#include "lwip/opt.h"
#include "lwip/tcp.h"
#include "lwip/mem.h"
#include "lwip/pbuf.h"
#include "lwip/ip.h"
#include "lwip/icmp.h"
#include "lwip/err.h"

Data Structures
struct	tcp_hdr

union	tcp_listen_pcbs_t

struct	tcp_seg

Macros
#define	LWIP_TCP_OPT_LENGTH(flags)

#define	TCP_ACK 0x10U

#define	tcp_ack(pcb)

#define	tcp_ack_now(pcb)

#define	TCP_BUILD_MSS_OPTION(mss) htonl(0x02040000 \| ((mss) & 0xFFFF))
	This returns a TCP header option for MSS in an u32_t. More...

#define	TCP_CHECKSUM_ON_COPY (LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_TCP)
	Don't generate checksum on copy if CHECKSUM_GEN_TCP is disabled. More...

#define	TCP_CWR 0x80U

#define	TCP_DEBUG_PCB_LISTS 0

#define	tcp_debug_print(tcphdr)

#define	tcp_debug_print_flags(flags)

#define	tcp_debug_print_pcbs()

#define	tcp_debug_print_state(s)

#define	tcp_do_output_nagle(tpcb)
	This is the Nagle algorithm: try to combine user data to send as few TCP segments as possible. More...

#define	TCP_ECE 0x40U

#define	TCP_EVENT_ACCEPT(pcb, err, ret)

#define	TCP_EVENT_CLOSED(pcb, ret)

#define	TCP_EVENT_CONNECTED(pcb, err, ret)

#define	TCP_EVENT_ERR(errf, arg, err)

#define	TCP_EVENT_POLL(pcb, ret)

#define	TCP_EVENT_RECV(pcb, p, err, ret)

#define	TCP_EVENT_SENT(pcb, space, ret)

#define	TCP_FAST_INTERVAL TCP_TMR_INTERVAL /* the fine grained timeout in milliseconds */

#define	TCP_FIN 0x01U

#define	TCP_FIN_WAIT_TIMEOUT 20000 /* milliseconds */

#define	TCP_FLAGS 0x3fU

#define	TCP_HLEN 20

#define	TCP_KEEPCNT_DEFAULT 9U /* Default Counter for KEEPALIVE probes */

#define	TCP_KEEPIDLE_DEFAULT 7200000UL /* Default KEEPALIVE timer in milliseconds */

#define	TCP_KEEPINTVL_DEFAULT 75000UL /* Default Time between KEEPALIVE probes in milliseconds */

#define	TCP_MAXIDLE TCP_KEEPCNT_DEFAULT * TCP_KEEPINTVL_DEFAULT /* Maximum KEEPALIVE probe time */

#define	TCP_MSL 60000UL /* The maximum segment lifetime in milliseconds */

#define	TCP_OOSEQ_TIMEOUT 6U /* x RTO */

#define	tcp_output_nagle(tpcb) (tcp_do_output_nagle(tpcb) ? tcp_output(tpcb) : ERR_OK)

#define	TCP_OVERSIZE_DBGCHECK 0
	Enabled extra-check for TCP_OVERSIZE if LWIP_DEBUG is enabled. More...

#define	TCP_PCB_REMOVE_ACTIVE(pcb)

#define	tcp_pcbs_sane() 1

#define	TCP_PSH 0x08U

#define	TCP_REG(pcbs, npcb)

#define	TCP_REG_ACTIVE(npcb)

#define	TCP_RMV(pcbs, npcb)

#define	TCP_RMV_ACTIVE(npcb)

#define	TCP_RST 0x04U

#define	TCP_SEQ_BETWEEN(a, b, c) (TCP_SEQ_GEQ(a,b) && TCP_SEQ_LEQ(a,c))

#define	TCP_SEQ_GEQ(a, b) ((s32_t)((u32_t)(a) - (u32_t)(b)) >= 0)

#define	TCP_SEQ_GT(a, b) ((s32_t)((u32_t)(a) - (u32_t)(b)) > 0)

#define	TCP_SEQ_LEQ(a, b) ((s32_t)((u32_t)(a) - (u32_t)(b)) <= 0)

#define	TCP_SEQ_LT(a, b) ((s32_t)((u32_t)(a) - (u32_t)(b)) < 0)

#define	TCP_SLOW_INTERVAL (2TCP_TMR_INTERVAL) / the coarse grained timeout in milliseconds */

#define	TCP_SYN 0x02U

#define	TCP_SYN_RCVD_TIMEOUT 20000 /* milliseconds */

#define	TCP_TCPLEN(seg) ((seg)->len + ((TCPH_FLAGS((seg)->tcphdr) & (TCP_FIN \| TCP_SYN)) != 0))

#define	TCP_TMR_INTERVAL 250 /* The TCP timer interval in milliseconds. */

#define	TCP_URG 0x20U

#define	TCPH_FLAGS(phdr) (ntohs((phdr)->_hdrlen_rsvd_flags) & TCP_FLAGS)

#define	TCPH_FLAGS_SET(phdr, flags) (phdr)->_hdrlen_rsvd_flags = (((phdr)->_hdrlen_rsvd_flags & PP_HTONS((u16_t)(~(u16_t)(TCP_FLAGS)))) \| htons(flags))

#define	TCPH_HDRLEN(phdr) (ntohs((phdr)->_hdrlen_rsvd_flags) >> 12)

#define	TCPH_HDRLEN_FLAGS_SET(phdr, len, flags) (phdr)->_hdrlen_rsvd_flags = htons(((len) << 12) \| (flags))

#define	TCPH_HDRLEN_SET(phdr, len) (phdr)->_hdrlen_rsvd_flags = htons(((len) << 12) \| TCPH_FLAGS(phdr))

#define	TCPH_SET_FLAG(phdr, flags) (phdr)->_hdrlen_rsvd_flags = ((phdr)->_hdrlen_rsvd_flags \| htons(flags))

#define	TCPH_UNSET_FLAG(phdr, flags) (phdr)->_hdrlen_rsvd_flags = htons(ntohs((phdr)->_hdrlen_rsvd_flags) \| (TCPH_FLAGS(phdr) & ~(flags)) )

#define	TF_CLOSED (u8_t)0x10U /* Connection was sucessfully closed. */

#define	TF_GOT_FIN (u8_t)0x20U /* Connection was closed by the remote end. */

#define	TF_RESET (u8_t)0x08U /* Connection was reset. */
	Flags used on input processing, not on pcb->flags. More...

#define	TF_SEG_DATA_CHECKSUMMED

#define	TF_SEG_OPTS_MSS (u8_t)0x01U /* Include MSS option. */

#define	TF_SEG_OPTS_TS (u8_t)0x02U /* Include timestamp option. */

Functions
void	tcp_abandon (struct tcp_pcb *pcb, int reset)
	Abandons a connection and optionally sends a RST to the remote host. More...

struct tcp_pcb *	tcp_alloc (u8_t prio)
	Allocate a new tcp_pcb structure. More...

u16_t	tcp_eff_send_mss (u16_t sendmss, ip_addr_t *addr)
	Calcluates the effective send mss that can be used for a specific IP address by using ip_route to determin the netif used to send to the address and calculating the minimum of TCP_MSS and that netif's mtu (if set). More...

err_t	tcp_enqueue_flags (struct tcp_pcb *pcb, u8_t flags)
	Enqueue TCP options for transmission. More...

void	tcp_fasttmr (void)
	Is called every TCP_FAST_INTERVAL (250 ms) and process data previously "refused" by upper layer (application) and sends delayed ACKs. More...

void	tcp_init (void)
	Initialize this module. More...

void	tcp_input (struct pbuf p, struct netif inp)
	The initial input processing of TCP. More...

void	tcp_keepalive (struct tcp_pcb *pcb)
	Send keepalive packets to keep a connection active although no data is sent over it. More...

u32_t	tcp_next_iss (void)
	Calculates a new initial sequence number for new connections. More...

struct tcp_pcb *	tcp_pcb_copy (struct tcp_pcb *pcb)

void	tcp_pcb_purge (struct tcp_pcb *pcb)
	Purges a TCP PCB. More...

void	tcp_pcb_remove (struct tcp_pcb *pcblist, struct tcp_pcb pcb)
	Purges the PCB and removes it from a PCB list. More...

err_t	tcp_process_refused_data (struct tcp_pcb *pcb)
	Pass pcb->refused_data to the recv callback. More...

err_t	tcp_recv_null (void arg, struct tcp_pcb pcb, struct pbuf *p, err_t err)
	Default receive callback that is called if the user didn't register a recv callback for the pcb. More...

void	tcp_rexmit (struct tcp_pcb *pcb)
	Requeue the first unacked segment for retransmission. More...

void	tcp_rexmit_fast (struct tcp_pcb *pcb)
	Handle retransmission after three dupacks received. More...

void	tcp_rexmit_rto (struct tcp_pcb *pcb)
	Requeue all unacked segments for retransmission. More...

void	tcp_rexmit_seg (struct tcp_pcb pcb, struct tcp_seg seg)

void	tcp_rst (u32_t seqno, u32_t ackno, ip_addr_t local_ip, ip_addr_t remote_ip, u16_t local_port, u16_t remote_port)
	Send a TCP RESET packet (empty segment with RST flag set) either to abort a connection or to show that there is no matching local connection for a received segment. More...

struct tcp_seg *	tcp_seg_copy (struct tcp_seg *seg)
	Returns a copy of the given TCP segment. More...

void	tcp_seg_free (struct tcp_seg *seg)
	Frees a TCP segment (tcp_seg structure). More...

void	tcp_segs_free (struct tcp_seg *seg)
	Deallocates a list of TCP segments (tcp_seg structures). More...

err_t	tcp_send_empty_ack (struct tcp_pcb *pcb)
	Send an ACK without data. More...

err_t	tcp_send_fin (struct tcp_pcb *pcb)
	Called by tcp_close() to send a segment including FIN flag but not data. More...

void	tcp_slowtmr (void)
	Called every 500 ms and implements the retransmission timer and the timer that removes PCBs that have been in TIME-WAIT for enough time. More...

void	tcp_timer_needed (void)
	External function (implemented in timers.c), called when TCP detects that a timer is needed (i.e. More...

void	tcp_tmr (void)
	Called periodically to dispatch TCP timers. More...

u32_t	tcp_update_rcv_ann_wnd (struct tcp_pcb *pcb)
	Update the state that tracks the available window space to advertise. More...

void	tcp_zero_window_probe (struct tcp_pcb *pcb)
	Send persist timer zero-window probes to keep a connection active when a window update is lost. More...

Variables
PACK_STRUCT_BEGIN struct tcp_hdr	PACK_STRUCT_STRUCT

struct tcp_pcb *	tcp_active_pcbs
	List of all TCP PCBs that are in a state in which they accept or send data. More...

u8_t	tcp_active_pcbs_changed

struct tcp_pcb *	tcp_bound_pcbs
	List of all TCP PCBs bound but not yet (connected \|\| listening) More...

struct tcp_pcb *	tcp_input_pcb

union tcp_listen_pcbs_t	tcp_listen_pcbs
	List of all TCP PCBs in LISTEN state. More...

u32_t	tcp_ticks

struct tcp_pcb *	tcp_tmp_pcb
	Only used for temporary storage. More...

struct tcp_pcb *	tcp_tw_pcbs
	List of all TCP PCBs in TIME-WAIT state. More...

#define LWIP_TCP_OPT_LENGTH ( flags )

Value:

(flags & TF_SEG_OPTS_MSS ? 4 : 0) + \

(flags & TF_SEG_OPTS_TS ? 12 : 0)

TF_SEG_OPTS_MSS

#define TF_SEG_OPTS_MSS

Definition: tcp_impl.h:291

TF_SEG_OPTS_TS

#define TF_SEG_OPTS_TS

Definition: tcp_impl.h:292

flags

static u8_t flags

Definition: tcp_in.c:66

Referenced by tcp_create_segment(), tcp_enqueue_flags(), tcp_send_empty_ack(), and tcp_write().

#define TCP_ACK 0x10U

Referenced by tcp_listen_input(), tcp_output(), tcp_output_alloc_header(), tcp_process(), tcp_receive(), tcp_rst(), and tcp_zero_window_probe().

#define tcp_ack ( pcb )

Value:

do {                                             \
    if((pcb)->flags & TF_ACK_DELAY) {              \
      (pcb)->flags &= ~TF_ACK_DELAY;               \
      (pcb)->flags |= TF_ACK_NOW;                  \
    }                                              \
    else {                                         \
      (pcb)->flags |= TF_ACK_DELAY;                \
    }                                              \
  } while (0)

Referenced by tcp_receive().

#define tcp_ack_now ( pcb )

Value:

do {                                             \
    (pcb)->flags |= TF_ACK_NOW;                    \
  } while (0)

Referenced by tcp_fasttmr(), tcp_process(), tcp_receive(), and tcp_recved().

#define TCP_BUILD_MSS_OPTION ( mss ) htonl(0x02040000 | ((mss) & 0xFFFF))

This returns a TCP header option for MSS in an u32_t.

Referenced by tcp_output_segment().

#define TCP_CHECKSUM_ON_COPY (LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_TCP)

Don't generate checksum on copy if CHECKSUM_GEN_TCP is disabled.

#define TCP_CWR 0x80U

#define TCP_DEBUG_PCB_LISTS 0

#define tcp_debug_print ( tcphdr )

Referenced by tcp_input().

#define tcp_debug_print_flags ( flags )

Referenced by tcp_input().

#define tcp_debug_print_pcbs ( )

#define tcp_debug_print_state ( s )

Referenced by tcp_close(), and tcp_input().

#define tcp_do_output_nagle ( tpcb )

Value:

((((tpcb)->unacked == NULL) || \
                            ((tpcb)->flags & (TF_NODELAY | TF_INFR)) || \
                            (((tpcb)->unsent != NULL) && (((tpcb)->unsent->next != NULL) || \
                              ((tpcb)->unsent->len >= (tpcb)->mss))) || \
                            ((tcp_sndbuf(tpcb) == 0) || (tcp_sndqueuelen(tpcb) >= TCP_SND_QUEUELEN)) \
                            ) ? 1 : 0)

This is the Nagle algorithm: try to combine user data to send as few TCP segments as possible.

Only send if

no previously transmitted data on the connection remains unacknowledged or
the TF_NODELAY flag is set (nagle algorithm turned off for this pcb) or
the only unsent segment is at least pcb->mss bytes long (or there is more than one unsent segment - with lwIP, this can happen although unsent->len < mss)
or if we are in fast-retransmit (TF_INFR)

Referenced by tcp_output().

#define TCP_ECE 0x40U

#define TCP_EVENT_ACCEPT	(	pcb,
		err,
		ret
	)

Value:

do {                                                         \
    if((pcb)->accept != NULL)                                  \
      (ret) = (pcb)->accept((pcb)->callback_arg,(pcb),(err));  \
    else (ret) = ERR_ARG;                                      \
  } while (0)

Referenced by tcp_process().

#define TCP_EVENT_CLOSED	(	pcb,
		ret
	)

Value:

do {                                                           \
    if(((pcb)->recv != NULL)) {                                  \
      (ret) = (pcb)->recv((pcb)->callback_arg,(pcb),NULL,ERR_OK);\
    } else {                                                     \
      (ret) = ERR_OK;                                            \
    }                                                            \
  } while (0)

Referenced by tcp_input(), and tcp_process_refused_data().

#define TCP_EVENT_CONNECTED	(	pcb,
		err,
		ret
	)

Value:

do {                                                           \
    if((pcb)->connected != NULL)                                 \
      (ret) = (pcb)->connected((pcb)->callback_arg,(pcb),(err)); \
    else (ret) = ERR_OK;                                         \
  } while (0)

Referenced by tcp_process().

#define TCP_EVENT_ERR	(	errf,
		arg,
		err
	)

Value:

do {                                                         \
    if((errf) != NULL)                                         \
      (errf)((arg),(err));                                     \
  } while (0)

Referenced by tcp_abandon(), tcp_input(), and tcp_slowtmr().

#define TCP_EVENT_POLL	(	pcb,
		ret
	)

Value:

do {                                                         \
    if((pcb)->poll != NULL)                                    \
      (ret) = (pcb)->poll((pcb)->callback_arg,(pcb));          \
    else (ret) = ERR_OK;                                       \
  } while (0)

Referenced by tcp_slowtmr().

#define TCP_EVENT_RECV	(	pcb,
		p,
		err,
		ret
	)

Value:

do {                                                         \
    if((pcb)->recv != NULL) {                                  \
      (ret) = (pcb)->recv((pcb)->callback_arg,(pcb),(p),(err));\
    } else {                                                   \
      (ret) = tcp_recv_null(NULL, (pcb), (p), (err));          \
    }                                                          \
  } while (0)

Referenced by tcp_input(), and tcp_process_refused_data().

#define TCP_EVENT_SENT	(	pcb,
		space,
		ret
	)

Value:

do {                                                         \
    if((pcb)->sent != NULL)                                    \
      (ret) = (pcb)->sent((pcb)->callback_arg,(pcb),(space));  \
    else (ret) = ERR_OK;                                       \
  } while (0)

Referenced by tcp_input().

#define TCP_FAST_INTERVAL TCP_TMR_INTERVAL /* the fine grained timeout in milliseconds */

#define TCP_FIN 0x01U

Referenced by tcp_enqueue_flags(), tcp_input(), tcp_oos_insert_segment(), tcp_receive(), tcp_send_fin(), tcp_timewait_input(), and tcp_zero_window_probe().

#define TCP_FIN_WAIT_TIMEOUT 20000 /* milliseconds */

Referenced by tcp_slowtmr().

#define TCP_FLAGS 0x3fU

#define TCP_HLEN 20

Referenced by tcp_create_segment(), tcp_eff_send_mss(), tcp_output_alloc_header(), tcp_parseopt(), tcp_rst(), and tcp_zero_window_probe().

#define TCP_KEEPCNT_DEFAULT 9U /* Default Counter for KEEPALIVE probes */

Referenced by tcp_alloc().

#define TCP_KEEPIDLE_DEFAULT 7200000UL /* Default KEEPALIVE timer in milliseconds */

Referenced by tcp_alloc().

#define TCP_KEEPINTVL_DEFAULT 75000UL /* Default Time between KEEPALIVE probes in milliseconds */

Referenced by tcp_alloc().

#define TCP_MAXIDLE TCP_KEEPCNT_DEFAULT * TCP_KEEPINTVL_DEFAULT /* Maximum KEEPALIVE probe time */

#define TCP_MSL 60000UL /* The maximum segment lifetime in milliseconds */

Referenced by tcp_slowtmr().

#define TCP_OOSEQ_TIMEOUT 6U /* x RTO */

Referenced by tcp_slowtmr().

#define tcp_output_nagle ( tpcb ) (tcp_do_output_nagle(tpcb) ? tcp_output(tpcb) : ERR_OK)

#define TCP_OVERSIZE_DBGCHECK 0

Enabled extra-check for TCP_OVERSIZE if LWIP_DEBUG is enabled.

#define TCP_PCB_REMOVE_ACTIVE ( pcb )

Value:

do {                                             \
    tcp_pcb_remove(&tcp_active_pcbs, pcb);         \
    tcp_active_pcbs_changed = 1;                   \
  } while (0)

Referenced by tcp_abandon(), and tcp_close_shutdown().

#define tcp_pcbs_sane ( ) 1

Referenced by tcp_input(), and tcp_pcb_remove().

#define TCP_PSH 0x08U

Referenced by tcp_input(), and tcp_write().

#define TCP_REG	(	pcbs,
		npcb
	)

Value:

do {                                             \
    (npcb)->next = *pcbs;                          \
    *(pcbs) = (npcb);                              \
    tcp_timer_needed();                            \
  } while (0)

Referenced by tcp_bind(), tcp_close_shutdown(), tcp_listen_with_backlog(), and tcp_process().

#define TCP_REG_ACTIVE ( npcb )

Value:

do {                                             \
    TCP_REG(&tcp_active_pcbs, npcb);               \
    tcp_active_pcbs_changed = 1;                   \
  } while (0)

Referenced by tcp_connect(), and tcp_listen_input().

#define TCP_RMV	(	pcbs,
		npcb
	)

Value:

do {                                             \
    if(*(pcbs) == (npcb)) {                        \
      (*(pcbs)) = (*pcbs)->next;                   \
    }                                              \
    else {                                         \
      for(tcp_tmp_pcb = *pcbs;                     \
          tcp_tmp_pcb != NULL;                     \
          tcp_tmp_pcb = tcp_tmp_pcb->next) {       \
        if(tcp_tmp_pcb->next == (npcb)) {          \
          tcp_tmp_pcb->next = (npcb)->next;        \
          break;                                   \
        }                                          \
      }                                            \
    }                                              \
    (npcb)->next = NULL;                           \
  } while(0)

Referenced by tcp_close_shutdown(), tcp_connect(), tcp_listen_with_backlog(), and tcp_pcb_remove().

#define TCP_RMV_ACTIVE ( npcb )

Value:

do {                                             \
    TCP_RMV(&tcp_active_pcbs, npcb);               \
    tcp_active_pcbs_changed = 1;                   \
  } while (0)

Referenced by tcp_close_shutdown(), and tcp_process().

#define TCP_RST 0x04U

Referenced by tcp_input(), tcp_listen_input(), tcp_output(), tcp_process(), tcp_rst(), tcp_send_fin(), and tcp_timewait_input().

#define TCP_SEQ_BETWEEN	(	a,
		b,
		c
	)	(TCP_SEQ_GEQ(a,b) && TCP_SEQ_LEQ(a,c))

Referenced by tcp_parseopt(), tcp_process(), tcp_receive(), and tcp_timewait_input().

#define TCP_SEQ_GEQ	(	a,
		b
	)	((s32_t)((u32_t)(a) - (u32_t)(b)) >= 0)

Referenced by tcp_oos_insert_segment(), tcp_receive(), and tcp_update_rcv_ann_wnd().

#define TCP_SEQ_GT	(	a,
		b
	)	((s32_t)((u32_t)(a) - (u32_t)(b)) > 0)

Referenced by tcp_oos_insert_segment(), tcp_receive(), and tcp_update_rcv_ann_wnd().

#define TCP_SEQ_LEQ	(	a,
		b
	)	((s32_t)((u32_t)(a) - (u32_t)(b)) <= 0)

Referenced by tcp_receive().

#define TCP_SEQ_LT	(	a,
		b
	)	((s32_t)((u32_t)(a) - (u32_t)(b)) < 0)

Referenced by tcp_output(), tcp_receive(), and tcp_rexmit().

#define TCP_SLOW_INTERVAL (2*TCP_TMR_INTERVAL) /* the coarse grained timeout in milliseconds */

Referenced by tcp_alloc(), tcp_receive(), and tcp_slowtmr().

#define TCP_SYN 0x02U

Referenced by tcp_connect(), tcp_enqueue_flags(), tcp_input(), tcp_listen_input(), tcp_parseopt(), tcp_process(), tcp_receive(), tcp_send_fin(), and tcp_timewait_input().

#define TCP_SYN_RCVD_TIMEOUT 20000 /* milliseconds */

Referenced by tcp_slowtmr().

#define TCP_TCPLEN ( seg ) ((seg)->len + ((TCPH_FLAGS((seg)->tcphdr) & (TCP_FIN | TCP_SYN)) != 0))

Referenced by tcp_enqueue_flags(), tcp_output(), tcp_receive(), and tcp_write().

#define TCP_TMR_INTERVAL 250 /* The TCP timer interval in milliseconds. */

Referenced by tcp_timer_needed(), and tcpip_tcp_timer().

#define TCP_URG 0x20U

#define TCPH_FLAGS ( phdr ) (ntohs((phdr)->_hdrlen_rsvd_flags) & TCP_FLAGS)

Referenced by tcp_input(), tcp_oos_insert_segment(), tcp_output(), tcp_receive(), tcp_send_fin(), and tcp_zero_window_probe().

#define TCPH_FLAGS_SET	(	phdr,
		flags
	)	(phdr)->_hdrlen_rsvd_flags = (((phdr)->_hdrlen_rsvd_flags & PP_HTONS((u16_t)(~(u16_t)(TCP_FLAGS)))) \| htons(flags))

Referenced by tcp_receive(), and tcp_zero_window_probe().

#define TCPH_HDRLEN ( phdr ) (ntohs((phdr)->_hdrlen_rsvd_flags) >> 12)

Referenced by tcp_input(), tcp_output_segment(), and tcp_parseopt().

#define TCPH_HDRLEN_FLAGS_SET	(	phdr,
		len,
		flags
	)	(phdr)->_hdrlen_rsvd_flags = htons(((len) << 12) \| (flags))

Referenced by tcp_create_segment(), tcp_output_alloc_header(), and tcp_rst().

#define TCPH_HDRLEN_SET	(	phdr,
		len
	)	(phdr)->_hdrlen_rsvd_flags = htons(((len) << 12) \| TCPH_FLAGS(phdr))

#define TCPH_SET_FLAG	(	phdr,
		flags
	)	(phdr)->_hdrlen_rsvd_flags = ((phdr)->_hdrlen_rsvd_flags \| htons(flags))

Referenced by tcp_oos_insert_segment(), tcp_output(), tcp_receive(), tcp_send_fin(), and tcp_write().

#define TCPH_UNSET_FLAG	(	phdr,
		flags
	)	(phdr)->_hdrlen_rsvd_flags = htons(ntohs((phdr)->_hdrlen_rsvd_flags) \| (TCPH_FLAGS(phdr) & ~(flags)) )

#define TF_CLOSED (u8_t)0x10U /* Connection was sucessfully closed. */

Referenced by tcp_input(), and tcp_process().

#define TF_GOT_FIN (u8_t)0x20U /* Connection was closed by the remote end. */

Referenced by tcp_input(), tcp_process(), and tcp_receive().

#define TF_RESET (u8_t)0x08U /* Connection was reset. */

Flags used on input processing, not on pcb->flags.

Referenced by tcp_input(), and tcp_process().

#define TF_SEG_DATA_CHECKSUMMED

Value:

(u8_t)0x04U /* ALL data (not the header) is

checksummed into 'chksum' */

u8_t

uint8_t u8_t

Definition: cc.h:44

Referenced by tcp_create_segment(), tcp_output_segment(), and tcp_write().

#define TF_SEG_OPTS_MSS (u8_t)0x01U /* Include MSS option. */

Referenced by tcp_enqueue_flags(), and tcp_output_segment().

#define TF_SEG_OPTS_TS (u8_t)0x02U /* Include timestamp option. */

Referenced by tcp_enqueue_flags(), tcp_output_segment(), tcp_send_empty_ack(), and tcp_write().

void tcp_abandon	(	struct tcp_pcb *	pcb,
		int	reset
	)

Abandons a connection and optionally sends a RST to the remote host.

Deletes the local protocol control block. This is done when a connection is killed because of shortage of memory.

Parameters

pcb	the tcp_pcb to abort
reset	boolean to indicate whether a reset should be sent

References ackno, ERR_ABRT, tcp_pcb::errf, LISTEN, LWIP_ASSERT, LWIP_DEBUGF, memp_free(), NULL, tcp_pcb::ooseq, tcp_pcb::rcv_nxt, tcp_pcb::remote_port, seqno, tcp_pcb::snd_nxt, TCP_EVENT_ERR, tcp_pcb_remove(), TCP_PCB_REMOVE_ACTIVE, tcp_rst(), TCP_RST_DEBUG, tcp_segs_free(), TIME_WAIT, tcp_pcb::unacked, and tcp_pcb::unsent.

Referenced by tcp_abort(), and tcp_listen_input().

struct tcp_pcb* tcp_alloc ( u8_t prio )

Allocate a new tcp_pcb structure.

Parameters

prio	priority for the new pcb

Returns: a new tcp_pcb that initially is in state CLOSED

References tcp_pcb::cwnd, tcp_pcb::keep_cnt_sent, tcp_pcb::keep_idle, tcp_pcb::last_timer, tcp_pcb::lastack, LWIP_DEBUGF, memp_malloc(), MEMP_STATS_DEC, tcp_pcb::mss, NULL, tcp_pcb::polltmr, tcp_pcb::rcv_ann_wnd, tcp_pcb::rcv_wnd, tcp_pcb::recv, tcp_pcb::rtime, tcp_pcb::rto, tcp_pcb::sa, tcp_pcb::snd_buf, tcp_pcb::snd_lbb, tcp_pcb::snd_nxt, tcp_pcb::snd_queuelen, tcp_pcb::snd_wl2, tcp_pcb::sv, TCP_DEBUG, TCP_KEEPCNT_DEFAULT, TCP_KEEPIDLE_DEFAULT, TCP_KEEPINTVL_DEFAULT, tcp_kill_prio(), tcp_kill_timewait(), TCP_MSS, tcp_next_iss(), tcp_recv_null(), TCP_SLOW_INTERVAL, TCP_SND_BUF, tcp_ticks, tcp_timer_ctr, TCP_WND, and tcp_pcb::tmr.

Referenced by tcp_listen_input(), and tcp_new().

u16_t tcp_eff_send_mss	(	u16_t	sendmss,
		ip_addr_t *	addr
	)

Calcluates the effective send mss that can be used for a specific IP address by using ip_route to determin the netif used to send to the address and calculating the minimum of TCP_MSS and that netif's mtu (if set).

References IP_HLEN, ip_route(), LWIP_MIN, netif::mtu, NULL, and TCP_HLEN.

Referenced by tcp_connect(), tcp_listen_input(), tcp_output_segment(), and tcp_process().

err_t tcp_enqueue_flags	(	struct tcp_pcb *	pcb,
		u8_t	flags
	)

Enqueue TCP options for transmission.

Called by tcp_connect(), tcp_listen_input(), and tcp_send_ctrl().

Parameters

pcb	Protocol control block for the TCP connection.
flags	TCP header flags to set in the outgoing segment.
optdata	pointer to TCP options, or NULL.
optlen	length of TCP options in bytes.

References ERR_MEM, ERR_OK, tcp_pcb::flags, pbuf::len, tcp_seg::len, LWIP_ASSERT, LWIP_DBG_TRACE, LWIP_DEBUGF, LWIP_TCP_OPT_LENGTH, MEM_ALIGNMENT, tcp_seg::next, ntohl, NULL, tcp_seg::p, pbuf_alloc(), pbuf_clen(), PBUF_RAM, PBUF_TRANSPORT, S16_F, tcp_pcb::snd_buf, tcp_pcb::snd_lbb, tcp_pcb::snd_queuelen, tcp_create_segment(), TCP_FIN, TCP_OUTPUT_DEBUG, TCP_QLEN_DEBUG, TCP_SNDQUEUELEN_OVERFLOW, TCP_STATS_INC, TCP_SYN, TCP_TCPLEN, tcp_seg::tcphdr, TF_FIN, TF_NAGLEMEMERR, TF_SEG_OPTS_MSS, TF_SEG_OPTS_TS, TF_TIMESTAMP, U16_F, U32_F, tcp_pcb::unacked, tcp_pcb::unsent, tcp_pcb::unsent_oversize, and X16_F.

Referenced by tcp_connect(), tcp_listen_input(), and tcp_send_fin().

void tcp_fasttmr ( void )

Is called every TCP_FAST_INTERVAL (250 ms) and process data previously "refused" by upper layer (application) and sends delayed ACKs.

Automatically called from tcp_tmr().

References tcp_pcb::flags, tcp_pcb::last_timer, LWIP_DEBUGF, next, NULL, tcp_pcb::refused_data, tcp_ack_now, tcp_active_pcbs, tcp_active_pcbs_changed, TCP_DEBUG, tcp_output(), tcp_process_refused_data(), tcp_timer_ctr, TF_ACK_DELAY, and TF_ACK_NOW.

Referenced by tcp_tmr().

void tcp_init ( void )

Initialize this module.

References TCP_ENSURE_LOCAL_PORT_RANGE, and tcp_port.

Referenced by lwip_init().

void tcp_input	(	struct pbuf *	p,
		struct netif *	inp
	)

The initial input processing of TCP.

It verifies the TCP header, demultiplexes the segment between the PCBs and passes it on to tcp_process(), which implements the TCP finite state machine. This function is called by the IP layer (in ip_input()).

Parameters

p	received TCP segment to process (p->payload pointing to the IP header)
inp	network interface on which this segment was received

References tcp_pcb::acked, ackno, CLOSED, current_iphdr_dest, current_iphdr_src, ERR_ABRT, ERR_CLSD, ERR_OK, ERR_RST, tcp_pcb::errf, flags, pbuf::flags, tcp_pcb::flags, inet_chksum_pseudo(), inseg, ip_addr_cmp, ip_addr_isany, ip_addr_isbroadcast, ip_addr_ismulticast, ip_current_dest_addr, ip_current_src_addr, IP_PROTO_TCP, IPH_HL, tcp_seg::len, LISTEN, tcp_listen_pcbs_t::listen_pcbs, LWIP_ASSERT, LWIP_DEBUGF, memp_free(), tcp_seg::next, ntohl, ntohs, NULL, tcp_seg::p, pbuf::payload, PBUF_FLAG_PUSH, PBUF_FLAG_TCP_FIN, pbuf_free(), pbuf_header(), PERF_START, PERF_STOP, tcp_pcb::rcv_wnd, recv_data, recv_flags, tcp_pcb::refused_data, tcp_pcb::remote_port, seqno, snmp_inc_tcpinerrs, snmp_inc_tcpinsegs, tcp_abort(), tcp_active_pcbs, tcp_debug_print, tcp_debug_print_flags, tcp_debug_print_state, TCP_EVENT_CLOSED, TCP_EVENT_ERR, TCP_EVENT_RECV, TCP_EVENT_SENT, TCP_FIN, TCP_INPUT_DEBUG, tcp_listen_input(), tcp_listen_pcbs, tcp_output(), tcp_pcb_remove(), tcp_pcbs_sane, tcp_process(), tcp_process_refused_data(), TCP_PSH, TCP_RST, tcp_rst(), TCP_RST_DEBUG, TCP_STATS_INC, TCP_SYN, tcp_timewait_input(), tcp_tw_pcbs, TCP_WND, TCPH_FLAGS, TCPH_HDRLEN, tcphdr, tcp_seg::tcphdr, tcplen, TF_CLOSED, TF_GOT_FIN, TF_RESET, TF_RXCLOSED, TIME_WAIT, pbuf::tot_len, U16_F, and X16_F.

Referenced by ip_input().

void tcp_keepalive ( struct tcp_pcb * pcb )

Send keepalive packets to keep a connection active although no data is sent over it.

Called by tcp_slowtmr()

Parameters

pcb	the tcp_pcb for which to send a keepalive packet

References CHECKSUM_GEN_TCP, htonl, inet_chksum_pseudo(), ip4_addr1_16, ip4_addr2_16, ip4_addr3_16, ip4_addr4_16, ip_output(), IP_PROTO_TCP, tcp_pcb::keep_cnt_sent, LWIP_DEBUGF, NULL, pbuf::payload, pbuf_free(), tcp_pcb::rcv_nxt, tcp_pcb::snd_nxt, TCP_DEBUG, tcp_output_alloc_header(), TCP_STATS_INC, tcp_ticks, tcphdr, tcp_pcb::tmr, pbuf::tot_len, U16_F, and U32_F.

Referenced by tcp_slowtmr().

u32_t tcp_next_iss ( void )

Calculates a new initial sequence number for new connections.

Returns: u32_t pseudo random sequence number

References tcp_ticks.

Referenced by tcp_alloc(), and tcp_connect().

struct tcp_pcb* tcp_pcb_copy ( struct tcp_pcb * pcb )

void tcp_pcb_purge ( struct tcp_pcb * pcb )

Purges a TCP PCB.

Removes any buffered data and frees the buffer memory (pcb->ooseq, pcb->unsent and pcb->unacked are freed).

Parameters

pcb	tcp_pcb to purge. The pcb itself is not deallocated!

References CLOSED, ip_addr_cmp, ip_addr_isany, LISTEN, tcp_listen_pcbs_t::listen_pcbs, LWIP_ASSERT, LWIP_DEBUGF, NULL, tcp_pcb::ooseq, pbuf_free(), tcp_pcb::refused_data, tcp_pcb::rtime, SYN_RCVD, TCP_DEBUG, tcp_listen_pcbs, tcp_segs_free(), TIME_WAIT, tcp_pcb::unacked, tcp_pcb::unsent, and tcp_pcb::unsent_oversize.

Referenced by tcp_close_shutdown(), tcp_pcb_remove(), tcp_process(), and tcp_slowtmr().

void tcp_pcb_remove	(	struct tcp_pcb **	pcblist,
		struct tcp_pcb *	pcb
	)

Purges the PCB and removes it from a PCB list.

Any delayed ACKs are sent first.

Parameters

pcblist	PCB list to purge.
pcb	tcp_pcb to purge. The pcb itself is NOT deallocated!

References CLOSED, tcp_pcb::flags, LISTEN, LWIP_ASSERT, NULL, tcp_pcb::ooseq, tcp_output(), tcp_pcb_purge(), tcp_pcbs_sane, TCP_RMV, TF_ACK_DELAY, TF_ACK_NOW, TIME_WAIT, tcp_pcb::unacked, and tcp_pcb::unsent.

Referenced by tcp_abandon(), tcp_close_shutdown(), and tcp_input().

err_t tcp_process_refused_data ( struct tcp_pcb * pcb )

Pass pcb->refused_data to the recv callback.

References ERR_ABRT, ERR_OK, pbuf::flags, LWIP_DEBUGF, NULL, PBUF_FLAG_TCP_FIN, tcp_pcb::rcv_wnd, tcp_pcb::refused_data, TCP_EVENT_CLOSED, TCP_EVENT_RECV, TCP_INPUT_DEBUG, and TCP_WND.

Referenced by tcp_fasttmr(), and tcp_input().

err_t tcp_recv_null	(	void *	arg,
		struct tcp_pcb *	pcb,
		struct pbuf *	p,
		err_t	err
	)

Default receive callback that is called if the user didn't register a recv callback for the pcb.

References ERR_OK, LWIP_UNUSED_ARG, NULL, pbuf_free(), tcp_close(), tcp_recved(), and pbuf::tot_len.

Referenced by tcp_alloc().

void tcp_rexmit ( struct tcp_pcb * pcb )

Requeue the first unacked segment for retransmission.

Called by tcp_receive() for fast retramsmit.

Parameters

pcb	the tcp_pcb for which to retransmit the first unacked segment

References tcp_seg::next, tcp_pcb::nrtx, ntohl, NULL, tcp_pcb::rttest, snmp_inc_tcpretranssegs, TCP_SEQ_LT, tcp_seg::tcphdr, tcp_pcb::unacked, tcp_pcb::unsent, and tcp_pcb::unsent_oversize.

Referenced by tcp_process(), and tcp_rexmit_fast().

void tcp_rexmit_fast ( struct tcp_pcb * pcb )

Handle retransmission after three dupacks received.

Parameters

pcb	the tcp_pcb for which to retransmit the first unacked segment

References tcp_pcb::cwnd, tcp_pcb::dupacks, tcp_pcb::flags, tcp_pcb::lastack, LWIP_DEBUGF, tcp_pcb::mss, ntohl, NULL, tcp_pcb::snd_wnd, tcp_pcb::ssthresh, TCP_FR_DEBUG, tcp_rexmit(), tcp_seg::tcphdr, TF_INFR, U16_F, U32_F, and tcp_pcb::unacked.

Referenced by tcp_receive().

void tcp_rexmit_rto ( struct tcp_pcb * pcb )

Requeue all unacked segments for retransmission.

Called by tcp_slowtmr() for slow retransmission.

Parameters

pcb	the tcp_pcb for which to re-enqueue all unacked segments

References tcp_seg::next, tcp_pcb::nrtx, NULL, tcp_pcb::rttest, tcp_output(), tcp_pcb::unacked, and tcp_pcb::unsent.

Referenced by tcp_slowtmr().

void tcp_rexmit_seg	(	struct tcp_pcb *	pcb,
		struct tcp_seg *	seg
	)

void tcp_rst	(	u32_t	seqno,
		u32_t	ackno,
		ip_addr_t *	local_ip,
		ip_addr_t *	remote_ip,
		u16_t	local_port,
		u16_t	remote_port
	)

Send a TCP RESET packet (empty segment with RST flag set) either to abort a connection or to show that there is no matching local connection for a received segment.

Called by tcp_abort() (to abort a local connection), tcp_input() (if no matching local pcb was found), tcp_listen_input() (if incoming segment has ACK flag set) and tcp_process() (received segment in the wrong state)

Since a RST segment is in most cases not sent for an active connection, tcp_rst() has a number of arguments that are taken from a tcp_pcb for most other segment output functions.

Parameters

seqno	the sequence number to use for the outgoing segment
ackno	the acknowledge number to use for the outgoing segment
local_ip	the local IP address to send the segment from
remote_ip	the remote IP address to send the segment to
local_port	the local TCP port to send the segment from
remote_port	the remote TCP port to send the segment to