From 1eead0e885d2fbeaa4f60aea1682eab895c85dff Mon Sep 17 00:00:00 2001
From: orignal <i2porignal@yandex.ru>
Date: Sat, 2 May 2020 21:18:44 -0400
Subject: [PATCH] GzipNoCompression witout zlib calls

---
 libi2pd/Gzip.cpp      | 15 +++++++++++++++
 libi2pd/Gzip.h        |  9 +++++++--
 libi2pd/Streaming.cpp |  8 +++-----
 3 files changed, 25 insertions(+), 7 deletions(-)

diff --git a/libi2pd/Gzip.cpp b/libi2pd/Gzip.cpp
index 1c06e941..a03640a7 100644
--- a/libi2pd/Gzip.cpp
+++ b/libi2pd/Gzip.cpp
@@ -10,6 +10,7 @@
 #include <string.h> /* memset */
 #include <iostream>
 #include "Log.h"
+#include "I2PEndian.h"
 #include "Gzip.h"
 
 namespace i2p
@@ -111,5 +112,19 @@ namespace data
 		LogPrint (eLogError, "Gzip: Deflate error ", err);
 		return 0;
 	}
+
+	size_t GzipNoCompression (const uint8_t * in, uint16_t inLen, uint8_t * out, size_t outLen)
+	{
+		static const uint8_t gzipHeader[11] = { 0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x03, 0x01 };
+		if (outLen < (size_t)inLen + 23) return 0;
+		memcpy (out, gzipHeader, 11);
+		htole16buf (out + 11, inLen);
+		htole16buf (out + 13, 0xffff - inLen);
+		memcpy (out + 15, in, inLen);
+		htole32buf (out + inLen + 15, crc32 (0, in, inLen));
+		htole32buf (out + inLen + 19, inLen);
+		return inLen + 23;
+	}
+	
 } // data
 } // i2p
diff --git a/libi2pd/Gzip.h b/libi2pd/Gzip.h
index 35661abe..cf08d920 100644
--- a/libi2pd/Gzip.h
+++ b/libi2pd/Gzip.h
@@ -3,8 +3,10 @@
 
 #include <zlib.h>
 
-namespace i2p {
-namespace data {
+namespace i2p 
+{
+namespace data 
+{
 	class GzipInflator
 	{
 		public:
@@ -38,6 +40,9 @@ namespace data {
 			z_stream m_Deflator;
 			bool m_IsDirty;
 	};
+
+	size_t GzipNoCompression (const uint8_t * in, uint16_t inLen, uint8_t * out, size_t outLen); // for < 64K
+		
 } // data
 } // i2p
 
diff --git a/libi2pd/Streaming.cpp b/libi2pd/Streaming.cpp
index 6b547170..2a4175f4 100644
--- a/libi2pd/Streaming.cpp
+++ b/libi2pd/Streaming.cpp
@@ -1212,14 +1212,12 @@ namespace stream
 		const uint8_t * payload, size_t len, uint16_t toPort, bool checksum)
 	{
 		auto msg = m_I2NPMsgsPool.AcquireShared ();
-		if (!m_Gzip || len <= i2p::stream::COMPRESSION_THRESHOLD_SIZE)
-			m_Deflator.SetCompressionLevel (Z_NO_COMPRESSION);
-		else
-			m_Deflator.SetCompressionLevel (Z_DEFAULT_COMPRESSION);
 		uint8_t * buf = msg->GetPayload ();
 		buf += 4; // reserve for lengthlength
 		msg->len += 4;
-		size_t size = m_Deflator.Deflate (payload, len, buf, msg->maxLen - msg->len);
+		size_t size = (!m_Gzip || len <= i2p::stream::COMPRESSION_THRESHOLD_SIZE)?
+			i2p::data::GzipNoCompression (payload, len, buf, msg->maxLen - msg->len):
+			m_Deflator.Deflate (payload, len, buf, msg->maxLen - msg->len);
 		if (size)
 		{
 			htobe32buf (msg->GetPayload (), size); // length