test: Use context system for guest commands

Extends the context system in the test scripts to allow executing commands
within a guest.  Do this without requiring an existing network in the guest
by using socat to run ssh via a vsock connection.

We do need some additional "sleep"s in the tests, because the new
faster dispatch means that sometimes we attempt to connect before
socat has managed to listen.

For now, only use this for the plain "passt" tests.  The "passt_in_ns" and
other tests have additional complications we still need to deal with.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

test/lib/context

@@ -41,12 +41,38 @@ context_setup_nsenter() {
 	echo "nsenter $@ sh -c" > "${__prefix}.enter"
 }
 
+# context_setup_guest() - Create a new context for running commands in a guest
+# $1:        Context name
+# $2:        CID to use for vsock
+context_setup_guest() {
+	__name="$1"
+	__cid="$2"
+	__prefix="${LOGDIR}/context_${__name}"
+	context_setup_common "${__name}"
+
+	cat > "${__prefix}.ssh" <<EOF
+Host ${__name}
+	User root
+	UserKnownHostsFile ${__prefix}.hosts
+	StrictHostKeyChecking no
+	IdentityFile ${BASEPATH}/guest-key
+	IdentityAgent none
+	ProxyCommand socat - VSOCK-CONNECT:${__cid}:22
+EOF
+	echo "ssh -F ${__prefix}.ssh ${__name}" > "${__prefix}.enter"
+
+	# Wait for the guest to be booted and accepting connections
+	while ! ssh -F "${__prefix}.ssh" "${__name}" :; do
+		sleep 0.1
+	done
+}
+
 # context_teardown() - Remove a context (leave log files intact)
 # $1:	Context name
 context_teardown() {
 	__name="$1"
 	__prefix="${LOGDIR}/context_${__name}"
-	rm -f "${__prefix}.enter"
+	rm -f "${__prefix}.enter" "${__prefix}.ssh" "${__prefix}.hosts"
 }
 
 # context_exists() - Test if a context currently exists