diff options
| author | Michael Brown <mcb30@ipxe.org> | 2010-10-09 01:24:18 +0100 |
|---|---|---|
| committer | Michael Brown <mcb30@ipxe.org> | 2010-10-09 01:24:18 +0100 |
| commit | 6d11229e83b91ac987bf34b811686f37ec750ef4 (patch) | |
| tree | 841cbb2d26804f79ee35bea37836b716b6d5286f /src/net/udp/dhcp.c | |
| parent | 831106a8752fbb7157458339a1693de54b6ad43c (diff) | |
| download | ipxe-6d11229e83b91ac987bf34b811686f37ec750ef4.tar.gz | |
[dhcp] Include session state metadata in packet traces
(Ab)use the "secs" field in transmitted DHCP packets to convey
metadata about the DHCP session state. In particular:
bit 0 represents the receipt of a ProxyDHCPOFFER
bit 1 represents the receipt of a DHCPOFFER
bits 2+ represent the transmitted packet sequence number
This allows some relevant information about the internal state of the
DHCP session to be read out from a packet trace from a non-debug build
of iPXE. It also potentially allows replies to be correlated to their
requests (for servers that copy the "secs" field from request to
reply).
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Diffstat (limited to 'src/net/udp/dhcp.c')
| -rw-r--r-- | src/net/udp/dhcp.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/src/net/udp/dhcp.c b/src/net/udp/dhcp.c index 9ab93dcf7..443ae3aa4 100644 --- a/src/net/udp/dhcp.c +++ b/src/net/udp/dhcp.c @@ -245,6 +245,8 @@ struct dhcp_session { /** Retransmission timer */ struct retry_timer timer; + /** Transmission counter */ + unsigned int count; /** Start time of the current state (in ticks) */ unsigned long start; }; @@ -1098,6 +1100,14 @@ static int dhcp_tx ( struct dhcp_session *dhcp ) { goto done; } + /* (Ab)use the "secs" field to convey metadata about the DHCP + * session state into packet traces. Useful for extracting + * debug information from non-debug builds. + */ + dhcppkt.dhcphdr->secs = htons ( ( ++(dhcp->count) << 2 ) | + ( dhcp->offer.s_addr ? 0x02 : 0 ) | + ( dhcp->proxy_offer ? 0x01 : 0 ) ); + /* Fill in packet based on current state */ if ( ( rc = dhcp->state->tx ( dhcp, &dhcppkt, &peer ) ) != 0 ) { DBGC ( dhcp, "DHCP %p could not fill DHCP request: %s\n", |