200772 - DNS: offline/online cycling should reload DNS cache (reload hosts file)

Status: VERIFIED DUPLICATE of bug 192798

(Core :: Networking, enhancement)

Description

[Felix Miata]

Build ID's 2003040120 OS/2; 2003040105 W32; 2003040105 Linux

Filed at the direction of timeless per IRC discussion.

To reproduce:
1-Add to hosts file "216.239.51.100 testcase.4..hosts.file"
2-Open browser
3-Enter "testcase.4..hosts.file" in the URL bar, thus loading Google
4-Go offline
5-Change previous hosts file entry IP from "216.239.51.100" to "207.200.81.215"
5-Go online
6-Reload

Actual results:
1-Google still displayed unless Mozilla is shut down & restarted

Expected results:
1-Mozilla.org displayed without shutting down Mozilla to reload hosts

Comment 1

[Boris Zbarsky [:bzbarsky]]

This is already filed, iirc...

Comment 2

[Nicholas Allen]

*** This bug has been marked as a duplicate of 192798 ***

Comment 3

[Felix Miata]

restoring "hosts" to summary so a search can find this keyword
v dupe

Comment 4

[benc]

I didn't know that resinit() cached the hosts file... Does anyone know if this
is documented?

Comment 5

[benc]

oh duh. the entry is cached in DNS cache. duh.

Comment 6

[benc]

Can you tell me what happens if you add new entries to your hosts file w/o
restarting. These should take effect, as far as I can tell. If not, there would
be potentially yet another bug...

Comment 7

[Felix Miata]

I'd like to see the hosts file stat'd on fetches so that hosts file changes
would take effect immediately. AFAICT, only shutting down Mozilla and restarting
causes hosts reload.

Comment 8

[Mike Kaply [:mkaply]]

This is not a function of Mozilla. Mozilla knows nothing about the HOSTS file.
This is totally a function of TCP/IP.

Comment 9

[benc]

The correct interaction here (absent a /etc/hosts caching resolver) is:

The DNS cache works by hostname.

So changing the IP of hostnames you have accessed in the past (regardless of the
actual IP address being in DNS -OR- hosts) by hacking /etc/hosts will not work,
because the hostname will hit an entry in DNS cache.

adding or changing /etc/hosts entries that have not ever been used in the
browser session should work.

Comment 10

[Darin Fisher]

mozilla should not know about /etc/hosts .. that is a detail of the operating
system's implementation of gethostbyname (and friends).  mozilla cannot know for
sure that /etc/hosts will be consulted.  it would have to check the
configuration of the system (e.g., under linux, only if /etc/host.conf includes
hosts).  i don't think we want to go the route of checking for such things.  it
is the job of glibc (in the case of linux).

Comment 11

[benc]

Darin: in Windows (and thus probably OS/2 as well), hosts support is hard coded,
as I understand it. In UNIX, you can configure resolver to ignore /etc/hosts,
but this far, I can't recall any UNIX DNS bug reports where someone messed that up.

Felix:
can you test this w/ a daily build and see how it works? the other bug was
fixed, but then I had to reopen it. Any test results you have would be appreciated.

Comment 12

[Felix Miata]

According to comment 0 procedure, this is broken in Mozilla/5.0 (OS/2; U; Warp
4.5; en-US; rv:1.4) Gecko/20030619

Comment 13

[Mike Kaply [:mkaply]]

The hosts file is managed by TCP/IP. There is nothing the browser can do to
reload it.

DNS resolution is handled by TCP/IP.