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IP
[Base Protocols]

Collaboration diagram for IP:

Detailed Description

RFC 791 Internet protocol version 4.

Before using IP based protocols, you must have registered a network device driver like PPP or one of the supported Ethernet controller drivers.

You must also have configured the IP network interface with NutDhcpIfConfig() or NutNetIfConfig().

Typical applications do not use the IP layer directly, but call the UDP Socket API or the TCP Socket API. A Raw IP API is currently not supported.

Todo:
Configurable checksum calculation for incoming datagrams.


Data Structures

struct  ifnet
 Network interface structure. More...
struct  ip
 Structure of an internet header. More...
struct  pseudo_hdr
struct  ifnet
 Network interface structure. More...

Defines

#define IPVERSION   4
 IP protocol version.
#define IP_DF   0x4000
 Don't fragment flag.
#define IP_MF   0x2000
 More fragments flag.
#define IP_OFFMASK   0x1fff
 Mask for fragmenting bits.
#define IPOPT_EOL   0
 End of option list.
#define IPOPT_NOP   1
 No operation.
#define IPOPT_RR   7
 Record packet route.
#define IPOPT_TS   68
 Timestamp.
#define IPOPT_SECURITY   130
 Provide s,c,h,tcc.
#define IPOPT_LSRR   131
 Loose source route.
#define IPOPT_SATID   136
 Satnet id.
#define IPOPT_SSRR   137
 Strict source route.
#define IPOPT_OPTVAL   0
 Option identifier offset.
#define IPOPT_OLEN   1
 Option length offset.
#define IPOPT_OFFSET   2
 Offset within option.
#define IPOPT_MINOFF   4
 Minimum offset within option.
#define MAXTTL   255
 Maximum time to live (seconds).
#define IPDEFTTL   64
 Default time to live.
#define IPFRAGTTL   60
 Time to live for fragments.
#define IPTTLDEC   1
 Subtracted from time to live when forwarding.

Typedefs

typedef ifnet IFNET
 Network interface type.
typedef ip IPHDR
 Internet header type.

Functions

int NutNetIfSetup (NUTDEVICE *dev, u_long ip_addr, u_long ip_mask, u_long gateway)
 Network interface setup.
int NutNetIfConfig (CONST char *name, void *params, u_long ip_addr, u_long ip_mask)
 Configure a network interface.
int NutNetIfConfig2 (CONST char *name, void *params, u_long ip_addr, u_long ip_mask, u_long gateway)
 Configure a network interface including the default gateway.
u_long inet_addr (CONST char *str)
 Convert decimal dotted ASCII representation into numeric IP address.
char * inet_ntoa (u_long addr)
 Convert numeric IP address into decimal dotted ASCII representation.
u_short NutIpChkSumPartial (u_short ics, CONST void *buf, size_t len)
 Calculate a partial IP checksum of a buffer.
u_short NutIpChkSum (u_short ics, CONST void *buf, size_t len)
 Calculates an the final IP checksum over a block of data.
u_long NutIpPseudoChkSumPartial (u_long src_addr, u_long dest_addr, u_char protocol, u_short len)
 Calculates the partial IP pseudo checksum.
void NutIpSetInputFilter (NutIpFilterFunc callbackFunc)
 Set filter function for incoming IP datagrams.
void NutIpInput (NUTDEVICE *dev, NETBUF *nb)
 Process incoming IP datagrams.
int NutIpOutput (u_char proto, u_long dest, NETBUF *nb)
 Send IP datagram.
int NutIpRouteAdd (u_long ip, u_long mask, u_long gate, NUTDEVICE *dev)
 Add a new entry to the IP routing table.
int NutIpRouteDelAll (NUTDEVICE *dev)
 Delete all route table entries for the given device.
int NutIpRouteDel (u_long ip, u_long mask, u_long gate, NUTDEVICE *dev)
 Delete the specified route table entry.
RTENTRY * NutIpRouteList (int *numEntries)
 Return an array of RTENTRY structures which contain all the current route table entries.
NUTDEVICE * NutIpRouteQuery (u_long ip, u_long *gate)
 Find a device associated with a particular IP route.

Variables

RTENTRY * rteList

Function Documentation

int NutNetIfSetup (  NUTDEVICE *  dev,
u_long  ip_addr,
u_long  ip_mask,
u_long  gateway
) 
 

Network interface setup.

Parameters:
dev Identifies the network device to setup.
ip_addr Specified IP address in network byte order.
ip_mask Specified IP network mask in network byte order.
gateway Optional default gateway.
Returns:
0 on success, -1 otherwise.
Note:
Typical applications do not use this function, but call NutDhcpIfConfig() or NutNetIfConfig().

int NutNetIfConfig (  CONST char *  name,
void *  params,
u_long  ip_addr,
u_long  ip_mask
) 
 

Configure a network interface.

Devices must have been registered by NutRegisterDevice() before calling this function.

For Ethernet devices applications may alternatively call NutDhcpIfConfig(), which allows automatic configuration by DHCP or the so called ARP method.

Parameters:
name Name of the device to configure.
params Pointer to interface specific parameters. For Ethernet interfaces this parameter may be a pointer to a buffer containing the 6 byte long MAC address. This will override the MAC address stored in the non-volatile configuration memory. If this memory is uninitialized or not available, the MAC address must be specified. For PPP interfaces this parameter is ignored and should be set to zero.
ip_addr Specified IP address in network byte order. This must be a unique address within the Internet. If you do not directly communicate with other Internet hosts, you can use a locally assigned address. With PPP interfaces this may be set to 0.0.0.0, in which case the remote peer will be queried for an IP address.
ip_mask Specified IP network mask in network byte order. Typical Ethernet networks use 255.255.255.0, which allows upto 254 hosts. For PPP interfaces 255.255.255.255 is the default.
Returns:
0 on success, -1 otherwise.
Note:
The whole interface configuration has become a mess over the years and need a major redesign.

int NutNetIfConfig2 (  CONST char *  name,
void *  params,
u_long  ip_addr,
u_long  ip_mask,
u_long  gateway
) 
 

Configure a network interface including the default gateway.

Devices must have been registered by NutRegisterDevice() before calling this function.

For Ethernet devices applications may alternatively call NutDhcpIfConfig(), which allows automatic configuration by DHCP or the so called ARP method.

Parameters:
name Name of the device to configure.
params Pointer to interface specific parameters.
ip_addr Specified IP address in network byte order. This must be a unique address within the Internet. If you do not directly communicate with other Internet hosts, you can use a locally assigned address. With PPP interfaces this may be set to 0.0.0.0, in which case the remote peer will be queried for an IP address.
ip_mask Specified IP network mask in network byte order. Typical Ethernet networks use 255.255.255.0, which allows upto 254 hosts. For PPP interfaces 255.255.255.255 is the default.
gateway Specified IP address of gateway or next router in LAN.
Returns:
0 on success, -1 otherwise.
Note:
I do not like this function, because setting a gateway should be handled by NutIpRouteAdd(). It's not yet deprecated, but I recommend not to use it in application code.

u_long inet_addr (  CONST char *  str  ) 
 

Convert decimal dotted ASCII representation into numeric IP address.

Parameters:
str String containing the ASCII representation.
Returns:
IP address in network byte order.

char* inet_ntoa (  u_long  addr  ) 
 

Convert numeric IP address into decimal dotted ASCII representation.

Note:
This function is not thread safe. Each subsequent call will destroy the previous result. Applications should locally store the result before calling the function again or allowing other threads to call it.
Parameters:
addr IP address in network byte order.
Returns:
Pointer to a static buffer containing the ASCII representation.

u_short NutIpChkSumPartial (  u_short  ics,
CONST void *  buf,
size_t  len
) 
 

Calculate a partial IP checksum of a buffer.

The caller must create the one's complement of the final result.

Parameters:
ics Initial checksum from previous parts.
buf Pointer to the buffer.
len Number of bytes in the buffer.
Returns:
Partial checksum in network byte order.

u_short NutIpChkSum (  u_short  ics,
CONST void *  buf,
size_t  len
) 
 

Calculates an the final IP checksum over a block of data.

Unlike the partial checksum in NutIpChkSumPartial(), this function takes the one's complement of the final result, thus making it the full checksum.

void NutIpSetInputFilter (  NutIpFilterFunc  callbackFunc  ) 
 

Set filter function for incoming IP datagrams.

The callbackFunc is called by the IP layer on every incoming IP datagram. Thus it must not block. The implementer returns 0 for allow, -1 for deny.

It is recommended to set the filer after DHCP has done its thing, just in case your DHCP server is on a different subnet for example.

Parameters:
callbackFunc Pointer to callback function to filter IP packets. Set to 0 to disable the filter again.

void NutIpInput (  NUTDEVICE *  dev,
NETBUF *  nb
) 
 

Process incoming IP datagrams.

Datagrams addressed to other destinations and datagrams whose version number is not 4 are silently discarded.

Note:
This routine is called by the Ethernet layer on incoming IP datagrams. Applications typically do not call this function.
Parameters:
dev Identifies the device that received this datagram.
nb The network buffer received.

int NutIpOutput (  u_char  proto,
u_long  dest,
NETBUF *  nb
) 
 

Send IP datagram.

Route an IP datagram to the proper interface.

The function will not return until the data has been stored in the network device hardware for transmission. If the device is not ready for transmitting a new packet, the calling thread will be suspended until the device becomes ready again. If the hardware address of the target host needs to be resolved the function will be suspended too.

Parameters:
proto Protocol type.
dest Destination IP address. The function will determine the proper network interface by checking the routing table. It will also perform any neccessary hardware address resolution.
nb Network buffer structure containing the datagram. This buffer will be released if the function returns an error.
Returns:
0 on success, -1 otherwise.

Bug:
Broadcasts to multiple network devices will fail after the first device returns an error.

int NutIpRouteAdd (  u_long  ip,
u_long  mask,
u_long  gate,
NUTDEVICE *  dev
) 
 

Add a new entry to the IP routing table.

Note, that there is currently no support for detecting duplicates. Anyway, newer entries will be found first, because they are inserted in front of older entries. However, this works only for equal masks, i.e. new network routes will never overwrite old host routes.

Parameters:
ip Network or host IP address to be routed. Set 0 for default route.
mask Mask for this entry. -1 for host routes, 0 for default or net mask for net routes.
gate Route through this gateway, otherwise 0.
dev Network interface to use.
Returns:
0 on success, -1 otherwise.

int NutIpRouteDelAll (  NUTDEVICE *  dev  ) 
 

Delete all route table entries for the given device.

Parameters:
dev Pointer to the device. If NULL, it deletes all route table entries.
Returns:
0 on success, -1 otherwise.

int NutIpRouteDel (  u_long  ip,
u_long  mask,
u_long  gate,
NUTDEVICE *  dev
) 
 

Delete the specified route table entry.

All fields must exactly match an existing entry.

Parameters:
ip Network or host IP address of the route entry.
mask Mask for this entry. -1 for host routes, 0 for default or net mask for net routes.
gate Route through this gateway, 0 for default gate.
dev Network interface to use.
Returns:
0 on success, -1 otherwise.

RTENTRY* NutIpRouteList (  int *  numEntries  ) 
 

Return an array of RTENTRY structures which contain all the current route table entries.

The calling function is responsible for deleting the array.

Parameters:
numEntries Points to an integer, which receives the length of the array.
Returns:
Pointer to the array. Will be NULL in case of an error.

NUTDEVICE* NutIpRouteQuery (  u_long  ip,
u_long *  gate
) 
 

Find a device associated with a particular IP route.

Gateway routes will be automatically resolved up to four levels of redirection.

Parameters:
ip IP address to find a route for, given in network byte order.
gate Points to a buffer which optionally receives the IP address of a gateway. The pointer may be NULL, if the caller is not interested in this information.
Returns:
Pointer to the interface structure or NULL if no route was found.

Variable Documentation

RTENTRY* rteList
 

Linked list of routing entries.

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