On Fri, Apr 11, 2025 at 03:10:21PM +0200, Laurent Vivier wrote:Use packet_base() and extract headers using IOV_REMOVE_HEADER() and iov_peek_header_() rather than packet_get(). Signed-off-by: Laurent Vivier <lvivier(a)redhat.com> --- tcp.c | 31 ++++++++++++++++++++++++------- 1 file changed, 24 insertions(+), 7 deletions(-) diff --git a/tcp.c b/tcp.c index 35626c914c6a..1838b73cf766 100644 --- a/tcp.c +++ b/tcp.c @@ -310,6 +310,16 @@ #include "tcp_buf.h" #include "tcp_vu.h" +/* + * The size of TCP header (including options) is given by doff (Data Offset) + * that is a 4-bit value specifying the number of 32-bit words in the header. + * The maximum value of doff is 15 [(1 << 4) - 1]. + * The maximum length in bytes of options is 15 minus the number of 32-bit + * words in the minimal TCP header (5) multiplied by the length of a 32-bit + * word (4). + */ +#define OPTLEN_MAX (((1UL << 4) - 6) * 4UL) + #ifndef __USE_MISC /* From Linux UAPI, missing in netinet/tcp.h provided by musl */ struct tcp_repair_opt { @@ -1957,7 +1967,10 @@ int tcp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af, { struct tcp_tap_conn *conn; const struct tcphdr *th; - size_t optlen, len; + char optsc[OPTLEN_MAX]; + struct iov_tail data; + size_t optlen, l4len; + struct tcphdr thc; const char *opts; union flow *flow; flow_sidx_t sidx; @@ -1966,15 +1979,19 @@ int tcp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af, (void)pif; - th = packet_get(p, idx, 0, sizeof(*th), &len); + if (!packet_base(p, idx, &data)) + return 1; + + l4len = iov_tail_size(&data); + + th = IOV_REMOVE_HEADER(&data, thc); if (!th) return 1; - len += sizeof(*th); optlen = th->doff * 4UL - sizeof(*th); /* Static checkers might fail to see this: */ - optlen = MIN(optlen, ((1UL << 4) /* from doff width */ - 6) * 4UL); - opts = packet_get(p, idx, sizeof(*th), optlen, NULL); + optlen = MIN(optlen, OPTLEN_MAX); + opts = (char *)iov_peek_header_(&data, &optsc[0], optlen, 1);Can you use remove_header here? AFAICT it makes logical sense to move the tail on to covering just the payload at this point.sidx = flow_lookup_af(c, IPPROTO_TCP, PIF_TAP, af, saddr, daddr, ntohs(th->source), ntohs(th->dest)); @@ -1986,7 +2003,7 @@ int tcp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af, tcp_conn_from_tap(c, af, saddr, daddr, th, opts, optlen, now); else - tcp_rst_no_conn(c, af, saddr, daddr, flow_lbl, th, len); + tcp_rst_no_conn(c, af, saddr, daddr, flow_lbl, th, l4len); return 1; } @@ -1994,7 +2011,7 @@ int tcp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af, ASSERT(pif_at_sidx(sidx) == PIF_TAP); conn = &flow->tcp; - flow_trace(conn, "packet length %zu from tap", len); + flow_trace(conn, "packet length %zu from tap", l4len); if (th->rst) { conn_event(c, conn, CLOSED);-- David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson