From 045702915c4b63d232b99d86a1ee0b16642098c8 Mon Sep 17 00:00:00 2001
From: Per Larsson <p3rl@protonmail.com>
Date: Wed, 19 Apr 2023 08:44:34 +0200
Subject: Support for HTTP range header (#245)

* Support for HTTP range header.

* Implement http range for HTTP sys.

* Validate range parameters.

---------

Co-authored-by: Stefan Boberg <stefan@boberg.org>
---
 zenhttp/httpserver.cpp | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)

(limited to 'zenhttp/httpserver.cpp')

diff --git a/zenhttp/httpserver.cpp b/zenhttp/httpserver.cpp
index 840b90931..952857f2c 100644
--- a/zenhttp/httpserver.cpp
+++ b/zenhttp/httpserver.cpp
@@ -185,6 +185,70 @@ ParseContentTypeInit(const std::string_view& ContentTypeString)
 
 HttpContentType (*ParseContentType)(const std::string_view& ContentTypeString) = &ParseContentTypeInit;
 
+bool
+TryParseHttpRangeHeader(std::string_view RangeHeader, HttpRanges& Ranges)
+{
+	if (RangeHeader.empty())
+	{
+		return false;
+	}
+
+	const size_t Count = Ranges.size();
+
+	std::size_t UnitDelim = RangeHeader.find_first_of('=');
+	if (UnitDelim == std::string_view::npos)
+	{
+		return false;
+	}
+
+	// only bytes for now
+	std::string_view Unit = RangeHeader.substr(0, UnitDelim);
+	if (Unit != "bytes"sv)
+	{
+		return false;
+	}
+
+	std::string_view Tokens = RangeHeader.substr(UnitDelim);
+	while (!Tokens.empty())
+	{
+		// Skip =,
+		Tokens = Tokens.substr(1);
+
+		size_t Delim = Tokens.find_first_of(',');
+		if (Delim == std::string_view::npos)
+		{
+			Delim = Tokens.length();
+		}
+
+		std::string_view Token = Tokens.substr(0, Delim);
+		Tokens				   = Tokens.substr(Delim);
+
+		Delim = Token.find_first_of('-');
+		if (Delim == std::string_view::npos)
+		{
+			return false;
+		}
+
+		const auto Start = ParseInt<uint32_t>(Token.substr(0, Delim));
+		const auto End	 = ParseInt<uint32_t>(Token.substr(Delim + 1));
+
+		if (Start.has_value() && End.has_value() && End.value() > Start.value())
+		{
+			Ranges.push_back({.Start = Start.value(), .End = End.value()});
+		}
+		else if (Start)
+		{
+			Ranges.push_back({.Start = Start.value()});
+		}
+		else if (End)
+		{
+			Ranges.push_back({.End = End.value()});
+		}
+	}
+
+	return Count != Ranges.size();
+}
+
 //////////////////////////////////////////////////////////////////////////
 
 const std::string_view
-- 
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