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</pre></div><pre class="rust"><code><span class="comment">// Copyright (C) 2019, Cloudflare, Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
//
// * Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
// IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
// THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
</span><span class="kw">use </span><span class="kw">super</span>::Error;
<span class="kw">use </span><span class="kw">super</span>::Result;
<span class="kw">use </span><span class="kw">crate</span>::h3::Header;
<span class="kw">use </span><span class="kw">super</span>::INDEXED;
<span class="kw">use </span><span class="kw">super</span>::INDEXED_WITH_POST_BASE;
<span class="kw">use </span><span class="kw">super</span>::LITERAL;
<span class="kw">use </span><span class="kw">super</span>::LITERAL_WITH_NAME_REF;
<span class="attr">#[derive(Clone, Copy, Debug, PartialEq)]
</span><span class="kw">enum </span>Representation {
Indexed,
IndexedWithPostBase,
Literal,
LiteralWithNameRef,
LiteralWithPostBase,
}
<span class="kw">impl </span>Representation {
<span class="kw">pub fn </span>from_byte(b: u8) -&gt; Representation {
<span class="kw">if </span>b &amp; INDEXED == INDEXED {
<span class="kw">return </span>Representation::Indexed;
}
<span class="kw">if </span>b &amp; LITERAL_WITH_NAME_REF == LITERAL_WITH_NAME_REF {
<span class="kw">return </span>Representation::LiteralWithNameRef;
}
<span class="kw">if </span>b &amp; LITERAL == LITERAL {
<span class="kw">return </span>Representation::Literal;
}
<span class="kw">if </span>b &amp; INDEXED_WITH_POST_BASE == INDEXED_WITH_POST_BASE {
<span class="kw">return </span>Representation::IndexedWithPostBase;
}
Representation::LiteralWithPostBase
}
}
<span class="doccomment">/// A QPACK decoder.
</span><span class="attr">#[derive(Default)]
</span><span class="kw">pub struct </span>Decoder {}
<span class="kw">impl </span>Decoder {
<span class="doccomment">/// Creates a new QPACK decoder.
</span><span class="kw">pub fn </span>new() -&gt; Decoder {
Decoder::default()
}
<span class="doccomment">/// Processes control instructions from the encoder.
</span><span class="kw">pub fn </span>control(<span class="kw-2">&amp;mut </span><span class="self">self</span>, _buf: <span class="kw-2">&amp;mut </span>[u8]) -&gt; <span class="prelude-ty">Result</span>&lt;()&gt; {
<span class="comment">// TODO: process control instructions
</span><span class="prelude-val">Ok</span>(())
}
<span class="doccomment">/// Decodes a QPACK header block into a list of headers.
</span><span class="kw">pub fn </span>decode(<span class="kw-2">&amp;mut </span><span class="self">self</span>, buf: <span class="kw-2">&amp;</span>[u8], max_size: u64) -&gt; <span class="prelude-ty">Result</span>&lt;Vec&lt;Header&gt;&gt; {
<span class="kw">let </span><span class="kw-2">mut </span>b = octets::Octets::with_slice(buf);
<span class="kw">let </span><span class="kw-2">mut </span>out = Vec::new();
<span class="kw">let </span><span class="kw-2">mut </span>left = max_size;
<span class="kw">let </span>req_insert_count = decode_int(<span class="kw-2">&amp;mut </span>b, <span class="number">8</span>)<span class="question-mark">?</span>;
<span class="kw">let </span>base = decode_int(<span class="kw-2">&amp;mut </span>b, <span class="number">7</span>)<span class="question-mark">?</span>;
<span class="macro">trace!</span>(<span class="string">"Header count={} base={}"</span>, req_insert_count, base);
<span class="kw">while </span>b.cap() &gt; <span class="number">0 </span>{
<span class="kw">let </span>first = b.peek_u8()<span class="question-mark">?</span>;
<span class="kw">match </span>Representation::from_byte(first) {
Representation::Indexed =&gt; {
<span class="kw">const </span>STATIC: u8 = <span class="number">0x40</span>;
<span class="kw">let </span>s = first &amp; STATIC == STATIC;
<span class="kw">let </span>index = decode_int(<span class="kw-2">&amp;mut </span>b, <span class="number">6</span>)<span class="question-mark">?</span>;
<span class="macro">trace!</span>(<span class="string">"Indexed index={} static={}"</span>, index, s);
<span class="kw">if </span>!s {
<span class="comment">// TODO: implement dynamic table
</span><span class="kw">return </span><span class="prelude-val">Err</span>(Error::InvalidHeaderValue);
}
<span class="kw">let </span>(name, value) = lookup_static(index)<span class="question-mark">?</span>;
left = left
.checked_sub((name.len() + value.len()) <span class="kw">as </span>u64)
.ok_or(Error::HeaderListTooLarge)<span class="question-mark">?</span>;
<span class="kw">let </span>hdr = Header::new(name, value);
out.push(hdr);
},
Representation::IndexedWithPostBase =&gt; {
<span class="kw">let </span>index = decode_int(<span class="kw-2">&amp;mut </span>b, <span class="number">4</span>)<span class="question-mark">?</span>;
<span class="macro">trace!</span>(<span class="string">"Indexed With Post Base index={}"</span>, index);
<span class="comment">// TODO: implement dynamic table
</span><span class="kw">return </span><span class="prelude-val">Err</span>(Error::InvalidHeaderValue);
},
Representation::Literal =&gt; {
<span class="kw">let </span>name_huff = b.as_ref()[<span class="number">0</span>] &amp; <span class="number">0x08 </span>== <span class="number">0x08</span>;
<span class="kw">let </span>name_len = decode_int(<span class="kw-2">&amp;mut </span>b, <span class="number">3</span>)<span class="question-mark">? </span><span class="kw">as </span>usize;
<span class="kw">let </span><span class="kw-2">mut </span>name = b.get_bytes(name_len)<span class="question-mark">?</span>;
<span class="kw">let </span>name = <span class="kw">if </span>name_huff {
<span class="kw">super</span>::huffman::decode(<span class="kw-2">&amp;mut </span>name)<span class="question-mark">?
</span>} <span class="kw">else </span>{
name.to_vec()
};
<span class="kw">let </span>name = name.to_vec();
<span class="kw">let </span>value = decode_str(<span class="kw-2">&amp;mut </span>b)<span class="question-mark">?</span>;
<span class="macro">trace!</span>(
<span class="string">"Literal Without Name Reference name={:?} value={:?}"</span>,
name,
value,
);
left = left
.checked_sub((name.len() + value.len()) <span class="kw">as </span>u64)
.ok_or(Error::HeaderListTooLarge)<span class="question-mark">?</span>;
<span class="comment">// Instead of calling Header::new(), create Header directly
// from `name` and `value`, which are already String.
</span><span class="kw">let </span>hdr = Header(name, value);
out.push(hdr);
},
Representation::LiteralWithNameRef =&gt; {
<span class="kw">const </span>STATIC: u8 = <span class="number">0x10</span>;
<span class="kw">let </span>s = first &amp; STATIC == STATIC;
<span class="kw">let </span>name_idx = decode_int(<span class="kw-2">&amp;mut </span>b, <span class="number">4</span>)<span class="question-mark">?</span>;
<span class="kw">let </span>value = decode_str(<span class="kw-2">&amp;mut </span>b)<span class="question-mark">?</span>;
<span class="macro">trace!</span>(
<span class="string">"Literal name_idx={} static={} value={:?}"</span>,
name_idx,
s,
value
);
<span class="kw">if </span>!s {
<span class="comment">// TODO: implement dynamic table
</span><span class="kw">return </span><span class="prelude-val">Err</span>(Error::InvalidHeaderValue);
}
<span class="kw">let </span>(name, <span class="kw">_</span>) = lookup_static(name_idx)<span class="question-mark">?</span>;
left = left
.checked_sub((name.len() + value.len()) <span class="kw">as </span>u64)
.ok_or(Error::HeaderListTooLarge)<span class="question-mark">?</span>;
<span class="comment">// Instead of calling Header::new(), create Header directly
// from `value`, which is already String, but clone `name`
// as it is just a reference.
</span><span class="kw">let </span>hdr = Header(name.to_vec(), value);
out.push(hdr);
},
Representation::LiteralWithPostBase =&gt; {
<span class="macro">trace!</span>(<span class="string">"Literal With Post Base"</span>);
<span class="comment">// TODO: implement dynamic table
</span><span class="kw">return </span><span class="prelude-val">Err</span>(Error::InvalidHeaderValue);
},
}
}
<span class="prelude-val">Ok</span>(out)
}
}
<span class="kw">fn </span>lookup_static(idx: u64) -&gt; <span class="prelude-ty">Result</span>&lt;(<span class="kw-2">&amp;</span><span class="lifetime">'static </span>[u8], <span class="kw-2">&amp;</span><span class="lifetime">'static </span>[u8])&gt; {
<span class="kw">if </span>idx &gt;= <span class="kw">super</span>::static_table::STATIC_DECODE_TABLE.len() <span class="kw">as </span>u64 {
<span class="kw">return </span><span class="prelude-val">Err</span>(Error::InvalidStaticTableIndex);
}
<span class="prelude-val">Ok</span>(<span class="kw">super</span>::static_table::STATIC_DECODE_TABLE[idx <span class="kw">as </span>usize])
}
<span class="kw">fn </span>decode_int(b: <span class="kw-2">&amp;mut </span>octets::Octets, prefix: usize) -&gt; <span class="prelude-ty">Result</span>&lt;u64&gt; {
<span class="kw">let </span>mask = <span class="number">2u64</span>.pow(prefix <span class="kw">as </span>u32) - <span class="number">1</span>;
<span class="kw">let </span><span class="kw-2">mut </span>val = u64::from(b.get_u8()<span class="question-mark">?</span>);
val &amp;= mask;
<span class="kw">if </span>val &lt; mask {
<span class="kw">return </span><span class="prelude-val">Ok</span>(val);
}
<span class="kw">let </span><span class="kw-2">mut </span>shift = <span class="number">0</span>;
<span class="kw">while </span>b.cap() &gt; <span class="number">0 </span>{
<span class="kw">let </span>byte = b.get_u8()<span class="question-mark">?</span>;
<span class="kw">let </span>inc = u64::from(byte &amp; <span class="number">0x7f</span>)
.checked_shl(shift)
.ok_or(Error::BufferTooShort)<span class="question-mark">?</span>;
val = val.checked_add(inc).ok_or(Error::BufferTooShort)<span class="question-mark">?</span>;
shift += <span class="number">7</span>;
<span class="kw">if </span>byte &amp; <span class="number">0x80 </span>== <span class="number">0 </span>{
<span class="kw">return </span><span class="prelude-val">Ok</span>(val);
}
}
<span class="prelude-val">Err</span>(Error::BufferTooShort)
}
<span class="kw">fn </span>decode_str(b: <span class="kw-2">&amp;mut </span>octets::Octets) -&gt; <span class="prelude-ty">Result</span>&lt;Vec&lt;u8&gt;&gt; {
<span class="kw">let </span>first = b.peek_u8()<span class="question-mark">?</span>;
<span class="kw">let </span>huff = first &amp; <span class="number">0x80 </span>== <span class="number">0x80</span>;
<span class="kw">let </span>len = decode_int(b, <span class="number">7</span>)<span class="question-mark">? </span><span class="kw">as </span>usize;
<span class="kw">let </span><span class="kw-2">mut </span>val = b.get_bytes(len)<span class="question-mark">?</span>;
<span class="kw">let </span>val = <span class="kw">if </span>huff {
<span class="kw">super</span>::huffman::decode(<span class="kw-2">&amp;mut </span>val)<span class="question-mark">?
</span>} <span class="kw">else </span>{
val.to_vec()
};
<span class="prelude-val">Ok</span>(val)
}
<span class="attr">#[cfg(test)]
</span><span class="kw">mod </span>tests {
<span class="kw">use super</span>::<span class="kw-2">*</span>;
<span class="attr">#[test]
</span><span class="kw">fn </span>decode_int1() {
<span class="kw">let </span>encoded = [<span class="number">0b01010</span>, <span class="number">0x02</span>];
<span class="kw">let </span><span class="kw-2">mut </span>b = octets::Octets::with_slice(<span class="kw-2">&amp;</span>encoded);
<span class="macro">assert_eq!</span>(decode_int(<span class="kw-2">&amp;mut </span>b, <span class="number">5</span>), <span class="prelude-val">Ok</span>(<span class="number">10</span>));
}
<span class="attr">#[test]
</span><span class="kw">fn </span>decode_int2() {
<span class="kw">let </span>encoded = [<span class="number">0b11111</span>, <span class="number">0b10011010</span>, <span class="number">0b00001010</span>];
<span class="kw">let </span><span class="kw-2">mut </span>b = octets::Octets::with_slice(<span class="kw-2">&amp;</span>encoded);
<span class="macro">assert_eq!</span>(decode_int(<span class="kw-2">&amp;mut </span>b, <span class="number">5</span>), <span class="prelude-val">Ok</span>(<span class="number">1337</span>));
}
<span class="attr">#[test]
</span><span class="kw">fn </span>decode_int3() {
<span class="kw">let </span>encoded = [<span class="number">0b101010</span>];
<span class="kw">let </span><span class="kw-2">mut </span>b = octets::Octets::with_slice(<span class="kw-2">&amp;</span>encoded);
<span class="macro">assert_eq!</span>(decode_int(<span class="kw-2">&amp;mut </span>b, <span class="number">8</span>), <span class="prelude-val">Ok</span>(<span class="number">42</span>));
}
}
</code></pre></div></section></main></body></html>