net: dhcp6: Add DHCPv6 (DHCP for IPv6)

Adds DHCPv6 protocol to u-boot.

Allows for address assignement with DHCPv6 4-message exchange
(SOLICIT->ADVERTISE->REQUEST->REPLY).  Includes DHCPv6 options
required by RFC 8415.  Also adds DHCPv6 options required
for PXE boot.

Possible enhancements:
- Duplicate address detection on DHCPv6 assigned address
- IPv6 address assignement through SLAAC
- Sending/parsing other DHCPv6 options (NTP, DNS, etc...)

Signed-off-by: Sean Edmond <seanedmond@microsoft.com>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>

5 files changed, 989 insertions, 4 deletions

diff --git a/include/net.h b/include/net.h
index 399af5e064..181a6e3b13 100644
--- a/include/net.h
+++ b/include/net.h
@@ -484,6 +484,8 @@ extern char	net_hostname[32];	/* Our hostname */
 #ifdef CONFIG_NET
 extern char	net_root_path[CONFIG_BOOTP_MAX_ROOT_PATH_LEN];	/* Our root path */
 #endif
+/* Indicates whether the pxe path prefix / config file was specified in dhcp option */
+extern char *pxelinux_configfile;
 /** END OF BOOTP EXTENTIONS **/
 extern u8		net_ethaddr[ARP_HLEN];		/* Our ethernet address */
 extern u8		net_server_ethaddr[ARP_HLEN];	/* Boot server enet address */
@@ -504,8 +506,8 @@ extern ushort		net_native_vlan;	/* Our Native VLAN */
 extern int		net_restart_wrap;	/* Tried all network devices */
 
 enum proto_t {
-	BOOTP, RARP, ARP, TFTPGET, DHCP, PING, PING6, DNS, NFS, CDP, NETCONS,
-	SNTP, TFTPSRV, TFTPPUT, LINKLOCAL, FASTBOOT, WOL, UDP, NCSI, WGET
+	BOOTP, RARP, ARP, TFTPGET, DHCP, DHCP6, PING, PING6, DNS, NFS, CDP,
+	NETCONS, SNTP, TFTPSRV, TFTPPUT, LINKLOCAL, FASTBOOT, WOL, UDP, NCSI, WGET
 };
 
 extern char	net_boot_file_name[1024];/* Boot File name */
diff --git a/net/Makefile b/net/Makefile
index bea000b206..5968110170 100644
--- a/net/Makefile
+++ b/net/Makefile
@@ -22,6 +22,7 @@ obj-$(CONFIG_IPV6)     += net6.o
 obj-$(CONFIG_CMD_NFS)  += nfs.o
 obj-$(CONFIG_CMD_PING) += ping.o
 obj-$(CONFIG_CMD_PING6) += ping6.o
+obj-$(CONFIG_CMD_DHCP6) += dhcpv6.o
 obj-$(CONFIG_CMD_PCAP) += pcap.o
 obj-$(CONFIG_CMD_RARP) += rarp.o
 obj-$(CONFIG_CMD_SNTP) += sntp.o
diff --git a/net/dhcpv6.c b/net/dhcpv6.c
new file mode 100644
index 0000000000..0d1c600632
--- /dev/null
+++ b/net/dhcpv6.c
@@ -0,0 +1,719 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) Microsoft Corporation
+ * Author: Sean Edmond <seanedmond@microsoft.com>
+ *
+ */
+
+/* Simple DHCP6 network layer implementation. */
+
+#include <common.h>
+#include <net6.h>
+#include <malloc.h>
+#include <linux/delay.h>
+#include "net_rand.h"
+#include "dhcpv6.h"
+
+#define PORT_DHCP6_S	547	/* DHCP6 server UDP port */
+#define PORT_DHCP6_C	546	/* DHCP6 client UDP port */
+
+/* default timeout parameters (in ms) */
+#define SOL_MAX_DELAY_MS	1000
+#define SOL_TIMEOUT_MS		1000
+#define SOL_MAX_RT_MS		3600000
+#define REQ_TIMEOUT_MS		1000
+#define REQ_MAX_RT_MS		30000
+#define REQ_MAX_RC		10
+#define MAX_WAIT_TIME_MS	60000
+
+/* global variable to track any updates from DHCP6 server */
+int updated_sol_max_rt_ms = SOL_MAX_RT_MS;
+/* state machine parameters/variables */
+struct dhcp6_sm_params sm_params;
+
+static void dhcp6_state_machine(bool timeout, uchar *rx_pkt, unsigned int len);
+
+/* Handle DHCP received packets (set as UDP handler) */
+static void dhcp6_handler(uchar *pkt, unsigned int dest, struct in_addr sip,
+			  unsigned int src, unsigned int len)
+{
+	/* return if ports don't match DHCPv6 ports */
+	if (dest != PORT_DHCP6_C || src != PORT_DHCP6_S)
+		return;
+
+	dhcp6_state_machine(false, pkt, len);
+}
+
+/**
+ * dhcp6_add_option() - Adds DHCP6 option to a packet
+ * @option_id: The option ID to add (See DHCP6_OPTION_* definitions)
+ * @pkt: A pointer to the current write location of the TX packet
+ *
+ * Return: The number of bytes written into "*pkt"
+ */
+static int dhcp6_add_option(int option_id, uchar *pkt)
+{
+	struct dhcp6_option_duid_ll *duid_opt;
+	struct dhcp6_option_elapsed_time *elapsed_time_opt;
+	struct dhcp6_option_ia_ta *ia_ta_opt;
+	struct dhcp6_option_ia_na *ia_na_opt;
+	struct dhcp6_option_oro *oro_opt;
+	struct dhcp6_option_client_arch *client_arch_opt;
+	struct dhcp6_option_vendor_class *vendor_class_opt;
+	int opt_len;
+	long elapsed_time;
+	size_t vci_strlen;
+	int num_oro = 0;
+	int num_client_arch = 0;
+	int num_vc_data = 0;
+	struct dhcp6_option_hdr *dhcp_option = (struct dhcp6_option_hdr *)pkt;
+	uchar *dhcp_option_start = pkt + sizeof(struct dhcp6_option_hdr);
+
+	dhcp_option->option_id = htons(option_id);
+
+	switch (option_id) {
+	case DHCP6_OPTION_CLIENTID:
+		/* Only support for DUID-LL in Client ID option for now */
+		duid_opt = (struct dhcp6_option_duid_ll *)dhcp_option_start;
+		duid_opt->duid_type = htons(DUID_TYPE_LL);
+		duid_opt->hw_type = htons(DUID_HW_TYPE_ENET);
+		memcpy(duid_opt->ll_addr, net_ethaddr, ETH_ALEN);
+		opt_len = sizeof(struct dhcp6_option_duid_ll) + ETH_ALEN;
+
+		/* Save DUID for comparison later */
+		memcpy(sm_params.duid, duid_opt, opt_len);
+		break;
+	case DHCP6_OPTION_ELAPSED_TIME:
+		/* calculate elapsed time in 1/100th of a second */
+		elapsed_time = (sm_params.dhcp6_retry_ms -
+			sm_params.dhcp6_start_ms) / 10;
+		if (elapsed_time > 0xFFFF)
+			elapsed_time = 0xFFFF;
+
+		elapsed_time_opt = (struct dhcp6_option_elapsed_time *)dhcp_option_start;
+		elapsed_time_opt->elapsed_time = htons(elapsed_time);
+
+		opt_len = sizeof(struct dhcp6_option_elapsed_time);
+		break;
+	case DHCP6_OPTION_IA_TA:
+		ia_ta_opt = (struct dhcp6_option_ia_ta *)dhcp_option_start;
+		ia_ta_opt->iaid = htonl(sm_params.ia_id);
+
+		opt_len = sizeof(struct dhcp6_option_ia_ta);
+		break;
+	case DHCP6_OPTION_IA_NA:
+		ia_na_opt = (struct dhcp6_option_ia_na *)dhcp_option_start;
+		ia_na_opt->iaid = htonl(sm_params.ia_id);
+		/* In a message sent by a client to a server,
+		 * the T1 and T2 fields SHOULD be set to 0
+		 */
+		ia_na_opt->t1 = 0;
+		ia_na_opt->t2 = 0;
+
+		opt_len = sizeof(struct dhcp6_option_ia_na);
+		break;
+	case DHCP6_OPTION_ORO:
+		oro_opt = (struct dhcp6_option_oro *)dhcp_option_start;
+		oro_opt->req_option_code[num_oro++] = htons(DHCP6_OPTION_OPT_BOOTFILE_URL);
+		oro_opt->req_option_code[num_oro++] = htons(DHCP6_OPTION_SOL_MAX_RT);
+		if (IS_ENABLED(CONFIG_DHCP6_PXE_DHCP_OPTION)) {
+			oro_opt->req_option_code[num_oro++] =
+				htons(DHCP6_OPTION_OPT_BOOTFILE_PARAM);
+		}
+
+		opt_len = sizeof(__be16) * num_oro;
+		break;
+	case DHCP6_OPTION_CLIENT_ARCH_TYPE:
+		client_arch_opt = (struct dhcp6_option_client_arch *)dhcp_option_start;
+		client_arch_opt->arch_type[num_client_arch++] = htons(CONFIG_DHCP6_PXE_CLIENTARCH);
+
+		opt_len = sizeof(__be16) * num_client_arch;
+		break;
+	case DHCP6_OPTION_VENDOR_CLASS:
+		vendor_class_opt = (struct dhcp6_option_vendor_class *)dhcp_option_start;
+		vendor_class_opt->enterprise_number = htonl(CONFIG_DHCP6_ENTERPRISE_ID);
+
+		vci_strlen = strlen(DHCP6_VCI_STRING);
+		vendor_class_opt->vendor_class_data[num_vc_data].vendor_class_len =
+			htons(vci_strlen);
+		memcpy(vendor_class_opt->vendor_class_data[num_vc_data].opaque_data,
+		       DHCP6_VCI_STRING, vci_strlen);
+		num_vc_data++;
+
+		opt_len = sizeof(struct dhcp6_option_vendor_class) +
+			  sizeof(struct vendor_class_data) * num_vc_data +
+			  vci_strlen;
+		break;
+	case DHCP6_OPTION_NII:
+		dhcp_option_start[0] = 1;
+		dhcp_option_start[1] = 0;
+		dhcp_option_start[2] = 0;
+
+		opt_len = 3;
+		break;
+	default:
+		printf("***Warning unknown DHCP6 option %d.  Not adding to message\n", option_id);
+		return 0;
+	}
+	dhcp_option->option_len = htons(opt_len);
+
+	return opt_len + sizeof(struct dhcp6_option_hdr);
+}
+
+/**
+ * dhcp6_send_solicit_packet() - Send a SOLICIT packet
+ *
+ * Implements RFC 8415:
+ *    - 16.2. Solicit Message
+ *    - 18.2.1. Creation and Transmission of Solicit Messages
+ *
+ * Adds DHCP6 header and DHCP6 options.  Sends the UDP packet
+ * and sets the UDP handler.
+ */
+static void dhcp6_send_solicit_packet(void)
+{
+	struct in6_addr dhcp_bcast_ip6;
+	int len = 0;
+	uchar *pkt;
+	uchar *dhcp_pkt_start_ptr;
+	struct dhcp6_hdr *dhcp_hdr;
+
+	pkt = net_tx_packet + net_eth_hdr_size() + IP6_HDR_SIZE + UDP_HDR_SIZE;
+	dhcp_pkt_start_ptr = pkt;
+
+	/* Add the DHCP6 header */
+	dhcp_hdr = (struct dhcp6_hdr *)pkt;
+	dhcp_hdr->msg_type = DHCP6_MSG_SOLICIT;
+	dhcp_hdr->trans_id = htons(sm_params.trans_id);
+	pkt += sizeof(struct dhcp6_hdr);
+
+	/* Add the options */
+	pkt += dhcp6_add_option(DHCP6_OPTION_CLIENTID, pkt);
+	pkt += dhcp6_add_option(DHCP6_OPTION_ELAPSED_TIME, pkt);
+	pkt += dhcp6_add_option(DHCP6_OPTION_IA_NA, pkt);
+	pkt += dhcp6_add_option(DHCP6_OPTION_ORO, pkt);
+	if (CONFIG_DHCP6_PXE_CLIENTARCH != 0xFF)
+		pkt += dhcp6_add_option(DHCP6_OPTION_CLIENT_ARCH_TYPE, pkt);
+	pkt += dhcp6_add_option(DHCP6_OPTION_VENDOR_CLASS, pkt);
+	pkt += dhcp6_add_option(DHCP6_OPTION_NII, pkt);
+
+	/* calculate packet length */
+	len = pkt - dhcp_pkt_start_ptr;
+
+	/* send UDP packet to DHCP6 multicast address */
+	string_to_ip6(DHCP6_MULTICAST_ADDR, sizeof(DHCP6_MULTICAST_ADDR), &dhcp_bcast_ip6);
+	net_set_udp_handler(dhcp6_handler);
+	net_send_udp_packet6((uchar *)net_bcast_ethaddr, &dhcp_bcast_ip6,
+			     PORT_DHCP6_S, PORT_DHCP6_C, len);
+}
+
+/**
+ * dhcp6_send_request_packet() - Send a REQUEST packet
+ *
+ *  * Implements RFC 8415:
+ *    - 16.4. Request Message
+ *    - 18.2.2. Creation and Transmission of Request Messages
+ *
+ * Adds DHCP6 header and DHCP6 options.  Sends the UDP packet
+ * and sets the UDP handler.
+ */
+static void dhcp6_send_request_packet(void)
+{
+	struct in6_addr dhcp_bcast_ip6;
+	int len = 0;
+	uchar *pkt;
+	uchar *dhcp_pkt_start_ptr;
+	struct dhcp6_hdr *dhcp_hdr;
+
+	pkt = net_tx_packet + net_eth_hdr_size() + IP6_HDR_SIZE + UDP_HDR_SIZE;
+	dhcp_pkt_start_ptr = pkt;
+
+	/* Add the DHCP6 header */
+	dhcp_hdr = (struct dhcp6_hdr *)pkt;
+	dhcp_hdr->msg_type = DHCP6_MSG_REQUEST;
+	dhcp_hdr->trans_id = htons(sm_params.trans_id);
+	pkt += sizeof(struct dhcp6_hdr);
+
+	/* add the options */
+	pkt += dhcp6_add_option(DHCP6_OPTION_CLIENTID, pkt);
+	pkt += dhcp6_add_option(DHCP6_OPTION_ELAPSED_TIME, pkt);
+	pkt += dhcp6_add_option(DHCP6_OPTION_IA_NA, pkt);
+	pkt += dhcp6_add_option(DHCP6_OPTION_ORO, pkt);
+	/* copy received IA_TA/IA_NA into the REQUEST packet */
+	if (sm_params.server_uid.uid_ptr) {
+		memcpy(pkt, sm_params.server_uid.uid_ptr, sm_params.server_uid.uid_size);
+		pkt += sm_params.server_uid.uid_size;
+	}
+	if (CONFIG_DHCP6_PXE_CLIENTARCH != 0xFF)
+		pkt += dhcp6_add_option(DHCP6_OPTION_CLIENT_ARCH_TYPE, pkt);
+	pkt += dhcp6_add_option(DHCP6_OPTION_VENDOR_CLASS, pkt);
+	pkt += dhcp6_add_option(DHCP6_OPTION_NII, pkt);
+
+	/* calculate packet length */
+	len = pkt - dhcp_pkt_start_ptr;
+
+	/* send UDP packet to DHCP6 multicast address */
+	string_to_ip6(DHCP6_MULTICAST_ADDR, strlen(DHCP6_MULTICAST_ADDR), &dhcp_bcast_ip6);
+	net_set_udp_handler(dhcp6_handler);
+	net_send_udp_packet6((uchar *)net_bcast_ethaddr, &dhcp_bcast_ip6,
+			     PORT_DHCP6_S, PORT_DHCP6_C, len);
+}
+
+static void dhcp6_parse_ia_options(struct dhcp6_option_hdr *ia_ptr, uchar *ia_option_ptr)
+{
+	struct dhcp6_option_hdr *ia_option_hdr;
+
+	ia_option_hdr = (struct dhcp6_option_hdr *)ia_option_ptr;
+
+	/* Search for options encapsulated in IA_NA/IA_TA (DHCP6_OPTION_IAADDR
+	 * or DHCP6_OPTION_STATUS_CODE)
+	 */
+	while (ia_option_ptr < ((uchar *)ia_ptr + ntohs(ia_ptr->option_len))) {
+		switch (ntohs(ia_option_hdr->option_id)) {
+		case DHCP6_OPTION_IAADDR:
+			sm_params.rx_status.ia_addr_found = true;
+			net_copy_ip6(&sm_params.rx_status.ia_addr_ipv6,
+				     (ia_option_ptr + sizeof(struct dhcp6_hdr)));
+			debug("DHCP6_OPTION_IAADDR FOUND\n");
+			break;
+		case DHCP6_OPTION_STATUS_CODE:
+			sm_params.rx_status.ia_status_code =
+				ntohs(*((u16 *)(ia_option_ptr + sizeof(struct dhcp6_hdr))));
+			printf("ERROR : IA STATUS %d\n", sm_params.rx_status.ia_status_code);
+			break;
+		default:
+			debug("Unknown Option in IA, skipping\n");
+			break;
+		}
+
+		ia_option_ptr += ntohs(((struct dhcp6_option_hdr *)ia_option_ptr)->option_len);
+	}
+}
+
+/**
+ * dhcp6_parse_options() - Parse the DHCP6 options
+ *
+ * @rx_pkt: pointer to beginning of received DHCP6 packet
+ * @len: Total length of the DHCP6 packet
+ *
+ * Parses the DHCP options from a received DHCP packet. Perform error checking
+ * on the options received.  Any relevant status is available in:
+ * "sm_params.rx_status"
+ *
+ */
+static void dhcp6_parse_options(uchar *rx_pkt, unsigned int len)
+{
+	uchar *option_ptr;
+	int sol_max_rt_sec, option_len;
+	char *s, *e;
+	struct dhcp6_option_hdr *option_hdr;
+
+	memset(&sm_params.rx_status, 0, sizeof(struct dhcp6_rx_pkt_status));
+
+	option_hdr = (struct dhcp6_option_hdr *)(rx_pkt + sizeof(struct dhcp6_hdr));
+	/* check that required options exist */
+	while (option_hdr < (struct dhcp6_option_hdr *)(rx_pkt + len)) {
+		option_ptr = ((uchar *)option_hdr) + sizeof(struct dhcp6_hdr);
+		option_len = ntohs(option_hdr->option_len);
+
+		switch (ntohs(option_hdr->option_id)) {
+		case DHCP6_OPTION_CLIENTID:
+			if (memcmp(option_ptr, sm_params.duid, option_len)
+			    != 0) {
+				debug("CLIENT ID DOESN'T MATCH\n");
+			} else {
+				debug("CLIENT ID FOUND and MATCHES\n");
+				sm_params.rx_status.client_id_match = true;
+			}
+			break;
+		case DHCP6_OPTION_SERVERID:
+			sm_params.rx_status.server_id_found = true;
+			sm_params.rx_status.server_uid_ptr = (uchar *)option_hdr;
+			sm_params.rx_status.server_uid_size = option_len +
+							      sizeof(struct dhcp6_option_hdr);
+			debug("SERVER ID FOUND\n");
+			break;
+		case DHCP6_OPTION_IA_TA:
+		case DHCP6_OPTION_IA_NA:
+			/* check the IA_ID */
+			if (*((u32 *)option_ptr) !=  htonl(sm_params.ia_id)) {
+				debug("IA_ID mismatch 0x%08x 0x%08x\n",
+				      *((u32 *)option_ptr), htonl(sm_params.ia_id));
+				break;
+			}
+
+			if (ntohs(option_hdr->option_id) == DHCP6_OPTION_IA_NA) {
+				/* skip past IA_ID/T1/T2 */
+				option_ptr += 3 * sizeof(u32);
+			} else if (ntohs(option_hdr->option_id) == DHCP6_OPTION_IA_TA) {
+				/* skip past IA_ID */
+				option_ptr += sizeof(u32);
+			}
+			/* parse the IA_NA/IA_TA encapsulated options */
+			dhcp6_parse_ia_options(option_hdr, option_ptr);
+			break;
+		case DHCP6_OPTION_STATUS_CODE:
+			debug("DHCP6_OPTION_STATUS_CODE FOUND\n");
+			sm_params.rx_status.status_code = ntohs(*((u16 *)option_ptr));
+			debug("DHCP6 top-level status code %d\n", sm_params.rx_status.status_code);
+			debug("DHCP6 status message: %.*s\n", len, option_ptr + 2);
+			break;
+		case DHCP6_OPTION_SOL_MAX_RT:
+			debug("DHCP6_OPTION_SOL_MAX_RT FOUND\n");
+			sol_max_rt_sec = ntohl(*((u32 *)option_ptr));
+
+			/* A DHCP client MUST ignore any SOL_MAX_RT option values that are less
+			 * than 60 or more than 86400
+			 */
+			if (sol_max_rt_sec >= 60 && sol_max_rt_sec <= 86400) {
+				updated_sol_max_rt_ms = sol_max_rt_sec * 1000;
+				if (sm_params.curr_state == DHCP6_SOLICIT)
+					sm_params.mrt_ms = updated_sol_max_rt_ms;
+			}
+			break;
+		case DHCP6_OPTION_OPT_BOOTFILE_URL:
+			debug("DHCP6_OPTION_OPT_BOOTFILE_URL FOUND\n");
+			copy_filename(net_boot_file_name, option_ptr, option_len + 1);
+			debug("net_boot_file_name: %s\n", net_boot_file_name);
+
+			/* copy server_ip6 (required for PXE) */
+			s = strchr(net_boot_file_name, '[');
+			e = strchr(net_boot_file_name, ']');
+			if (s && e && e > s)
+				string_to_ip6(s + 1, e - s - 1, &net_server_ip6);
+			break;
+		case DHCP6_OPTION_OPT_BOOTFILE_PARAM:
+			if (IS_ENABLED(CONFIG_DHCP6_PXE_DHCP_OPTION)) {
+				debug("DHCP6_OPTION_OPT_BOOTFILE_PARAM FOUND\n");
+
+				if (pxelinux_configfile)
+					free(pxelinux_configfile);
+
+				pxelinux_configfile = (char *)malloc((option_len + 1) *
+						      sizeof(char));
+				if (pxelinux_configfile)
+					strlcpy(pxelinux_configfile, option_ptr, option_len + 1);
+				else
+					printf("Error: Failed to allocate pxelinux_configfile\n");
+
+				debug("PXE CONFIG FILE %s\n", pxelinux_configfile);
+			}
+			break;
+		case DHCP6_OPTION_PREFERENCE:
+			debug("DHCP6_OPTION_PREFERENCE FOUND\n");
+			sm_params.rx_status.preference = *option_ptr;
+			break;
+		default:
+			debug("Unknown Option ID: %d, skipping parsing\n",
+			      ntohs(option_hdr->option_id));
+			break;
+		}
+		/* Increment to next option header */
+		option_hdr = (struct dhcp6_option_hdr *)(((uchar *)option_hdr) +
+			     sizeof(struct dhcp6_option_hdr) + option_len);
+	}
+}
+
+/**
+ * dhcp6_check_advertise_packet() - Perform error checking on an expected
+ *                                  ADVERTISE packet.
+ *
+ * @rx_pkt: pointer to beginning of received DHCP6 packet
+ * @len: Total length of the DHCP6 packet
+ *
+ * Implements RFC 8415:
+ *    - 16.3.  Advertise Message
+ *    - 18.2.10.  Receipt of Reply Messages
+ *
+ * Return : 0 : ADVERTISE packet was received with no errors.
+ *              State machine can progress
+ *          1 : - packet received is not an ADVERTISE packet
+ *              - there were errors in the packet received,
+ *              - this is the first SOLICIT packet, but
+ *                received preference is not 255, so we have
+ *                to wait for more server responses.
+ */
+static int dhcp6_check_advertise_packet(uchar *rx_pkt, unsigned int len)
+{
+	u16 rx_uid_size;
+	struct dhcp6_hdr *dhcp6_hdr = (struct dhcp6_hdr *)rx_pkt;
+
+	/* Ignore message if msg-type != advertise */
+	if (dhcp6_hdr->msg_type != DHCP6_MSG_ADVERTISE)
+		return 1;
+	/* Ignore message if transaction ID doesn't match */
+	if (dhcp6_hdr->trans_id != htons(sm_params.trans_id))
+		return 1;
+
+	dhcp6_parse_options(rx_pkt, len);
+
+	/* Ignore advertise if any of these conditions met */
+	if (!sm_params.rx_status.server_id_found  ||
+	    !sm_params.rx_status.client_id_match  ||
+	    sm_params.rx_status.status_code != DHCP6_SUCCESS) {
+		return 1;
+	}
+
+	if (sm_params.rx_status.server_id_found) {
+		/* if no server UID has been received yet, or if the server UID
+		 * received has a higher preference value than the currently saved
+		 * server UID, save the new server UID and preference
+		 */
+		if (!sm_params.server_uid.uid_ptr ||
+		    (sm_params.server_uid.uid_ptr &&
+		    sm_params.server_uid.preference < sm_params.rx_status.preference)) {
+			rx_uid_size = sm_params.rx_status.server_uid_size;
+			if (sm_params.server_uid.uid_ptr)
+				free(sm_params.server_uid.uid_ptr);
+			sm_params.server_uid.uid_ptr = malloc(rx_uid_size * sizeof(uchar));
+			if (sm_params.server_uid.uid_ptr)
+				memcpy(sm_params.server_uid.uid_ptr,
+				       sm_params.rx_status.server_uid_ptr, rx_uid_size);
+
+			sm_params.server_uid.uid_size = rx_uid_size;
+			sm_params.server_uid.preference = sm_params.rx_status.preference;
+		}
+
+		/* If the first SOLICIT and preference code is 255, use right away.
+		 * Otherwise, wait for the first SOLICIT period for more
+		 * DHCP6 servers to respond.
+		 */
+		if (sm_params.retry_cnt == 1 &&
+		    sm_params.server_uid.preference != 255) {
+			debug("valid ADVERTISE, waiting for first SOLICIT period\n");
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * dhcp6_check_reply_packet() - Perform error checking on an expected
+ *                              REPLY packet.
+ *
+ * @rx_pkt: pointer to beginning of received DHCP6 packet
+ * @len: Total length of the DHCP6 packet
+ *
+ * Implements RFC 8415:
+ *    - 16.10. Reply Message
+ *    - 18.2.10. Receipt of Reply Messages
+ *
+ * Return : 0 - REPLY packet was received with no errors
+ *          1 - packet received is not an REPLY packet,
+ *              or there were errors in the packet received
+ */
+static int dhcp6_check_reply_packet(uchar *rx_pkt, unsigned int len)
+{
+	struct dhcp6_hdr *dhcp6_hdr = (struct dhcp6_hdr *)rx_pkt;
+
+	/* Ignore message if msg-type != reply */
+	if (dhcp6_hdr->msg_type != DHCP6_MSG_REPLY)
+		return 1;
+	/* check that transaction ID matches */
+	if (dhcp6_hdr->trans_id != htons(sm_params.trans_id))
+		return 1;
+
+	dhcp6_parse_options(rx_pkt, len);
+
+	/* if no addresses found, restart DHCP */
+	if (!sm_params.rx_status.ia_addr_found ||
+	    sm_params.rx_status.ia_status_code == DHCP6_NO_ADDRS_AVAIL ||
+	    sm_params.rx_status.status_code == DHCP6_NOT_ON_LINK) {
+		/* restart DHCP */
+		debug("No address found in reply.  Restarting DHCP\n");
+		dhcp6_start();
+	}
+
+	/* ignore reply if any of these conditions met */
+	if (!sm_params.rx_status.server_id_found  ||
+	    !sm_params.rx_status.client_id_match ||
+	    sm_params.rx_status.status_code == DHCP6_UNSPEC_FAIL) {
+		return 1;
+	}
+
+	return 0;
+}
+
+/* Timeout for DHCP6 SOLICIT/REQUEST */
+static void dhcp6_timeout_handler(void)
+{
+	/* call state machine with the timeout flag */
+	dhcp6_state_machine(true, NULL, 0);
+}
+
+/**
+ * dhcp6_state_machine() - DHCP6 state machine
+ *
+ * @timeout: TRUE : timeout waiting for response from
+ *                  DHCP6 server
+ *           FALSE : init or received response from DHCP6 server
+ * @rx_pkt: Pointer to the beginning of received DHCP6 packet.
+ *          Will be NULL if called as part of init
+ *          or timeout==TRUE
+ * @len: Total length of the DHCP6 packet if rx_pkt != NULL
+ *
+ * Implements RFC 8415:
+ *    - 5.2.  Client/Server Exchanges Involving Four Messages
+ *    - 15.  Reliability of Client-Initiated Message Exchanges
+ *
+ * Handles:
+ *    - transmission of SOLICIT and REQUEST packets
+ *    - retransmission of SOLICIT and REQUEST packets if no
+ *      response is received within the timeout window
+ *    - checking received ADVERTISE and REPLY packets to
+ *      assess if the DHCP state machine can progress
+ */
+static void dhcp6_state_machine(bool timeout, uchar *rx_pkt, unsigned int len)
+{
+	int rand_minus_plus_100;
+
+	switch (sm_params.curr_state) {
+	case DHCP6_INIT:
+		sm_params.next_state = DHCP6_SOLICIT;
+		break;
+	case DHCP6_SOLICIT:
+		if (!timeout) {
+			/* check the rx packet and determine if we can transition to next
+			 * state.
+			 */
+			if (dhcp6_check_advertise_packet(rx_pkt, len))
+				return;
+
+			debug("ADVERTISE good, transition to REQUEST\n");
+			sm_params.next_state = DHCP6_REQUEST;
+		} else if (sm_params.retry_cnt == 1)  {
+			/* If a server UID was received in the first SOLICIT period
+			 * transition to REQUEST
+			 */
+			if (sm_params.server_uid.uid_ptr)
+				sm_params.next_state = DHCP6_REQUEST;
+		}
+		break;
+	case DHCP6_REQUEST:
+		if (!timeout) {
+			/* check the rx packet and determine if we can transition to next state */
+			if (dhcp6_check_reply_packet(rx_pkt, len))
+				return;
+
+			debug("REPLY good, transition to DONE\n");
+			sm_params.next_state = DHCP6_DONE;
+		}
+		break;
+	case DHCP6_DONE:
+	case DHCP6_FAIL:
+		/* Shouldn't get here, as state machine should exit
+		 * immediately when DHCP6_DONE or DHCP6_FAIL is entered.
+		 * Proceed anyway to proceed DONE/FAIL actions
+		 */
+		debug("Unexpected DHCP6 state : %d\n", sm_params.curr_state);
+		break;
+	}
+	/* re-seed the RNG */
+	srand(get_ticks() + rand());
+
+	/* handle state machine entry conditions */
+	if (sm_params.curr_state != sm_params.next_state) {
+		sm_params.retry_cnt = 0;
+
+		if (sm_params.next_state == DHCP6_SOLICIT) {
+			/* delay a random ammount (special for SOLICIT) */
+			udelay((rand() % SOL_MAX_DELAY_MS) * 1000);
+			/* init timestamp variables after SOLICIT delay */
+			sm_params.dhcp6_start_ms = get_timer(0);
+			sm_params.dhcp6_retry_start_ms = sm_params.dhcp6_start_ms;
+			sm_params.dhcp6_retry_ms = sm_params.dhcp6_start_ms;
+			/* init transaction and ia_id */
+			sm_params.trans_id = rand() & 0xFFFFFF;
+			sm_params.ia_id = rand();
+			/* initialize retransmission parameters */
+			sm_params.irt_ms = SOL_TIMEOUT_MS;
+			sm_params.mrt_ms = updated_sol_max_rt_ms;
+			/* RFCs default MRC is be 0 (try infinitely)
+			 * give up after CONFIG_NET_RETRY_COUNT number of tries (same as DHCPv4)
+			 */
+			sm_params.mrc = CONFIG_NET_RETRY_COUNT;
+			sm_params.mrd_ms = 0;
+
+		} else if (sm_params.next_state == DHCP6_REQUEST) {
+			/* init timestamp variables  */
+			sm_params.dhcp6_retry_start_ms = get_timer(0);
+			sm_params.dhcp6_retry_ms = sm_params.dhcp6_start_ms;
+			/* initialize retransmission parameters */
+			sm_params.irt_ms = REQ_TIMEOUT_MS;
+			sm_params.mrt_ms = REQ_MAX_RT_MS;
+			sm_params.mrc = REQ_MAX_RC;
+			sm_params.mrd_ms = 0;
+		}
+	}
+
+	if (timeout)
+		sm_params.dhcp6_retry_ms = get_timer(0);
+
+	/* Check if MRC or MRD have been passed */
+	if ((sm_params.mrc != 0 &&
+	     sm_params.retry_cnt >= sm_params.mrc) ||
+	    (sm_params.mrd_ms != 0 &&
+	     ((sm_params.dhcp6_retry_ms - sm_params.dhcp6_retry_start_ms) >= sm_params.mrd_ms))) {
+		sm_params.next_state = DHCP6_FAIL;
+	}
+
+	/* calculate retransmission timeout (RT) */
+	rand_minus_plus_100 = ((rand() % 200) - 100);
+	if (sm_params.retry_cnt == 0) {
+		sm_params.rt_ms = sm_params.irt_ms +
+				  ((sm_params.irt_ms * rand_minus_plus_100) / 1000);
+	} else {
+		sm_params.rt_ms = (2 * sm_params.rt_prev_ms) +
+				  ((sm_params.rt_prev_ms * rand_minus_plus_100) / 1000);
+	}
+
+	if (sm_params.rt_ms > sm_params.mrt_ms) {
+		sm_params.rt_ms = sm_params.mrt_ms +
+				  ((sm_params.mrt_ms * rand_minus_plus_100) / 1000);
+	}
+
+	sm_params.rt_prev_ms = sm_params.rt_ms;
+
+	net_set_timeout_handler(sm_params.rt_ms, dhcp6_timeout_handler);
+
+	/* send transmit/retransmit message or fail */
+	sm_params.curr_state = sm_params.next_state;
+
+	if (sm_params.curr_state == DHCP6_SOLICIT) {
+		/* send solicit packet */
+		dhcp6_send_solicit_packet();
+		printf("DHCP6 SOLICIT %d\n", sm_params.retry_cnt);
+	} else if (sm_params.curr_state == DHCP6_REQUEST) {
+		/* send request packet */
+		dhcp6_send_request_packet();
+		printf("DHCP6 REQUEST %d\n", sm_params.retry_cnt);
+	} else if (sm_params.curr_state == DHCP6_DONE) {
+		net_set_timeout_handler(0, NULL);
+
+		/* Duplicate address detection (DAD) should be
+		 * performed here before setting net_ip6
+		 * (enhancement should be considered)
+		 */
+		net_copy_ip6(&net_ip6, &sm_params.rx_status.ia_addr_ipv6);
+		printf("DHCP6 client bound to %pI6c\n", &net_ip6);
+		/* will load with TFTP6 */
+		net_auto_load();
+	} else if (sm_params.curr_state == DHCP6_FAIL) {
+		printf("DHCP6 FAILED, TERMINATING\n");
+		net_set_state(NETLOOP_FAIL);
+	}
+	sm_params.retry_cnt++;
+}
+
+/* Start or restart DHCP6 */
+void dhcp6_start(void)
+{
+	memset(&sm_params, 0, sizeof(struct dhcp6_sm_params));
+
+	/* seed the RNG with MAC address */
+	srand_mac();
+
+	sm_params.curr_state = DHCP6_INIT;
+	dhcp6_state_machine(false, NULL, 0);
+}
diff --git a/net/dhcpv6.h b/net/dhcpv6.h
new file mode 100644
index 0000000000..80ca520432
--- /dev/null
+++ b/net/dhcpv6.h
@@ -0,0 +1,256 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (C) Microsoft Corporation
+ * Author: Sean Edmond <seanedmond@microsoft.com>
+ *
+ */
+
+#ifndef __DHCP6_H__
+#define __DHCP6_H__
+
+/* Message types */
+#define DHCP6_MSG_SOLICIT	1
+#define DHCP6_MSG_ADVERTISE	2
+#define DHCP6_MSG_REQUEST	3
+#define DHCP6_MSG_REPLY		7
+
+/* Option Codes */
+#define DHCP6_OPTION_CLIENTID		1
+#define DHCP6_OPTION_SERVERID		2
+#define DHCP6_OPTION_IA_NA		3
+#define DHCP6_OPTION_IA_TA		4
+#define DHCP6_OPTION_IAADDR		5
+#define DHCP6_OPTION_ORO		6
+#define DHCP6_OPTION_PREFERENCE		7
+#define DHCP6_OPTION_ELAPSED_TIME	8
+#define DHCP6_OPTION_STATUS_CODE	13
+#define DHCP6_OPTION_OPT_BOOTFILE_URL	59
+#define DHCP6_OPTION_OPT_BOOTFILE_PARAM	60
+#define DHCP6_OPTION_SOL_MAX_RT		82
+#define DHCP6_OPTION_CLIENT_ARCH_TYPE	61
+#define DHCP6_OPTION_VENDOR_CLASS	16
+#define DHCP6_OPTION_NII		62
+
+/* DUID */
+#define DUID_TYPE_LL		3
+#define DUID_HW_TYPE_ENET	1
+#define DUID_LL_SIZE		(sizeof(struct dhcp6_option_duid_ll) + ETH_ALEN)
+#define DUID_MAX_SIZE		DUID_LL_SIZE /* only supports DUID-LL currently */
+
+/* vendor-class-data to send in vendor clas option */
+#define DHCP6_VCI_STRING	"U-boot"
+
+#define DHCP6_MULTICAST_ADDR	"ff02::1:2"	/* DHCP multicast address */
+
+/* DHCP6 States supported */
+enum dhcp6_state {
+	DHCP6_INIT,
+	DHCP6_SOLICIT,
+	DHCP6_REQUEST,
+	DHCP6_DONE,
+	DHCP6_FAIL,
+};
+
+/* DHCP6 Status codes */
+enum dhcp6_status {
+	DHCP6_SUCCESS = 0,
+	DHCP6_UNSPEC_FAIL = 1,
+	DHCP6_NO_ADDRS_AVAIL = 2,
+	DHCP6_NO_BINDING = 3,
+	DHCP6_NOT_ON_LINK = 4,
+	DHCP6_USE_MULTICAST = 5,
+	DHCP6_NO_PREFIX_AVAIL = 6,
+};
+
+/* DHCP6 message header format */
+struct dhcp6_hdr {
+	unsigned int msg_type : 8;	/* message type */
+	unsigned int trans_id : 24;	/* transaction ID */
+} __packed;
+
+/* DHCP6 option header format */
+struct dhcp6_option_hdr {
+	__be16	option_id;	/* option id */
+	__be16	option_len;	/* Option length */
+	u8	option_data[0];	/* Option data */
+} __packed;
+
+/* DHCP6_OPTION_CLIENTID option (DUID-LL) */
+struct dhcp6_option_duid_ll {
+	__be16	duid_type;
+	__be16	hw_type;
+	u8	ll_addr[0];
+} __packed;
+
+/* DHCP6_OPTION_ELAPSED_TIME option */
+struct dhcp6_option_elapsed_time {
+	__be16	elapsed_time;
+} __packed;
+
+/* DHCP6_OPTION_IA_TA option */
+struct dhcp6_option_ia_ta {
+	__be32	iaid;
+	u8	ia_ta_options[0];
+} __packed;
+
+/* DHCP6_OPTION_IA_NA option */
+struct dhcp6_option_ia_na {
+	__be32	iaid;
+	__be32	t1;
+	__be32	t2;
+	u8	ia_na_options[0];
+} __packed;
+
+/* OPTION_ORO option */
+struct dhcp6_option_oro  {
+	__be16	req_option_code[0];
+} __packed;
+
+/* DHCP6_OPTION_CLIENT_ARCH_TYPE option */
+struct dhcp6_option_client_arch {
+	__be16	arch_type[0];
+} __packed;
+
+/* vendor-class-data inside OPTION_VENDOR_CLASS option */
+struct vendor_class_data {
+	__be16	vendor_class_len;
+	u8	opaque_data[0];
+} __packed;
+
+/* DHCP6_OPTION_VENDOR_CLASS option */
+struct dhcp6_option_vendor_class {
+	__be32				enterprise_number;
+	struct vendor_class_data	vendor_class_data[0];
+} __packed;
+
+/**
+ * struct dhcp6_rx_pkt_status - Structure that holds status
+ *                              from a received message
+ * @client_id_match: Client ID was found and matches DUID sent
+ * @server_id_found: Server ID was found in the message
+ * @server_uid_ptr: Pointer to received server ID
+ * @server_uid_size: Size of received server ID
+ * @ia_addr_found: IA addr option was found in received message
+ * @ia_addr_ipv6: The IPv6 address received in IA
+ * @ia_status_code: Status code received in the IA
+ * @status_code: Top-level status code received
+ * @preference: Preference code received
+ */
+struct dhcp6_rx_pkt_status {
+	bool			client_id_match;
+	bool			server_id_found;
+	uchar			*server_uid_ptr;
+	u16			server_uid_size;
+	bool			ia_addr_found;
+	struct in6_addr		ia_addr_ipv6;
+	enum dhcp6_status	ia_status_code;
+	enum dhcp6_status	status_code;
+	u8			preference;
+};
+
+/**
+ * struct dhcp6_server_uid - Structure that holds the server UID
+ *                             received from an ADVERTISE and saved
+ *                             given the server selection criteria.
+ * @uid_ptr: Dynamically allocated and copied server UID
+ * @uid_size: Size of the server UID in uid_ptr (in bytes)
+ * @preference: Preference code associated with this server UID
+ */
+struct dhcp6_server_uid {
+	uchar	*uid_ptr;
+	u16	uid_size;
+	u8	preference;
+};
+
+/**
+ * struct dhcp6_sm_params - Structure that holds DHCP6
+ *                          state machine parameters
+ * @curr_state: current DHCP6 state
+ * @next_state: next DHCP6 state
+ * @dhcp6_start_ms: timestamp DHCP6 start
+ * @dhcp6_retry_start_ms: timestamp of current TX message start
+ * @dhcp6_retry_ms: timestamp of last retransmission
+ * @retry_cnt: retry count
+ * @trans_id: transaction ID
+ * @ia_id: transmitted IA ID
+ * @irt_ms: Initial retransmission time (in ms)
+ * @mrt_ms: Maximum retransmission time (in ms)
+ * @mrc: Maximum retransmission count
+ * @mrd_ms: Maximum retransmission duration (in ms)
+ * @rt_ms: retransmission timeout (is ms)
+ * @rt_prev_ms: previous retransmission timeout
+ * @rx_status: Status from received message
+ * @server_uid: Saved Server UID for selected server
+ * @duid: pointer to transmitted Client DUID
+ */
+struct dhcp6_sm_params {
+	enum dhcp6_state		curr_state;
+	enum dhcp6_state		next_state;
+	ulong				dhcp6_start_ms;
+	ulong				dhcp6_retry_start_ms;
+	ulong				dhcp6_retry_ms;
+	u32				retry_cnt;
+	u32				trans_id;
+	u32				ia_id;
+	int				irt_ms;
+	int				mrt_ms;
+	int				mrc;
+	int				mrd_ms;
+	int				rt_ms;
+	int				rt_prev_ms;
+	struct dhcp6_rx_pkt_status	rx_status;
+	struct dhcp6_server_uid		server_uid;
+	char				duid[DUID_MAX_SIZE];
+};
+
+/* Starts a DHCPv6 4-message exchange as a DHCPv6 client. On successful exchange,
+ * the DHCPv6 state machine will transition from internal states:
+ *	DHCP6_INIT->DHCP6_SOLICIT->DHCP6_REQUEST->DHCP6_DONE
+ *
+ * Transmitted SOLICIT and REQUEST packets will set/request the minimum required
+ * DHCPv6 options to PXE boot.
+ *
+ * After a successful exchange, the DHCPv6 assigned address will be set in net_ip6
+ *
+ * Additionally, the following will be set after receiving these options:
+ * DHCP6_OPTION_OPT_BOOTFILE_URL (option 59) -> net_server_ip6, net_boot_file_name
+ * DHCP6_OPTION_OPT_BOOTFILE_PARAM (option 60) - > pxelinux_configfile
+ *
+ * Illustration of a 4-message exchange with 2 servers (copied from
+ * https://www.rfc-editor.org/rfc/rfc8415):
+ *
+ *               Server                          Server
+ *           (not selected)      Client        (selected)
+ *
+ *                 v               v               v
+ *                 |               |               |
+ *                 |     Begins initialization     |
+ *                 |               |               |
+ *    start of     | _____________/|\_____________ |
+ *    4-message    |/ Solicit      | Solicit      \|
+ *    exchange     |               |               |
+ *             Determines          |          Determines
+ *            configuration        |         configuration
+ *                 |               |               |
+ *                 |\              |  ____________/|
+ *                 | \________     | /Advertise    |
+ *                 | Advertise\    |/              |
+ *                 |           \   |               |
+ *                 |      Collects Advertises      |
+ *                 |             \ |               |
+ *                 |     Selects configuration     |
+ *                 |               |               |
+ *                 | _____________/|\_____________ |
+ *                 |/ Request      |  Request     \|
+ *                 |               |               |
+ *                 |               |     Commits configuration
+ *                 |               |               |
+ *    end of       |               | _____________/|
+ *    4-message    |               |/ Reply        |
+ *    exchange     |               |               |
+ *                 |    Initialization complete    |
+ *                 |               |               |
+ */
+void dhcp6_start(void);
+
+#endif /* __DHCP6_H__ */
diff --git a/net/net.c b/net/net.c
index c9a749f6cc..8cb8b4b9f3 100644
--- a/net/net.c
+++ b/net/net.c
@@ -107,6 +107,8 @@
 #include <watchdog.h>
 #include <linux/compiler.h>
 #include <test/test.h>
+#include <net/tcp.h>
+#include <net/wget.h>
 #include "arp.h"
 #include "bootp.h"
 #include "cdp.h"
@@ -120,8 +122,7 @@
 #if defined(CONFIG_CMD_WOL)
 #include "wol.h"
 #endif
-#include <net/tcp.h>
-#include <net/wget.h>
+#include "dhcpv6.h"
 
 /** BOOTP EXTENTIONS **/
 
@@ -135,6 +136,8 @@ struct in_addr net_dns_server;
 /* Our 2nd DNS IP address */
 struct in_addr net_dns_server2;
 #endif
+/* Indicates whether the pxe path prefix / config file was specified in dhcp option */
+char *pxelinux_configfile;
 
 /** END OF BOOTP EXTENTIONS **/
 
@@ -510,6 +513,10 @@ restart:
 			dhcp_request();		/* Basically same as BOOTP */
 			break;
 #endif
+		case DHCP6:
+			if (IS_ENABLED(CONFIG_CMD_DHCP6))
+				dhcp6_start();
+			break;
 #if defined(CONFIG_CMD_BOOTP)
 		case BOOTP:
 			bootp_reset();