1 files changed, 447 insertions, 0 deletions
diff --git a/contrib/syslinux-4.02/gpxe/src/net/dhcpopts.c b/contrib/syslinux-4.02/gpxe/src/net/dhcpopts.c
new file mode 100644
index 0000000..6482c62
--- /dev/null
+++ b/contrib/syslinux-4.02/gpxe/src/net/dhcpopts.c
@@ -0,0 +1,447 @@
+/*
+ * Copyright (C) 2008 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 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <gpxe/dhcp.h>
+#include <gpxe/dhcpopts.h>
+
+/** @file
+ *
+ * DHCP options
+ *
+ */
+
+/**
+ * Obtain printable version of a DHCP option tag
+ *
+ * @v tag		DHCP option tag
+ * @ret name		String representation of the tag
+ *
+ */
+static inline char * dhcp_tag_name ( unsigned int tag ) {
+	static char name[8];
+
+	if ( DHCP_IS_ENCAP_OPT ( tag ) ) {
+		snprintf ( name, sizeof ( name ), "%d.%d",
+			   DHCP_ENCAPSULATOR ( tag ),
+			   DHCP_ENCAPSULATED ( tag ) );
+	} else {
+		snprintf ( name, sizeof ( name ), "%d", tag );
+	}
+	return name;
+}
+
+/**
+ * Get pointer to DHCP option
+ *
+ * @v options		DHCP options block
+ * @v offset		Offset within options block
+ * @ret option		DHCP option
+ */
+static inline __attribute__ (( always_inline )) struct dhcp_option *
+dhcp_option ( struct dhcp_options *options, unsigned int offset ) {
+	return ( ( struct dhcp_option * ) ( options->data + offset ) );
+}
+
+/**
+ * Get offset of a DHCP option
+ *
+ * @v options		DHCP options block
+ * @v option		DHCP option
+ * @ret offset		Offset within options block
+ */
+static inline __attribute__ (( always_inline )) int
+dhcp_option_offset ( struct dhcp_options *options,
+		     struct dhcp_option *option ) {
+	return ( ( ( void * ) option ) - options->data );
+}
+
+/**
+ * Calculate length of any DHCP option
+ *
+ * @v option		DHCP option
+ * @ret len		Length (including tag and length field)
+ */
+static unsigned int dhcp_option_len ( struct dhcp_option *option ) {
+	if ( ( option->tag == DHCP_END ) || ( option->tag == DHCP_PAD ) ) {
+		return 1;
+	} else {
+		return ( option->len + DHCP_OPTION_HEADER_LEN );
+	}
+}
+
+/**
+ * Find DHCP option within DHCP options block, and its encapsulator (if any)
+ *
+ * @v options		DHCP options block
+ * @v tag		DHCP option tag to search for
+ * @ret encap_offset	Offset of encapsulating DHCP option
+ * @ret offset		Offset of DHCP option, or negative error
+ *
+ * Searches for the DHCP option matching the specified tag within the
+ * DHCP option block.  Encapsulated options may be searched for by
+ * using DHCP_ENCAP_OPT() to construct the tag value.
+ *
+ * If the option is encapsulated, and @c encap_offset is non-NULL, it
+ * will be filled in with the offset of the encapsulating option.
+ *
+ * This routine is designed to be paranoid.  It does not assume that
+ * the option data is well-formatted, and so must guard against flaws
+ * such as options missing a @c DHCP_END terminator, or options whose
+ * length would take them beyond the end of the data block.
+ */
+static int find_dhcp_option_with_encap ( struct dhcp_options *options,
+					 unsigned int tag,
+					 int *encap_offset ) {
+	unsigned int original_tag __attribute__ (( unused )) = tag;
+	struct dhcp_option *option;
+	int offset = 0;
+	ssize_t remaining = options->len;
+	unsigned int option_len;
+
+	/* Sanity check */
+	if ( tag == DHCP_PAD )
+		return -ENOENT;
+
+	/* Search for option */
+	while ( remaining ) {
+		/* Calculate length of this option.  Abort processing
+		 * if the length is malformed (i.e. takes us beyond
+		 * the end of the data block).
+		 */
+		option = dhcp_option ( options, offset );
+		option_len = dhcp_option_len ( option );
+		remaining -= option_len;
+		if ( remaining < 0 )
+			break;
+		/* Check for explicit end marker */
+		if ( option->tag == DHCP_END ) {
+			if ( tag == DHCP_END )
+				/* Special case where the caller is interested
+				 * in whether we have this marker or not.
+				 */
+				return offset;
+			else
+				break;
+		}
+		/* Check for matching tag */
+		if ( option->tag == tag ) {
+			DBGC ( options, "DHCPOPT %p found %s (length %d)\n",
+			       options, dhcp_tag_name ( original_tag ),
+			       option_len );
+			return offset;
+		}
+		/* Check for start of matching encapsulation block */
+		if ( DHCP_IS_ENCAP_OPT ( tag ) &&
+		     ( option->tag == DHCP_ENCAPSULATOR ( tag ) ) ) {
+			if ( encap_offset )
+				*encap_offset = offset;
+			/* Continue search within encapsulated option block */
+			tag = DHCP_ENCAPSULATED ( tag );
+			remaining = option_len;
+			offset += DHCP_OPTION_HEADER_LEN;
+			continue;
+		}
+		offset += option_len;
+	}
+
+	return -ENOENT;
+}
+
+/**
+ * Resize a DHCP option
+ *
+ * @v options		DHCP option block
+ * @v offset		Offset of option to resize
+ * @v encap_offset	Offset of encapsulating offset (or -ve for none)
+ * @v old_len		Old length (including header)
+ * @v new_len		New length (including header)
+ * @v can_realloc	Can reallocate options data if necessary
+ * @ret rc		Return status code
+ */
+static int resize_dhcp_option ( struct dhcp_options *options,
+				int offset, int encap_offset,
+				size_t old_len, size_t new_len,
+				int can_realloc ) {
+	struct dhcp_option *encapsulator;
+	struct dhcp_option *option;
+	ssize_t delta = ( new_len - old_len );
+	size_t new_options_len;
+	size_t new_encapsulator_len;
+	void *new_data;
+	void *source;
+	void *dest;
+	void *end;
+
+	/* Check for sufficient space, and update length fields */
+	if ( new_len > DHCP_MAX_LEN ) {
+		DBGC ( options, "DHCPOPT %p overlength option\n", options );
+		return -ENOSPC;
+	}
+	new_options_len = ( options->len + delta );
+	if ( new_options_len > options->max_len ) {
+		/* Reallocate options block if allowed to do so. */
+		if ( can_realloc ) {
+			new_data = realloc ( options->data, new_options_len );
+			if ( ! new_data ) {
+				DBGC ( options, "DHCPOPT %p could not "
+				       "reallocate to %zd bytes\n", options,
+				       new_options_len );
+				return -ENOMEM;
+			}
+			options->data = new_data;
+			options->max_len = new_options_len;
+		} else {
+			DBGC ( options, "DHCPOPT %p out of space\n", options );
+			return -ENOMEM;
+		}
+	}
+	if ( encap_offset >= 0 ) {
+		encapsulator = dhcp_option ( options, encap_offset );
+		new_encapsulator_len = ( encapsulator->len + delta );
+		if ( new_encapsulator_len > DHCP_MAX_LEN ) {
+			DBGC ( options, "DHCPOPT %p overlength encapsulator\n",
+			       options );
+			return -ENOSPC;
+		}
+		encapsulator->len = new_encapsulator_len;
+	}
+	options->len = new_options_len;
+
+	/* Move remainder of option data */
+	option = dhcp_option ( options, offset );
+	source = ( ( ( void * ) option ) + old_len );
+	dest = ( ( ( void * ) option ) + new_len );
+	end = ( options->data + options->max_len );
+	memmove ( dest, source, ( end - dest ) );
+
+	return 0;
+}
+
+/**
+ * Set value of DHCP option
+ *
+ * @v options		DHCP option block
+ * @v tag		DHCP option tag
+ * @v data		New value for DHCP option
+ * @v len		Length of value, in bytes
+ * @v can_realloc	Can reallocate options data if necessary
+ * @ret offset		Offset of DHCP option, or negative error
+ *
+ * Sets the value of a DHCP option within the options block.  The
+ * option may or may not already exist.  Encapsulators will be created
+ * (and deleted) as necessary.
+ *
+ * This call may fail due to insufficient space in the options block.
+ * If it does fail, and the option existed previously, the option will
+ * be left with its original value.
+ */
+static int set_dhcp_option ( struct dhcp_options *options, unsigned int tag,
+			     const void *data, size_t len,
+			     int can_realloc ) {
+	static const uint8_t empty_encapsulator[] = { DHCP_END };
+	int offset;
+	int encap_offset = -1;
+	int creation_offset;
+	struct dhcp_option *option;
+	unsigned int encap_tag = DHCP_ENCAPSULATOR ( tag );
+	size_t old_len = 0;
+	size_t new_len = ( len ? ( len + DHCP_OPTION_HEADER_LEN ) : 0 );
+	int rc;
+
+	/* Sanity check */
+	if ( tag == DHCP_PAD )
+		return -ENOTTY;
+
+	creation_offset = find_dhcp_option_with_encap ( options, DHCP_END,
+							NULL );
+	if ( creation_offset < 0 )
+		creation_offset = options->len;
+	/* Find old instance of this option, if any */
+	offset = find_dhcp_option_with_encap ( options, tag, &encap_offset );
+	if ( offset >= 0 ) {
+		old_len = dhcp_option_len ( dhcp_option ( options, offset ) );
+		DBGC ( options, "DHCPOPT %p resizing %s from %zd to %zd\n",
+		       options, dhcp_tag_name ( tag ), old_len, new_len );
+	} else {
+		DBGC ( options, "DHCPOPT %p creating %s (length %zd)\n",
+		       options, dhcp_tag_name ( tag ), new_len );
+	}
+
+	/* Ensure that encapsulator exists, if required */
+	if ( encap_tag ) {
+		if ( encap_offset < 0 )
+			encap_offset = set_dhcp_option ( options, encap_tag,
+							 empty_encapsulator, 1,
+							 can_realloc );
+		if ( encap_offset < 0 )
+			return encap_offset;
+		creation_offset = ( encap_offset + DHCP_OPTION_HEADER_LEN );
+	}
+
+	/* Create new option if necessary */
+	if ( offset < 0 )
+		offset = creation_offset;
+
+	/* Resize option to fit new data */
+	if ( ( rc = resize_dhcp_option ( options, offset, encap_offset,
+					 old_len, new_len,
+					 can_realloc ) ) != 0 )
+		return rc;
+
+	/* Copy new data into option, if applicable */
+	if ( len ) {
+		option = dhcp_option ( options, offset );
+		option->tag = tag;
+		option->len = len;
+		memcpy ( &option->data, data, len );
+	}
+
+	/* Delete encapsulator if there's nothing else left in it */
+	if ( encap_offset >= 0 ) {
+		option = dhcp_option ( options, encap_offset );
+		if ( option->len <= 1 )
+			set_dhcp_option ( options, encap_tag, NULL, 0, 0 );
+	}
+
+	return offset;
+}
+
+/**
+ * Store value of DHCP option setting
+ *
+ * @v options		DHCP option block
+ * @v tag		Setting tag number
+ * @v data		Setting data, or NULL to clear setting
+ * @v len		Length of setting data
+ * @ret rc		Return status code
+ */
+int dhcpopt_store ( struct dhcp_options *options, unsigned int tag,
+		    const void *data, size_t len ) {
+	int offset;
+
+	offset = set_dhcp_option ( options, tag, data, len, 0 );
+	if ( offset < 0 )
+		return offset;
+	return 0;
+}
+
+/**
+ * Store value of DHCP option setting, extending options block if necessary
+ *
+ * @v options		DHCP option block
+ * @v tag		Setting tag number
+ * @v data		Setting data, or NULL to clear setting
+ * @v len		Length of setting data
+ * @ret rc		Return status code
+ */
+int dhcpopt_extensible_store ( struct dhcp_options *options, unsigned int tag,
+			       const void *data, size_t len ) {
+	int offset;
+
+	offset = set_dhcp_option ( options, tag, data, len, 1 );
+	if ( offset < 0 )
+		return offset;
+	return 0;
+}
+
+/**
+ * Fetch value of DHCP option setting
+ *
+ * @v options		DHCP option block
+ * @v tag		Setting tag number
+ * @v data		Buffer to fill with setting data
+ * @v len		Length of buffer
+ * @ret len		Length of setting data, or negative error
+ */
+int dhcpopt_fetch ( struct dhcp_options *options, unsigned int tag,
+		    void *data, size_t len ) {
+	int offset;
+	struct dhcp_option *option;
+	size_t option_len;
+
+	offset = find_dhcp_option_with_encap ( options, tag, NULL );
+	if ( offset < 0 )
+		return offset;
+
+	option = dhcp_option ( options, offset );
+	option_len = option->len;
+	if ( len > option_len )
+		len = option_len;
+	memcpy ( data, option->data, len );
+
+	return option_len;
+}
+
+/**
+ * Recalculate length of DHCP options block
+ *
+ * @v options		Uninitialised DHCP option block
+ *
+ * The "used length" field will be updated based on scanning through
+ * the block to find the end of the options.
+ */
+static void dhcpopt_update_len ( struct dhcp_options *options ) {
+	struct dhcp_option *option;
+	int offset = 0;
+	ssize_t remaining = options->max_len;
+	unsigned int option_len;
+
+	/* Find last non-pad option */
+	options->len = 0;
+	while ( remaining ) {
+		option = dhcp_option ( options, offset );
+		option_len = dhcp_option_len ( option );
+		remaining -= option_len;
+		if ( remaining < 0 )
+			break;
+		offset += option_len;
+		if ( option->tag != DHCP_PAD )
+			options->len = offset;
+	}
+}
+
+/**
+ * Initialise prepopulated block of DHCP options
+ *
+ * @v options		Uninitialised DHCP option block
+ * @v data		Memory for DHCP option data
+ * @v max_len		Length of memory for DHCP option data
+ *
+ * The memory content must already be filled with valid DHCP options.
+ * A zeroed block counts as a block of valid DHCP options.
+ */
+void dhcpopt_init ( struct dhcp_options *options, void *data,
+		    size_t max_len ) {
+
+	/* Fill in fields */
+	options->data = data;
+	options->max_len = max_len;
+
+	/* Update length */
+	dhcpopt_update_len ( options );
+
+	DBGC ( options, "DHCPOPT %p created (data %p len %#zx max_len %#zx)\n",
+	       options, options->data, options->len, options->max_len );
+}