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<a name="Error-handling"></a>
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Next: <a href="Common-types.html#Common-types" accesskey="n" rel="next">Common types</a>, Previous: <a href="General-idea.html#General-idea" accesskey="p" rel="prev">General idea</a>, Up: <a href="Introduction-to-the-library.html#Introduction-to-the-library" accesskey="u" rel="up">Introduction to the library</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Function-and-Data-Index.html#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
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<hr>
<a name="Error-handling-1"></a>
<h4 class="subsection">6.1.2 Error handling</h4>
<p>In <acronym>GnuTLS</acronym> most functions return an integer type as a result.
In almost all cases a zero or a positive number means success, and a
negative number indicates failure, or a situation that some action has
to be taken. Thus negative error codes may be fatal or not.
</p>
<p>Fatal errors terminate the connection immediately and further sends
and receives will be disallowed. Such an example is
<code>GNUTLS_E_DECRYPTION_FAILED</code>. Non-fatal errors may warn about
something, i.e., a warning alert was received, or indicate the some
action has to be taken. This is the case with the error code
<code>GNUTLS_E_REHANDSHAKE</code> returned by <a href="Core-TLS-API.html#gnutls_005frecord_005frecv">gnutls_record_recv</a>.
This error code indicates that the server requests a re-handshake. The
client may ignore this request, or may reply with an alert. You can
test if an error code is a fatal one by using the
<a href="Core-TLS-API.html#gnutls_005ferror_005fis_005ffatal">gnutls_error_is_fatal</a>.
All errors can be converted to a descriptive string using <a href="Core-TLS-API.html#gnutls_005fstrerror">gnutls_strerror</a>.
</p>
<p>If any non fatal errors, that require an action, are to be returned by
a function, these error codes will be documented in the function’s
reference. For example the error codes <code>GNUTLS_E_WARNING_ALERT_RECEIVED</code> and <code>GNUTLS_E_FATAL_ALERT_RECEIVED</code>
that may returned when receiving data, should be handled by notifying the
user of the alert (as explained in <a href="Handling-alerts.html#Handling-alerts">Handling alerts</a>).
See <a href="Error-codes.html#Error-codes">Error codes</a>, for a description of the available error codes.
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