ETHER: Add Apple vmnet support when running on macOS

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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.

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This commit is contained in:

Mark Pizzolato

2025-06-06 14:51:46 -10:00

parent fd60c6b0f7

commit 61fe27cb47

7 changed files with 1491 additions and 638 deletions

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sim_ether.c

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