mirror of
https://github.com/topjohnwu/ndk-busybox.git
synced 2024-11-24 12:19:49 +00:00
45 lines
1.6 KiB
Plaintext
45 lines
1.6 KiB
Plaintext
This document is meant to convince you to not use ifup/ifdown.
|
|
|
|
|
|
The general problem with ifupdown is that it is "copulated in vertical
|
|
fashion" by design. It tries to do the job of shell script in C,
|
|
and this is invariably doomed to fail. You need ifup/ifdown
|
|
to be adaptable by local admins, and C is an extremely poor choice
|
|
for that.
|
|
|
|
We are doomed to have problems with ifup/ifdown. Just look as this code:
|
|
|
|
static const struct dhcp_client_t ext_dhcp_clients[] = {
|
|
{ "dhcpcd", "<up cmd>", "<down cmd>" },
|
|
{ "dhclient", ........ },
|
|
{ "pump", ........ },
|
|
{ "udhcpc", ........ },
|
|
};
|
|
|
|
static int dhcp_down(struct interface_defn_t *ifd, execfn *exec)
|
|
{
|
|
#if ENABLE_FEATURE_IFUPDOWN_EXTERNAL_DHCP
|
|
int i ;
|
|
for (i = 0; i < ARRAY_SIZE(ext_dhcp_clients); i++) {
|
|
if (exists_execable(ext_dhcp_clients[i].name))
|
|
return execute(ext_dhcp_clients[i].stopcmd, ifd, exec);
|
|
}
|
|
bb_error_msg("no dhcp clients found, using static interface shutdown");
|
|
return static_down(ifd, exec);
|
|
#elif ENABLE_UDHCPC
|
|
return execute("kill "
|
|
"`cat /var/run/udhcpc.%iface%.pid` 2>/dev/null", ifd, exec);
|
|
#else
|
|
return 0; /* no dhcp support */
|
|
#endif
|
|
}
|
|
|
|
How the hell it is supposed to work reliably this way? Just imagine that
|
|
admin is using pump and ifup/ifdown. It works. Then, for whatever reason,
|
|
admin installs dhclient, but does NOT use it. ifdown will STOP WORKING,
|
|
just because it will see installed dhclient binary in e.g. /usr/bin/dhclient!
|
|
This is stupid.
|
|
|
|
I seriously urge people to not use ifup/ifdown.
|
|
Use something less brain damaged.
|