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| author | Denis Vlasenko <vda.linux@googlemail.com> | 2007-08-25 22:16:04 +0000 |
|---|---|---|
| committer | Denis Vlasenko <vda.linux@googlemail.com> | 2007-08-25 22:16:04 +0000 |
| commit | 6dd333dfe677858e73651b80d3d190eebddf2709 (patch) | |
| tree | c7230c39b45e354cbec3d17c37a3db3f7d9ba624 /docs/ifupdown_design.txt | |
| parent | 30bab71f7bd8b3b31fedb90c2510fc89ade04619 (diff) | |
| download | busybox-w32-6dd333dfe677858e73651b80d3d190eebddf2709.tar.gz busybox-w32-6dd333dfe677858e73651b80d3d190eebddf2709.tar.bz2 busybox-w32-6dd333dfe677858e73651b80d3d190eebddf2709.zip | |
Start a small document "why ifupdown is bad"
Diffstat (limited to 'docs/ifupdown_design.txt')
| -rw-r--r-- | docs/ifupdown_design.txt | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/docs/ifupdown_design.txt b/docs/ifupdown_design.txt new file mode 100644 index 000000000..9df579289 --- /dev/null +++ b/docs/ifupdown_design.txt | |||
| @@ -0,0 +1,44 @@ | |||
| 1 | This document is meant to convince you to not use ifup/ifdown. | ||
| 2 | |||
| 3 | |||
| 4 | The general problem with ifupdown is that it is "copulated in vertical | ||
| 5 | fashion" by design. It tries to do the job of shell script in C, | ||
| 6 | and this is invariably doomed to fail. You need ifup/ifdown | ||
| 7 | to be adaptable by local admins, and C is an extremely poor choice | ||
| 8 | for that. | ||
| 9 | |||
| 10 | We are doomed to have problems with ifup/ifdown. Just look as this code: | ||
| 11 | |||
| 12 | static const struct dhcp_client_t ext_dhcp_clients[] = { | ||
| 13 | { "dhcpcd", "<up cmd>", "<down cmd>" }, | ||
| 14 | { "dhclient", ........ }, | ||
| 15 | { "pump", ........ }, | ||
| 16 | { "udhcpc", ........ }, | ||
| 17 | }; | ||
| 18 | |||
| 19 | static int dhcp_down(struct interface_defn_t *ifd, execfn *exec) | ||
| 20 | { | ||
| 21 | #if ENABLE_FEATURE_IFUPDOWN_EXTERNAL_DHCP | ||
| 22 | int i ; | ||
| 23 | for (i = 0; i < ARRAY_SIZE(ext_dhcp_clients); i++) { | ||
| 24 | if (exists_execable(ext_dhcp_clients[i].name)) | ||
| 25 | return execute(ext_dhcp_clients[i].stopcmd, ifd, exec); | ||
| 26 | } | ||
| 27 | bb_error_msg("no dhcp clients found, using static interface shutdown"); | ||
| 28 | return static_down(ifd, exec); | ||
| 29 | #elif ENABLE_APP_UDHCPC | ||
| 30 | return execute("kill " | ||
| 31 | "`cat /var/run/udhcpc.%iface%.pid` 2>/dev/null", ifd, exec); | ||
| 32 | #else | ||
| 33 | return 0; /* no dhcp support */ | ||
| 34 | #endif | ||
| 35 | } | ||
| 36 | |||
| 37 | How the hell it is supposed to work reliably this way? Just imagine that | ||
| 38 | admin is using pump and ifup/ifdown. It works. Then, for whatever reason, | ||
| 39 | admin installs dhclient, but does NOT use it. ifdown will STOP WORKING, | ||
| 40 | just because it will see installed dhclient binary in e.g. /usr/bin/dhclient! | ||
| 41 | This is stupid. | ||
| 42 | |||
| 43 | I seriously urge people to not use ifup/ifdown. | ||
| 44 | Use something less brain damaged. | ||