#include #include #include #include #include #include #include #include #include #include #include #include #include /** @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 packet buffer * * This buffer is allocated prior to calling the application's * senddata() method, to provide temporary storage space. */ struct pk_buff *tx_pkb; /** 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 pk_buff *pkb; 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 */ pkb = alloc_pkb ( MAX_PKB_LEN ); if ( ! pkb ) { 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 packet 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; } pkb_reserve ( pkb, 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_pkb = pkb; stream_senddata ( &tcp->stream, pkb->data, pkb_tailroom ( pkb ) ); tcp->tx_pkb = NULL; } /* Truncate payload length to fit transmit window */ len = pkb_len ( pkb ); 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_pkb ( pkb ); 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 = pkb->data; if ( flags & TCP_SYN ) { mssopt = pkb_push ( pkb, sizeof ( *mssopt ) ); mssopt->kind = TCP_OPTION_MSS; mssopt->length = sizeof ( *mssopt ); mssopt->mss = htons ( TCP_MSS ); } tcphdr = pkb_push ( pkb, 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 - pkb->data ) << 2 ); tcphdr->flags = flags; tcphdr->win = htons ( window ); tcphdr->csum = tcpip_chksum ( pkb->data, pkb_len ( pkb ) ); /* 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 ( pkb, &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 pk_buff *pkb; /* Check that we have a packet buffer to fill */ pkb = tcp->tx_pkb; if ( ! pkb ) { DBGC ( tcp, "TCP %p tried to send data outside of the " "senddata() method\n", tcp ); return -EINVAL; } /* Truncate length to fit packet buffer */ if ( len > pkb_tailroom ( pkb ) ) len = pkb_tailroom ( pkb ); /* Copy payload */ memmove ( pkb_put ( pkb, 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 pk_buff *pkb; struct tcp_header *tcphdr; /* Allocate space for dataless TX buffer */ pkb = alloc_pkb ( MAX_HDR_LEN ); if ( ! pkb ) { DBGC ( tcp, "TCP %p could not allocate data buffer\n", tcp ); return -ENOMEM; } pkb_reserve ( pkb, MAX_HDR_LEN ); /* Construct RST response */ tcphdr = pkb_push ( pkb, 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 ( pkb->data, pkb_len ( pkb ) ); /* 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 ( pkb, &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 pkb Packet 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 pk_buff *pkb, struct sockaddr_tcpip *st_src __unused, struct sockaddr_tcpip *st_dest __unused, uint16_t pshdr_csum ) { struct tcp_header *tcphdr = pkb->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 ( pkb_len ( pkb ) < sizeof ( *tcphdr ) ) { DBG ( "TCP packet too short at %d bytes (min %d bytes)\n", pkb_len ( pkb ), 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 > pkb_len ( pkb ) ) { DBG ( "TCP header too long at %d bytes (max %d bytes)\n", hlen, pkb_len ( pkb ) ); rc = -EINVAL; goto done; } csum = tcpip_continue_chksum ( pshdr_csum, pkb->data, pkb_len ( pkb )); 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 = pkb_pull ( pkb, hlen ); len = pkb_len ( pkb ); /* 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_pkb ( pkb ); 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, };