[Settings] Remove assumption that all settings have DHCP tag values

Allow for settings to be described by something other than a DHCP option
tag if desirable.  Currently used only for the MAC address setting.

Separate out fake DHCP packet creation code from dhcp.c to fakedhcp.c.

Remove notion of settings from dhcppkt.c.

Rationalise dhcp.c to use settings API only for final registration of the
DHCP options, rather than using {store,fetch}_setting throughout.

src/arch/i386/image/nbi.c

@@ -8,8 +8,7 @@
 #include <gpxe/segment.h>
 #include <gpxe/init.h>
 #include <gpxe/netdevice.h>
-#include <gpxe/dhcp.h>
-#include <gpxe/dhcppkt.h>
+#include <gpxe/fakedhcp.h>
 #include <gpxe/image.h>
 #include <gpxe/features.h>
 
@@ -400,8 +399,8 @@ static int nbi_prepare_dhcp ( struct image *image ) {
 		return -ENODEV;
 	}
 
-	if ( ( rc = create_dhcpack ( boot_netdev, basemem_packet,
-				     sizeof ( basemem_packet ) ) ) != 0 ) {
+	if ( ( rc = create_fakedhcpack ( boot_netdev, basemem_packet,
+					 sizeof ( basemem_packet ) ) ) != 0 ) {
 		DBGC ( image, "NBI %p failed to build DHCP packet\n", image );
 		return rc;
 	}

src/core/ibft.c

@@ -123,15 +123,16 @@ static void ibft_set_ipaddr ( struct ibft_ipaddr *ipaddr, struct in_addr in ) {
 }
 
 /**
- * Fill in an IP address within iBFT from DHCP option
+ * Fill in an IP address within iBFT from configuration setting
  *
  * @v ipaddr		IP address field
+ * @v setting		Configuration setting
  * @v tag		DHCP option tag
  */
 static void ibft_set_ipaddr_option ( struct ibft_ipaddr *ipaddr,
-				     unsigned int tag ) {
+				     struct setting *setting ) {
 	struct in_addr in = { 0 };
-	fetch_ipv4_setting ( NULL, tag, &in );
+	fetch_ipv4_setting ( NULL, setting, &in );
 	ibft_set_ipaddr ( ipaddr, in );
 }
 
@@ -182,21 +183,21 @@ static int ibft_set_string ( struct ibft_string_block *strings,
 }
 
 /**
- * Fill in a string field within iBFT from DHCP option
+ * Fill in a string field within iBFT from configuration setting
  *
  * @v strings		iBFT string block descriptor
  * @v string		String field
- * @v tag		DHCP option tag
+ * @v setting		Configuration setting
  * @ret rc		Return status code
  */
 static int ibft_set_string_option ( struct ibft_string_block *strings,
 				    struct ibft_string *string,
-				    unsigned int tag ) {
+				    struct setting *setting ) {
 	int len;
 	char *dest;
 	int rc;
 
-	len = fetch_setting_len ( NULL, tag );
+	len = fetch_setting_len ( NULL, setting );
 	if ( len < 0 ) {
 		string->offset = 0;
 		string->length = 0;
@@ -206,7 +207,7 @@ static int ibft_set_string_option ( struct ibft_string_block *strings,
 	if ( ( rc = ibft_alloc_string ( strings, string, len ) ) != 0 )
 		return rc;
 	dest = ( ( ( char * ) strings->table ) + string->offset );
-	fetch_string_setting ( NULL, tag, dest, ( len + 1 ) );
+	fetch_string_setting ( NULL, setting, dest, ( len + 1 ) );
 	return 0;
 }
 
@@ -226,15 +227,15 @@ static int ibft_fill_nic ( struct ibft_nic *nic,
 	int rc;
 
 	/* Extract values from DHCP configuration */
-	ibft_set_ipaddr_option ( &nic->ip_address, DHCP_EB_YIADDR );
-	ibft_set_ipaddr_option ( &nic->gateway, DHCP_ROUTERS );
-	ibft_set_ipaddr_option ( &nic->dns[0], DHCP_DNS_SERVERS );
+	ibft_set_ipaddr_option ( &nic->ip_address, &ip_setting );
+	ibft_set_ipaddr_option ( &nic->gateway, &gateway_setting );
+	ibft_set_ipaddr_option ( &nic->dns[0], &dns_setting );
 	if ( ( rc = ibft_set_string_option ( strings, &nic->hostname,
-					     DHCP_HOST_NAME ) ) != 0 )
+					     &hostname_setting ) ) != 0 )
 		return rc;
 
 	/* Derive subnet mask prefix from subnet mask */
-	fetch_ipv4_setting ( NULL, DHCP_SUBNET_MASK, &netmask_addr );
+	fetch_ipv4_setting ( NULL, &netmask_setting, &netmask_addr );
 	while ( netmask_addr.s_addr ) {
 		if ( netmask_addr.s_addr & 0x1 )
 			netmask_count++;

src/core/nvo.c

@@ -138,19 +138,20 @@ static void nvo_init_dhcpopts ( struct nvo_block *nvo ) {
  * Store value of NVO setting
  *
  * @v settings		Settings block
- * @v tag		Setting tag number
+ * @v setting		Setting to store
  * @v data		Setting data, or NULL to clear setting
  * @v len		Length of setting data
  * @ret rc		Return status code
  */
-static int nvo_store ( struct settings *settings, unsigned int tag,
+static int nvo_store ( struct settings *settings, struct setting *setting,
 		       const void *data, size_t len ) {
 	struct nvo_block *nvo =
 		container_of ( settings, struct nvo_block, settings );
 	int rc;
 
 	/* Update stored options */
-	if ( ( rc = dhcpopt_store ( &nvo->dhcpopts, tag, data, len ) ) != 0 ) {
+	if ( ( rc = dhcpopt_store ( &nvo->dhcpopts, setting->tag,
+				    data, len ) ) != 0 ) {
 		DBGC ( nvo, "NVO %p could not store %zd bytes: %s\n",
 		       nvo, len, strerror ( rc ) );
 		return rc;
@@ -167,20 +168,20 @@ static int nvo_store ( struct settings *settings, unsigned int tag,
  * Fetch value of NVO setting
  *
  * @v settings		Settings block
- * @v tag		Setting tag number
+ * @v setting		Setting to fetch
  * @v data		Buffer to fill with setting data
  * @v len		Length of buffer
  * @ret len		Length of setting data, or negative error
  *
  * The actual length of the setting will be returned even if
  * the buffer was too small.
  */
-static int nvo_fetch ( struct settings *settings, unsigned int tag,
+static int nvo_fetch ( struct settings *settings, struct setting *setting,
 		       void *data, size_t len ) {
 	struct nvo_block *nvo =
 		container_of ( settings, struct nvo_block, settings );
 
-	return dhcpopt_fetch ( &nvo->dhcpopts, tag, data, len );
+	return dhcpopt_fetch ( &nvo->dhcpopts, setting->tag, data, len );
 }
 
 /** NVO settings operations */