SCNetwork

Overview

The SCNetwork API contains functions an application can use to determine remote host reachability and notify the system of configuration changes.

The two SCNetworkCheckReachability functions allow an application to determine the status of the system's current network configuration and the reachability of a target host or address.

"Reachability" reflects whether a data packet, sent by an application into the network stack, can leave the local computer. Note that reachability does not guarantee that the data packet will actually be received by the host.

Functions

SCNetworkCheckReachabilityByAddress

SCNetworkCheckReachabilityByName

SCNetworkInterfaceRefreshConfiguration

Boolean SCNetworkCheckReachabilityByAddress ( 
    const struct sockaddr *address, 
    socklen_t addrlen, 
    SCNetworkConnectionFlags *flags );  

Parameters

address

The network address of the desired host.

addrlen

The length, in bytes, of the address.

flags

A pointer to memory that will be filled with a set of SCNetworkConnectionFlags detailing the reachability of the specified address.

Return Value

Returns TRUE if the network connection flags are valid; FALSE if the status could not be determined.

Discussion

Determines if the given network address is reachable using the current network configuration.

Boolean SCNetworkCheckReachabilityByName ( 
    const char *nodename, 
    SCNetworkConnectionFlags *flags );  

Parameters

nodename

The node name of the desired host. This name would be the same as that passed to the gethostbyname(3) or getaddrinfo(3) functions.

flags

A pointer to memory that will be filled with a set of SCNetworkConnectionFlags detailing the reachability of the specified node name.

Return Value

Returns TRUE if the network connection flags are valid; FALSE if the status could not be determined.

Discussion

Determines if the given network host or node name is reachable using the current network configuration.

Deprecated: in version 10.4. Replaced with SCNetworkInterfaceForceConfigurationRefresh.

Boolean SCNetworkInterfaceRefreshConfiguration ( 
    CFStringRef ifName );  

Parameters

ifName

The BSD name of the network interface, such as CFSTR("en0").

Return Value

Returns TRUE if the notification was sent; FALSE otherwise.

Discussion

Sends a notification to interested configuration agents to have them immediately retry their configuration over a particular network interface.

Note: This function must be invoked by root (uid == 0).

Availability

Deprecated in Mac OS X v10.5.

Enumerations

enum { 
    kSCNetworkFlagsTransientConnection = 1<<0, 
    kSCNetworkFlagsReachable = 1<<1, 
    kSCNetworkFlagsConnectionRequired = 1<<2, 
    kSCNetworkFlagsConnectionAutomatic = 1<<3, 
    kSCNetworkFlagsInterventionRequired = 1<<4, 
    kSCNetworkFlagsIsLocalAddress = 1<<16, 
    kSCNetworkFlagsIsDirect = 1<<17 
};  

Constants

kSCNetworkFlagsTransientConnection

This flag indicates that the specified nodename or address can be reached via a transient connection, such as PPP.

kSCNetworkFlagsReachable

This flag indicates that the specified nodename or address can be reached using the current network configuration.

kSCNetworkFlagsConnectionRequired

This flag indicates that the specified nodename or address can be reached using the current network configuration, but a connection must first be established.

As an example, this status would be returned for a dialup connection that was not currently active, but could handle network traffic for the target system.

kSCNetworkFlagsConnectionAutomatic

This flag indicates that the specified nodename or address can be reached using the current network configuration, but a connection must first be established. Any traffic directed to the specified name or address will initiate the connection.

kSCNetworkFlagsInterventionRequired

This flag indicates that the specified nodename or address can be reached using the current network configuration, but a connection must first be established. In addition, some form of user intervention will be required to establish this connection, such as providing a password, an authentication token, etc.

Note: At the present time, this flag will only be returned in the case where you have a dial-on-traffic configuration (ConnectionAutomatic), where an attempt to connect has already been made, and where some error (e.g. no dial tone, no answer, bad password, ...) was encountered during the automatic connection attempt. In this case the PPP controller will stop attempting to establish a connection until the user has intervened.

kSCNetworkFlagsIsLocalAddress

This flag indicates that the specified nodename or address is one associated with a network interface on the current system.

kSCNetworkFlagsIsDirect

This flag indicates that network traffic to the specified nodename or address will not go through a gateway, but is routed directly to one of the interfaces in the system.

Discussion

Flags that indicate whether the specified network nodename or address is reachable, whether a connection is required, and whether some user intervention may be required when establishing a connection.

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Last Updated: 2008-03-11