr->ack ), ntohl ( in_tcphdr->seq ) ); - 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 */ - DBGC2 ( tcp, "TCP %p TX %d->%d %08x..%08x %08x %4d", - tcp, ntohs ( tcphdr->src ), ntohs ( tcphdr->dest ), - ntohl ( tcphdr->seq ), ( ntohl ( tcphdr->seq ) ), - ntohl ( tcphdr->ack ), 0 ); - tcp_dump_flags ( tcp, tcphdr->flags ); - DBGC2 ( tcp, "\n" ); - - /* Transmit packet */ - if ( ( rc = tcpip_tx ( iobuf, &tcp_protocol, NULL, st_dest, - NULL, &tcphdr->csum ) ) != 0 ) { - DBGC ( tcp, "TCP %p could not transmit RST %08x..%08x %08x: " - "%s\n", tcp, ntohl ( in_tcphdr->ack ), - ntohl ( in_tcphdr->ack ), ntohl ( in_tcphdr->seq ), - strerror ( rc ) ); - return rc; - } - - return 0; -} - -/*************************************************************************** - * - * Receive data path - * - *************************************************************************** - */ - -/** - * 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 ( unsigned int local_port ) { - struct tcp_connection *tcp; - - list_for_each_entry ( tcp, &tcp_conns, list ) { - if ( tcp->local_port == local_port ) - return tcp; - } - return NULL; -} - -/** - * Parse TCP received options - * - * @v tcp TCP connection - * @v data Raw options data - * @v len Raw options length - * @v options Options structure to fill in - */ -static void tcp_rx_opts ( struct tcp_connection *tcp, const void *data, - size_t len, struct tcp_options *options ) { - const void *end = ( data + len ); - const struct tcp_option *option; - unsigned int kind; - - memset ( options, 0, sizeof ( *options ) ); - while ( data < end ) { - option = data; - kind = option->kind; - if ( kind == TCP_OPTION_END ) - return; - if ( kind == TCP_OPTION_NOP ) { - data++; - continue; - } - switch ( kind ) { - case TCP_OPTION_MSS: - options->mssopt = data; - break; - case TCP_OPTION_TS: - options->tsopt = data; - break; - default: - DBGC ( tcp, "TCP %p received unknown option %d\n", - tcp, kind ); - break; - } - data += option->length; - } -} - -/** - * Consume received sequence space - * - * @v tcp TCP connection - * @v seq_len Sequence space length to consume - */ -static void tcp_rx_seq ( struct tcp_connection *tcp, uint32_t seq_len ) { - tcp->rcv_ack += seq_len; - if ( tcp->rcv_win > seq_len ) { - tcp->rcv_win -= seq_len; - } else { - tcp->rcv_win = 0; - } -} - -/** - * Handle TCP received SYN - * - * @v tcp TCP connection - * @v seq SEQ value (in host-endian order) - * @v options TCP options - * @ret rc Return status code - */ -static int tcp_rx_syn ( struct tcp_connection *tcp, uint32_t seq, - struct tcp_options *options ) { - - /* Synchronise sequence numbers on first SYN */ - if ( ! ( tcp->tcp_state & TCP_STATE_RCVD ( TCP_SYN ) ) ) { - tcp->rcv_ack = seq; - if ( options->tsopt ) - tcp->timestamps = 1; - } - - /* 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_rx_seq ( tcp, 1 ); - - 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 ) { - uint32_t ack_len = ( ack - tcp->snd_seq ); - size_t len; - unsigned int acked_flags; - - /* Check for out-of-range or old duplicate ACKs */ - if ( ack_len > tcp->snd_sent ) { - DBGC ( tcp, "TCP %p received ACK for %08x..%08x, " - "sent only %08x..%08x\n", tcp, tcp->snd_seq, - ( tcp->snd_seq + ack_len ), tcp->snd_seq, - ( tcp->snd_seq + tcp->snd_sent ) ); - - if ( TCP_HAS_BEEN_ESTABLISHED ( tcp->tcp_state ) ) { - /* Just ignore what might be old duplicate ACKs */ - return 0; - } else { - /* Send RST if an out-of-range ACK is received - * on a not-yet-established connection, as per - * RFC 793. - */ - return -EINVAL; - } - } - - /* Ignore ACKs that don't actually acknowledge any new data. - * (In particular, do not stop the retransmission timer; this - * avoids creating a sorceror's apprentice syndrome when a - * duplicate ACK is received and we still have data in our - * transmit queue.) - */ - if ( ack_len == 0 ) - return 0; - - /* Stop the retransmission timer */ - stop_timer ( &tcp->timer ); - - /* Determine acknowledged flags and data length */ - len = ack_len; - 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; - - /* Remove any acknowledged data from transmit queue */ - tcp_process_queue ( tcp, len, NULL, 1 ); - - /* Mark SYN/FIN as acknowledged if applicable. */ - if ( acked_flags ) - tcp->tcp_state |= TCP_STATE_ACKED ( acked_flags ); - - /* Start sending FIN if we've had all possible data ACKed */ - if ( list_empty ( &tcp->queue ) && tcp->xfer_closed ) - tcp->tcp_state |= TCP_STATE_SENT ( TCP_FIN ); - - return 0; -} - -/** - * Handle TCP received data - * - * @v tcp TCP connection - * @v seq SEQ value (in host-endian order) - * @v iobuf I/O buffer - * @ret rc Return status code - * - * This function takes ownership of the I/O buffer. - */ -static int tcp_rx_data ( struct tcp_connection *tcp, uint32_t seq, - struct io_buffer *iobuf ) { - uint32_t already_rcvd; - uint32_t len; - int rc; - - /* Ignore duplicate or out-of-order data */ - already_rcvd = ( tcp->rcv_ack - seq ); - len = iob_len ( iobuf ); - if ( already_rcvd >= len ) { - free_iob ( iobuf ); - return 0; - } - iob_pull ( iobuf, already_rcvd ); - len -= already_rcvd; - - /* Deliver data to application */ - if ( ( rc = xfer_deliver_iob ( &tcp->xfer, iobuf ) ) != 0 ) { - DBGC ( tcp, "TCP %p could not deliver %08x..%08x: %s\n", - tcp, seq, ( seq + len ), strerror ( rc ) ); - return rc; - } - - /* Acknowledge new data */ - tcp_rx_seq ( tcp, 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 or out-of-order FIN */ - if ( ( tcp->rcv_ack - seq ) > 0 ) - return 0; - - /* Mark FIN as received and acknowledge it */ - tcp->tcp_state |= TCP_STATE_RCVD ( TCP_FIN ); - tcp_rx_seq ( tcp, 1 ); - - /* Close connection */ - tcp_close ( tcp, 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 ( ( seq - tcp->rcv_ack ) >= tcp->rcv_win ) - return 0; - } else { - if ( ! ( tcp->tcp_state & TCP_STATE_ACKED ( TCP_SYN ) ) ) - return 0; - } - - /* Abort connection */ - tcp->tcp_state = TCP_CLOSED; - tcp_dump_state ( tcp ); - tcp_close ( tcp, -ECONNRESET ); - - DBGC ( tcp, "TCP %p connection reset by peer\n", tcp ); - 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, - struct sockaddr_tcpip *st_dest __unused, - uint16_t pshdr_csum ) { - struct tcp_header *tcphdr = iobuf->data; - struct tcp_connection *tcp; - struct tcp_options options; - size_t hlen; - uint16_t csum; - uint32_t start_seq; - uint32_t seq; - uint32_t ack; - uint32_t win; - unsigned int flags; - size_t len; - int rc; - - /* Sanity check packet */ - if ( iob_len ( iobuf ) < sizeof ( *tcphdr ) ) { - DBG ( "TCP packet too short at %zd bytes (min %zd bytes)\n", - iob_len ( iobuf ), sizeof ( *tcphdr ) ); - rc = -EINVAL; - goto discard; - } - hlen = ( ( tcphdr->hlen & TCP_MASK_HLEN ) / 16 ) * 4; - if ( hlen < sizeof ( *tcphdr ) ) { - DBG ( "TCP header too short at %zd bytes (min %zd bytes)\n", - hlen, sizeof ( *tcphdr ) ); - rc = -EINVAL; - goto discard; - } - if ( hlen > iob_len ( iobuf ) ) { - DBG ( "TCP header too long at %zd bytes (max %zd bytes)\n", - hlen, iob_len ( iobuf ) ); - rc = -EINVAL; - goto discard; - } - 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 discard; - } - - /* 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; - tcp_rx_opts ( tcp, ( ( ( void * ) tcphdr ) + sizeof ( *tcphdr ) ), - ( hlen - sizeof ( *tcphdr ) ), &options ); - iob_pull ( iobuf, hlen ); - len = iob_len ( iobuf ); - - /* Dump header */ - DBGC2 ( tcp, "TCP %p RX %d<-%d %08x %08x..%08zx %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 ); - DBGC2 ( tcp, "\n" ); - - /* If no connection was found, send RST */ - if ( ! tcp ) { - tcp_xmit_reset ( tcp, st_src, tcphdr ); - rc = -ENOTCONN; - goto discard; - } - - /* Handle ACK, if present */ - if ( flags & TCP_ACK ) { - if ( ( rc = tcp_rx_ack ( tcp, ack, win ) ) != 0 ) { - tcp_xmit_reset ( tcp, st_src, tcphdr ); - goto discard; - } - } - - /* Handle SYN, if present */ - if ( flags & TCP_SYN ) { - tcp_rx_syn ( tcp, seq, &options ); - seq++; - } - - /* Handle RST, if present */ - if ( flags & TCP_RST ) { - if ( ( rc = tcp_rx_rst ( tcp, seq ) ) != 0 ) - goto discard; - } - - /* Handle new data, if any */ - tcp_rx_data ( tcp, seq, iobuf ); - seq += len; - - /* Handle FIN, if present */ - if ( flags & TCP_FIN ) { - tcp_rx_fin ( tcp, seq ); - seq++; - } - - /* Update timestamp, if present and applicable */ - if ( ( seq == tcp->rcv_ack ) && options.tsopt ) - tcp->ts_recent = ntohl ( options.tsopt->tsval ); - - /* Dump out any state change as a result of the received packet */ - tcp_dump_state ( tcp ); - - /* Send out any pending data. We force sending a reply if either - * - * a) the peer is expecting an ACK (i.e. consumed sequence space), or - * b) either end of the packet was outside the receive window - * - * Case (b) enables us to support TCP keepalives using - * zero-length packets, which we would otherwise ignore. Note - * that for case (b), we need *only* consider zero-length - * packets, since non-zero-length packets will already be - * caught by case (a). - */ - tcp_xmit ( tcp, ( ( start_seq != seq ) || - ( ( seq - tcp->rcv_ack ) > tcp->rcv_win ) ) ); - - /* 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 ); - } - - return 0; - - discard: - /* Free received packet */ - free_iob ( iobuf ); - return rc; -} - -/** TCP protocol */ -struct tcpip_protocol tcp_protocol __tcpip_protocol = { - .name = "TCP", - .rx = tcp_rx, - .tcpip_proto = IP_TCP, -}; - -/*************************************************************************** - * - * Data transfer interface - * - *************************************************************************** - */ - -/** - * Close interface - * - * @v xfer Data transfer interface - * @v rc Reason for close - */ -static void tcp_xfer_close ( struct xfer_interface *xfer, int rc ) { - struct tcp_connection *tcp = - container_of ( xfer, struct tcp_connection, xfer ); - - /* Close data transfer interface */ - tcp_close ( tcp, rc ); - - /* Transmit FIN, if possible */ - tcp_xmit ( tcp, 0 ); -} - -/** - * Check flow control window - * - * @v xfer Data transfer interface - * @ret len Length of window - */ -static size_t tcp_xfer_window ( struct xfer_interface *xfer ) { - struct tcp_connection *tcp = - container_of ( xfer, struct tcp_connection, xfer ); - - /* Not ready if data queue is non-empty. This imposes a limit - * of only one unACKed packet in the TX queue at any time; we - * do this to conserve memory usage. - */ - if ( ! list_empty ( &tcp->queue ) ) - return 0; - - /* Return TCP window length */ - return tcp_xmit_win ( tcp ); -} - -/** - * Deliver datagram as I/O buffer - * - * @v xfer Data transfer interface - * @v iobuf Datagram I/O buffer - * @v meta Data transfer metadata - * @ret rc Return status code - */ -static int tcp_xfer_deliver_iob ( struct xfer_interface *xfer, - struct io_buffer *iobuf, - struct xfer_metadata *meta __unused ) { - struct tcp_connection *tcp = - container_of ( xfer, struct tcp_connection, xfer ); - - /* Enqueue packet */ - list_add_tail ( &iobuf->list, &tcp->queue ); - - /* Transmit data, if possible */ - tcp_xmit ( tcp, 0 ); - - return 0; -} - -/** TCP data transfer interface operations */ -static struct xfer_interface_operations tcp_xfer_operations = { - .close = tcp_xfer_close, - .vredirect = ignore_xfer_vredirect, - .window = tcp_xfer_window, - .alloc_iob = default_xfer_alloc_iob, - .deliver_iob = tcp_xfer_deliver_iob, - .deliver_raw = xfer_deliver_as_iob, -}; - -/*************************************************************************** - * - * Openers - * - *************************************************************************** - */ - -/** TCP socket opener */ -struct socket_opener tcp_socket_opener __socket_opener = { - .semantics = TCP_SOCK_STREAM, - .family = AF_INET, - .open = tcp_open, -}; - -/** Linkage hack */ -int tcp_sock_stream = TCP_SOCK_STREAM; - -/** - * Open TCP URI - * - * @v xfer Data transfer interface - * @v uri URI - * @ret rc Return status code - */ -static int tcp_open_uri ( struct xfer_interface *xfer, struct uri *uri ) { - struct sockaddr_tcpip peer; - - /* Sanity check */ - if ( ! uri->host ) - return -EINVAL; - - memset ( &peer, 0, sizeof ( peer ) ); - peer.st_port = htons ( uri_port ( uri, 0 ) ); - return xfer_open_named_socket ( xfer, SOCK_STREAM, - ( struct sockaddr * ) &peer, - uri->host, NULL ); -} - -/** TCP URI opener */ -struct uri_opener tcp_uri_opener __uri_opener = { - .scheme = "tcp", - .open = tcp_open_uri, -}; - |