[Bug 1812466] [NEW] netboot: failed to parse DNS settings set by dhclient

[cuihao]

Public bug reported:

I am setting up diskless netboot for Ubuntu LiveCDs, with following
kernel arguments:

```
boot=casper netboot=nfs nfsroot=192.168.89.10:/extracted/livecd toram
```

I have noticed the following strange error messages after dhcp (also see
the attachment):

```
/init: /run/net-ens3.conf: line 8: 202.38.64.56: not found
/init: /run/net-ens3.conf: line 8: 202.38.64.56: not found
/init: /run/net-ens3.conf: line 8: 202.38.64.56: not found
no search or nameservers found in /run/net-ens3.conf /run/net-ens3.conf /run/net6-*.conf
/init: /run/net-ens3.conf: line 8: 202.38.64.56: not found
/init: /run/net-ens3.conf: line 8: 202.38.64.56: not found
```

I manually broke the init process, and found line 8 of /run/net-
ens3.conf is:

```
IPV4DNS0=192.168.88.1 202.38.64.56 202.38.64.17
```

The problematic code is in the `netinfo_to_resolv_conf` function of
`scripts/functions`. It sources `/run/net-ens3.conf` (which is obviously
not in correct shell syntax due to the space inserted between multiple
DNS servers) to get network settings:

```
. "$f" || { echo "WARN: failed '. \"$f\"'" 1>&2; return 1; }
```

The bug is introduced by commit a77729e9, which replaced IP-config with
dhclient. While IP-config seems to write each DNS in `IPV4DNS0`,
`IPV4DNS1`, etc., dhclient write all DNS in `IPV4DNS0`, which is not
expected by `netinfo_to_resolv_conf`.

I can confirm 18.10 LiveCDs are affected.

** Affects: initramfs-tools (Ubuntu)
     Importance: Undecided
         Status: New

** Attachment added: "bug.png"
   https://bugs.launchpad.net/bugs/1812466/+attachment/5230482/+files/bug.png

** Description changed:

- I am setting up diskless netboot for Ubuntu LiveCDs.
+ I am setting up diskless netboot for Ubuntu LiveCDs, with following
+ kernel arguments:
  
  ```
  boot=casper netboot=nfs nfsroot=192.168.89.10:/extracted/livecd toram
  ```
  
  I have noticed the following strange error messages after dhcp (also see
  the attachment):
  
  ```
  /init: /run/net-ens3.conf: line 8: 202.38.64.56: not found
  /init: /run/net-ens3.conf: line 8: 202.38.64.56: not found
  /init: /run/net-ens3.conf: line 8: 202.38.64.56: not found
  no search or nameservers found in /run/net-ens3.conf /run/net-ens3.conf /run/net6-*.conf
  /init: /run/net-ens3.conf: line 8: 202.38.64.56: not found
  /init: /run/net-ens3.conf: line 8: 202.38.64.56: not found
  ```
  
  I manually broke the init process, and found line 8 of /run/net-
  ens3.conf is:
  
  ```
  IPV4DNS0=192.168.88.1 202.38.64.56 202.38.64.17
  ```
  
  The problematic code is in the `netinfo_to_resolv_conf` function of
  `scripts/functions`. It sources `/run/net-ens3.conf` (which is obviously
  not in correct shell syntax due to the space inserted between multiple
  DNS servers) to get network settings:
  
  ```
  . "$f" || { echo "WARN: failed '. \"$f\"'" 1>&2; return 1; }
  ```
  
  The bug is introduced by commit a77729e9, which replaced IP-config with
  dhclient. While IP-config seems to write each DNS in `IPV4DNS0`,
  `IPV4DNS1`, etc., dhclient write all DNS in `IPV4DNS0`, which is not
  expected by `netinfo_to_resolv_conf`.
  
  I can confirm 18.10 LiveCDs are affected.

-- 
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https://bugs.launchpad.net/bugs/1812466

Title:
  netboot: failed to parse DNS settings set by dhclient

Status in initramfs-tools package in Ubuntu:
  New

Bug description:
  I am setting up diskless netboot for Ubuntu LiveCDs, with following
  kernel arguments:

  ```
  boot=casper netboot=nfs nfsroot=192.168.89.10:/extracted/livecd toram
  ```

  I have noticed the following strange error messages after dhcp (also
  see the attachment):

  ```
  /init: /run/net-ens3.conf: line 8: 202.38.64.56: not found
  /init: /run/net-ens3.conf: line 8: 202.38.64.56: not found
  /init: /run/net-ens3.conf: line 8: 202.38.64.56: not found
  no search or nameservers found in /run/net-ens3.conf /run/net-ens3.conf /run/net6-*.conf
  /init: /run/net-ens3.conf: line 8: 202.38.64.56: not found
  /init: /run/net-ens3.conf: line 8: 202.38.64.56: not found
  ```

  I manually broke the init process, and found line 8 of /run/net-
  ens3.conf is:

  ```
  IPV4DNS0=192.168.88.1 202.38.64.56 202.38.64.17
  ```

  The problematic code is in the `netinfo_to_resolv_conf` function of
  `scripts/functions`. It sources `/run/net-ens3.conf` (which is
  obviously not in correct shell syntax due to the space inserted
  between multiple DNS servers) to get network settings:

  ```
  . "$f" || { echo "WARN: failed '. \"$f\"'" 1>&2; return 1; }
  ```

  The bug is introduced by commit a77729e9, which replaced IP-config
  with dhclient. While IP-config seems to write each DNS in `IPV4DNS0`,
  `IPV4DNS1`, etc., dhclient write all DNS in `IPV4DNS0`, which is not
  expected by `netinfo_to_resolv_conf`.

  I can confirm 18.10 LiveCDs are affected.

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