[pxe] Obey lists of PXE Boot Servers and associated Discovery Control bits

Various combinations of options 43.6, 43.7 and 43.8 dictate which
servers we send Boot Server Discovery requests to, and which servers
we should accept responses from.  Obey these options, and remove the
explicit specification of a single Boot Server from start_pxebs() and
dependent functions.

1 files changed, 169 insertions, 29 deletions

diff --git a/src/net/udp/dhcp.c b/src/net/udp/dhcp.c
index 6ebf6021..d1492146 100644
--- a/src/net/udp/dhcp.c
+++ b/src/net/udp/dhcp.c
@@ -175,11 +175,12 @@ struct dhcp_session_state {
 	 * @v dhcppkt		DHCP packet
 	 * @v peer		DHCP server address
 	 * @v msgtype		DHCP message type
+	 * @v server_id		DHCP server ID
 	 */
 	void ( * rx ) ( struct dhcp_session *dhcp,
 			struct dhcp_packet *dhcppkt,
 			struct sockaddr_in *peer,
-			uint8_t msgtype );
+			uint8_t msgtype, struct in_addr server_id );
 	/** Handle timer expiry
 	 *
 	 * @v dhcp		DHCP session
@@ -226,10 +227,12 @@ struct dhcp_session {
 	/** ProxyDHCP server priority */
 	int proxy_priority;
 
-	/** PXE Boot Server */
-	struct in_addr pxe_server;
 	/** PXE Boot Server type */
 	uint16_t pxe_type;
+	/** List of PXE Boot Servers to attempt */
+	struct in_addr *pxe_attempt;
+	/** List of PXE Boot Servers to accept */
+	struct in_addr *pxe_accept;
 
 	/** Retransmission timer */
 	struct retry_timer timer;
@@ -322,11 +325,12 @@ static int dhcp_discovery_tx ( struct dhcp_session *dhcp,
  * @v dhcppkt		DHCP packet
  * @v peer		DHCP server address
  * @v msgtype		DHCP message type
+ * @v server_id		DHCP server ID
  */
 static void dhcp_discovery_rx ( struct dhcp_session *dhcp,
 				struct dhcp_packet *dhcppkt,
-				struct sockaddr_in *peer, uint8_t msgtype ) {
-	struct in_addr server_id = { 0 };
+				struct sockaddr_in *peer, uint8_t msgtype,
+				struct in_addr server_id ) {
 	struct in_addr ip;
 	char vci[9]; /* "PXEClient" */
 	int vci_len;
@@ -338,10 +342,6 @@ static void dhcp_discovery_rx ( struct dhcp_session *dhcp,
 	DBGC ( dhcp, "DHCP %p %s from %s:%d", dhcp,
 	       dhcp_msgtype_name ( msgtype ), inet_ntoa ( peer->sin_addr ),
 	       ntohs ( peer->sin_port ) );
-
-	/* Identify server ID */
-	dhcppkt_fetch ( dhcppkt, DHCP_SERVER_IDENTIFIER,
-			&server_id, sizeof ( server_id ) );
 	if ( server_id.s_addr != peer->sin_addr.s_addr )
 		DBGC ( dhcp, " (%s)", inet_ntoa ( server_id ) );
 
@@ -480,11 +480,12 @@ static int dhcp_request_tx ( struct dhcp_session *dhcp,
  * @v dhcppkt		DHCP packet
  * @v peer		DHCP server address
  * @v msgtype		DHCP message type
+ * @v server_id		DHCP server ID
  */
 static void dhcp_request_rx ( struct dhcp_session *dhcp,
 			      struct dhcp_packet *dhcppkt,
-			      struct sockaddr_in *peer, uint8_t msgtype ) {
-	struct in_addr server_id = { 0 };
+			      struct sockaddr_in *peer, uint8_t msgtype,
+			      struct in_addr server_id ) {
 	struct in_addr ip;
 	struct settings *parent;
 	int rc;
@@ -492,10 +493,6 @@ static void dhcp_request_rx ( struct dhcp_session *dhcp,
 	DBGC ( dhcp, "DHCP %p %s from %s:%d", dhcp,
 	       dhcp_msgtype_name ( msgtype ), inet_ntoa ( peer->sin_addr ),
 	       ntohs ( peer->sin_port ) );
-
-	/* Identify server ID */
-	dhcppkt_fetch ( dhcppkt, DHCP_SERVER_IDENTIFIER,
-			&server_id, sizeof ( server_id ) );
 	if ( server_id.s_addr != peer->sin_addr.s_addr )
 		DBGC ( dhcp, " (%s)", inet_ntoa ( server_id ) );
 
@@ -591,20 +588,17 @@ static int dhcp_proxy_tx ( struct dhcp_session *dhcp,
  * @v dhcppkt		DHCP packet
  * @v peer		DHCP server address
  * @v msgtype		DHCP message type
+ * @v server_id		DHCP server ID
  */
 static void dhcp_proxy_rx ( struct dhcp_session *dhcp,
 			    struct dhcp_packet *dhcppkt,
-			    struct sockaddr_in *peer, uint8_t msgtype ) {
-	struct in_addr server_id = { 0 };
+			    struct sockaddr_in *peer, uint8_t msgtype,
+			    struct in_addr server_id ) {
 	int rc;
 
 	DBGC ( dhcp, "DHCP %p %s from %s:%d", dhcp,
 	       dhcp_msgtype_name ( msgtype ), inet_ntoa ( peer->sin_addr ),
 	       ntohs ( peer->sin_port ) );
-
-	/* Identify server ID */
-	dhcppkt_fetch ( dhcppkt, DHCP_SERVER_IDENTIFIER,
-			&server_id, sizeof ( server_id ) );
 	if ( server_id.s_addr != peer->sin_addr.s_addr )
 		DBGC ( dhcp, " (%s)", inet_ntoa ( server_id ) );
 	DBGC ( dhcp, "\n" );
@@ -673,7 +667,7 @@ static int dhcp_pxebs_tx ( struct dhcp_session *dhcp,
 	int rc;
 
 	DBGC ( dhcp, "DHCP %p PXEBS REQUEST to %s:%d for type %d\n",
-	       dhcp, inet_ntoa ( dhcp->pxe_server ), PXE_PORT,
+	       dhcp, inet_ntoa ( *(dhcp->pxe_attempt) ), PXE_PORT,
 	       ntohs ( dhcp->pxe_type ) );
 
 	/* Set boot menu item */
@@ -683,29 +677,59 @@ static int dhcp_pxebs_tx ( struct dhcp_session *dhcp,
 		return rc;
 
 	/* Set server address */
-	peer->sin_addr = dhcp->pxe_server;
+	peer->sin_addr = *(dhcp->pxe_attempt);
 	peer->sin_port = htons ( PXE_PORT );
 
 	return 0;
 }
 
 /**
+ * Check to see if PXE Boot Server address is acceptable
+ *
+ * @v dhcp		DHCP session
+ * @v bs		Boot Server address
+ * @ret accept		Boot Server is acceptable
+ */
+static int dhcp_pxebs_accept ( struct dhcp_session *dhcp,
+			       struct in_addr bs ) {
+	struct in_addr *accept;
+
+	/* Accept if we have no acceptance filter */
+	if ( ! dhcp->pxe_accept )
+		return 1;
+
+	/* Scan through acceptance list */
+	for ( accept = dhcp->pxe_accept ; accept->s_addr ; accept++ ) {
+		if ( accept->s_addr == bs.s_addr )
+			return 1;
+	}
+
+	DBGC ( dhcp, "DHCP %p rejecting server %s\n",
+	       dhcp, inet_ntoa ( bs ) );
+	return 0;
+}
+
+/**
  * Handle received packet during PXE Boot Server Discovery
  *
  * @v dhcp		DHCP session
  * @v dhcppkt		DHCP packet
  * @v peer		DHCP server address
  * @v msgtype		DHCP message type
+ * @v server_id		DHCP server ID
  */
 static void dhcp_pxebs_rx ( struct dhcp_session *dhcp,
 			    struct dhcp_packet *dhcppkt,
-			    struct sockaddr_in *peer, uint8_t msgtype ) {
+			    struct sockaddr_in *peer, uint8_t msgtype,
+			    struct in_addr server_id ) {
 	struct dhcp_pxe_boot_menu_item menu_item = { 0, 0 };
 	int rc;
 
 	DBGC ( dhcp, "DHCP %p %s from %s:%d", dhcp,
 	       dhcp_msgtype_name ( msgtype ), inet_ntoa ( peer->sin_addr ),
 	       ntohs ( peer->sin_port ) );
+	if ( server_id.s_addr != peer->sin_addr.s_addr )
+		DBGC ( dhcp, " (%s)", inet_ntoa ( server_id ) );
 
 	/* Identify boot menu item */
 	dhcppkt_fetch ( dhcppkt, DHCP_PXE_BOOT_MENU_ITEM,
@@ -721,6 +745,9 @@ static void dhcp_pxebs_rx ( struct dhcp_session *dhcp,
 		return;
 	if ( menu_item.type != dhcp->pxe_type )
 		return;
+	if ( ! dhcp_pxebs_accept ( dhcp, ( server_id.s_addr ?
+					   server_id : peer->sin_addr ) ) )
+		return;
 
 	/* Register settings */
 	dhcppkt->settings.name = PXEBS_SETTINGS_NAME;
@@ -741,6 +768,21 @@ static void dhcp_pxebs_rx ( struct dhcp_session *dhcp,
  * @v dhcp		DHCP session
  */
 static void dhcp_pxebs_expired ( struct dhcp_session *dhcp ) {
+	unsigned long elapsed = ( currticks() - dhcp->start );
+
+	/* 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 ) {
+		dhcp->pxe_attempt++;
+		if ( dhcp->pxe_attempt->s_addr ) {
+			dhcp_set_state ( dhcp, &dhcp_state_pxebs );
+			return;
+		} else {
+			dhcp_finished ( dhcp, -ETIMEDOUT );
+			return;
+		}
+	}
 
 	/* Retransmit current packet */
 	dhcp_tx ( dhcp );
@@ -1006,6 +1048,7 @@ static int dhcp_deliver_iob ( struct xfer_interface *xfer,
 	struct dhcp_packet *dhcppkt;
 	struct dhcphdr *dhcphdr;
 	uint8_t msgtype = 0;
+	struct in_addr server_id = { 0 };
 	int rc = 0;
 
 	/* Sanity checks */
@@ -1042,6 +1085,10 @@ static int dhcp_deliver_iob ( struct xfer_interface *xfer,
 	dhcppkt_fetch ( dhcppkt, DHCP_MESSAGE_TYPE, &msgtype,
 			sizeof ( msgtype ) );
 
+	/* Identify server ID */
+	dhcppkt_fetch ( dhcppkt, DHCP_SERVER_IDENTIFIER,
+			&server_id, sizeof ( server_id ) );
+
 	/* Check for matching transaction ID */
 	if ( dhcphdr->xid != dhcp_xid ( dhcp->netdev ) ) {
 		DBGC ( dhcp, "DHCP %p %s from %s:%d has bad transaction "
@@ -1053,7 +1100,7 @@ static int dhcp_deliver_iob ( struct xfer_interface *xfer,
 	};
 
 	/* Handle packet based on current state */
-	dhcp->state->rx ( dhcp, dhcppkt, peer, msgtype );
+	dhcp->state->rx ( dhcp, dhcppkt, peer, msgtype, server_id );
 
  err_xid:
 	dhcppkt_put ( dhcppkt );
@@ -1184,11 +1231,49 @@ int start_dhcp ( struct job_interface *job, struct net_device *netdev ) {
 }
 
 /**
+ * Retrieve list of PXE boot servers for a given server type
+ *
+ * @v dhcp		DHCP session
+ * @v raw		DHCP PXE boot server list
+ * @v raw_len		Length of DHCP PXE boot server list
+ * @v ip		IP address list to fill in
+ *
+ * The caller must ensure that the IP address list has sufficient
+ * space.
+ */
+static void pxebs_list ( struct dhcp_session *dhcp, void *raw,
+			 size_t raw_len, struct in_addr *ip ) {
+	struct dhcp_pxe_boot_server *server = raw;
+	size_t server_len;
+	unsigned int i;
+
+	while ( raw_len ) {
+		if ( raw_len < sizeof ( *server ) ) {
+			DBGC ( dhcp, "DHCP %p malformed PXE server list\n",
+			       dhcp );
+			break;
+		}
+		server_len = offsetof ( typeof ( *server ),
+					ip[ server->num_ip ] );
+		if ( raw_len < server_len ) {
+			DBGC ( dhcp, "DHCP %p malformed PXE server list\n",
+			       dhcp );
+			break;
+		}
+		if ( server->type == dhcp->pxe_type ) {
+			for ( i = 0 ; i < server->num_ip ; i++ )
+				*(ip++) = server->ip[i];
+		}
+		server = ( ( ( void * ) server ) + server_len );
+		raw_len -= server_len;
+	}
+}
+
+/**
  * Start PXE Boot Server Discovery on a network device
  *
  * @v job		Job control interface
  * @v netdev		Network device
- * @v pxe_server	PXE server (may be a multicast address)
  * @v pxe_type		PXE server type
  * @ret rc		Return status code
  *
@@ -1197,12 +1282,28 @@ int start_dhcp ( struct job_interface *job, struct net_device *netdev ) {
  * source.
  */
 int start_pxebs ( struct job_interface *job, struct net_device *netdev,
-		  struct in_addr pxe_server, unsigned int pxe_type ) {
+		  unsigned int pxe_type ) {
+	struct setting pxe_discovery_control_setting =
+		{ .tag = DHCP_PXE_DISCOVERY_CONTROL };
+	struct setting pxe_boot_servers_setting =
+		{ .tag = DHCP_PXE_BOOT_SERVERS };
+	struct setting pxe_boot_server_mcast_setting =
+		{ .tag = DHCP_PXE_BOOT_SERVER_MCAST };
+	ssize_t pxebs_list_len;
 	struct dhcp_session *dhcp;
+	struct in_addr *ip;
+	unsigned int pxe_discovery_control;
 	int rc;
 
+	/* Get upper bound for PXE boot server IP address list */
+	pxebs_list_len = fetch_setting_len ( NULL, &pxe_boot_servers_setting );
+	if ( pxebs_list_len < 0 )
+		pxebs_list_len = 0;
+
 	/* Allocate and initialise structure */
-	dhcp = zalloc ( sizeof ( *dhcp ) );
+	dhcp = zalloc ( sizeof ( *dhcp ) + sizeof ( *ip ) /* mcast */ +
+			sizeof ( *ip ) /* bcast */ + pxebs_list_len +
+			sizeof ( *ip ) /* terminator */ );
 	if ( ! dhcp )
 		return -ENOMEM;
 	dhcp->refcnt.free = dhcp_free;
@@ -1213,10 +1314,49 @@ int start_pxebs ( struct job_interface *job, struct net_device *netdev,
 	fetch_ipv4_setting ( netdev_settings ( netdev ), &ip_setting,
 			     &dhcp->local.sin_addr );
 	dhcp->local.sin_port = htons ( BOOTPC_PORT );
-	dhcp->pxe_server = pxe_server;
 	dhcp->pxe_type = htons ( pxe_type );
 	dhcp->timer.expired = dhcp_timer_expired;
 
+	/* Construct PXE boot server IP address lists */
+	pxe_discovery_control =
+		fetch_uintz_setting ( NULL, &pxe_discovery_control_setting );
+	ip = ( ( ( void * ) dhcp ) + sizeof ( *dhcp ) );
+	dhcp->pxe_attempt = ip;
+	if ( ! ( pxe_discovery_control & PXEBS_NO_MULTICAST ) ) {
+		fetch_ipv4_setting ( NULL, &pxe_boot_server_mcast_setting, ip);
+		if ( ip->s_addr )
+			ip++;
+	}
+	if ( ! ( pxe_discovery_control & PXEBS_NO_BROADCAST ) )
+		(ip++)->s_addr = INADDR_BROADCAST;
+	if ( pxe_discovery_control & PXEBS_NO_UNKNOWN_SERVERS )
+		dhcp->pxe_accept = ip;
+	if ( pxebs_list_len ) {
+		uint8_t buf[pxebs_list_len];
+
+		fetch_setting ( NULL, &pxe_boot_servers_setting,
+				buf, sizeof ( buf ) );
+		pxebs_list ( dhcp, buf, sizeof ( buf ), ip );
+	}
+	if ( ! dhcp->pxe_attempt->s_addr ) {
+		DBGC ( dhcp, "DHCP %p has no PXE boot servers for type %04x\n",
+		       dhcp, pxe_type );
+		rc = -EINVAL;
+		goto err;
+	}
+
+	/* Dump out PXE server lists */
+	DBGC ( dhcp, "DHCP %p attempting", dhcp );
+	for ( ip = dhcp->pxe_attempt ; ip->s_addr ; ip++ )
+		DBGC ( dhcp, " %s", inet_ntoa ( *ip ) );
+	DBGC ( dhcp, "\n" );
+	if ( dhcp->pxe_accept ) {
+		DBGC ( dhcp, "DHCP %p accepting", dhcp );
+		for ( ip = dhcp->pxe_accept ; ip->s_addr ; ip++ )
+			DBGC ( dhcp, " %s", inet_ntoa ( *ip ) );
+		DBGC ( dhcp, "\n" );
+	}
+
 	/* Instantiate child objects and attach to our interfaces */
 	if ( ( rc = xfer_open_socket ( &dhcp->xfer, SOCK_DGRAM, &dhcp_peer,
 				  ( struct sockaddr * ) &dhcp->local ) ) != 0 )