Initial implementation of network configuration

1 files changed, 95 insertions, 1 deletions

diff --git a/init b/init
index 0caf718..b733fde 100755
--- a/init
+++ b/init
@@ -57,7 +57,101 @@ udevadm settle || true
 cmdline="$(cat /proc/cmdline)"
 info "boot cmdline: $cmdline"
 
-sleep 2
+# Figure out network configuration and generate the corresponding
+# /etc/network/interfaces.
+#
+info "starting network..."
+
+# We are using udev's predictable interface names. The two character prefixes
+# based on the type of interface:
+#
+#  en -- ethernet
+#  sl -- serial line IP (slip)
+#  wl -- wlan
+#  ww -- wwan
+#
+eth_all="$(cd /sys/class/net && ls -d en?*)"
+
+if [ -z "$eth_all" ]; then
+  info "no ethernet interfaces found among:"
+  ip link show
+fi
+
+eth=
+eth_up=
+for s in 1 2 4 8; do
+
+  # Try to bring them all up and find the one that has carrier.
+  #
+  for i in $eth_all; do
+    ip link set "$i" up || true
+  done
+
+  sleep "$s"
+
+  for i in $eth_all; do
+    if [ "$(cat "/sys/class/net/$i/carrier")" -eq "1" ]; then
+      info "detected carrier on $i"
+      eth_up+=" $i"
+    fi
+  done
+
+  # Bring them all down.
+  #
+  for i in $eth_all; do
+    ip link set "$i" down || true
+  done
+
+  # If we didn't find anything, try to wait for carrier longer.
+  #
+  if [ -z "$eth_up" ]; then
+    continue
+  fi
+
+  # If we end up with several interfaces we simply unleash dhcp on all of
+  # them and use the first that gets configured.
+  #
+  # Note also that it's possible the interface that we want is not yet ready
+  # in which case we will try to wait for carrier a bit longer.
+  #
+  for i in $eth_up; do
+    if dhclient -v "$i"; then
+      eth="$i"
+      break
+    fi
+  done
+
+  if [ -n "$eth" ]; then
+    break
+  fi
+done
+
+if [ -z "$eth_up" ]; then
+  error "no ethernet interfaces with carrier among:"
+  ip link show
+fi
+
+if [ -z "$eth" ]; then
+  error "no ethernet interfaces with DHCP among:"
+  ip link show
+fi
+
+mac="$(cat "/sys/class/net/$eth/address")"
+
+info "configured $eth ($mac)"
+
+# Set the hostname.
+#
+hname="$(hostname)"
+
+if [ "$hname" = "(none)" ]; then
+  hname="build-$(sed -e 's/://g' <<<"$mac")"
+  hostname "$hname"
+fi
+
+echo "$hname" >/etc/hostname
+
+info "hostname $hname"
 
 # --machine-id
 #