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List: busybox
Subject: Re: udhcpd: HOST_NAME support for static leases
From: Philippe Jounin <philippe.jounin () orange ! fr>
Date: 2019-05-21 19:44:37
Message-ID: 93f81b2a-493c-d009-b0d9-a081c653b52f () orange ! fr
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Hello Denys,
That's perfect !!
Thanks.
Just a question:
In line 69, [optlen = (opts ? 1+1+strnlen(opts, 120) : 0);], you choose
to limit the hostname to 120 characters.
It seems more than enough, however it this not fully compliant with the
RFC 2132 and 1035.
RFC 1035 limits the FQDN to 255 characters with labels limited to 63
chars, while RFC2132 mentions that the HOSTNAME option may contain the
domain name.
Is it a tradeoff to keep DHCP messages shorter than MTU ?
Best regards,
Philippe
2.3.4 <https://tools.ietf.org/html/rfc1035#section-2.3.4>. Size
limits
Various objects and parameters in the DNS have size limits. They are
listed below. Some could be easily changed, others are more
fundamental.
labels 63 octets or less
names 255 octets or less
3.14 <https://tools.ietf.org/html/rfc2132#section-3.14>. Host Name
Option
This option specifies the name of the client. The name may or may
not be qualified with the local domain name (seesection 3.17 \
<https://tools.ietf.org/html/rfc2132#section-3.17> for the preferred way to \
retrieve the domain name). SeeRFC 1035 <https://tools.ietf.org/html/rfc1035> for \
character set restrictions.
The code for this option is 12, and its minimum length is 1.
Code Len Host Name
+-----+-----+-----+-----+-----+-----+-----+-----+--
| 12 | n | h1 | h2 | h3 | h4 | h5 | h6 | ...
+-----+-----+-----+-----+-----+-----+-----+-----+--
Le 21/05/2019 à 16:07, Denys Vlasenko a écrit :
>
> On Mon, May 20, 2019 at 6:30 PM Philippe Jounin
> <philippe.jounin@orange.fr <mailto:philippe.jounin@orange.fr>> wrote:
>
>
> Hello Denys,
>
> Tested under a debian box: Works as expected with the
> configuration file joined !!
> Targets tried: debian, centOS, cisco routers
>
> A few very minor remarks:
> - with high verbose level (3v), log_static_leases dumps all
> static leases, but is called for each new static lease. May be log
> should be moved into add_static_lease.
>
>
> Done, please try current git.
>
---
L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel \
antivirus Avast. https://www.avast.com/antivirus
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<div class="moz-cite-prefix">Hello Denys,</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">That's perfect !!</div>
<div class="moz-cite-prefix">Thanks.</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">Just a question: <br>
</div>
<div class="moz-cite-prefix">In line 69, [optlen = (opts ?
1+1+strnlen(opts, 120) : 0);], you choose to limit the hostname to
120 characters.</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">It seems more than enough, however it
this not fully compliant with the RFC 2132 and 1035.</div>
<div class="moz-cite-prefix">RFC 1035 limits the FQDN to 255
characters with labels limited to 63 chars, while RFC2132 mentions
that the HOSTNAME option may contain the domain name.<br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">Is it a tradeoff to keep DHCP messages
shorter than MTU ?</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">Best regards,</div>
<div class="moz-cite-prefix">Philippe<br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">
<pre class="newpage" style="font-size: 13.3333px; margin-top: 0px; \
margin-bottom: 0px; break-before: page; color: rgb(0, 0, 0); font-style: normal; \
font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; \
letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; \
text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; \
text-decoration-style: initial; text-decoration-color: initial;"><span class="h4" \
style="line-height: 0pt; display: inline; white-space: pre; font-family: monospace; \
font-size: 1em; font-weight: bold;"><h4 style="line-height: 0pt; display: inline; \
white-space: pre; font-family: monospace; font-size: 1em; font-weight: bold;"><a \
class="selflink" name="section-2.3.4" \
href="https://tools.ietf.org/html/rfc1035#section-2.3.4" style="color: black; \
text-decoration: none;">2.3.4</a>. Size limits</h4></span>
Various objects and parameters in the DNS have size limits. They are
listed below. Some could be easily changed, others are more
fundamental.
labels 63 octets or less
names 255 octets or less</pre>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">
<pre class="newpage" style="font-size: 13.3333px; margin-top: 0px; \
margin-bottom: 0px; break-before: page; color: rgb(0, 0, 0); font-style: normal; \
font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; \
letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; \
text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; \
text-decoration-style: initial; text-decoration-color: initial;"><span class="h3" \
style="line-height: 0pt; display: inline; white-space: pre; font-family: monospace; \
font-size: 1em; font-weight: bold;"><h3 style="line-height: 0pt; display: inline; \
white-space: pre; font-family: monospace; font-size: 1em; font-weight: bold;"><a \
class="selflink" name="section-3.14" \
href="https://tools.ietf.org/html/rfc2132#section-3.14" style="color: black; \
text-decoration: none;">3.14</a>. Host Name Option</h3></span>
This option specifies the name of the client. The name may or may
not be qualified with the local domain name (see <a \
href="https://tools.ietf.org/html/rfc2132#section-3.17">section 3.17</a> for the \
preferred way to retrieve the domain name). See <a \
href="https://tools.ietf.org/html/rfc1035">RFC 1035</a> for character set \
restrictions.
The code for this option is 12, and its minimum length is 1.
Code Len Host Name
+-----+-----+-----+-----+-----+-----+-----+-----+--
| 12 | n | h1 | h2 | h3 | h4 | h5 | h6 | ...
+-----+-----+-----+-----+-----+-----+-----+-----+--</pre>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">Le 21/05/2019 à 16:07, Denys Vlasenko a
écrit :<br>
</div>
<blockquote type="cite"
cite="mid:CAK1hOcM0ekb==mGTiTi46p2utntnw6LKdsuO9ZxjLGojpR=QGw@mail.gmail.com">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<div dir="ltr"><br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Mon, May 20, 2019 at 6:30
PM Philippe Jounin <<a
href="mailto:philippe.jounin@orange.fr"
moz-do-not-send="true">philippe.jounin@orange.fr</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
<div bgcolor="#FFFFFF">
<div class="gmail-m_8928238418457367286moz-cite-prefix">
<table
class="gmail-m_8928238418457367286mail-content-readonly-table"
style="margin:0px;padding:0px;border:0px
none;border-spacing:0px;color:rgb(68,68,68);font-family:arial,sans-serif;font-size:12p \
x;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight \
:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white- \
space:normal;word-spacing:0px;text-decoration-style:initial;text-decoration-color:initial"
width="991" height="14">
<tbody style="margin:0px;padding:0px;border:0px none">
<tr style="margin:0px;padding:0px;border:0px none">
<td style="margin:0px;padding:0px;border:0px
none;vertical-align:top"><br>
</td>
</tr>
</tbody>
</table>
</div>
Hello Denys,<br>
<br>
Tested under a debian box: Works as expected with the
configuration file joined !!<br>
Targets tried: debian, centOS, cisco routers<br>
<br>
A few very minor remarks: <br>
- with high verbose level (3v), log_static_leases dumps
all static leases, but is called for each new static
lease. May be log should be moved into add_static_lease.<br>
</div>
</blockquote>
<div><br>
</div>
<div>Done, please try current git.</div>
<br>
</div>
</div>
</blockquote>
<p><br>
</p>
<div id="DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2"><br /> <table style="border-top: 1px \
solid #D3D4DE;"> <tr>
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alt="" width="46" height="29" style="width: 46px; height: 29px;" /></a></td> <td \
style="width: 470px; padding-top: 17px; color: #41424e; font-size: 13px; font-family: \
Arial, Helvetica, sans-serif; line-height: 18px;">Garanti sans virus. <a \
href="https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient" \
target="_blank" style="color: #4453ea;">www.avast.com</a> </td> </tr>
</table>
<a href="#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2" width="1" height="1"> \
</a></div></body> </html>
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