From b929b048a1839c3da1cadf7f116b0f767f40267e Mon Sep 17 00:00:00 2001
From: Timo Weingärtner <timo@tiwe.de>
Date: Thu, 22 Apr 2021 23:29:10 +0200
Subject: implement separate rfc4251::(string|mpint|name_list) types

---
 rfc4251.H | 116 ++++++++++++++++++++++++++++++++++++--------------------------
 1 file changed, 67 insertions(+), 49 deletions(-)

(limited to 'rfc4251.H')

diff --git a/rfc4251.H b/rfc4251.H
index fe8ccd4..6647d15 100644
--- a/rfc4251.H
+++ b/rfc4251.H
@@ -5,7 +5,9 @@
  * rfc4251::boolean	boolean
  * rfc4251::uint32	uint32
  * rfc4251::uint64	uint64
- * rfc4251::string	string, incl. mpint and name-list
+ * rfc4251::string	string
+ * rfc4251::mpint	mpint
+ * rfc4251::name_list	name-list
  *
  * those structs contain the objects in their RFC 4251 representation,
  * conversions are provided via constructors and cast operators
@@ -85,6 +87,48 @@ namespace internal {
 			return os.write(x.buf.data(), x.buf.size());
 		}
 	};
+
+	template<typename Length_Type>
+	struct variable_length  : boost::totally_ordered<variable_length<Length_Type>> {
+		using length_type = Length_Type;
+		static_assert(std::is_unsigned_v<length_type>, "negative lengths are not supported");
+
+		std::vector<char> buf;
+
+		variable_length () = default;
+		explicit variable_length (std::istream & is) { is >> *this; }
+
+		size_t size () const noexcept { return buf.size(); }
+		char const * data () const noexcept { return buf.data(); }
+		char * data () noexcept { return buf.data(); }
+
+		friend std::istream & operator>> (std::istream & is, variable_length & v) {
+			if (length_type const len{fixed_length<length_type>{is}}; is) {
+				v.buf.clear();
+				v.buf.resize(len);
+				is.read(v.buf.data(), len);
+			}
+			return is;
+		}
+		friend std::ostream & operator<< (std::ostream & os, variable_length const & v) {
+			check_length_against_limit(v.buf.size());
+			if (os << fixed_length<length_type>{static_cast<length_type>(v.buf.size())})
+				os.write(v.buf.data(), v.buf.size());
+			return os;
+		}
+		friend bool operator== (variable_length const & l, variable_length const & r) {
+			return l.buf == r.buf;
+		}
+		friend bool operator< (variable_length const & l, variable_length const & r) {
+			return l.buf < r.buf;
+		}
+
+		constexpr static void check_length_against_limit(size_t const length) {
+			if (length > std::numeric_limits<length_type>::max())
+				throw std::length_error{"numeric limit for length field in rfc4251::variable_length type exceeded"};
+		}
+
+	};
 }
 
 using byte    = internal::fixed_length<uint8_t>;
@@ -92,59 +136,33 @@ using boolean = internal::fixed_length<bool>;
 using uint32  = internal::fixed_length<uint32_t>;
 using uint64  = internal::fixed_length<uint64_t>;
 
-struct string : boost::totally_ordered<string> {
-	std::vector<char> value;
-	
-	string () = default;
-	inline explicit string (char const *, size_t);
+struct string : internal::variable_length<uint32_t> {
+	using variable_length::variable_length;
+
+	inline explicit string (char const * s, size_t l) {
+		check_length_against_limit(l);
+		buf.insert(buf.end(), s, s + l);
+	}
 	explicit string (std::string const & s) : string{s.data(), s.size()} {}
-	explicit string (std::vector<std::string> const &);
-	explicit string (mpz_srcptr);
-	explicit string (mpz_class const & x) : string{x.get_mpz_t()} {}
-	inline explicit string (std::istream &);
 
-	size_t size () const noexcept { return value.size(); }
-	char const * data () const noexcept { return value.data(); }
-	char * data () noexcept { return value.data(); }
+	operator std::string () const { return {buf.cbegin(), buf.cend()}; }
+};
 
-	operator std::string () const { return {value.begin(), value.end()}; }
+struct name_list : internal::variable_length<uint32_t> {
+	using variable_length::variable_length;
+	
+	explicit name_list (std::vector<std::string> const &);
+	
 	operator std::vector<std::string> () const;
-	operator mpz_class () const;
 };
 
-inline string::string (char const * s, size_t l) {
-	if (l > std::numeric_limits<uint32_t>::max())
-		throw std::length_error{"32-bit limit for rfc4251::string exceeded"};
-	value.insert(value.end(), s, s + l);
-}
-
-inline std::istream & operator>> (std::istream & is, string & s) {
-	s.value.clear();
-	if (uint32_t const len{uint32{is}}; is) {
-		s.value.resize(len);
-		is.read(s.value.data(), len);
-	}
-	return is;
-}
-
-inline std::ostream & operator<< (std::ostream & os, string const & s) {
-	if (s.value.size() > std::numeric_limits<uint32_t>::max())
-		throw std::length_error{"32-bit limit for rfc4251::string exceeded"};
-	if (os << uint32{static_cast<uint32_t>(s.value.size())})
-		os.write(s.value.data(), s.value.size());
-	return os;
-}
-
-inline string::string (std::istream & is) {
-	is >> *this;
-}
-
-inline bool operator== (string const & l, string const & r) {
-	return l.value == r.value;
-}
-
-inline bool operator< (string const & l, string const & r) {
-	return l.value < r.value;
-}
+struct mpint : internal::variable_length<uint32_t> {
+	using variable_length::variable_length;
+	
+	explicit mpint (mpz_srcptr);
+	explicit mpint (mpz_class const & x) : mpint{x.get_mpz_t()} {}
+	
+	operator mpz_class () const;
+};
 
 }
-- 
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