Initial PoC of the madness

cleanup.sh

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+#!/bin/sh
+
+for mach in machines/*; do
+	statedir="state/${mach##*/}"
+	rm -rvf "$statedir"
+done

init-shim.sh

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+#!/bin/sh
+unshare -rnm ./init.sh

init.sh

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+#!/bin/sh
+
+set -eu
+for mach in machines/*; do
+	$mach/run-shim.sh
+done
+
+tmux

lib.shs

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+#!/bin/false
+
+mach=$(basename $(dirname "$0"))
+
+netns=netns
+nethorror_root="`pwd`" # and hope?
+
+ensure_started() {
+	test -e state/$mach/$netns || machines/$mach/start.sh
+}
+
+attach() {
+	machines/$mach/attach.sh "$@"
+}
+
+setup_statedir() {
+	dir="state/$mach"
+	mkdir "$dir"
+	for ns in $namespaces; do
+		nsfile="${ns#*=}"
+		touch "$nsfile"
+	done
+}
+

machines/iana/attach.sh

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+#!/bin/sh
+set -eu
+. ./lib.shs
+. machines/$mach/opts.shs
+
+nsenter --wdns=$nethorror_root $namespaces "$@"

machines/iana/opts.shs

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+#!/bin/false
+
+namespaces="--net=./state/$mach/netns --mount=./state/$mach/mntns"

machines/iana/run-shim.sh

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+#!/bin/sh
+
+set -eu
+. ./lib.shs
+
+ensure_started
+attach machines/$mach/setup.sh

machines/iana/setup.sh

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+#!/bin/sh
+set -eu
+
+# typically: bring up the networks
+# TODO: veth naming?
+
+# dummy for now:
+ip route add unreachable 192.168.3.0/24

machines/iana/start.sh

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+#!/bin/sh
+set -eu
+. ./lib.shs
+. machines/$mach/opts.shs
+
+setup_statedir
+
+unshare $namespaces /bin/true # just create the namespaces
+
+# TODO: connect to the bridges