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<head><title>dkim_get_sigsubstring()</title></head>
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<h1>dkim_get_sigsubstring()</h1>
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<!---------- Synopsis ----------->
<tr><th valign="top" align=left width=150>SYNOPSIS</th><td>
<pre>
#include <dkim.h>
<a href="dkim_stat.html"><tt>DKIM_STAT</tt></a> dkim_get_sigsubstring(
<a href="dkim.html"><tt>DKIM</tt></a> *dkim,
<a href="dkim_siginfo.html"><tt>DKIM_SIGINFO</tt></a> *sig,
char *buf,
size_t *buflen
);
</pre>
Retrieve a minimal substring of the actual signature (i.e. the "b=" tag
value) from a specified signature, of sufficient length to identify this
signature uniquely from others.
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<!----------- Description ---------->
<tr><th valign="top" align=left>DESCRIPTION</th><td>
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<th width="80">Called When</th>
<td><tt>dkim_getsig()</tt> is called after
<a href="dkim_eom.html"><tt>dkim_eom()</tt></a> when <tt>dkim</tt> is a
verifying handle, i.e. one returned by an earlier call to
<a href="dkim_verify.html"><tt>dkim_verify()</tt></a>. </td>
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<!----------- Arguments ---------->
<tr><th valign="top" align=left>ARGUMENTS</th><td>
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<tr bgcolor="#dddddd"><th>Argument</th><th>Description</th></tr>
<tr valign="top"><td>dkim</td>
<td>Message-specific handle, returned by <a href="dkim_sign.html">
<tt>dkim_sign()</tt></a>.
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<tr valign="top"><td>sig</td>
<td>Signature-specific handle, retrieved by a prior call to
<a href="dkim_getsiglist.html"><tt>dkim_getsiglist()</tt></a>.
</td></tr>
<tr valign="top"><td>buf</td>
<td>Pointer to a buffer that should receive a minimal unique
substring of the digital signature portion of <tt>sig</tt>.
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<tr valign="top"><td>buflen</td>
<td>The address of an integer that should contain the number of
bytes available at <tt>buf</tt> and will be updated to contain
the number of bytes needed to produce a minimal substring.
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<!----------- Notes ---------->
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<th valign="top" align=left>NOTES</th>
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<ul>
<li>No fewer than eight bytes will be requested. If two or more signatures
have the same initial byte sequences in "b=" tags, larger lengths will
be required, theoretically requiring as much as the entire signature.
<li>If the size of <tt>buf</tt> is too small to contain the minimal substring
of <tt>sig</tt>, <tt>DKIM_STAT_NORESOURCE</tt> is returned, <tt>buflen</tt>
will be updated to indicate the minimal number of bytes required,
and <tt>buf</tt> will be unchanged.
<li>The string written to <tt>buf</tt> will be NULL-terminated unless the
provided buffer is exactly the right size to contain the output.
</ul>
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Copyright (c) 2005, 2007 Sendmail, Inc. and its suppliers.
All rights reserved.
<br>
Copyright (c) 2010, 2011, The OpenDKIM Project. All rights reserved.
<br>
By using this file, you agree to the terms and conditions set
forth in the respective licenses.
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