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Network handling

Network handling

Owned by Michael Bachmeier
Last updated: Mar 10, 2022 by Michael StruweVersion comment


This GOAL core module provides an interface to the application for TCP/IP connections, see Figure 15. A TCP/IP stack is required. The TCP/IP stack must be enabled by the compiler-define GOAL_CONFIG_TCPIP_STACK = 1.

 

Figure: topology for net channels


GOAL creates the number of GOAL_CONFIG_NET_CHAN_MAX net channels during initialization automatically for this purpose. Each net channel can be opened as one of the following network connection types:

  • GOAL_NET_UDP_SERVER

  • GOAL_NET_UDP_CLIENT

  • GOAL_NET_TCP_LISTENER represents the TCP server

  • GOAL_NET_TCP_CLIENT

The connection between the net channels and the TCP/IP stack is addressed by the local IP address, local netmask and local gateway address. The connection between the TCP/IP Stack to a remote Ethernet device is addressed by the remote IP address, the remote netmask and remote gateway address. The rules for the determination of the local address are shown in Figure 16. The local address is determined during creation of the net channels in the state GOAL_FSA_INIT automatically. The remote address is configured by calling the function goal_netOpen().

Figure: determination of the local address of net channels

 

The connection to the application is realized by a callback function, see Chapter: Callback functions. Each net channel must be activated before data can be transmitted or received via the net channel. The activation is done by function goal_netActivate().
The following options are available to configure the TCP/IP stack:

  • GOAL_NET_OPTION_NONBLOCK: socket connection between net channel and TCP/IP stack is

    • 0: blocking

    • 1: non-blocking

  • GOAL_NET_OPTION_BROADCAST:

    • 0: no broadcast reception

    • 1: broadcast reception supported

  • GOAL_NET_OPTION_TTL:

    • set TTL value in IP-header

  • GOAL_NET_OPTION_TOS:

    • set TOS-value in IP-header

  • GOAL_NET_OPTION_MCAST_ADD:

    • enable the specified multicast address for the receipt of multicast packets

  • GOAL_NET_OPTION_MCAST_DROP:

    • disable the specified multicast address for the receipt of multicast packets

  • GOAL_NET_OPTION_REUSEADDR:

    • 0: TCP/IP socket shall be not reusable

    • 1: TCP/IP socket shall be reusable

The options can be can be changed by function goal_netSetOption(). The availability and the default setting of the options depends on the TCP/IP stack.

  • GOAL files:

    • goal_net.[h,c], goal_net_dhcp.[h,c], goal_net_cli.c

  • example:

    • …\goal\appl\00410_goal\tcp_client

Configuration

Compiler-defines


The following compiler-defines are available to configure the network handling:

  • GOAL_CONFIG_TCPIP_STACK:

    • 0: network handling is disabled (default)

    • 1: network handling is enabled

  • GOAL_CONFIG_NET_CHAN_MAX:

    • number of network channels (default: 4)

  • GOAL_CONFIG_DHCP:

    • 0: static assignment of IP-addresses (default)

    • 1: dynamic assignment of IP-addresses via DHCP

  • GOAL_CONFIG_IP_STATS:

    • 0: output of IP-statistics switched off (default)

    • 1: output of IP-statistics switched on

CM-variables


The following CM-variables are available to configure the network handling:

Table: NET_CM_VAR_IP

CM-Module-ID

GOAL_ID_NET

CM-variable-ID

0

CM-variable name

NET_CM_VAR_IP

Description

IP address of first interface

CM data type

GOAL_CM_IPV4

Size

4 bytes

Default value

from NVS or 0

 

Table: NET_CM_VAR_ NETMASK

CM-Module-ID

GOAL_ID_NET

CM-variable-ID

1

CM-variable name

NET_CM_VAR_ NETMASK

Description

netmask of first interface

CM data type

GOAL_CM_IPV4

Size

4 bytes

Default value

from NVS or 0

 

Table: NET_CM_VAR_ GW

CM-Module-ID

GOAL_ID_NET

CM-variable-ID

2

CM-variable name

NET_CM_VAR_ GW

Description

gateway of first interface

CM data type

GOAL_CM_IPV4

Size

4 bytes

Default value

from NVS or 0

 

Table: NET_CM_VAR_ COMMIT

CM-Module-ID

GOAL_ID_NET

CM-variable-ID

3

CM-variable name

NET_CM_VAR_ COMMIT

Description

Write any value to this CM-variable applies the IP settings

CM data type

GOAL_CM_UINT8

Size

1 byte

Default value

from NVS or 0

 

Table: NET_CM_VAR_ VALID

CM-Module-ID

GOAL_ID_NET

CM-variable-ID

4

CM-variable name

NET_CM_VAR_ VALID

Description

validity of IP address:

  • 0: stored IP address is not valid, interface settings originate from network stack of system

  • 1: stored IP address is valid, will be applied to interface at start of device

CM data type

GOAL_CM_UINT8

Size

1 byte

Default value

from NVS or 0

 

Table: NET_CM_VAR_ DHCP_ENABLED

CM-Module-ID

GOAL_ID_NET

CM-variable-ID

5

CM-variable name

NET_CM_VAR_ DHCP_ENABLED

Description

CM-variable to disable/enable DHCP:

  • 0: DHCP disabled

  • 1: DHCP enabled

CM data type

GOAL_CM_UINT8

Size

1 byte

Default value

from NVS or 0

 

Table: NET_CM_VAR_ DHCP_STATE

CM-Module-ID

GOAL_ID_NET

CM-variable-ID

6

CM-variable name

NET_CM_VAR_ DHCP_STATE

Description

CM-variable to indicate the current state of DHCP if DHCP is enabled:

  • 0: DHCP initialized

  • 1: DHCP selecting server

  • 2: DHCP requesting configuration

  • 3: DHCP IP address bound

  • 4: DHCP renewing configuration

  • 5: DHCP rebinding IP address to interface

CM data type

GOAL_CM_UINT8

Size

1 byte

Default value

from NVS or 0

 

Table: NET_CM_VAR_ DNS0

CM-Module-ID

GOAL_ID_NET

CM-variable-ID

7

CM-variable name

NET_CM_VAR_ DNS0

Description

first DNS server of the first interface

CM data type

GOAL_CM_IPV4

Size

4 bytes

Default value

from NVS or 0

 

Table: NET_CM_VAR_ DNS1

CM-Module-ID

GOAL_ID_NET

CM-variable-ID

8

CM-variable name

NET_CM_VAR_ DNS1

Description

second DNS server of the first interface

CM data type

GOAL_CM_IPV4

Size

4 bytes

Default value

from NVS or 0

 

Table: NET_CM_VAR_ HOSTNAME

CM-Module-ID

GOAL_ID_NET

CM-variable-ID

9

CM-variable name

NET_CM_VAR_ HOSTNAME

Description

host name of the first interface

CM data type

GOAL_CM_STRING

Size

20 bytes

Default value

from NVS or 0

Callback functions


The user of this module can specify the following callback function for each network channel:

Table: Callback function cbNetFunc()

Prototype

void cbNetFunc(GOAL_NET_CB_TYPE_T cbType, struct GOAL_NET_CHAN_T *pChan, struct GOAL_BUFFER_T *pBuf)

Description

This callback function is used for the following operations:

  • GOAL_NET_CB_NEW_DATA: to transfer received data to the application

  • GOAL_NET_CB_NEW_SOCKET: to inform the application, that a new connection of a net channel to the TCP/IP stack was opened

  • GOAL_NET_CB_CONNECTED: to inform the application, that the net channel was activated

  • GOAL_NET_CB_CLOSING: to inform the application, that the net channel was closed

Parameters

cbType

type of operation:

  • GOAL_NET_CB_NEW_DATA,

  • GOAL_NET_CB_NEW_SOCKET,

  • GOAL_NET_CB_CONNECTED,

  • GOAL_NET_CB_CLOSING



pChan

handle of the network channel



pBuf

for GOAL_NET_CB_NEW_DATA: buffer with the received data
else: NUL

Return values

none

Category

optional
If a callback function is not available, specify NULL in the call of goal_netOpen().

Registration

during runtime via function goal_netOpen()

IP statistics


GOAL provides the possibility to analyze communication problems by IP statistics. The supported IP statistics bases on /RFC_1213/ and depend on the platform. GOAL provides the following typical IP statistics:

Table: provided IP statistic by GOAL

GOAL number of IP statistic



Description /RFC_1213/

Number

Identifier (object type)

0

GOAL_NET_IP_STATS_IPINHDRERRORS

The number of input datagrams discarded due to errors in their IP headers, including bad checksums, version number mismatch, other format errors, time-to-live exceeded, errors discovered in processing their IP options, etc.

1

GOAL_NET_IP_STATS_IPINADDRERRORS

The number of input datagrams discarded because the IP address in their IP headers destination field was not a valid address to be received at this entity. This count includes invalid addresses and addresses of unsupported classes. For entities which are not IP gateways and therefore do not forward datagrams, this counter includes datagrams discarded because the destination address was not a local address.

2

GOAL_NET_IP_STATS_IPINUNKNOWNPROTOS

The number of locally-addressed datagrams received successfully but discarded because of an unknown or unsupported protocol.

3

GOAL_NET_IP_STATS_IPINDISCARDS

The number of input IP datagrams for which no problems were encountered to prevent their continued processing, but which were discarded. Note that this counter does not include any datagrams discarded while awaiting re-assembly.

4

GOAL_NET_IP_STATS_IPINDELIVERS

The total number of input datagrams successfully delivered to IP user-protocols (including ICMP).

5

GOAL_NET_IP_STATS_IPOUTREQUESTS

The total number of IP datagrams which local IP user-protocols (including ICMP) supplied to IP in requests for transmission. Note that this counter does not include any datagrams counted in 14/GOAL_NET_IP_STATS_IPFORWDATAGRAMS.

6

GOAL_NET_IP_STATS_IPOUTDISCARDS

The number of output IP datagrams for which no problem was encountered to prevent their transmission to their destination, but which were discarded. Note that this counter would include datagrams counted in 14/GOAL_NET_IP_STATS_IPFORWDATAGRAMS if any such packets met this discard criterion.

7

GOAL_NET_IP_STATS_IPOUTNOROUTES

The number of IP datagrams discarded because no route could be found to transmit them to their destination. Note that this counter includes any packets counted in 14/GOAL_NET_IP_STATS_IPFORWDATAGRAMS which meet this "no-route" criterion. Note that this includes any datagram which a host cannot route because all of its default gateways are down.

8

GOAL_NET_IP_STATS_IPREASMOKS

The number of IP datagrams successfully reassembled.

9

GOAL_NET_IP_STATS_IPREASMFAILS

The number of failures detected by the IP reassembly algorithm. Note that this is not necessarily a count of discarded IP fragments since some algorithms can lose track of the number of fragments by combining them as they are received.

10

GOAL_NET_IP_STATS_IPFRAGOKS

The number of IP datagrams that have been successfully fragmented at this entity.

11

GOAL_NET_IP_STATS_IPFRAGFAILS

The number of IP datagrams that have been discarded because they needed to be fragmented at this entity but could not be.

12

GOAL_NET_IP_STATS_IPFRAGCREATES

The number of IP datagram fragments that have been generated as a result of fragmentation at this entity.

13

GOAL_NET_IP_STATS_IPREASMREQGDS

The number of IP fragments received which needed to be reassembled at this entity.

14

GOAL_NET_IP_STATS_IPFORWDATAGRAMS

The number of input datagrams for which this entity was not their final IP destination, as a result of which an attempt was made to find a route to forward them to that final destination. In entities which do not act as IP gateways, this counter will include only those packets which were source-routed via this entity, and the source-route option processing was successful.

15

GOAL_NET_IP_STATS_IPINRECEIVES

The total number of input datagrams received from interfaces, including those received in error.

16

GOAL_NET_IP_STATS_TCPACTIVEOPENS

The number of times TCP connections have made a direct transition from the CLOSED state to the SYN-SENT state.

17

GOAL_NET_IP_STATS_TCPPASSIVEOPENS

The number of times TCP connections have made a direct transition from the LISTEN state to the SYN-RCVD state.

18

GOAL_NET_IP_STATS_TCPATTEMPTFAILS

The number of times TCP connections have made a direct transition from either the SYN-SENT or SYN-RCVD state to the CLOSED state, plus the number of times TCP connections have made a direct transition from the SYN-RCVD state to the LISTEN state.

19

GOAL_NET_IP_STATS_TCPESTABRESETS

The number of times TCP connections have made a direct transition from either the ESTABLISHED or CLOSE-WAIT state to the CLOSE state.

20

GOAL_NET_IP_STATS_TCPOUTSEGS

The total number of segments sent, including those on current connections but excluding those containing only retransmitted octets.

21

GOAL_NET_IP_STATS_TCPRETRANSSEGS

The total number of segments retransmitted. That is the number of TCP segments transmitted containing one or more previously transmitted.

22

GOAL_NET_IP_STATS_TCPINSEGS

The total number of segments received, including those received in error. This count includes segments received on currently established connections.

23

GOAL_NET_IP_STATS_TCPINERRS

The total number of segments received in error.

24

GOAL_NET_IP_STATS_TCPOUTRSTS

The number of TCP segments sent containing the RST flag.

25

GOAL_NET_IP_STATS_UDPINDATAGRAMS

The total number of UDP datagrams delivered to UDP user.

26

GOAL_NET_IP_STATS_UDPNOPORTS

The total number of received UDP datagrams for which there was no application at the destination port.

27

GOAL_NET_IP_STATS_UDPINERRORS

The number of received UDP datagrams that could not be delivered for reasons other than the lack of an application at the destination port.

28

GOAL_NET_IP_STATS_UDPOUTDATAGRAMS

The total number of UDP datagrams sent from this entity.

29

GOAL_NET_IP_STATS_ICMPINMSGS

The total number of ICMP messages which the entity received. Note that this counter includes all those counted by 30/ GOAL_NET_IP_STATS_ICMPINERRORS.

30

GOAL_NET_IP_STATS_ICMPINERRORS

The number of ICMP messages which the entity received but determined as having ICMP-specific errors.

31

GOAL_NET_IP_STATS_ICMPINDESTUNREACHS

The number of ICMP Destination Unreachable messages received.

32

GOAL_NET_IP_STATS_ICMPINTIMEEXDS

The number of ICMP Time Exceeded messages received.

33

GOAL_NET_IP_STATS_ICMPINPARMPROBS

The number of ICMP Parameter Problem messages received.

34

GOAL_NET_IP_STATS_ICMPINSRCQUENCHS

The number of ICMP Source Quench messages received.

35

GOAL_NET_IP_STATS_ICMPINREDIRECTS

The number of ICMP Redirect messages received.

36

GOAL_NET_IP_STATS_ICMPINECHOS

The number of ICMP Echo (request) messages received.

37

GOAL_NET_IP_STATS_ICMPINECHOREPS

The number of ICMP Echo Reply messages received.

38

GOAL_NET_IP_STATS_ICMPINTIMESTAMPS

The number of ICMP Timestamp (request) messages received.

39

GOAL_NET_IP_STATS_ICMPINTIMESTAMPREPS

The number of ICMP Timestamp Reply messages received.

40

GOAL_NET_IP_STATS_ICMPINADDRMASKS

The number of ICMP Address Mask Request messages received.

41

GOAL_NET_IP_STATS_ICMPINADDRMASKREPS

The number of ICMP Address Mask Reply messages received.

42

GOAL_NET_IP_STATS_ICMPOUTMSGS

The total number of ICMP messages which this entity attempted to send. Note that this counter includes all those counted by 43/ GOAL_NET_IP_STATS_ICMPOUTERRORS.

43

GOAL_NET_IP_STATS_ICMPOUTERRORS

The number of ICMP messages which this entity did not send due to problems discovered within ICMP such as a lack of buffers. This value should not include errors discovered outside the ICMP layer such as the inability of IP zo route the resultant datagram. In some implementations there may be no types of error which contribute to this counter's value.

44

GOAL_NET_IP_STATS_ICMPOUTDESTUNREACHS

The number of ICMP Destination Unreachable message sent.

45

GOAL_NET_IP_STATS_ICMPOUTTIMEEXCDS

The number of ICMP Time Exceeded messages sent.

46

GOAL_NET_IP_STATS_ICMPOUTECHOS

The number of ICMP Echo (request) messages sent.

47

GOAL_NET_IP_STATS_ICMPOUTECHOREPS

The number of TCMP Echo Reply messages sent.

48

GOAL_NET_IP_STATS_IFINOCTETS

The total number of octets received on the interface, including framing characters.

49

GOAL_NET_IP_STATS_IFINUCASTPKTS

The number of subnetwork-unicast packets delivered to a higher-layer protocol.

50

GOAL_NET_IP_STATS_IFINNUCASTPKTS

The number of non-unicast packets delivered to a higher-layer protocol.

51

GOAL_NET_IP_STATS_IFINDISCARDS

The number of inbound packet which were chosen to be discarded even though no errors had been detected to prevent their being deliverable to a higher-layer protocol.

52

GOAL_NET_IP_STATS_IFINERRORS

The number of inbound packets that contained errors preventing them from being deliverable to a higher-layer protocol.

53

GOAL_NET_IP_STATS_IFINUNKNOWNPROTOS

The number of packets received via the interface which were discarded because of an unknown or unsupported protocol.

54

GOAL_NET_IP_STATS_IFOUTOCTETS

The total number of octets transmitted out of the interface, including framing characters.

55

GOAL_NET_IP_STATS_IFOUTUCASTPKTS