From c9949a3605173a5af75f53e8b1a96633ebe1072b Mon Sep 17 00:00:00 2001
From: Vadim Vetrov <vetrovvd@gmail.com>
Date: Wed, 7 Aug 2024 11:38:26 +0300
Subject: [PATCH] Fix tcp4 frag error caused by enabled IP fragmentation

If the packet is fragmented here is no way to deal with it, but we don't
care about DF flag in real
---
 mangle.c         |  6 +++++-
 youtubeUnblock.c | 10 +++++-----
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/mangle.c b/mangle.c
index 8ccf705..f0e2cea 100644
--- a/mangle.c
+++ b/mangle.c
@@ -226,7 +226,11 @@ int tcp4_frag(const __u8 *pkt, __u32 buflen, __u32 payload_offset,
 	}
 
 
-	if (!(ntohs(hdr->frag_off) & IP_DF)) {
+	if (
+		ntohs(hdr->frag_off) & IP_MF || 
+		ntohs(hdr->frag_off) & IP_OFFMASK) {
+		printf("tcp4_frag: frag value: %d\n",
+			ntohs(hdr->frag_off));
 		lgerror("tcp4_frag: ip fragmentation is set", -EINVAL);
 		return -EINVAL;
 	}
diff --git a/youtubeUnblock.c b/youtubeUnblock.c
index 4eda718..239d116 100644
--- a/youtubeUnblock.c
+++ b/youtubeUnblock.c
@@ -383,7 +383,7 @@ static int process_packet(const struct packet_data packet, struct queue_data qda
 			 mid_offset, frag1, &f1len, frag2, &f2len)) < 0) {
 			errno = -ret;
 			perror("tcp4_frag");
-			goto send_verd;
+			goto fallback;
 		}
 
 #elif defined(USE_IP_FRAGMENTATION)
@@ -395,7 +395,7 @@ static int process_packet(const struct packet_data packet, struct queue_data qda
 			 mid_offset, frag1, &f1len, frag2, &f2len)) < 0) {
 			errno = -ret;
 			perror("ip4_frag");
-			goto send_verd;
+			goto fallback;
 		}
 
 #else
@@ -404,7 +404,7 @@ static int process_packet(const struct packet_data packet, struct queue_data qda
 			errno = -ret;
 			perror("raw pack send");
 		}
-		goto send_verd;
+		goto fallback;
 #endif
 
 		ret = send_raw_socket(frag2, f2len);
@@ -412,7 +412,7 @@ static int process_packet(const struct packet_data packet, struct queue_data qda
 			errno = -ret;
 			perror("raw frags send: frag2");
 
-			goto send_verd;
+			goto fallback;
 		}
 		
 #ifdef SEG2_DELAY
@@ -430,7 +430,7 @@ static int process_packet(const struct packet_data packet, struct queue_data qda
 			errno = -ret;
 			perror("raw frags send: frag1");
 
-			goto send_verd;
+			goto fallback;
 		}
 
 #endif