[ntp] Add simple NTP client

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/include/ipxe/errfile.h

@@ -265,6 +265,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #define ERRFILE_peerblk			( ERRFILE_NET | 0x00460000 )
 #define ERRFILE_peermux			( ERRFILE_NET | 0x00470000 )
 #define ERRFILE_xsigo			( ERRFILE_NET | 0x00480000 )
+#define ERRFILE_ntp			( ERRFILE_NET | 0x00490000 )
 
 #define ERRFILE_image		      ( ERRFILE_IMAGE | 0x00000000 )
 #define ERRFILE_elf		      ( ERRFILE_IMAGE | 0x00010000 )

src/include/ipxe/ntp.h

@@ -0,0 +1,109 @@
+#ifndef _IPXE_NTP_H
+#define _IPXE_NTP_H
+
+/** @file
+ *
+ * Network Time Protocol
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+#include <stdint.h>
+#include <ipxe/in.h>
+#include <ipxe/interface.h>
+
+/** NTP port */
+#define NTP_PORT 123
+
+/** An NTP short-format timestamp */
+struct ntp_short {
+	/** Seconds */
+	uint16_t seconds;
+	/** Fraction of a second */
+	uint16_t fraction;
+} __attribute__ (( packed ));
+
+/** An NTP timestamp */
+struct ntp_timestamp {
+	/** Seconds */
+	uint32_t seconds;
+	/** Fraction of a second */
+	uint32_t fraction;
+} __attribute__ (( packed ));
+
+/** An NTP reference identifier */
+union ntp_id {
+	/** Textual identifier */
+	char text[4];
+	/** IPv4 address */
+	struct in_addr in;
+	/** Opaque integer */
+	uint32_t opaque;
+};
+
+/** An NTP header */
+struct ntp_header {
+	/** Flags */
+	uint8_t flags;
+	/** Stratum */
+	uint8_t stratum;
+	/** Polling rate */
+	int8_t poll;
+	/** Precision */
+	int8_t precision;
+	/** Root delay */
+	struct ntp_short delay;
+	/** Root dispersion */
+	struct ntp_short dispersion;
+	/** Reference clock identifier */
+	union ntp_id id;
+	/** Reference timestamp */
+	struct ntp_timestamp reference;
+	/** Originate timestamp */
+	struct ntp_timestamp originate;
+	/** Receive timestamp */
+	struct ntp_timestamp receive;
+	/** Transmit timestamp */
+	struct ntp_timestamp transmit;
+} __attribute__ (( packed ));
+
+/** Leap second indicator: unknown */
+#define NTP_FL_LI_UNKNOWN 0xc0
+
+/** NTP version: 1 */
+#define NTP_FL_VN_1 0x20
+
+/** NTP mode: client */
+#define NTP_FL_MODE_CLIENT 0x03
+
+/** NTP mode: server */
+#define NTP_FL_MODE_SERVER 0x04
+
+/** NTP mode mask */
+#define NTP_FL_MODE_MASK 0x07
+
+/** NTP timestamp for start of Unix epoch */
+#define NTP_EPOCH 2208988800UL
+
+/** NTP fraction of a second magic value
+ *
+ * This is a policy decision.
+ */
+#define NTP_FRACTION_MAGIC 0x69505845UL
+
+/** NTP minimum retransmission timeout
+ *
+ * This is a policy decision.
+ */
+#define NTP_MIN_TIMEOUT ( 1 * TICKS_PER_SEC )
+
+/** NTP maximum retransmission timeout
+ *
+ * This is a policy decision.
+ */
+#define NTP_MAX_TIMEOUT ( 10 * TICKS_PER_SEC )
+
+extern int start_ntp ( struct interface *job, const char *hostname );
+
+#endif /* _IPXE_NTP_H */

src/net/udp/ntp.c

@@ -0,0 +1,275 @@
+/*
+ * Copyright (C) 2016 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ *
+ * You can also choose to distribute this program under the terms of
+ * the Unmodified Binary Distribution Licence (as given in the file
+ * COPYING.UBDL), provided that you have satisfied its requirements.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+#include <stdint.h>
+#include <string.h>
+#include <errno.h>
+#include <time.h>
+#include <ipxe/malloc.h>
+#include <ipxe/refcnt.h>
+#include <ipxe/iobuf.h>
+#include <ipxe/xfer.h>
+#include <ipxe/open.h>
+#include <ipxe/retry.h>
+#include <ipxe/timer.h>
+#include <ipxe/time.h>
+#include <ipxe/tcpip.h>
+#include <ipxe/ntp.h>
+
+/** @file
+ *
+ * Network Time Protocol
+ *
+ */
+
+/** An NTP client */
+struct ntp_client {
+	/** Reference count */
+	struct refcnt refcnt;
+	/** Job control interface */
+	struct interface job;
+	/** Data transfer interface */
+	struct interface xfer;
+	/** Retransmission timer */
+	struct retry_timer timer;
+};
+
+/**
+ * Close NTP client
+ *
+ * @v ntp		NTP client
+ * @v rc		Reason for close
+ */
+static void ntp_close ( struct ntp_client *ntp, int rc ) {
+
+	/* Stop timer */
+	stop_timer ( &ntp->timer );
+
+	/* Shut down interfaces */
+	intf_shutdown ( &ntp->xfer, rc );
+	intf_shutdown ( &ntp->job, rc );
+}
+
+/**
+ * Send NTP request
+ *
+ * @v ntp		NTP client
+ * @ret rc		Return status code
+ */
+static int ntp_request ( struct ntp_client *ntp ) {
+	struct ntp_header hdr;
+	int rc;
+
+	DBGC ( ntp, "NTP %p sending request\n", ntp );
+
+	/* Construct header */
+	memset ( &hdr, 0, sizeof ( hdr ) );
+	hdr.flags = ( NTP_FL_LI_UNKNOWN | NTP_FL_VN_1 | NTP_FL_MODE_CLIENT );
+	hdr.transmit.seconds = htonl ( time ( NULL ) + NTP_EPOCH );
+	hdr.transmit.fraction = htonl ( NTP_FRACTION_MAGIC );
+
+	/* Send request */
+	if ( ( rc = xfer_deliver_raw ( &ntp->xfer, &hdr,
+				       sizeof ( hdr ) ) ) != 0 ) {
+		DBGC ( ntp, "NTP %p could not send request: %s\n",
+		       ntp, strerror ( rc ) );
+		return rc;
+	}
+
+	return 0;
+}
+
+/**
+ * Handle NTP response
+ *
+ * @v ntp		NTP client
+ * @v iobuf		I/O buffer
+ * @v meta		Data transfer metadata
+ * @ret rc		Return status code
+ */
+static int ntp_deliver ( struct ntp_client *ntp, struct io_buffer *iobuf,
+			 struct xfer_metadata *meta ) {
+	struct ntp_header *hdr;
+	struct sockaddr_tcpip *st_src;
+	int32_t delta;
+	int rc;
+
+	/* Check source port */
+	st_src = ( ( struct sockaddr_tcpip * ) meta->src );
+	if ( st_src->st_port != htons ( NTP_PORT ) ) {
+		DBGC ( ntp, "NTP %p received non-NTP packet:\n", ntp );
+		DBGC_HDA ( ntp, 0, iobuf->data, iob_len ( iobuf ) );
+		goto ignore;
+	}
+
+	/* Check packet length */
+	if ( iob_len ( iobuf ) < sizeof ( *hdr ) ) {
+		DBGC ( ntp, "NTP %p received malformed packet:\n", ntp );
+		DBGC_HDA ( ntp, 0, iobuf->data, iob_len ( iobuf ) );
+		goto ignore;
+	}
+	hdr = iobuf->data;
+
+	/* Check mode */
+	if ( ( hdr->flags & NTP_FL_MODE_MASK ) != NTP_FL_MODE_SERVER ) {
+		DBGC ( ntp, "NTP %p received non-server packet:\n", ntp );
+		DBGC_HDA ( ntp, 0, iobuf->data, iob_len ( iobuf ) );
+		goto ignore;
+	}
+
+	/* Check magic value */
+	if ( hdr->originate.fraction != htonl ( NTP_FRACTION_MAGIC ) ) {
+		DBGC ( ntp, "NTP %p received unrecognised packet:\n", ntp );
+		DBGC_HDA ( ntp, 0, iobuf->data, iob_len ( iobuf ) );
+		goto ignore;
+	}
+
+	/* Check for Kiss-o'-Death packets */
+	if ( ! hdr->stratum ) {
+		DBGC ( ntp, "NTP %p received kiss-o'-death:\n", ntp );
+		DBGC_HDA ( ntp, 0, iobuf->data, iob_len ( iobuf ) );
+		rc = -EPROTO;
+		goto close;
+	}
+
+	/* Calculate clock delta */
+	delta = ( ntohl ( hdr->receive.seconds ) -
+		  ntohl ( hdr->originate.seconds ) );
+	DBGC ( ntp, "NTP %p delta %d seconds\n", ntp, delta );
+
+	/* Adjust system clock */
+	time_adjust ( delta );
+
+	/* Success */
+	rc = 0;
+
+ close:
+	ntp_close ( ntp, rc );
+ ignore:
+	free_iob ( iobuf );
+	return 0;
+}
+
+/**
+ * Handle data transfer window change
+ *
+ * @v ntp		NTP client
+ */
+static void ntp_window_changed ( struct ntp_client *ntp ) {
+
+	/* Start timer to send initial request */
+	start_timer_nodelay ( &ntp->timer );
+}
+
+/** Data transfer interface operations */
+static struct interface_operation ntp_xfer_op[] = {
+	INTF_OP ( xfer_deliver, struct ntp_client *, ntp_deliver ),
+	INTF_OP ( xfer_window_changed, struct ntp_client *,
+		  ntp_window_changed ),
+	INTF_OP ( intf_close, struct ntp_client *, ntp_close ),
+};
+
+/** Data transfer interface descriptor */
+static struct interface_descriptor ntp_xfer_desc =
+	INTF_DESC_PASSTHRU ( struct ntp_client, xfer, ntp_xfer_op, job );
+
+/** Job control interface operations */
+static struct interface_operation ntp_job_op[] = {
+	INTF_OP ( intf_close, struct ntp_client *, ntp_close ),
+};
+
+/** Job control interface descriptor */
+static struct interface_descriptor ntp_job_desc =
+	INTF_DESC_PASSTHRU ( struct ntp_client, job, ntp_job_op, xfer );
+
+/**
+ * Handle NTP timer expiry
+ *
+ * @v timer		Retransmission timer
+ * @v fail		Failure indicator
+ */
+static void ntp_expired ( struct retry_timer *timer, int fail ) {
+	struct ntp_client *ntp =
+		container_of ( timer, struct ntp_client, timer );
+
+	/* Shut down client if we have failed */
+	if ( fail ) {
+		ntp_close ( ntp, -ETIMEDOUT );
+		return;
+	}
+
+	/* Otherwise, restart timer and (re)transmit request */
+	start_timer ( &ntp->timer );
+	ntp_request ( ntp );
+}
+
+/**
+ * Start NTP client
+ *
+ * @v job		Job control interface
+ * @v hostname		NTP server
+ * @ret rc		Return status code
+ */
+int start_ntp ( struct interface *job, const char *hostname ) {
+	struct ntp_client *ntp;
+	union {
+		struct sockaddr_tcpip st;
+		struct sockaddr sa;
+	} server;
+	int rc;
+
+	/* Allocate and initialise structure*/
+	ntp = zalloc ( sizeof ( *ntp ) );
+	if ( ! ntp ) {
+		rc = -ENOMEM;
+		goto err_alloc;
+	}
+	ref_init ( &ntp->refcnt, NULL );
+	intf_init ( &ntp->job, &ntp_job_desc, &ntp->refcnt );
+	intf_init ( &ntp->xfer, &ntp_xfer_desc, &ntp->refcnt );
+	timer_init ( &ntp->timer, ntp_expired, &ntp->refcnt );
+	set_timer_limits ( &ntp->timer, NTP_MIN_TIMEOUT, NTP_MAX_TIMEOUT );
+
+	/* Open socket */
+	memset ( &server, 0, sizeof ( server ) );
+	server.st.st_port = htons ( NTP_PORT );
+	if ( ( rc = xfer_open_named_socket ( &ntp->xfer, SOCK_DGRAM, &server.sa,
+					     hostname, NULL ) ) != 0 ) {
+		DBGC ( ntp, "NTP %p could not open socket: %s\n",
+		       ntp, strerror ( rc ) );
+		goto err_open;
+	}
+
+	/* Attach parent interface, mortalise self, and return */
+	intf_plug_plug ( &ntp->job, job );
+	ref_put ( &ntp->refcnt );
+	return 0;
+
+ err_open:
+	ntp_close ( ntp, rc );
+	ref_put ( &ntp->refcnt );
+ err_alloc:
+	return rc;
+}