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minix/servers/inet/generic/tcp_recv.c

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Initial revision
2005-04-21 16:53:53 +02:00
/*
tcp_recv.c
Copyright 1995 Philip Homburg
*/
#include "inet.h"
#include "buf.h"
#include "clock.h"
#include "event.h"
#include "type.h"
#include "io.h"
#include "tcp_int.h"
#include "tcp.h"
#include "assert.h"
THIS_FILE
FORWARD void create_RST ARGS(( tcp_conn_t *tcp_conn,
ip_hdr_t *ip_hdr, tcp_hdr_t *tcp_hdr, int data_len ));
FORWARD void process_data ARGS(( tcp_conn_t *tcp_conn,
tcp_hdr_t *tcp_hdr, acc_t *tcp_data, int data_len ));
FORWARD void process_advanced_data ARGS(( tcp_conn_t *tcp_conn,
tcp_hdr_t *tcp_hdr, acc_t *tcp_data, int data_len ));
PUBLIC void tcp_frag2conn(tcp_conn, ip_hdr, tcp_hdr, tcp_data, data_len)
tcp_conn_t *tcp_conn;
ip_hdr_t *ip_hdr;
tcp_hdr_t *tcp_hdr;
acc_t *tcp_data;
size_t data_len;
{
tcp_fd_t *connuser;
int tcp_hdr_flags;
int ip_hdr_len, tcp_hdr_len;
u32_t seg_ack, seg_seq, rcv_hi;
u16_t seg_wnd;
int acceptable_ACK, segm_acceptable;
ip_hdr_len= (ip_hdr->ih_vers_ihl & IH_IHL_MASK) << 2;
tcp_hdr_len= (tcp_hdr->th_data_off & TH_DO_MASK) >> 2;
tcp_hdr_flags= tcp_hdr->th_flags & TH_FLAGS_MASK;
seg_ack= ntohl(tcp_hdr->th_ack_nr);
seg_seq= ntohl(tcp_hdr->th_seq_nr);
seg_wnd= ntohs(tcp_hdr->th_window);
switch (tcp_conn->tc_state)
{
case TCS_CLOSED:
/*
CLOSED:
discard all data.
!RST ?
ACK ?
<SEQ=SEG.ACK><CTL=RST>
exit
:
<SEQ=0><ACK=SEG.SEQ+SEG.LEN><CTL=RST,ACK>
exit
:
discard packet
exit
*/
if (!(tcp_hdr_flags & THF_RST))
{
create_RST(tcp_conn, ip_hdr, tcp_hdr, data_len);
tcp_conn_write(tcp_conn, 1);
}
break;
case TCS_LISTEN:
/*
LISTEN:
RST ?
discard packet
exit
ACK ?
<SEQ=SEG.ACK><CTL=RST>
exit
SYN ?
BUG: no security check
RCV.NXT= SEG.SEQ+1
IRS= SEG.SEQ
ISS should already be selected
<SEQ=ISS><ACK=RCV.NXT><CTL=SYN,ACK>
SND.NXT=ISS+1
SND.UNA=ISS
state= SYN-RECEIVED
exit
:
shouldnot occur
discard packet
exit
*/
if (tcp_hdr_flags & THF_RST)
break;
if (tcp_hdr_flags & THF_ACK)
{
create_RST (tcp_conn, ip_hdr, tcp_hdr, data_len);
tcp_conn_write(tcp_conn, 1);
break;
}
if (tcp_hdr_flags & THF_SYN)
{
tcp_extract_ipopt(tcp_conn, ip_hdr);
tcp_extract_tcpopt(tcp_conn, tcp_hdr);
tcp_conn->tc_RCV_LO= seg_seq+1;
tcp_conn->tc_RCV_NXT= seg_seq+1;
tcp_conn->tc_RCV_HI= tcp_conn->tc_RCV_LO+
tcp_conn->tc_rcv_wnd;
tcp_conn->tc_RCV_UP= seg_seq;
tcp_conn->tc_IRS= seg_seq;
tcp_conn->tc_SND_UNA= tcp_conn->tc_ISS;
tcp_conn->tc_SND_TRM= tcp_conn->tc_ISS;
tcp_conn->tc_SND_NXT= tcp_conn->tc_ISS+1;
tcp_conn->tc_SND_UP= tcp_conn->tc_ISS-1;
tcp_conn->tc_SND_PSH= tcp_conn->tc_ISS-1;
tcp_conn->tc_state= TCS_SYN_RECEIVED;
tcp_conn->tc_stt= 0;
assert (tcp_check_conn(tcp_conn));
tcp_conn->tc_locaddr= ip_hdr->ih_dst;
tcp_conn->tc_locport= tcp_hdr->th_dstport;
tcp_conn->tc_remaddr= ip_hdr->ih_src;
tcp_conn->tc_remport= tcp_hdr->th_srcport;
tcp_conn_write(tcp_conn, 1);
DIFBLOCK(0x10, seg_seq == 0,
printf("warning got 0 IRS from ");
writeIpAddr(tcp_conn->tc_remaddr);
printf("\n"));
/* Start the timer (if necessary) */
tcp_set_send_timer(tcp_conn);
break;
}
/* do nothing */
break;
case TCS_SYN_SENT:
/*
SYN-SENT:
ACK ?
SEG.ACK <= ISS || SEG.ACK > SND.NXT ?
RST ?
discard packet
exit
:
<SEQ=SEG.ACK><CTL=RST>
exit
SND.UNA <= SEG.ACK && SEG.ACK <= SND.NXT ?
ACK is acceptable
:
ACK is !acceptable
:
ACK is !acceptable
RST ?
ACK acceptable ?
discard segment
state= CLOSED
error "connection refused"
exit
:
discard packet
exit
BUG: no security check
SYN ?
IRS= SEG.SEQ
RCV.NXT= IRS+1
ACK ?
SND.UNA= SEG.ACK
SND.UNA > ISS ?
state= ESTABLISHED
<SEQ=SND.NXT><ACK= RCV.NXT><CTL=ACK>
process ev. URG and text
exit
:
state= SYN-RECEIVED
SND.WND= SEG.WND
SND.WL1= SEG.SEQ
SND.WL2= SEG.ACK
<SEQ=ISS><ACK=RCV.NXT><CTL=SYN,ACK>
exit
:
discard segment
exit
*/
if (tcp_hdr_flags & THF_ACK)
{
if (tcp_LEmod4G(seg_ack, tcp_conn->tc_ISS) ||
tcp_Gmod4G(seg_ack, tcp_conn->tc_SND_NXT))
if (tcp_hdr_flags & THF_RST)
break;
else
{
create_RST (tcp_conn, ip_hdr,
tcp_hdr, data_len);
tcp_conn_write(tcp_conn, 1);
break;
}
acceptable_ACK= (tcp_LEmod4G(tcp_conn->tc_SND_UNA,
seg_ack) && tcp_LEmod4G(seg_ack,
tcp_conn->tc_SND_NXT));
}
else
acceptable_ACK= FALSE;
if (tcp_hdr_flags & THF_RST)
{
if (acceptable_ACK)
{
DBLOCK(1, printf(
"calling tcp_close_connection\n"));
tcp_close_connection(tcp_conn,
ECONNREFUSED);
}
break;
}
if (tcp_hdr_flags & THF_SYN)
{
tcp_conn->tc_RCV_LO= seg_seq+1;
tcp_conn->tc_RCV_NXT= seg_seq+1;
tcp_conn->tc_RCV_HI= tcp_conn->tc_RCV_LO +
tcp_conn->tc_rcv_wnd;
tcp_conn->tc_RCV_UP= seg_seq;
tcp_conn->tc_IRS= seg_seq;
if (tcp_hdr_flags & THF_ACK)
tcp_conn->tc_SND_UNA= seg_ack;
if (tcp_Gmod4G(tcp_conn->tc_SND_UNA,
tcp_conn->tc_ISS))
{
tcp_conn->tc_state= TCS_ESTABLISHED;
tcp_conn->tc_rt_dead= TCP_DEF_RT_DEAD;
assert (tcp_check_conn(tcp_conn));
assert(tcp_conn->tc_connInprogress);
tcp_restart_connect(tcp_conn->tc_fd);
tcp_conn->tc_flags |= TCF_SEND_ACK;
tcp_conn_write(tcp_conn, 1);
if (data_len != 0)
{
tcp_frag2conn(tcp_conn, ip_hdr,
tcp_hdr, tcp_data, data_len);
/* tcp_data is already freed */
return;
}
break;
}
tcp_conn->tc_state= TCS_SYN_RECEIVED;
assert (tcp_check_conn(tcp_conn));
tcp_conn->tc_SND_TRM= tcp_conn->tc_ISS;
tcp_conn_write(tcp_conn, 1);
}
break;
case TCS_SYN_RECEIVED:
/*
SYN-RECEIVED:
test if segment is acceptable:
Segment Receive Test
Length Window
0 0 SEG.SEQ == RCV.NXT
0 >0 RCV.NXT <= SEG.SEQ && SEG.SEQ < RCV.NXT+RCV.WND
>0 0 not acceptable
>0 >0 (RCV.NXT <= SEG.SEQ && SEG.SEQ < RCV.NXT+RCV.WND)
|| (RCV.NXT <= SEG.SEQ+SEG.LEN-1 &&
SEG.SEQ+SEG.LEN-1 < RCV.NXT+RCV.WND)
for urgent data: use RCV.WND+1 for RCV.WND
*/
rcv_hi= tcp_conn->tc_RCV_HI;
if (tcp_hdr_flags & THF_URG)
rcv_hi++;
if (!data_len)
{
if (rcv_hi == tcp_conn->tc_RCV_NXT)
segm_acceptable= (seg_seq == rcv_hi);
else
{
assert (tcp_Gmod4G(rcv_hi,
tcp_conn->tc_RCV_NXT));
segm_acceptable= (tcp_LEmod4G(tcp_conn->
tc_RCV_NXT, seg_seq) &&
tcp_Lmod4G(seg_seq, rcv_hi));
}
}
else
{
if (tcp_Gmod4G(rcv_hi, tcp_conn->tc_RCV_NXT))
{
segm_acceptable= (tcp_LEmod4G(tcp_conn->
tc_RCV_NXT, seg_seq) &&
tcp_Lmod4G(seg_seq, rcv_hi)) ||
(tcp_LEmod4G(tcp_conn->tc_RCV_NXT,
seg_seq+data_len-1) &&
tcp_Lmod4G(seg_seq+data_len-1,
rcv_hi));
}
else
{
segm_acceptable= FALSE;
}
}
/*
!segment acceptable ?
RST ?
discard packet
exit
:
<SEG=SND.NXT><ACK=RCV.NXT><CTL=ACK>
exit
*/
if (!segm_acceptable)
{
if (!(tcp_hdr_flags & THF_RST))
{
tcp_conn->tc_flags |= TCF_SEND_ACK;
tcp_conn_write(tcp_conn, 1);
}
break;
}
/*
RST ?
initiated by a LISTEN ?
state= LISTEN
exit
:
state= CLOSED
error "connection refused"
exit
*/
if (tcp_hdr_flags & THF_RST)
{
if (tcp_conn->tc_orglisten)
{
connuser= tcp_conn->tc_fd;
tcp_conn->tc_connInprogress= 0;
tcp_conn->tc_fd= NULL;
tcp_close_connection (tcp_conn, ECONNREFUSED);
if (connuser)
(void)tcp_su4listen(connuser);
break;
}
else
{
tcp_close_connection(tcp_conn, ECONNREFUSED);
break;
}
}
/*
SYN in window ?
initiated by a LISTEN ?
state= LISTEN
exit
:
state= CLOSED
error "connection reset"
exit
*/
if ((tcp_hdr_flags & THF_SYN) && tcp_GEmod4G(seg_seq,
tcp_conn->tc_RCV_NXT))
{
if (tcp_conn->tc_orglisten)
{
connuser= tcp_conn->tc_fd;
tcp_conn->tc_connInprogress= 0;
tcp_conn->tc_fd= NULL;
tcp_close_connection(tcp_conn, ECONNRESET);
if (connuser)
(void)tcp_su4listen(connuser);
break;
}
tcp_close_connection(tcp_conn, ECONNRESET);
break;
}
/*
!ACK ?
discard packet
exit
*/
if (!(tcp_hdr_flags & THF_ACK))
break;
/*
SND.UNA < SEG.ACK <= SND.NXT ?
state= ESTABLISHED
:
<SEG=SEG.ACK><CTL=RST>
exit
*/
if (tcp_Lmod4G(tcp_conn->tc_SND_UNA, seg_ack) &&
tcp_LEmod4G(seg_ack, tcp_conn->tc_SND_NXT))
{
tcp_conn->tc_state= TCS_ESTABLISHED;
tcp_conn->tc_rt_dead= TCP_DEF_RT_DEAD;
tcp_release_retrans(tcp_conn, seg_ack, seg_wnd);
assert (tcp_check_conn(tcp_conn));
assert(tcp_conn->tc_connInprogress);
tcp_restart_connect(tcp_conn->tc_fd);
tcp_frag2conn(tcp_conn, ip_hdr, tcp_hdr, tcp_data,
data_len);
/* tcp_data is already freed */
return;
}
else
{
create_RST (tcp_conn, ip_hdr, tcp_hdr, data_len);
tcp_conn_write(tcp_conn, 1);
break;
}
break;
case TCS_ESTABLISHED:
case TCS_CLOSING:
/*
ESTABLISHED:
FIN-WAIT-1:
FIN-WAIT-2:
CLOSE-WAIT:
CLOSING:
LAST-ACK:
TIME-WAIT:
test if segment is acceptable:
Segment Receive Test
Length Window
0 0 SEG.SEQ == RCV.NXT
0 >0 RCV.NXT <= SEG.SEQ && SEG.SEQ < RCV.NXT+RCV.WND
>0 0 not acceptable
>0 >0 (RCV.NXT <= SEG.SEQ && SEG.SEQ < RCV.NXT+RCV.WND)
|| (RCV.NXT <= SEG.SEQ+SEG.LEN-1 &&
SEG.SEQ+SEG.LEN-1 < RCV.NXT+RCV.WND)
for urgent data: use RCV.WND+1 for RCV.WND
*/
rcv_hi= tcp_conn->tc_RCV_HI;
if (tcp_hdr_flags & THF_URG)
rcv_hi++;
if (!data_len)
{
if (rcv_hi == tcp_conn->tc_RCV_NXT)
segm_acceptable= (seg_seq == rcv_hi);
else
{
assert (tcp_Gmod4G(rcv_hi,
tcp_conn->tc_RCV_NXT));
segm_acceptable= (tcp_LEmod4G(tcp_conn->
tc_RCV_NXT, seg_seq) &&
tcp_Lmod4G(seg_seq, rcv_hi));
}
}
else
{
if (tcp_Gmod4G(rcv_hi, tcp_conn->tc_RCV_NXT))
{
segm_acceptable= (tcp_LEmod4G(tcp_conn->
tc_RCV_NXT, seg_seq) &&
tcp_Lmod4G(seg_seq, rcv_hi)) ||
(tcp_LEmod4G(tcp_conn->tc_RCV_NXT,
seg_seq+data_len-1) &&
tcp_Lmod4G(seg_seq+data_len-1,
rcv_hi));
}
else
{
segm_acceptable= FALSE;
}
}
/*
!segment acceptable ?
RST ?
discard packet
exit
:
<SEG=SND.NXT><ACK=RCV.NXT><CTL=ACK>
exit
*/
if (!segm_acceptable)
{
if (!(tcp_hdr_flags & THF_RST))
{
DBLOCK(0x20,
printf("segment is not acceptable\n");
printf("\t");
tcp_print_pack(ip_hdr, tcp_hdr);
printf("\n\t");
tcp_print_conn(tcp_conn);
printf("\n"));
tcp_conn->tc_flags |= TCF_SEND_ACK;
tcp_conn_write(tcp_conn, 1);
/* Sometimes, a retransmission sets the PSH
* flag (Solaris 2.4)
*/
if (tcp_conn->tc_rcvd_data != NULL &&
(tcp_hdr_flags & THF_PSH))
{
tcp_conn->tc_flags |= TCF_RCV_PUSH;
if (tcp_conn->tc_fd &&
(tcp_conn->tc_fd->tf_flags &
TFF_READ_IP))
{
tcp_fd_read(tcp_conn, 1);
}
}
}
break;
}
/*
RST ?
state == CLOSING || state == LAST-ACK ||
state == TIME-WAIT ?
state= CLOSED
exit
:
state= CLOSED
error "connection reset"
exit
*/
if (tcp_hdr_flags & THF_RST)
{
if ((tcp_conn->tc_flags &
(TCF_FIN_SENT|TCF_FIN_RECV)) ==
(TCF_FIN_SENT|TCF_FIN_RECV) &&
tcp_conn->tc_send_data == NULL)
{
/* Clean shutdown, but the other side
* doesn't want to ACK our FIN.
*/
tcp_close_connection (tcp_conn, 0);
}
else
tcp_close_connection(tcp_conn, ECONNRESET);
break;
}
/*
SYN in window ?
state= CLOSED
error "connection reset"
exit
*/
if ((tcp_hdr_flags & THF_SYN) && tcp_GEmod4G(seg_seq,
tcp_conn->tc_RCV_NXT))
{
tcp_close_connection(tcp_conn, ECONNRESET);
break;
}
/*
!ACK ?
discard packet
exit
*/
if (!(tcp_hdr_flags & THF_ACK))
break;
/*
SND.UNA < SEG.ACK <= SND.NXT ?
SND.UNA= SEG.ACK
reply "send ok"
SND.WL1 < SEG.SEQ || (SND.WL1 == SEG.SEQ &&
SND.WL2 <= SEG.ACK ?
SND.WND= SEG.WND
SND.Wl1= SEG.SEQ
SND.WL2= SEG.ACK
SEG.ACK <= SND.UNA ?
ignore ACK
SEG.ACK > SND.NXT ?
<SEQ=SND.NXT><ACK=RCV.NXT><CTL=ACK>
discard packet
exit
*/
/* Always reset the send timer after a valid ack is
* received. The assumption is that either the ack really
* acknowledges some data (normal case), contains a zero
* window, or the remote host has another reason not
* to accept any data. In all cases, the remote host is
* alive, so the connection should stay alive too.
* Do not reset stt if the state is CLOSING, i.e. if
* the user closed the connection and we still have
* some data to deliver. We don't want a zero window
* to keep us from closing the connection.
*/
if (tcp_conn->tc_state != TCS_CLOSING)
tcp_conn->tc_stt= 0;
if (seg_ack == tcp_conn->tc_SND_UNA)
{
/* This ACK doesn't acknowledge any new data, this
* is a likely situation if we are only receiving
* data. We only update the window if we are
* actually sending or if we currently have a
* zero window.
*/
if (tcp_conn->tc_snd_cwnd == tcp_conn->tc_SND_UNA &&
seg_wnd != 0)
{
DBLOCK(2, printf("zero window opened\n"));
/* The other side opened up its receive
* window. */
if (seg_wnd > 2*tcp_conn->tc_mss)
seg_wnd= 2*tcp_conn->tc_mss;
tcp_conn->tc_snd_cwnd=
tcp_conn->tc_SND_UNA+seg_wnd;
tcp_conn_write(tcp_conn, 1);
}
if (seg_wnd == 0)
{
tcp_conn->tc_snd_cwnd= tcp_conn->tc_SND_TRM=
tcp_conn->tc_SND_UNA;
}
}
else if (tcp_Lmod4G(tcp_conn->tc_SND_UNA, seg_ack)
&& tcp_LEmod4G(seg_ack, tcp_conn->
tc_SND_NXT))
{
tcp_release_retrans(tcp_conn, seg_ack, seg_wnd);
if (tcp_conn->tc_state == TCS_CLOSED)
break;
}
else if (tcp_Gmod4G(seg_ack,
tcp_conn->tc_SND_NXT))
{
tcp_conn->tc_flags |= TCF_SEND_ACK;
tcp_conn_write(tcp_conn, 1);
DBLOCK(1, printf(
"got an ack of something I haven't send\n");
printf( "seg_ack= %lu, SND_NXT= %lu\n",
seg_ack, tcp_conn->tc_SND_NXT));
break;
}
/*
process data...
*/
tcp_extract_ipopt(tcp_conn, ip_hdr);
tcp_extract_tcpopt(tcp_conn, tcp_hdr);
if (data_len)
{
if (tcp_LEmod4G(seg_seq, tcp_conn->tc_RCV_NXT))
{
process_data (tcp_conn, tcp_hdr,
tcp_data, data_len);
}
else
{
process_advanced_data (tcp_conn,
tcp_hdr, tcp_data, data_len);
}
tcp_conn->tc_flags |= TCF_SEND_ACK;
tcp_conn_write(tcp_conn, 1);
/* Don't process a FIN if we got new data */
break;
}
/*
FIN ?
reply pending receives
advace RCV.NXT over the FIN
<SEQ=SND.NXT><ACK=RCV.NXT><CTL=ACK>
state == ESTABLISHED ?
state= CLOSE-WAIT
state == FIN-WAIT-1 ?
state= CLOSING
state == FIN-WAIT-2 ?
state= TIME-WAIT
state == TIME-WAIT ?
restart the TIME-WAIT timer
exit
*/
if ((tcp_hdr_flags & THF_FIN) && tcp_LEmod4G(seg_seq,
tcp_conn->tc_RCV_NXT))
{
if (!(tcp_conn->tc_flags & TCF_FIN_RECV) &&
tcp_Lmod4G(tcp_conn->tc_RCV_NXT,
tcp_conn->tc_RCV_HI))
{
tcp_conn->tc_RCV_NXT++;
tcp_conn->tc_flags |= TCF_FIN_RECV;
}
tcp_conn->tc_flags |= TCF_SEND_ACK;
tcp_conn_write(tcp_conn, 1);
if (tcp_conn->tc_fd &&
(tcp_conn->tc_fd->tf_flags & TFF_READ_IP))
{
tcp_fd_read(tcp_conn, 1);
}
}
break;
default:
#if !CRAMPED
printf("tcp_frag2conn: unknown state ");
tcp_print_state(tcp_conn);
#endif
break;
}
if (tcp_data != NULL)
bf_afree(tcp_data);
}
PRIVATE void
process_data(tcp_conn, tcp_hdr, tcp_data, data_len)
tcp_conn_t *tcp_conn;
tcp_hdr_t *tcp_hdr;
acc_t *tcp_data;
int data_len;
{
u32_t lo_seq, hi_seq, urg_seq, seq_nr, adv_seq, nxt;
u16_t urgptr;
int tcp_hdr_flags;
unsigned int offset;
acc_t *tmp_data, *rcvd_data, *adv_data;
int len_diff;
assert(tcp_conn->tc_busy);
/* Note, tcp_data will be freed by the caller. */
assert (!(tcp_hdr->th_flags & THF_SYN));
seq_nr= ntohl(tcp_hdr->th_seq_nr);
urgptr= ntohs(tcp_hdr->th_urgptr);
tcp_data->acc_linkC++;
lo_seq= seq_nr;
tcp_hdr_flags= tcp_hdr->th_flags & TH_FLAGS_MASK;
if (tcp_hdr_flags & THF_URG)
{
if (urgptr > data_len)
urgptr= data_len;
urg_seq= lo_seq+ urgptr;
if (tcp_GEmod4G(urg_seq, tcp_conn->tc_RCV_HI))
urg_seq= tcp_conn->tc_RCV_HI;
if (tcp_conn->tc_flags & TCF_BSD_URG)
{
if (tcp_Gmod4G(tcp_conn->tc_RCV_NXT,
tcp_conn->tc_RCV_LO))
{
DBLOCK(1, printf(
"ignoring urgent data\n"));
bf_afree(tcp_data);
/* Should set advertised window to
* zero */
/* Flush */
tcp_conn->tc_flags |= TCF_RCV_PUSH;
if (tcp_conn->tc_fd &&
(tcp_conn->tc_fd->tf_flags &
TFF_READ_IP))
{
tcp_fd_read(tcp_conn, 1);
}
return;
}
}
if (tcp_Gmod4G(urg_seq, tcp_conn->tc_RCV_UP))
tcp_conn->tc_RCV_UP= urg_seq;
if (urgptr < data_len)
{
data_len= urgptr;
tmp_data= bf_cut(tcp_data, 0, data_len);
bf_afree(tcp_data);
tcp_data= tmp_data;
tcp_hdr_flags &= ~THF_FIN;
}
tcp_conn->tc_flags |= TCF_RCV_PUSH;
}
else
{
/* Normal data. */
}
if (tcp_hdr_flags & THF_PSH)
{
tcp_conn->tc_flags |= TCF_RCV_PUSH;
}
if (tcp_Lmod4G(lo_seq, tcp_conn->tc_RCV_NXT))
{
DBLOCK(0x10,
printf("segment is a retransmission\n"));
offset= tcp_conn->tc_RCV_NXT-lo_seq;
tcp_data= bf_delhead(tcp_data, offset);
lo_seq += offset;
data_len -= offset;
}
assert (lo_seq == tcp_conn->tc_RCV_NXT);
hi_seq= lo_seq+data_len;
if (tcp_Gmod4G(hi_seq, tcp_conn->tc_RCV_HI))
{
data_len= tcp_conn->tc_RCV_HI-lo_seq;
tmp_data= bf_cut(tcp_data, 0, data_len);
bf_afree(tcp_data);
tcp_data= tmp_data;
hi_seq= lo_seq+data_len;
tcp_hdr_flags &= ~THF_FIN;
}
assert (tcp_LEmod4G (hi_seq, tcp_conn->tc_RCV_HI));
rcvd_data= tcp_conn->tc_rcvd_data;
tcp_conn->tc_rcvd_data= 0;
tmp_data= bf_append(rcvd_data, tcp_data);
tcp_conn->tc_rcvd_data= tmp_data;
tcp_conn->tc_RCV_NXT= hi_seq;
if ((tcp_hdr_flags & THF_FIN) &&
tcp_Lmod4G(tcp_conn->tc_RCV_NXT, tcp_conn->tc_RCV_HI) &&
!(tcp_conn->tc_flags & TCF_FIN_RECV))
{
tcp_conn->tc_RCV_NXT++;
tcp_conn->tc_flags |= TCF_FIN_RECV;
}
if (tcp_conn->tc_fd && (tcp_conn->tc_fd->tf_flags & TFF_READ_IP))
tcp_fd_read(tcp_conn, 1);
DIFBLOCK(2, (tcp_conn->tc_RCV_NXT == tcp_conn->tc_RCV_HI),
printf("conn[[%d] full receive buffer\n",
tcp_conn-tcp_conn_table));
if (tcp_conn->tc_adv_data == NULL)
return;
if (tcp_hdr_flags & THF_FIN)
{
#if !CRAMPED
printf("conn[%d]: advanced data after FIN\n",
tcp_conn-tcp_conn_table);
#endif
tcp_data= tcp_conn->tc_adv_data;
tcp_conn->tc_adv_data= NULL;
bf_afree(tcp_data);
return;
}
lo_seq= tcp_conn->tc_adv_seq;
if (tcp_Gmod4G(lo_seq, tcp_conn->tc_RCV_NXT))
return; /* Not yet */
tcp_data= tcp_conn->tc_adv_data;
tcp_conn->tc_adv_data= NULL;
data_len= bf_bufsize(tcp_data);
if (tcp_Lmod4G(lo_seq, tcp_conn->tc_RCV_NXT))
{
offset= tcp_conn->tc_RCV_NXT-lo_seq;
if (offset >= data_len)
{
bf_afree(tcp_data);
return;
}
tcp_data= bf_delhead(tcp_data, offset);
lo_seq += offset;
data_len -= offset;
}
assert (lo_seq == tcp_conn->tc_RCV_NXT);
hi_seq= lo_seq+data_len;
assert (tcp_LEmod4G (hi_seq, tcp_conn->tc_RCV_HI));
rcvd_data= tcp_conn->tc_rcvd_data;
tcp_conn->tc_rcvd_data= 0;
tmp_data= bf_append(rcvd_data, tcp_data);
tcp_conn->tc_rcvd_data= tmp_data;
tcp_conn->tc_RCV_NXT= hi_seq;
assert (tcp_conn->tc_RCV_LO + bf_bufsize(tcp_conn->tc_rcvd_data) ==
tcp_conn->tc_RCV_NXT ||
(tcp_print_conn(tcp_conn), printf("\n"), 0));
if (tcp_conn->tc_fd && (tcp_conn->tc_fd->tf_flags & TFF_READ_IP))
tcp_fd_read(tcp_conn, 1);
adv_data= tcp_conn->tc_adv_data;
if (adv_data != NULL)
{
/* Try to use advanced data. */
adv_seq= tcp_conn->tc_adv_seq;
nxt= tcp_conn->tc_RCV_NXT;
if (tcp_Gmod4G(adv_seq, nxt))
return; /* not yet */
tcp_conn->tc_adv_data= NULL;
data_len= bf_bufsize(adv_data);
if (tcp_Lmod4G(adv_seq, nxt))
{
if (tcp_LEmod4G(adv_seq+data_len, nxt))
{
/* Data is not needed anymore. */
bf_afree(adv_data);
return;
}
len_diff= nxt-adv_seq;
adv_data= bf_delhead(adv_data, len_diff);
data_len -= len_diff;
}
DBLOCK(1, printf("using advanced data\n"));
/* Append data to the input buffer */
if (tcp_conn->tc_rcvd_data == NULL)
{
tcp_conn->tc_rcvd_data= adv_data;
}
else
{
tcp_conn->tc_rcvd_data=
bf_append(tcp_conn->tc_rcvd_data, adv_data);
}
tcp_conn->tc_SND_NXT += data_len;
assert(tcp_check_conn(tcp_conn));
if (tcp_conn->tc_fd &&
(tcp_conn->tc_fd->tf_flags & TFF_READ_IP))
{
tcp_fd_read(tcp_conn, 1);
}
}
}
PRIVATE void process_advanced_data(tcp_conn, tcp_hdr, tcp_data, data_len)
tcp_conn_t *tcp_conn;
tcp_hdr_t *tcp_hdr;
acc_t *tcp_data;
int data_len;
{
u32_t seq, adv_seq;
acc_t *adv_data;
assert(tcp_conn->tc_busy);
/* Note, tcp_data will be freed by the caller. */
/* Always send an ACK, this allows the sender to do a fast
* retransmit.
*/
tcp_conn->tc_flags |= TCF_SEND_ACK;
tcp_conn_write(tcp_conn, 1);
if (tcp_hdr->th_flags & THF_URG)
return; /* Urgent data is to complicated */
if (tcp_hdr->th_flags & THF_PSH)
tcp_conn->tc_flags |= TCF_RCV_PUSH;
seq= ntohl(tcp_hdr->th_seq_nr);
/* Make sure that the packet doesn't fall outside of the window
* we offered.
*/
if (tcp_Gmod4G(seq+data_len, tcp_conn->tc_RCV_HI))
return;
adv_data= tcp_conn->tc_adv_data;
adv_seq= tcp_conn->tc_adv_seq;
tcp_conn->tc_adv_data= NULL;
tcp_data->acc_linkC++;
if (adv_data == NULL)
{
adv_seq= seq;
adv_data= tcp_data;
}
else if (seq + data_len == adv_seq)
{
/* New data fits right before exiting data. */
adv_data= bf_append(tcp_data, adv_data);
adv_seq= seq;
}
else if (adv_seq + bf_bufsize(adv_data) == seq)
{
/* New data fits right after exiting data. */
adv_data= bf_append(adv_data, tcp_data);
}
else
{
/* New data doesn't fit. */
bf_afree(tcp_data);
}
tcp_conn->tc_adv_data= adv_data;
tcp_conn->tc_adv_seq= adv_seq;
}
PRIVATE void create_RST(tcp_conn, ip_hdr, tcp_hdr, data_len)
tcp_conn_t *tcp_conn;
ip_hdr_t *ip_hdr;
tcp_hdr_t *tcp_hdr;
int data_len;
{
acc_t *tmp_ipopt, *tmp_tcpopt, *tcp_pack;
ip_hdropt_t ip_hdropt;
tcp_hdropt_t tcp_hdropt;
acc_t *RST_acc;
ip_hdr_t *RST_ip_hdr;
tcp_hdr_t *RST_tcp_hdr;
char *ptr2RSThdr;
size_t pack_size, ip_hdr_len;
DBLOCK(0x10, printf("in create_RST, bad pack is:\n");
tcp_print_pack(ip_hdr, tcp_hdr); tcp_print_state(tcp_conn);
printf("\n"));
assert(tcp_conn->tc_busy);
/* Only send RST packets in reponse to actual data (or SYN, FIN)
* this solves a problem during connection shutdown. The problem
* is the follow senario: a senders closes the connection instead
* of doing a shutdown and waiting for the receiver to shutdown.
* The receiver is slow in processing the last data. After the
* sender has completely closed the connection, the receiver
* sends a window update which triggers the sender to send a
* RST. The receiver closes the connection in reponse to the RST.
*/
if ((tcp_hdr->th_flags & (THF_FIN|THF_SYN)) == 0 &&
data_len == 0)
{
#if DEBUG
{ printf("tcp_recv`create_RST: no data, no RST\n"); }
#endif
return;
}
tmp_ipopt= tcp_conn->tc_remipopt;
if (tmp_ipopt)
tmp_ipopt->acc_linkC++;
tmp_tcpopt= tcp_conn->tc_tcpopt;
if (tmp_tcpopt)
tmp_tcpopt->acc_linkC++;
tcp_extract_ipopt (tcp_conn, ip_hdr);
tcp_extract_tcpopt (tcp_conn, tcp_hdr);
RST_acc= tcp_make_header (tcp_conn, &RST_ip_hdr, &RST_tcp_hdr,
(acc_t *)0);
if (tcp_conn->tc_remipopt)
bf_afree(tcp_conn->tc_remipopt);
tcp_conn->tc_remipopt= tmp_ipopt;
if (tcp_conn->tc_tcpopt)
bf_afree(tcp_conn->tc_tcpopt);
tcp_conn->tc_tcpopt= tmp_tcpopt;
RST_ip_hdr->ih_src= ip_hdr->ih_dst;
RST_ip_hdr->ih_dst= ip_hdr->ih_src;
RST_tcp_hdr->th_srcport= tcp_hdr->th_dstport;
RST_tcp_hdr->th_dstport= tcp_hdr->th_srcport;
if (tcp_hdr->th_flags & THF_ACK)
{
RST_tcp_hdr->th_seq_nr= tcp_hdr->th_ack_nr;
RST_tcp_hdr->th_flags= THF_RST;
}
else
{
RST_tcp_hdr->th_seq_nr= 0;
RST_tcp_hdr->th_ack_nr=
htonl(
ntohl(tcp_hdr->th_seq_nr)+
data_len +
(tcp_hdr->th_flags & THF_SYN ? 1 : 0) +
(tcp_hdr->th_flags & THF_FIN ? 1 : 0));
RST_tcp_hdr->th_flags= THF_RST|THF_ACK;
}
pack_size= bf_bufsize(RST_acc);
RST_ip_hdr->ih_length= htons(pack_size);
RST_tcp_hdr->th_window= htons(tcp_conn->tc_rcv_wnd);
RST_tcp_hdr->th_chksum= 0;
RST_acc->acc_linkC++;
ip_hdr_len= (ip_hdr->ih_vers_ihl & IH_IHL_MASK) << 2;
tcp_pack= bf_delhead(RST_acc, ip_hdr_len);
RST_tcp_hdr->th_chksum= ~tcp_pack_oneCsum (RST_ip_hdr, tcp_pack);
bf_afree(tcp_pack);
DBLOCK(2, tcp_print_pack(ip_hdr, tcp_hdr); printf("\n");
tcp_print_pack(RST_ip_hdr, RST_tcp_hdr); printf("\n"));
if (tcp_conn->tc_frag2send)
bf_afree(tcp_conn->tc_frag2send);
tcp_conn->tc_frag2send= RST_acc;
tcp_conn_write(tcp_conn, 1);
}
PUBLIC void
tcp_fd_read(tcp_conn, enq)
tcp_conn_t *tcp_conn;
int enq; /* Enqueue writes. */
{
tcp_fd_t *tcp_fd;
size_t data_size, read_size;
acc_t *data;
int fin_recv, urg, push, result;
i32_t old_window, new_window;
assert(tcp_conn->tc_busy);
tcp_fd= tcp_conn->tc_fd;
assert (tcp_fd->tf_flags & TFF_READ_IP);
if (tcp_conn->tc_state == TCS_CLOSED)
{
if (tcp_fd->tf_read_offset)
tcp_reply_read (tcp_fd, tcp_fd->tf_read_offset);
else
tcp_reply_read (tcp_fd, tcp_conn->tc_error);
return;
}
urg= tcp_Gmod4G(tcp_conn->tc_RCV_UP, tcp_conn->tc_RCV_LO);
push= (tcp_conn->tc_flags & TCF_RCV_PUSH);
fin_recv= (tcp_conn->tc_flags & TCF_FIN_RECV);
data_size= tcp_conn->tc_RCV_NXT-tcp_conn->tc_RCV_LO;
if (fin_recv)
data_size--;
if (urg)
read_size= tcp_conn->tc_RCV_UP-tcp_conn->tc_RCV_LO;
else
read_size= data_size;
if (read_size >= tcp_fd->tf_read_count)
read_size= tcp_fd->tf_read_count;
else if (!push && !fin_recv && !urg &&
data_size < TCP_MIN_RCV_WND_SIZE)
{
/* Defer the copy out until later. */
return;
}
else if (data_size == 0 && !fin_recv)
{
/* No data, and no end of file. */
return;
}
if (read_size)
{
if (urg && !(tcp_fd->tf_flags & TFF_RECV_URG))
{
if (tcp_fd->tf_read_offset)
{
tcp_reply_read (tcp_fd,
tcp_fd->tf_read_offset);
}
else
{
tcp_reply_read (tcp_fd, EURG);
}
return;
}
else if (!urg && (tcp_fd->tf_flags & TFF_RECV_URG))
{
if (tcp_fd->tf_read_offset)
{
tcp_reply_read (tcp_fd,
tcp_fd->tf_read_offset);
}
else
{
tcp_reply_read(tcp_fd, ENOURG);
}
return;
}
if (read_size == data_size)
{
data= tcp_conn->tc_rcvd_data;
data->acc_linkC++;
}
else
{
data= bf_cut(tcp_conn->tc_rcvd_data, 0, read_size);
}
result= (*tcp_fd->tf_put_userdata) (tcp_fd->tf_srfd,
tcp_fd->tf_read_offset, data, FALSE);
if (result<0)
{
if (tcp_fd->tf_read_offset)
tcp_reply_read(tcp_fd, tcp_fd->
tf_read_offset);
else
tcp_reply_read(tcp_fd, result);
return;
}
tcp_fd->tf_read_offset += read_size;
tcp_fd->tf_read_count -= read_size;
if (data_size == read_size)
{
bf_afree(tcp_conn->tc_rcvd_data);
tcp_conn->tc_rcvd_data= 0;
}
else
{
tcp_conn->tc_rcvd_data=
bf_delhead(tcp_conn->tc_rcvd_data,
read_size);
}
tcp_conn->tc_RCV_LO += read_size;
data_size -= read_size;
}
if (tcp_conn->tc_RCV_HI-tcp_conn->tc_RCV_LO <= (tcp_conn->
tc_rcv_wnd-tcp_conn->tc_mss))
{
old_window= tcp_conn->tc_RCV_HI-tcp_conn->tc_RCV_NXT;
tcp_conn->tc_RCV_HI= tcp_conn->tc_RCV_LO +
tcp_conn->tc_rcv_wnd;
new_window= tcp_conn->tc_RCV_HI-tcp_conn->tc_RCV_NXT;
assert(old_window >=0 && new_window >= old_window);
if (old_window < tcp_conn->tc_mss &&
new_window >= tcp_conn->tc_mss)
{
tcp_conn->tc_flags |= TCF_SEND_ACK;
DBLOCK(2, printf("opening window\n"));
tcp_conn_write(tcp_conn, 1);
}
}
if (tcp_conn->tc_rcvd_data == NULL &&
tcp_conn->tc_adv_data == NULL)
{
/* Out of data, clear PUSH flag and reply to a read. */
tcp_conn->tc_flags &= ~TCF_RCV_PUSH;
}
if (fin_recv || urg || !tcp_fd->tf_read_count)
{
tcp_reply_read (tcp_fd, tcp_fd->tf_read_offset);
return;
}
if (tcp_fd->tf_read_offset)
{
tcp_reply_read (tcp_fd, tcp_fd->tf_read_offset);
return;
}
}
/*
* $PchId: tcp_recv.c,v 1.13.2.1 2000/05/02 18:53:06 philip Exp $
*/
Reference in a new issue Copy permalink