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tcp: Remove some redundant packet_get() operations

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Both tcp_data_from_tap() and tcp_tap_handler() call packet_get() to get
the entire L4 packet length, then immediately call it again to check that
the packet is long enough to include a TCP header.  The features of
packet_get() let us easily combine these together, we just need to adjust
the length slightly, because we want the value to include the TCP header
length.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
David Gibson 2023-09-08 11:49:48 +10:00 committed by Stefano Brivio
parent 7b56117dae
commit 805dd109a4
1 changed files with 4 additions and 10 deletions
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14
tcp.c
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@ -2320,16 +2320,12 @@ static void tcp_data_from_tap(struct ctx *c, struct tcp_tap_conn *conn,
char *data; char *data;
size_t off; size_t off;
if (!packet_get(p, i, 0, 0, &len)) { th = packet_get(p, i, 0, sizeof(*th), &len);
tcp_rst(c, conn);
return;
}
th = packet_get(p, i, 0, sizeof(*th), NULL);
if (!th) { if (!th) {
tcp_rst(c, conn); tcp_rst(c, conn);
return; return;
} }
len += sizeof(*th);
off = th->doff * 4UL; off = th->doff * 4UL;
if (off < sizeof(*th) || off > len) { if (off < sizeof(*th) || off > len) {
@ -2545,12 +2541,10 @@ int tcp_tap_handler(struct ctx *c, int af, const void *saddr, const void *daddr,
int ack_due = 0; int ack_due = 0;
char *opts; char *opts;
if (!packet_get(p, idx, 0, 0, &len)) th = packet_get(p, idx, 0, sizeof(*th), &len);
return 1;
th = packet_get(p, idx, 0, sizeof(*th), NULL);
if (!th) if (!th)
return 1; return 1;
len += sizeof(*th);
optlen = th->doff * 4UL - sizeof(*th); optlen = th->doff * 4UL - sizeof(*th);
/* Static checkers might fail to see this: */ /* Static checkers might fail to see this: */