a22f7e777b
Some DHCPv4 servers do not respect BROADCAST flag set on DHCP Discover,
replying with unicast packet, making it impossible to obtain DHCP
address by Zephyr in such cases.
RFC1542 chapter 3.1.1 makes the following statement about the BROADCAST
flag:
This addition to the protocol is a workaround for old host
implementations. Such implementations SHOULD be modified so
that they may receive unicast BOOTREPLY messages, thus making
use of this workaround unnecessary. In general, the use of
this mechanism is discouraged.
Making it clear that being able to process unicast replies from the DHCP
server is not only an optional behavior, but a recommended solution.
Therefore, introduce a support for unicast DHCPv4 in Zephyr. To achieve
this, add additional filtering rule at the IPv4 level - in case DHCPv4
is enabled, there is an active query and the packet is destined for the
DHCPv4 module, let it through for the DHCPv4 module to process,
regardless of the destination IP address.
Signed-off-by: Robert Lubos <robert.lubos@nordicsemi.no>
146 lines
3.8 KiB
C
146 lines
3.8 KiB
C
/** @file
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*
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* @brief DHCPv4 handler.
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*
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* This is not to be included by the application.
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*/
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/*
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* Copyright (c) 2017 ARM Ltd.
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* Copyright (c) 2018 Intel Corporation
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#ifndef __INTERNAL_DHCPV4_H
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#define __INTERNAL_DHCPV4_H
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struct dhcp_msg {
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uint8_t op; /* Message type, 1:BOOTREQUEST, 2:BOOTREPLY */
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uint8_t htype; /* Hardware Address Type */
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uint8_t hlen; /* Hardware Address length */
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uint8_t hops; /* used by relay agents when booting via relay
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* agent, client sets zero
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*/
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uint32_t xid; /* Transaction ID, random number */
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uint16_t secs; /* Seconds elapsed since client began address
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* acquisition or renewal process
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*/
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uint16_t flags; /* Broadcast or Unicast */
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uint8_t ciaddr[4]; /* Client IP Address */
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uint8_t yiaddr[4]; /* your (client) IP address */
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uint8_t siaddr[4]; /* IP address of next server to use in bootstrap
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* returned in DHCPOFFER, DHCPACK by server
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*/
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uint8_t giaddr[4]; /* Relat agent IP address */
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uint8_t chaddr[16]; /* Client hardware address */
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} __packed;
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#define SIZE_OF_SNAME 64
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#define SIZE_OF_FILE 128
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#define SIZE_OF_MAGIC_COOKIE 4
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#define DHCPV4_MSG_BROADCAST 0x8000
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#define DHCPV4_MSG_UNICAST 0x0000
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#define DHCPV4_MSG_BOOT_REQUEST 1
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#define DHCPV4_MSG_BOOT_REPLY 2
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#define HARDWARE_ETHERNET_TYPE 1
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#define DHCPV4_SERVER_PORT 67
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#define DHCPV4_CLIENT_PORT 68
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#define DHCPV4_OPTIONS_SUBNET_MASK 1
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#define DHCPV4_OPTIONS_ROUTER 3
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#define DHCPV4_OPTIONS_DNS_SERVER 6
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#define DHCPV4_OPTIONS_HOST_NAME 12
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#define DHCPV4_OPTIONS_REQ_IPADDR 50
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#define DHCPV4_OPTIONS_LEASE_TIME 51
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#define DHCPV4_OPTIONS_MSG_TYPE 53
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#define DHCPV4_OPTIONS_SERVER_ID 54
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#define DHCPV4_OPTIONS_REQ_LIST 55
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#define DHCPV4_OPTIONS_RENEWAL 58
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#define DHCPV4_OPTIONS_REBINDING 59
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#define DHCPV4_OPTIONS_END 255
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/* Useful size macros */
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#define DHCPV4_OLV_MSG_HOST_NAME 2
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#define DHCPV4_OLV_MSG_REQ_IPADDR 6
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#define DHCPV4_OLV_MSG_TYPE_SIZE 3
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#define DHCPV4_OLV_MSG_SERVER_ID 6
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#define DHCPV4_OLV_MSG_REQ_LIST 5
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#define DHCPV4_OLV_END_SIZE 1
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#define DHCPV4_MESSAGE_SIZE (sizeof(struct dhcp_msg) + \
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SIZE_OF_SNAME + SIZE_OF_FILE + \
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SIZE_OF_MAGIC_COOKIE + \
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DHCPV4_OLV_MSG_TYPE_SIZE + \
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DHCPV4_OLV_END_SIZE)
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/* TODO:
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* 1) Support T2(Rebind) timer.
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*/
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/* Maximum number of REQUEST or RENEWAL retransmits before reverting
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* to DISCOVER.
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*/
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#define DHCPV4_MAX_NUMBER_OF_ATTEMPTS 3
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/* Initial message retry timeout (s). This timeout increases
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* exponentially on each retransmit.
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* RFC2131 4.1
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*/
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#define DHCPV4_INITIAL_RETRY_TIMEOUT 4
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/* Initial minimum delay in INIT state before sending the
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* initial DISCOVER message. MAx value is defined with
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* CONFIG_NET_DHCPV4_INITIAL_DELAY_MAX. Default max value
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* should be 10.
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* RFC2131 4.1.1
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*/
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#define DHCPV4_INITIAL_DELAY_MIN 1
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#if defined(CONFIG_NET_DHCPV4)
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int net_dhcpv4_init(void);
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#else
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#define net_dhcpv4_init() 0
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#endif /* CONFIG_NET_DHCPV4 */
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#if defined(CONFIG_NET_DHCPV4) && defined(CONFIG_NET_DHCPV4_ACCEPT_UNICAST)
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/**
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* @brief Verify if the incoming packet should be accepted for the DHCPv4
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* module to process.
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*
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* In case server responds with an unicast IP packet, the IP stack needs to
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* pass it through for the DHCPv4 module to process, before the actual
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* destination IP address is configured on an interface.
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* This function allows to determine whether there is an active DHCPv4 query on
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* the interface and the packet is destined for the DHCPv4 module to process.
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*
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* @param pkt A packet to analyze
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*
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* @return true if the packet shall be accepted, false otherwise
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*/
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bool net_dhcpv4_accept_unicast(struct net_pkt *pkt);
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#else
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static inline bool net_dhcpv4_accept_unicast(struct net_pkt *pkt)
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{
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ARG_UNUSED(pkt);
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return false;
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}
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#endif /* CONFIG_NET_DHCPV4 && CONFIG_NET_DHCPV4_ACCEPT_UNICAST */
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#endif /* __INTERNAL_DHCPV4_H */
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