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<p style="color: #777777;">
<a href="https://gitlab.com/dueno">Daiki Ueno</a>
started a new
discussion on <a href="https://gitlab.com/gnutls/gnutls/-/merge_requests/1350#note_444687501">lib/handshake.c</a>:
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2213
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2213
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<pre style="margin: 0;"> <span id="LC2213" class="line" lang="c"></span>
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<td class="diff-line-num old_line" data-linenumber="2214" style="width: 35px; color: rgba(0,0,0,0.3); border-right-width: 1px; border-right-color: #f0f0f0; border-right-style: solid; padding: 0 5px;" align="right" bgcolor="#fafafa">
2214
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<td class="diff-line-num new_line" data-linenumber="2214" style="width: 35px; color: rgba(0,0,0,0.3); border-right-width: 1px; border-right-color: #f0f0f0; border-right-style: solid; padding: 0 5px;" align="right" bgcolor="#fafafa">
2214
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<pre style="margin: 0;"> <span id="LC2214" class="line" lang="c"><span class="cp" style="color: #999; font-weight: 600;">#ifdef TLS13_APPENDIX_D4</span></span>
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<td class="diff-line-num old_line" data-linenumber="2215" style="width: 35px; color: rgba(0,0,0,0.3); border-right-width: 1px; border-right-color: #f0f0f0; border-right-style: solid; padding: 0 5px;" align="right" bgcolor="#fafafa">
2215
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2215
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<pre style="margin: 0;"> <span id="LC2215" class="line" lang="c">           <span class="k" style="font-weight: 600;">if</span> <span class="p">(</span><span class="n" style="color: #333;">max_ver</span><span class="o" style="font-weight: 600;">-></span><span class="n" style="color: #333;">tls13_sem</span> <span class="o" style="font-weight: 600;">&&</span></span>
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<td class="diff-line-num old old_line" data-linenumber="2216" style="width: 35px; color: rgba(0,0,0,0.3); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: 0 5px;" align="right" bgcolor="#f9d7dc">
2216
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<td class="diff-line-num new_line old" data-linenumber="2216" style="width: 35px; color: rgba(0,0,0,0.3); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: 0 5px;" align="right" bgcolor="#f9d7dc">
 
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<pre style="margin: 0;">-<span id="LC2216" class="line" lang="c">               <span class="n" style="color: #333;">session</span><span class="o" style="font-weight: 600;">-></span><span class="n" style="color: #333;">security_parameters</span><span class="p">.</span><span class="n" style="color: #333;">session_id_size</span> <span class="o" style="font-weight: 600;">==</span> <span class="mi" style="color: #099;">0</span><span class="p">)</span> <span class="p">{</span></span>
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<td class="diff-line-num new old_line" data-linenumber="2217" style="width: 35px; color: rgba(0,0,0,0.3); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: 0 5px;" align="right" bgcolor="#ddfbe6">
 
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2216
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<pre style="margin: 0;">+<span id="LC2216" class="line" lang="c">               <span class="n" style="color: #333;">session</span><span class="o" style="font-weight: 600;">-></span><span class="n" style="color: #333;"><span class="idiff left">internals</span></span><span class="p"><span class="idiff">.</span></span><span class="n" style="color: #333;"><span class="idiff right">resumed_</span>security_parameters</span><span class="p">.</span><span class="n" style="color: #333;">session_id_size</span> <span class="o" style="font-weight: 600;">==</span> <span class="mi" style="color: #099;">0</span><span class="p">)</span> <span class="p">{</span></span>
</pre>
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<td class="diff-line-num old_line" data-linenumber="2217" style="width: 35px; color: rgba(0,0,0,0.3); border-right-width: 1px; border-right-color: #f0f0f0; border-right-style: solid; padding: 0 5px;" align="right" bgcolor="#fafafa">
2217
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2217
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<pre style="margin: 0;"> <span id="LC2217" class="line" lang="c"></span>
</pre>
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<td class="diff-line-num old_line" data-linenumber="2218" style="width: 35px; color: rgba(0,0,0,0.3); border-right-width: 1px; border-right-color: #f0f0f0; border-right-style: solid; padding: 0 5px;" align="right" bgcolor="#fafafa">
2218
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2218
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<pre style="margin: 0;"> <span id="LC2218" class="line" lang="c">                   <span class="cm" style="color: #998; font-style: italic;">/* Under TLS1.3 we generate a random session ID to make</span></span>
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<td class="diff-line-num old_line" data-linenumber="2219" style="width: 35px; color: rgba(0,0,0,0.3); border-right-width: 1px; border-right-color: #f0f0f0; border-right-style: solid; padding: 0 5px;" align="right" bgcolor="#fafafa">
2219
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2219
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<pre style="margin: 0;"> <span id="LC2219" class="line" lang="c"><span class="cm" style="color: #998; font-style: italic;">                        * the TLS1.3 session look like a resumed TLS1.2 session */</span></span>
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<td class="diff-line-num old old_line" data-linenumber="2220" style="width: 35px; color: rgba(0,0,0,0.3); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: 0 5px;" align="right" bgcolor="#f9d7dc">
2220
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<pre style="margin: 0;">-<span id="LC2220" class="line" lang="c">                   <span class="n" style="color: #333;">ret</span> <span class="o" style="font-weight: 600;">=</span> <span class="n" style="color: #333;">_gnutls_generate_session_id</span><span class="p">(</span><span class="n" style="color: #333;">session</span><span class="o" style="font-weight: 600;">-></span><span class="n" style="color: #333;">security_parameters</span><span class="p">.</span></span>
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<td class="diff-line-num new old_line" data-linenumber="2221" style="width: 35px; color: rgba(0,0,0,0.3); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: 0 5px;" align="right" bgcolor="#ddfbe6">
 
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<pre style="margin: 0;">+<span id="LC2220" class="line" lang="c">                   <span class="n" style="color: #333;">ret</span> <span class="o" style="font-weight: 600;">=</span> <span class="n" style="color: #333;">_gnutls_generate_session_id</span><span class="p">(</span><span class="n" style="color: #333;">session</span><span class="o" style="font-weight: 600;">-></span><span class="n" style="color: #333;"><span class="idiff left">internals</span></span><span class="p"><span class="idiff">.</span></span><span class="n" style="color: #333;"><span class="idiff right">resumed_</span>security_parameters</span><span class="p">.</span></span>
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<p dir="auto">While it seemed like a good idea to actually reuse the <code>resumed_security_parameters</code>, it actually confuses the TLS 1.3 client as the first connection is seen as a resumed session (see the failure in <code>tls13-resume-x509</code>).</p>
<p dir="auto">I suppose on the way to avoid this is to use the local variables to temporarily store the generated session ID and its length.</p>
<p dir="auto">Also note that, as the presence of session ID in Client Hello affects the transcript hash, you might need to update <code>tests/tls13/prf.c</code>.</p>
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