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Re: RedBoot sequenecnumber generation
- From: Mark Salter <msalter at redhat dot com>
- To: roland dot cassebohm at visionsystems dot de
- Cc: ecos-discuss at ecos dot sourceware dot org
- Date: Tue, 16 Mar 2004 09:15:53 -0500 (EST)
- Subject: Re: [ECOS] RedBoot sequenecnumber generation
- References: <200403151752.40157.roland.cassebohm@visionsystems.de>
>>>>> Roland =?iso-8859-15?q?Ca=DFebohm?= writes:
> Hello,
> i have a problem with RedBoot connecting to other hosts.
> In RedBoot the initial sequencenumber for TCP is always the same.
> If RedBoot try to connect to the same host and port multiple
> times, it couldn't connect while the port is in TIME_WAIT state
> on the host. I think this is because the thinks it gets old lost
> packets and just drops them.
> The attached patch solved the problem for me, but I think it is
> maybe not what is really right. At least the part in do_retrans().
Right. You don't want to mess with the sequence number in do_retrans.
It would be wrong to do so in the case where the retrans happens
because of a missed SYN response from the remote host.
Could you try the following patch to see if it works for you?
--Mark
Index: redboot/current/src/net/tcp.c
===================================================================
RCS file: /cvs/ecos/ecos/packages/redboot/current/src/net/tcp.c,v
retrieving revision 1.11
diff -u -p -5 -r1.11 tcp.c
--- redboot/current/src/net/tcp.c 21 Dec 2003 13:17:52 -0000 1.11
+++ redboot/current/src/net/tcp.c 16 Mar 2004 14:05:26 -0000
@@ -58,10 +58,12 @@
#include <cyg/hal/hal_if.h>
#define MAX_TCP_SEGMENT (ETH_MAX_PKTLEN - (sizeof(eth_header_t) + sizeof(ip_header_t)))
#define MAX_TCP_DATA (MAX_TCP_SEGMENT - sizeof(tcp_header_t))
+/* setting this to 1 is technically wrong, but BSD does it too... */
+static int initial_seqnum = 1;
/* sequence number comparison macros */
#define SEQ_LT(a,b) ((int)((a)-(b)) < 0)
#define SEQ_LE(a,b) ((int)((a)-(b)) <= 0)
#define SEQ_GT(a,b) ((int)((a)-(b)) > 0)
@@ -479,10 +481,11 @@ __tcp_handler(pktbuf_t *pkt, ip_route_t
return;
}
s->state = _ESTABLISHED;
s->ack = ntohl(tcp->seqnum) + 1;
s->seq = ntohl(tcp->acknum);
+ initial_seqnum += 64000;
__timer_cancel(&s->timer);
send_ack(s);
break;
case _LISTEN:
@@ -523,10 +526,11 @@ __tcp_handler(pktbuf_t *pkt, ip_route_t
} else if ((tcp->flags & TCP_FLAG_ACK) &&
ntohl(tcp->acknum) == (s->seq + 1)) {
/* we've established the connection */
s->state = _ESTABLISHED;
s->seq++;
+ initial_seqnum += 64000;
BSPLOG(bsp_log("ACK received - connection established\n"));
}
break;
@@ -643,10 +647,13 @@ void
__tcp_poll(void)
{
__enet_poll();
MS_TICKS_DELAY();
__timer_poll();
+
+ /* rfc793 says this should be incremented approx. once per 4ms */
+ initial_seqnum += 1000 / 4;
}
int
__tcp_listen(tcp_socket_t *s, word port)
@@ -890,11 +897,11 @@ __tcp_open(tcp_socket_t *s, struct socka
s->his_port = host->sin_port;
s->pkt.buf = (word *)s->pktbuf;
s->pkt.bufsize = ETH_MAX_PKTLEN;
s->pkt.ip_hdr = (ip_header_t *)s->pkt.buf;
s->pkt.tcp_hdr = (tcp_header_t *)(s->pkt.ip_hdr + 1);
- s->seq = (port << 16) | 0xDE77;
+ s->seq = initial_seqnum;
s->ack = 0;
if (__arp_lookup((ip_addr_t *)&host->sin_addr, &s->his_addr) < 0) {
diag_printf("%s: Can't find address of server\n", __FUNCTION__);
return -1;
}
--
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