ircd: Improve base64 suite.

include/ircd/lex_cast.h

@@ -48,9 +48,17 @@ namespace ircd
 	string_view u2a(const mutable_buffer &out, const const_raw_buffer &in);
 	const_raw_buffer a2u(const mutable_raw_buffer &out, const const_buffer &in);
 
-	// Binary <-> Base64 conversion suite
+	// Binary -> Base64 conversion suite
 	string_view b64encode(const mutable_buffer &out, const const_raw_buffer &in);
+	std::string b64encode(const const_raw_buffer &in);
+
+	// Binary -> Base64 conversion without padding
 	string_view b64encode_unpadded(const mutable_buffer &out, const const_raw_buffer &in);
+	std::string b64encode_unpadded(const const_raw_buffer &in);
+
+	// Base64 -> Binary conversion (padded or unpadded)
+	const_raw_buffer b64decode(const mutable_raw_buffer &out, const string_view &in);
+	std::string b64decode(const string_view &in);
 }
 
 namespace ircd

ircd/lexical.cc

@@ -31,9 +31,8 @@
 #include <RB_INC_BOOST_TOKENIZER_HPP
 #include <RB_INC_BOOST_LEXICAL_CAST_HPP
 #include <boost/archive/iterators/base64_from_binary.hpp>
-#include <boost/archive/iterators/insert_linebreaks.hpp>
+#include <boost/archive/iterators/binary_from_base64.hpp>
 #include <boost/archive/iterators/transform_width.hpp>
-#include <boost/archive/iterators/ostream_iterator.hpp>
 
 ///////////////////////////////////////////////////////////////////////////////
 //
@@ -561,26 +560,174 @@ ircd::try_lex_cast<long double>(const string_view &s)
 // ircd/stringops.h
 //
 
-ircd::string_view
-ircd::b64encode_unpadded(const mutable_buffer &out,
-                         const const_raw_buffer &in)
+namespace ircd
 {
-	return rstrip(b64encode(out, in), '=');
+	const char _b64_pad_
+	{
+		'='
+	};
+
+	using _b64_encoder = std::function<string_view (const mutable_buffer &, const const_raw_buffer &)>;
+	static std::string _b64encode(const const_raw_buffer &in, const _b64_encoder &);
 }
 
+/// Allocate and return a string without padding from the encoding of in
+std::string
+ircd::b64encode_unpadded(const const_raw_buffer &in)
+{
+	return _b64encode(in, [](const auto &out, const auto &in)
+	{
+		return b64encode_unpadded(out, in);
+	});
+}
+
+/// Allocate and return a string from the encoding of in
+std::string
+ircd::b64encode(const const_raw_buffer &in)
+{
+	return _b64encode(in, [](const auto &out, const auto &in)
+	{
+		return b64encode(out, in);
+	});
+}
+
+/// Internal; dedupes encoding functions that create and return a string
+static std::string
+ircd::_b64encode(const const_raw_buffer &in,
+                 const _b64_encoder &encoder)
+{
+	// Allocate a buffer 1.33 times larger than input with pessimistic
+	// extra space for any padding and nulling.
+	const auto max
+	{
+		ceil(size(in) * (4.0 / 3.0)) + 4
+	};
+
+	std::string ret;
+	ret.resize(max, char{});
+	const mutable_buffer buf
+	{
+		const_cast<char *>(ret.data()), ret.size()
+	};
+
+	const string_view encoded
+	{
+		encoder(buf, in)
+	};
+
+	assert(size(encoded) <= ret.size());
+	ret.resize(size(encoded));
+	return ret;
+}
+
+/// Encoding in to base64 at out. Out must be 1.33+ larger than in
+/// padding is not present in the returned view.
 ircd::string_view
 ircd::b64encode(const mutable_buffer &out,
                 const const_raw_buffer &in)
 {
+	const auto pads
+	{
+		(3 - size(in) % 3) % 3
+	};
 
-	using transform = boost::archive::iterators::transform_width<unsigned char *, 6, 8>;
-	using b64fb = boost::archive::iterators::base64_from_binary<transform>;
-	using ostream_iterator = boost::archive::iterators::ostream_iterator<char>;
+	const auto encoded
+	{
+		b64encode_unpadded(out, in)
+	};
 
-	std::stringstream ss;
-	std::copy(b64fb(data(in)), b64fb(data(in) + size(in)), ostream_iterator(ss));
-	const auto outlen(ss.str().copy(data(out), size(out)));
-	return { data(out), outlen };
+	assert(size(encoded) + pads <= size(out));
+	memset(data(out) + size(encoded), _b64_pad_, pads);
+
+	const auto len
+	{
+		size(encoded) + pads
+	};
+
+	return { data(out), len };
+}
+
+/// Encoding in to base64 at out. Out must be 1.33+ larger than in.
+ircd::string_view
+ircd::b64encode_unpadded(const mutable_buffer &out,
+                         const const_raw_buffer &in)
+{
+	namespace iterators = boost::archive::iterators;
+	using transform = iterators::transform_width<unsigned char *, 6, 8>;
+	using b64fb = iterators::base64_from_binary<transform>;
+
+	const auto cpsz
+	{
+		std::min(size(in), size_t(size(out) * (3.0 / 4.0)))
+	};
+
+	const auto end
+	{
+		std::copy(b64fb(data(in)), b64fb(data(in) + cpsz), begin(out))
+	};
+
+	const auto len
+	{
+		size_t(std::distance(begin(out), end))
+	};
+
+	assert(len <= size(out));
+	return { data(out), len };
+}
+
+std::string
+ircd::b64decode(const string_view &in)
+{
+	// Allocate a buffer 75% than input with pessimistic extra space
+	const auto max
+	{
+		ceil(size(in) * 0.75) + 4
+	};
+
+	std::string ret;
+	ret.resize(max, char{});
+	const mutable_raw_buffer buf
+	{
+		reinterpret_cast<unsigned char *>(const_cast<char *>(ret.data())), ret.size()
+	};
+
+	const auto decoded
+	{
+		b64decode(buf, in)
+	};
+
+	assert(size(decoded) <= ret.size());
+	ret.resize(size(decoded));
+	return ret;
+}
+
+/// Decode base64 from in to the buffer at out; out can be 75% of the size
+/// of in.
+ircd::const_raw_buffer
+ircd::b64decode(const mutable_raw_buffer &out,
+                const string_view &in)
+{
+	namespace iterators = boost::archive::iterators;
+	using b64bf = iterators::binary_from_base64<const char *>;
+	using transform = iterators::transform_width<b64bf, 8, 6>;
+
+	const auto pads
+	{
+		endswith_count(in, _b64_pad_)
+	};
+
+	const auto e
+	{
+		std::copy(transform(begin(in)), transform(begin(in) + size(in) - pads), begin(out))
+	};
+
+	const auto len
+	{
+		std::distance(begin(out), e)
+	};
+
+	assert(len <= size(out));
+	return { data(out), size_t(len) };
 }
 
 ircd::const_raw_buffer