dhcp.h

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/*! \file dhcp.h \brief DHCP Protocol Library. */
//*****************************************************************************
//
// File Name    : 'dhcp.h'
// Title        : DHCP Protocol Library
// Author       : Pascal Stang
// Created      : 9/17/2005
// Revised      : 9/17/2005
// Version      : 0.1
// Target MCU   : Atmel AVR series
// Editor Tabs  : 4
//
/// \ingroup network
/// \defgroup dhcp DHCP Protocol Library (dhcp.c)
/// \code #include "net/dhcp.h" \endcode
/// \par Description
///     This library provides a limited implementation of DHCP (Dynamic Host
///     Configuration Protocol) as described in RFC2131.  DHCP allows a
///     network device to automatically obtain an IP address and other network
///     configuration settings from a DHCP server.
///     
/// \note This code is currently below version 1.0, and therefore is considered
/// to be lacking in some functionality or documentation, or may not be fully
/// tested.  Nonetheless, you can expect most functions to work.
///
//  This code is distributed under the GNU Public License
//      which can be found at http://www.gnu.org/licenses/gpl.txt
//*****************************************************************************
//@{

#ifndef DHCP_H
#define DHCP_H

#include "global.h"
#include "net.h"

//#define DHCP_DEBUG_PRINT
//#define DHCP_DEBUG

/// Bootp Header (DHCP is transported by BOOTP/UDP/IP)
struct netBootpHeader
{
    uint8_t     op;         ///< Message op-code / message type
    uint8_t     htype;      ///< Hardware address type   (Ethernet=1)
    uint8_t     hlen;       ///< Hardware address length (Ethernet=6 byte MAC addr)
    uint8_t     hops;       ///< hop count (client set to zero)
    uint32_t    xid;        ///< Transaction ID (randomly chosen by client, must remain same)
    uint16_t    secs;       ///< Seconds elapsed since DHCP negotiation began (filled by client)
    uint16_t    flags;      ///< Flags
    uint32_t    ciaddr;     ///< Client IP address (filled only if already bound, renewing, or rebinding)
    uint32_t    yiaddr;     ///< 'Your' IP address (client)
    uint32_t    siaddr;     ///< Server IP address
    uint32_t    giaddr;     ///< Gateway IP address
    uint8_t     chaddr[16]; ///< Client Hardware Address
    uint8_t     sname[64];  ///< Server Host Name
    uint8_t     file[128];  ///< Boot file name (null-term string)
} GNUC_PACKED;

#define BOOTP_HEADER_LEN        236 ///< length of BOOTP header not including options

#define BOOTP_OP_BOOTREQUEST    1   ///< BOOTP Request operation (message from client to server)
#define BOOTP_OP_BOOTREPLY      2   ///< BOOTP Reply operation (message from server to client)

#define BOOTP_HTYPE_ETHERNET    1
#define BOOTP_HLEN_ETHERNET     6

/// DHCP Header
struct netDhcpHeader
{
    struct netBootpHeader bootp;    ///< BOOTP header
    uint32_t    cookie;             ///< magic cookie value
    uint8_t     options[];          ///< DHCP options
} GNUC_PACKED;

#define DHCP_HEADER_LEN         240 ///< length of DHCP header not including options

#define DHCP_UDP_SERVER_PORT    67  ///< UDP port where DHCP requests should be sent
#define DHCP_UDP_CLIENT_PORT    68  ///< UDP port clients will receive DHCP replies


#define DHCP_OPT_PAD            0   ///< token padding value (make be skipped)
#define DHCP_OPT_NETMASK        1   ///< subnet mask client should use (4 byte mask)
#define DHCP_OPT_ROUTERS        3   ///< routers client should use (IP addr list)
#define DHCP_OPT_TIMESERVERS    4   ///< time servers client should use (IP addr list)
#define DHCP_OPT_NAMESERVERS    5   ///< name servers client should use (IP addr list)
#define DHCP_OPT_DNSSERVERS     6   ///< DNS servers client should use (IP addr list)
#define DHCP_OPT_HOSTNAME       12  ///< host name client should use (string)
#define DHCP_OPT_DOMAINNAME     15  ///< domain name client should use (string)
#define DHCP_OPT_REQUESTEDIP    50  ///< IP address requested by client (IP address)
#define DHCP_OPT_LEASETIME      51  ///< DHCP Lease Time (uint32 seconds)
#define DHCP_OPT_DHCPMSGTYPE    53  ///< DHCP message type (1 byte)
#define DHCP_OPT_SERVERID       54  ///< Server Identifier (IP address)
#define DHCP_OPT_PARAMREQLIST   55  ///< Paramerter Request List (n OPT codes)
#define DHCP_OPT_RENEWALTIME    58  ///< DHCP Lease Renewal Time (uint32 seconds)
#define DHCP_OPT_REBINDTIME     59  ///< DHCP Lease Rebinding Time (uint32 seconds)
#define DHCP_OPT_END            255 ///< token end value (marks end of options list)

#define DHCP_MSG_DHCPDISCOVER   1   ///< DISCOVER is broadcast by client to solicit OFFER from any/all DHCP servers.
#define DHCP_MSG_DHCPOFFER      2   ///< OFFER(s) are made to client by server to offer IP address and config info.
#define DHCP_MSG_DHCPREQUEST    3   ///< REQUEST is made my client in response to best/favorite OFFER message.
#define DHCP_MSG_DHCPDECLINE    4   ///< DECLINE may be sent by client to server to indicate IP already in use.
#define DHCP_MSG_DHCPACK        5   ///< ACK is sent to client by server in confirmation of REQUEST, contains config and IP.
#define DHCP_MSG_DHCPNAK        6   ///< NAK is sent to client by server to indicate problem with REQUEST.
#define DHCP_MSG_DHCPRELEASE    7   ///< RELEASE is sent by client to server to relinquish DHCP lease on IP address, etc.
#define DHCP_MSG_DHCPINFORM     8   ///< INFORM is sent by client to server to request config info, IP address configured locally.


/*! Initialize DHCP system.
    Prepares DHCP for use and initializes lease time to zero. */
void dhcpInit(void);

/*! Processes incoming DHCP packets from UDP port 68.
    This function is to be called by the stack when a DHCP packet
    arrives over the network.  The DHCP packet will be parsed, handled,
    and a response will be generated and sent if needed.  When the DHCP
    process completes, the IP addressing will be automatically updated. */
void dhcpIn(unsigned int len, struct netDhcpHeader* packet);

/*! Request DHCP assigned network parameters.
    This function begins the DHCP process.  The remainder of operations
    are handled in dhcpIn(). */
void dhcpRequest(void);

/*! Release DHCP lease and assigned network parameters.
    This function releases the DHCP assigned address and allows the
    DHCP server to reallocate it. */
void dhcpRelease(void);

/*! Periodic DHCP maintenance.
    This function is to be called once per second and will 
    expire the DHCP lease. */
void dhcpTimer(void);

/*! Get a DHCP option from the option list.
    \param options is a pointer to the options field of a DHCP packet.
    \param optcode is the desired option number to retrieve.
    \param optlen is the maximum data length that should be retrieved (less data will be retrieved if option is shorter).
    \param optvalptr is a pointer to where the option value will be stored.
    \return actual length of the option data, as stored in the options list. */
uint8_t dhcpGetOption(uint8_t* options, uint8_t optcode, uint8_t optlen, void* optvalptr);

/*! Set a DHCP option in the option list.
    \param options is a pointer to the options field of a DHCP packet.
    \param optcode is the option number to write.
    \param optlen is the data length of the option value.
    \param optvalptr is a pointer to the option data to be read.
    \return pointer to write location of the next option. */
uint8_t* dhcpSetOption(uint8_t* options, uint8_t optcode, uint8_t optlen, void* optvalptr);

/*! Print diagnotic information about BOOTP/DHCP packet.
*/
void dhcpPrintHeader(struct netDhcpHeader* packet);

#endif
//@}

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