use std::string_view for I2P HTTP headers. constexpr for ecxluded headers list

libi2pd_client/I2PTunnel.cpp

@@ -428,7 +428,7 @@ namespace client
 					else
 					{
 						// strip up some headers
-						static const std::array<std::string_view, 2> excluded // list of excluded headers
+						static constexpr std::array<std::string_view, 2> excluded // list of excluded headers
 						{
 							"Keep-Alive:", "X-I2P"
 						};
@@ -511,7 +511,7 @@ namespace client
 					if (line == "\r") endOfHeader = true;
 					else
 					{
-						static const std::array<std::string_view, 5> excluded // list of excluded headers
+						static constexpr std::array<std::string_view, 5> excluded // list of excluded headers
 						{
 							"Server:", "Date:", "X-Runtime:", "X-Powered-By:", "Proxy"
 						};

libi2pd_client/I2PTunnel.h

@@ -11,6 +11,7 @@
 
 #include <inttypes.h>
 #include <string>
+#include <string_view>
 #include <set>
 #include <tuple>
 #include <memory>
@@ -30,13 +31,13 @@ namespace client
 	constexpr size_t I2P_TUNNEL_CONNECTION_BUFFER_SIZE = 8192;
 	constexpr size_t I2P_TUNNEL_CONNECTION_STREAM_MAX_SEND_BUFFER_SIZE = 8*I2P_TUNNEL_CONNECTION_BUFFER_SIZE;
 	constexpr size_t I2P_TUNNEL_CONNECTION_STREAM_BUFFER_SIZE = 16384;
-	const int I2P_TUNNEL_CONNECTION_MAX_IDLE = 3600; // in seconds
-	const int I2P_TUNNEL_DESTINATION_REQUEST_TIMEOUT = 10; // in seconds
+	constexpr int I2P_TUNNEL_CONNECTION_MAX_IDLE = 3600; // in seconds
+	constexpr int I2P_TUNNEL_DESTINATION_REQUEST_TIMEOUT = 10; // in seconds
 	// for HTTP tunnels
-	constexpr char X_I2P_DEST_HASH[] = "X-I2P-DestHash"; // hash in base64
-	constexpr char X_I2P_DEST_B64[] = "X-I2P-DestB64"; // full address in base64
-	constexpr char X_I2P_DEST_B32[] = "X-I2P-DestB32"; // .b32.i2p address
-	const int I2P_TUNNEL_HTTP_MAX_HEADER_SIZE = 8192;
+	constexpr std::string_view X_I2P_DEST_HASH { "X-I2P-DestHash" }; // hash in base64
+	constexpr std::string_view X_I2P_DEST_B64 { "X-I2P-DestB64" }; // full address in base64
+	constexpr std::string_view X_I2P_DEST_B32 { "X-I2P-DestB32" }; // .b32.i2p address
+	constexpr int I2P_TUNNEL_HTTP_MAX_HEADER_SIZE = 8192;
 
 	class I2PTunnelConnection: public I2PServiceHandler, public std::enable_shared_from_this<I2PTunnelConnection>
 	{