Chapter 198. APIs

Standard networking

The APIs for the standard networking calls such as socket(), recv() and so on, are in header files relative to the top-level include directory, within the standard subdirectories as conventionally found in /usr/include. For example:

 install/include/arpa/tftp.h
 install/include/netinet/tcpip.h
 install/include/sys/socket.h
 install/include/sys/socketvar.h
 install/include/sys/sockio.h

network.h at the top level defines various extensions, for example the API init_all_network_interfaces(void) described above. We advise including network.h whether you use these features or not.

In general, using the networking code may require definition of two symbols: _KERNEL and __ECOS. _KERNEL is not normally required; __ECOS is normally required. So add this to your compile lines for files which use the network stack:

	-D__ECOS

To expand a little, it’s like this because this is a port of a standard distribution external to Red Hat. One goal is to perturb the sources as little as possible, so that upgrading and maintenance from the external distribution is simplified. The __ECOS symbol marks out Red Hat’s additions in making the port. The _KERNEL symbol is traditional UNIX practice: it distinguishes a compilation which is to be linked into the kernel from one which is part of an application. eCos applications are fully linked, so this distinction does not apply. _KERNEL can however be used to control the visibility of the internals of the stack, so depending on what features your application uses, it may or may not be necessary.

The include file network.h undefines _KERNEL unconditionally, to provide an application-like compilation environment. If you were writing code which, for example, enumerates the stack’s internal structures, that is a kernel-like compilation environment, so you would need to define _KERNEL (in addition to __ECOS) and avoid including network.h.

2017-02-09
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