From: Steinar H. Gunderson <sgunderson@bigfoot.com>
Date: Mon, 9 Apr 2018 20:56:24 +0000 (+0200)
Subject: Make HTTP header parsing case-insensitive.
X-Git-Tag: 1.4.0~17
X-Git-Url: https://git.sesse.net/?p=cubemap;a=commitdiff_plain;h=fa431bfab848624c2490a1134e084e6c1dd0dbfa

Make HTTP header parsing case-insensitive.
---

diff --git a/httpinput.cpp b/httpinput.cpp
index 7967c76..bac6b05 100644
--- a/httpinput.cpp
+++ b/httpinput.cpp
@@ -249,17 +249,15 @@ bool HTTPInput::parse_response(const string &request)
 		return false;
 	}
 
-	unordered_multimap<string, string> parameters = extract_headers(lines, url);
+	HTTPHeaderMultimap parameters = extract_headers(lines, url);
 
 	// Remove “Content-encoding: metacube”.
-	// TODO: Make case-insensitive.
-	const auto encoding_it = parameters.find("Content-encoding");
+	const auto encoding_it = parameters.find("Content-Encoding");
 	if (encoding_it != parameters.end() && encoding_it->second == "metacube") {
 		parameters.erase(encoding_it);
 	}
 
 	// Change “Server: foo” to “Server: metacube/0.1 (reflecting: foo)”
-	// TODO: Make case-insensitive.
 	// XXX: Use a Via: instead?
 	if (parameters.count("Server") == 0) {
 		parameters.insert(make_pair("Server", SERVER_IDENTIFICATION));
@@ -273,7 +271,6 @@ bool HTTPInput::parse_response(const string &request)
 	}
 
 	// Erase “Connection: close”; we'll set it on the sending side if needed.
-	// TODO: Make case-insensitive.
 	parameters.erase("Connection");
 
 	// Construct the new HTTP header.
diff --git a/parse.cpp b/parse.cpp
index bec742b..3f373c4 100644
--- a/parse.cpp
+++ b/parse.cpp
@@ -56,9 +56,9 @@ vector<string> split_lines(const string &str)
 	return ret;
 }
 
-unordered_multimap<string, string> extract_headers(const vector<string> &lines, const string &log_context)
+HTTPHeaderMultimap extract_headers(const vector<string> &lines, const string &log_context)
 {
-	unordered_multimap<string, string> parameters;
+	HTTPHeaderMultimap parameters;
 	for (size_t i = 1; i < lines.size(); ++i) {
 		size_t split = lines[i].find(":");
 		if (split == string::npos) {
diff --git a/parse.h b/parse.h
index 1924cc0..a2e3580 100644
--- a/parse.h
+++ b/parse.h
@@ -5,9 +5,42 @@
 
 #include <stddef.h>
 #include <string>
+#include <algorithm>
+#include <string>
 #include <unordered_map>
 #include <vector>
 
+// Locale-unaware tolower(); matches RFC 2616 no matter what the locale is set to.
+static inline char ascii_tolower(const char ch)
+{
+	if (ch >= 'A' && ch <= 'Z') {
+		return ch + 'a' - 'A';
+	} else {
+		return ch;
+	}
+}
+
+// Case-insensitive header comparison and hashing.
+struct HTTPLess {
+	bool operator() (const std::string &a, const std::string &b) const
+	{
+		return std::lexicographical_compare(
+			begin(a), end(a), begin(b), end(b),
+			[](char a, char b) {
+				return ascii_tolower(a) < ascii_tolower(b);
+			});
+	}
+};
+struct HTTPHash {
+	size_t operator() (const std::string &s) const
+	{
+		std::string s_low = s;
+		for (char &ch : s_low) { ch = ascii_tolower(ch); }
+		return std::hash<std::string>() (s_low);
+	}
+};
+using HTTPHeaderMultimap = std::unordered_multimap<std::string, std::string, HTTPHash, HTTPLess>;
+
 // Split a line on whitespace, e.g. "foo  bar baz" -> {"foo", "bar", "baz"}.
 std::vector<std::string> split_tokens(const std::string &line);
 
@@ -16,8 +49,7 @@ std::vector<std::string> split_lines(const std::string &str);
 
 // Extract HTTP headers from a request or response. Ignores the first line,
 // where the verb or the return code is.
-std::unordered_multimap<std::string, std::string> extract_headers(
-	const std::vector<std::string> &lines, const std::string &log_context);
+HTTPHeaderMultimap extract_headers(const std::vector<std::string> &lines, const std::string &log_context);
 
 // Add the new data to an existing string, looking for \r\n\r\n
 // (typical of HTTP requests and/or responses). Will return one
diff --git a/server.cpp b/server.cpp
index 40f3b48..0e056fb 100644
--- a/server.cpp
+++ b/server.cpp
@@ -911,8 +911,7 @@ int Server::parse_request(Client *client)
 	}
 
 	// Parse the headers, for logging purposes.
-	// TODO: Case-insensitivity.
-	unordered_multimap<string, string> headers = extract_headers(lines, client->remote_addr);
+	HTTPHeaderMultimap headers = extract_headers(lines, client->remote_addr);
 	const auto referer_it = headers.find("Referer");
 	if (referer_it != headers.end()) {
 		client->referer = referer_it->second;