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dhcp: extend options utilities
Provide utilities for appending new options to an existing DHCP packet and a utility for finding existing options that returns a typed option object. Remove old version that return untyped options. Ref #2490
This commit is contained in:
Martin Stein
Christian Helmuth
parent
791fd9806f
commit
d63c40af3e
@ -17,6 +17,7 @@
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/* Genode */
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#include <base/exception.h>
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#include <base/stdint.h>
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#include <util/construct_at.h>
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#include <util/endian.h>
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#include <net/ethernet.h>
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@ -65,7 +66,8 @@ class Net::Dhcp_packet
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{
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public:
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class No_dhcp_packet : Genode::Exception {};
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struct No_dhcp_packet : Genode::Exception { };
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struct Option_not_found : Genode::Exception { };
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private:
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@ -92,32 +94,6 @@ class Net::Dhcp_packet
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enum class Htype : Genode::uint8_t { ETH = 1 };
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/**
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* This class represents the data layout of an DHCP option.
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*/
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class Option
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{
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private:
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Genode::uint8_t _code;
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Genode::uint8_t _len;
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Genode::uint8_t _value[0];
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public:
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Option() {}
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Genode::uint8_t code() { return _code; }
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Genode::size_t length() { return _len; }
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void* value() { return _value; }
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/**
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* Placement new.
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*/
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void * operator new(__SIZE_TYPE__, void* addr) { return addr; }
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} __attribute__((packed));
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enum Opcode {
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REQUEST = 1,
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REPLY = 2,
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@ -129,39 +105,6 @@ class Net::Dhcp_packet
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BOOTPC = 68
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};
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enum Option_type {
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REQ_IP_ADDR = 50,
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IP_LEASE_TIME = 51,
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OPT_OVERLOAD = 52,
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MSG_TYPE = 53,
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SRV_ID = 54,
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REQ_PARAMETER = 55,
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MESSAGE = 56,
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MAX_MSG_SZ = 57,
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RENEWAL = 58,
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REBINDING = 59,
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VENDOR = 60,
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CLI_ID = 61,
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TFTP_SRV_NAME = 66,
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BOOT_FILE = 67,
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END = 255
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};
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enum Message_type {
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DHCP_DISCOVER = 1,
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DHCP_OFFER = 2,
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DHCP_REQUEST = 3,
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DHCP_DECLINE = 4,
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DHCP_ACK = 5,
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DHCP_NAK = 6,
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DHCP_RELEASE = 7,
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DHCP_INFORM = 8
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};
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/*****************
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** Constructor **
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*****************/
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Dhcp_packet(Genode::size_t size) {
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/* dhcp packet needs to fit in */
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@ -170,6 +113,228 @@ class Net::Dhcp_packet
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}
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/*******************************
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** Utilities for the options **
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*******************************/
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/**
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* Header of a DHCP option or DHCP option without a payload
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*/
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class Option
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{
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private:
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Genode::uint8_t _code;
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Genode::uint8_t _len;
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Genode::uint8_t _value[0];
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public:
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enum class Code : Genode::uint8_t {
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INVALID = 0,
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SUBNET_MASK = 1,
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ROUTER = 3,
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DNS_SERVER = 6,
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BROADCAST_ADDR = 28,
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REQ_IP_ADDR = 50,
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IP_LEASE_TIME = 51,
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OPT_OVERLOAD = 52,
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MSG_TYPE = 53,
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SERVER = 54,
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REQ_PARAMETER = 55,
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MESSAGE = 56,
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MAX_MSG_SZ = 57,
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RENEWAL = 58,
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REBINDING = 59,
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VENDOR = 60,
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CLI_ID = 61,
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TFTP_SRV_NAME = 66,
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BOOT_FILE = 67,
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END = 255,
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};
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Option(Code code, Genode::uint8_t len)
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: _code((Genode::uint8_t)code), _len(len) { }
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Option() { }
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Code code() const { return (Code)_code; }
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Genode::uint8_t len() const { return _len; }
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/*********
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** log **
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*********/
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void print(Genode::Output &output) const;
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} __attribute__((packed));
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/**
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* DHCP option that contains a payload of type T
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*/
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template <typename T>
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class Option_tpl : public Option
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{
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protected:
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T _value;
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public:
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Option_tpl(Code code, T value)
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: Option(code, sizeof(T)), _value(value) { }
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} __attribute__((packed));
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/**
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* DHCP option that specifies the IP packet lease time in seconds
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*/
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struct Ip_lease_time : Option_tpl<Genode::uint32_t>
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{
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static constexpr Code CODE = Code::IP_LEASE_TIME;
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Ip_lease_time(Genode::uint32_t time)
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: Option_tpl(CODE, host_to_big_endian(time)) { }
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};
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enum class Message_type : Genode::uint8_t {
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DISCOVER = 1,
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OFFER = 2,
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REQUEST = 3,
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DECLINE = 4,
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ACK = 5,
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NAK = 6,
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RELEASE = 7,
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INFORM = 8
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};
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/**
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* DHCP option that specifies the DHCP message type
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*/
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struct Message_type_option : Option_tpl<Genode::uint8_t>
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{
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static constexpr Code CODE = Code::MSG_TYPE;
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Message_type_option(Message_type value)
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: Option_tpl(CODE, (Genode::uint8_t)value) { }
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Message_type value() const { return (Message_type)_value; }
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};
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/**
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* DHCP options that have only one IPv4 address as payload
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*/
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template <Option::Code _CODE>
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struct Ipv4_option : Option_tpl<Genode::uint32_t>
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{
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static constexpr Code CODE = _CODE;
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Ipv4_option(Ipv4_address value)
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: Option_tpl(CODE, value.to_uint32_big_endian()) { }
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Ipv4_address value() const {
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return Ipv4_address::from_uint32_big_endian(_value); }
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};
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using Dns_server_ipv4 = Ipv4_option<Option::Code::DNS_SERVER>;
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using Subnet_mask = Ipv4_option<Option::Code::SUBNET_MASK>;
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using Broadcast_addr = Ipv4_option<Option::Code::BROADCAST_ADDR>;
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using Router_ipv4 = Ipv4_option<Option::Code::ROUTER>;
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using Server_ipv4 = Ipv4_option<Option::Code::SERVER>;
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/**
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* DHCP option that marks the end of an options field
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*/
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struct Options_end : Option
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{
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static constexpr Code CODE = Code::END;
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Options_end() : Option(CODE, 0) { }
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};
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/**
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* Utility to append individual options to an existing DHCP packet
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*
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* \param SIZE_GUARD guard that may limit the options list size
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*
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* Overwrites existing options if any!
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*/
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template <typename SIZE_GUARD>
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class Options_aggregator
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{
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private:
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Genode::addr_t _base;
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SIZE_GUARD &_size_guard;
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public:
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Options_aggregator(Dhcp_packet &packet,
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SIZE_GUARD &size_guard)
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:
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_base((Genode::addr_t)packet.opts()),
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_size_guard(size_guard)
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{ }
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template <typename OPTION, typename... ARGS>
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void append_option(ARGS &&... args)
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{
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_size_guard.add(sizeof(OPTION));
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Genode::construct_at<OPTION>((void *)_base,
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static_cast<ARGS &&>(args)...);
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_base += sizeof(OPTION);
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}
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};
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/*
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* Call 'functor' of type 'FUNC' for each option (except END options)
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*/
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template <typename FUNC>
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void for_each_option(FUNC && functor) const
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{
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for (unsigned i = 0; ; ) {
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Option &opt = *(Option*)&_opts[i];
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if (opt.code() == Option::Code::INVALID ||
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opt.code() == Option::Code::END)
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{
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return;
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}
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functor(opt);
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i += 2 + opt.len();
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}
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}
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/*
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* Find and return option of given type 'T'
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*
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* \throw Option_not_found
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*/
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template <typename T>
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T &option()
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{
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void *ptr = &_opts;
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while (true) {
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Option &opt = *Genode::construct_at<Option>(ptr);
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if (opt.code() == Option::Code::INVALID ||
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opt.code() == Option::Code::END)
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{
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throw Option_not_found();
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}
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if (opt.code() == T::CODE) {
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return *reinterpret_cast<T *>(ptr);
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}
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ptr = (void *)((Genode::addr_t)ptr + sizeof(opt) + opt.len());
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}
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}
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/***************
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** Accessors **
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***************/
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@ -208,25 +373,6 @@ class Net::Dhcp_packet
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void client_mac(Mac_address v) { v.copy(&_chaddr); }
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/**********************
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** Option utilities **
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**********************/
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Option *option(Option_type op)
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{
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void *ptr = &_opts;
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while (true) {
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Option *ext = new (ptr) Option();
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if (ext->code() == op)
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return ext;
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if (ext->code() == END || ext->code() == 0)
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break;
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ptr = ext + ext->length();
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}
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return 0;
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}
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/*************************
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** Convenience methods **
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*************************/
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@ -82,14 +82,16 @@ bool Net::Nic::handle_ip(Ethernet_frame *eth, Genode::size_t size) {
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/* check for DHCP ACKs containing new client ips */
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if (dhcp->op() == Dhcp_packet::REPLY) {
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Dhcp_packet::Option *ext = dhcp->option(Dhcp_packet::MSG_TYPE);
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if (ext) {
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try {
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Dhcp_packet::Message_type const msg_type =
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dhcp->option<Dhcp_packet::Message_type_option>().value();
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/*
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* extract the IP address and set it in the
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* client's session-component
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* Extract the IP address and set it in the client's
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* session-component
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*/
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Genode::uint8_t *msg_type = (Genode::uint8_t*) ext->value();
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if (*msg_type == Dhcp_packet::DHCP_ACK) {
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if (msg_type == Dhcp_packet::Message_type::ACK) {
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Mac_address_node *node =
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vlan().mac_tree.first();
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if (node)
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@ -98,6 +100,7 @@ bool Net::Nic::handle_ip(Ethernet_frame *eth, Genode::size_t size) {
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node->component().set_ipv4_address(dhcp->yiaddr());
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}
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}
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catch (Dhcp_packet::Option_not_found) { }
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}
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}
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}
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