From 82f54ed91ab0dbf9b2fdab7b3ea80b7b9f02ae13 Mon Sep 17 00:00:00 2001 From: Alex Williamson Date: Tue, 28 Apr 2015 21:23:57 +0200 Subject: [PATCH 1/2] Extract timing parameters out to config/dhcp.h Message-id: <20150428212357.31299.65270.stgit@gimli.home> Patchwork-id: 64950 O-Subject: [RHEL7.2 ipxe PATCH 1/2] [dhcp] Extract timing parameters out to config/dhcp.h Bugzilla: 1196352 RH-Acked-by: Miroslav Rezanina RH-Acked-by: Gerd Hoffmann RH-Acked-by: Laszlo Ersek iPXE uses DHCP timeouts loosely based on values recommended by the specification, but often abbreviated to reduce timeouts for reliable and/or simple network topologies. Extract the DHCP timing parameters to config/dhcp.h and document them. The resulting default iPXE behavior is exactly the same, but downstreams are now afforded the opportunity to implement spec-compliant behavior via config file overrides. Signed-off-by: Alex Williamson Modified-by: Michael Brown Signed-off-by: Michael Brown Signed-off-by: Miroslav Rezanina --- src/config/dhcp.h | 87 +++++++++++++++++++++++++++++++++++++++++++++++++ src/include/ipxe/dhcp.h | 10 ------ src/net/udp/dhcp.c | 32 ++++++++++-------- 3 files changed, 106 insertions(+), 23 deletions(-) create mode 100644 src/config/dhcp.h diff --git a/src/config/dhcp.h b/src/config/dhcp.h new file mode 100644 index 0000000..21e863b --- /dev/null +++ b/src/config/dhcp.h @@ -0,0 +1,87 @@ +#ifndef CONFIG_DHCP_H +#define CONFIG_DHCP_H + +/** @file + * + * DHCP configuration + * + */ + +FILE_LICENCE ( GPL2_OR_LATER ); + +#include + +/* + * DHCP and PXE Boot Server timeout parameters + * + * Initial and final timeout for DHCP discovery + * + * The PXE spec indicates discover request are sent 4 times, with + * timeouts of 4, 8, 16, 32 seconds. iPXE by default uses 1, 2, 4, 8. + */ +#define DHCP_DISC_START_TIMEOUT_SEC 1 +#define DHCP_DISC_END_TIMEOUT_SEC 10 +//#define DHCP_DISC_START_TIMEOUT_SEC 4 /* as per PXE spec */ +//#define DHCP_DISC_END_TIMEOUT_SEC 32 /* as per PXE spec */ + +/* + * ProxyDHCP offers are given precedence by continue to wait for them + * after a valid DHCPOFFER is received. We'll wait through this + * timeout for it. The PXE spec indicates waiting through the 4 & 8 + * second timeouts, iPXE by default stops after 2. + */ +#define DHCP_DISC_PROXY_TIMEOUT_SEC 2 +//#define DHCP_DISC_PROXY_TIMEOUT_SEC 11 /* as per PXE spec */ + +/* + * Per the PXE spec, requests are also tried 4 times, but at timeout + * intervals of 1, 2, 3, 4 seconds. To adapt this to an exponential + * backoff timer, we can either do 1, 2, 4, 8, ie. 4 retires with a + * longer interval or start at 0 (0.25s) for 0.25, 0.5, 1, 2, 4, + * ie. one extra try and shorter initial timeouts. iPXE by default + * does a combination of both, starting at 0 and going through the 8 + * second timeout. + */ +#define DHCP_REQ_START_TIMEOUT_SEC 0 +#define DHCP_REQ_END_TIMEOUT_SEC 10 +//#define DHCP_REQ_END_TIMEOUT_SEC 4 /* as per PXE spec */ + +/* + * A ProxyDHCP offer without PXE options also goes through a request + * phase using these same parameters, but note the early break below. + */ +#define DHCP_PROXY_START_TIMEOUT_SEC 0 +#define DHCP_PROXY_END_TIMEOUT_SEC 10 +//#define DHCP_PROXY_END_TIMEOUT_SEC 8 /* as per PXE spec */ + +/* + * A ProxyDHCP request timeout should not induce a failure condition, + * so we always want to break before the above set of timers expire. + * The iPXE default value of 2 breaks at the first timeout after 2 + * seconds, which will be after the 2 second timeout. + */ +#define DHCP_REQ_PROXY_TIMEOUT_SEC 2 +//#define DHCP_REQ_PROXY_TIMEOUT_SEC 7 /* as per PXE spec */ + +/* + * Per the PXE spec, a PXE boot server request is also be retried 4 + * times at timeouts of 1, 2, 3, 4. iPXE uses the same timeouts as + * discovery, 1, 2, 4, 8, but will move on to the next server if + * available after an elapsed time greater than 3 seconds, therefore + * effectively only sending 3 tries at timeouts of 1, 2, 4. + */ +#define PXEBS_START_TIMEOUT_SEC 1 +#define PXEBS_END_TIMEOUT_SEC 10 +//#define PXEBS_START_TIMEOUT_SEC 0 /* as per PXE spec */ +//#define PXEBS_END_TIMEOUT_SEC 8 /* as per PXE spec */ + +/* + * Increment to the next PXE Boot server, if available, after this + * this much time has elapsed. + */ +#define PXEBS_MAX_TIMEOUT_SEC 3 +//#define PXEBS_MAX_TIMEOUT_SEC 7 /* as per PXE spec */ + +#include + +#endif /* CONFIG_DHCP_H */ diff --git a/src/include/ipxe/dhcp.h b/src/include/ipxe/dhcp.h index b97dfe3..13c8ca4 100644 --- a/src/include/ipxe/dhcp.h +++ b/src/include/ipxe/dhcp.h @@ -631,16 +631,6 @@ struct dhcphdr { */ #define DHCP_MIN_LEN 552 -/** Timeouts for sending DHCP packets */ -#define DHCP_MIN_TIMEOUT ( 1 * TICKS_PER_SEC ) -#define DHCP_MAX_TIMEOUT ( 10 * TICKS_PER_SEC ) - -/** Maximum time that we will wait for ProxyDHCP responses */ -#define PROXYDHCP_MAX_TIMEOUT ( 2 * TICKS_PER_SEC ) - -/** Maximum time that we will wait for Boot Server responses */ -#define PXEBS_MAX_TIMEOUT ( 3 * TICKS_PER_SEC ) - /** Settings block name used for DHCP responses */ #define DHCP_SETTINGS_NAME "dhcp" diff --git a/src/net/udp/dhcp.c b/src/net/udp/dhcp.c index 762ae73..6c4f29e 100644 --- a/src/net/udp/dhcp.c +++ b/src/net/udp/dhcp.c @@ -44,6 +44,7 @@ FILE_LICENCE ( GPL2_OR_LATER ); #include #include #include +#include /** @file * @@ -185,8 +186,9 @@ struct dhcp_session_state { void ( * expired ) ( struct dhcp_session *dhcp ); /** Transmitted message type */ uint8_t tx_msgtype; - /** Apply minimum timeout */ - uint8_t apply_min_timeout; + /** Timeout parameters */ + uint8_t min_timeout_sec; + uint8_t max_timeout_sec; }; static struct dhcp_session_state dhcp_state_discover; @@ -286,9 +288,8 @@ static void dhcp_set_state ( struct dhcp_session *dhcp, dhcp->state = state; dhcp->start = currticks(); stop_timer ( &dhcp->timer ); - dhcp->timer.min_timeout = - ( state->apply_min_timeout ? DHCP_MIN_TIMEOUT : 0 ); - dhcp->timer.max_timeout = DHCP_MAX_TIMEOUT; + dhcp->timer.min_timeout = state->min_timeout_sec * TICKS_PER_SEC; + dhcp->timer.max_timeout = state->max_timeout_sec * TICKS_PER_SEC; start_timer_nodelay ( &dhcp->timer ); } @@ -429,7 +430,7 @@ static void dhcp_discovery_rx ( struct dhcp_session *dhcp, /* If we can't yet transition to DHCPREQUEST, do nothing */ elapsed = ( currticks() - dhcp->start ); if ( ! ( dhcp->no_pxedhcp || dhcp->proxy_offer || - ( elapsed > PROXYDHCP_MAX_TIMEOUT ) ) ) + ( elapsed > DHCP_DISC_PROXY_TIMEOUT_SEC * TICKS_PER_SEC ) ) ) return; /* Transition to DHCPREQUEST */ @@ -445,7 +446,8 @@ static void dhcp_discovery_expired ( struct dhcp_session *dhcp ) { unsigned long elapsed = ( currticks() - dhcp->start ); /* Give up waiting for ProxyDHCP before we reach the failure point */ - if ( dhcp->offer.s_addr && ( elapsed > PROXYDHCP_MAX_TIMEOUT ) ) { + if ( dhcp->offer.s_addr && + ( elapsed > DHCP_DISC_PROXY_TIMEOUT_SEC * TICKS_PER_SEC ) ) { dhcp_set_state ( dhcp, &dhcp_state_request ); return; } @@ -461,7 +463,8 @@ static struct dhcp_session_state dhcp_state_discover = { .rx = dhcp_discovery_rx, .expired = dhcp_discovery_expired, .tx_msgtype = DHCPDISCOVER, - .apply_min_timeout = 1, + .min_timeout_sec = DHCP_DISC_START_TIMEOUT_SEC, + .max_timeout_sec = DHCP_DISC_END_TIMEOUT_SEC, }; /** @@ -598,7 +601,8 @@ static struct dhcp_session_state dhcp_state_request = { .rx = dhcp_request_rx, .expired = dhcp_request_expired, .tx_msgtype = DHCPREQUEST, - .apply_min_timeout = 0, + .min_timeout_sec = DHCP_REQ_START_TIMEOUT_SEC, + .max_timeout_sec = DHCP_REQ_END_TIMEOUT_SEC, }; /** @@ -683,7 +687,7 @@ static void dhcp_proxy_expired ( struct dhcp_session *dhcp ) { unsigned long elapsed = ( currticks() - dhcp->start ); /* Give up waiting for ProxyDHCP before we reach the failure point */ - if ( elapsed > PROXYDHCP_MAX_TIMEOUT ) { + if ( elapsed > DHCP_REQ_PROXY_TIMEOUT_SEC * TICKS_PER_SEC ) { dhcp_finished ( dhcp, 0 ); return; } @@ -699,7 +703,8 @@ static struct dhcp_session_state dhcp_state_proxy = { .rx = dhcp_proxy_rx, .expired = dhcp_proxy_expired, .tx_msgtype = DHCPREQUEST, - .apply_min_timeout = 0, + .min_timeout_sec = DHCP_PROXY_START_TIMEOUT_SEC, + .max_timeout_sec = DHCP_PROXY_END_TIMEOUT_SEC, }; /** @@ -824,7 +829,7 @@ static void dhcp_pxebs_expired ( struct dhcp_session *dhcp ) { /* Give up waiting before we reach the failure point, and fail * over to the next server in the attempt list */ - if ( elapsed > PXEBS_MAX_TIMEOUT ) { + if ( elapsed > PXEBS_MAX_TIMEOUT_SEC * TICKS_PER_SEC ) { dhcp->pxe_attempt++; if ( dhcp->pxe_attempt->s_addr ) { dhcp_set_state ( dhcp, &dhcp_state_pxebs ); @@ -846,7 +851,8 @@ static struct dhcp_session_state dhcp_state_pxebs = { .rx = dhcp_pxebs_rx, .expired = dhcp_pxebs_expired, .tx_msgtype = DHCPREQUEST, - .apply_min_timeout = 1, + .min_timeout_sec = PXEBS_START_TIMEOUT_SEC, + .max_timeout_sec = PXEBS_END_TIMEOUT_SEC, }; /**************************************************************************** -- 1.8.3.1