Base vmnet support covers bridged network interfaces and locally
accessible TAP network connections. These reflect the vmnet bridged
and host behaviors which are leveraged under the covers, but configured
using the original sim_ether commands. The resulting bridged case
behaves like the Windows network connections do (with direct access
to and from the local LAN as well as the host system) using the natural
interface name. NAT behaviors are specifically supported using the
original SLiRP code since the vmnet support depends on simulators
primarily getting IPv4 addressing via DHCP, but essentially no simh
simulators actually had OS network code which used DHCP and all
merely used static network address setup. The vmnet (shared/NAT)
support can't be configured to operate with the same DHCP and static
IP addresses provided by the original SLiRP implementation and to
avoid the need to specifically change hard coded simulator IPv4
addresses before things could work.
- Detect which network interfaces are WiFi (when possible) and thus
not useful candidates for bridging.
- Cleanly report when running as root is needed.
- Avoid allowing network connections to interfaces which aren't
actually connected to a network.
- Add support to explicitly set TAP network host side network
interface's IPv4 address and netmask. This optional support is
provided specifically for the Apple vmnet case, but not for other
platforms using TAP network connections due to the various ways
that must be handled with external commands.
- Add host system's IPv4 address, netmask, media type and connection
state to interface descriptions visible via SHOW ETHERNET.
Some system environments may have a significant number of potential
network interfaces, most of which aren't interesting to connect
simulators to. Knowing which interfaces are actually in useful
states helps users select the correct device.
The vmnet aspect of this functionality was originally inspired by
Calvin Buckley's pull request to the open-simh repository. That
solution wouldn't actually operate well certainly for NAT cases due
to the forced DHCP to non-configurable address blocks and the lack
of any way to support static addresses TCP or UDP port mapping.
- Add common system includes used in may places which are allowed
and thus added directly in sim_defs.h.
- Separate completely private system data structures and system APIs
for use only by SCP library routines into sim_scp_private.h.
Outbound connections are rare and most may have wanted explicit blocking
behavior, so no one noticed the missing non-blocking case.
Any place which did do outbound connects have explicitly added
SIM_SOCK_OPT_BLOCKING so that the prior behavior is preserved.
The SIM_SOCK_OPT_BLOCKING flag is no honored as it was originally
intended to be.
These changes facilitate more robust parameter type checking and helps
to identify unexpected coding errors.
Most simulators can now also be compiled with a C++ compiler without
warnings.
Additionally, these changes have also been configured to facilitate easier
backporting of simulator and device simulation modules to run under the
simh v3.9+ SCP framework.
