From 562964df547e9cdbb3ee32edae5592ab5a513b25 Mon Sep 17 00:00:00 2001
From: lonkaars <loek@pipeframe.xyz>
Date: Tue, 30 Apr 2024 16:30:47 +0200
Subject: tweak packet dumper

---
 src/frontend/qt_sdl/LocalMP.cpp | 60 +++++++++++++++++++++++++++--------------
 1 file changed, 40 insertions(+), 20 deletions(-)

diff --git a/src/frontend/qt_sdl/LocalMP.cpp b/src/frontend/qt_sdl/LocalMP.cpp
index b90ff05..cc42706 100644
--- a/src/frontend/qt_sdl/LocalMP.cpp
+++ b/src/frontend/qt_sdl/LocalMP.cpp
@@ -41,8 +41,11 @@
 
 #include <pcap/pcap.h>
 #include <time.h>
+#include <vector>
+#include <stdint.h>
 
 pcap_dumper_t* dumper;
+unsigned long test_start = time(NULL);
 
 using namespace melonDS;
 using namespace melonDS::Platform;
@@ -76,15 +79,6 @@ struct MPPacketHeader
     u64 Timestamp;
 };
 
-struct MPSync
-{
-    u32 Magic;
-    u32 SenderID;
-    u16 ClientMask;
-    u16 Type;
-    u64 Timestamp;
-};
-
 QSharedMemory* MPQueue;
 int InstanceID;
 u32 PacketReadOffset;
@@ -399,11 +393,13 @@ void FIFORead(int fifo, void* buf, int len)
     if (fifo == 0) PacketReadOffset = offset;
     else           ReplyReadOffset = offset;
 
-    struct pcap_pkthdr p;
-    p.len = len;
-    p.caplen = len;
-    gettimeofday(&p.ts, NULL);
-    pcap_dump((u_char*) dumper, &p, (u_char*) buf);
+    // WIP: temporarily capture sent packets only, capture is done on both
+    // sides anyways, so who cares
+    // struct pcap_pkthdr p;
+    // p.len = len;
+    // p.caplen = len;
+    // gettimeofday(&p.ts, NULL);
+    // pcap_dump((u_char*) dumper, &p, (u_char*) buf);
 }
 
 void FIFOWrite(int fifo, void* buf, int len)
@@ -440,12 +436,6 @@ void FIFOWrite(int fifo, void* buf, int len)
 
     if (fifo == 0) header->PacketWriteOffset = offset;
     else           header->ReplyWriteOffset = offset;
-
-    struct pcap_pkthdr p;
-    p.len = len;
-    p.caplen = len;
-    gettimeofday(&p.ts, NULL);
-    pcap_dump((u_char*) dumper, &p, (u_char*) buf);
 }
 
 int SendPacketGeneric(u32 type, u8* packet, int len, u64 timestamp)
@@ -457,6 +447,17 @@ int SendPacketGeneric(u32 type, u8* packet, int len, u64 timestamp)
 
     u16 mask = header->ConnectedBitmask;
 
+    // // packet dropping test
+    // unsigned long now = time(NULL);
+    // static bool first = true;
+    // bool dropping = false;
+    // if (now - test_start > 20 && InstanceID == 0) {
+    //     if (first == true)
+    //         printf("[INSTANCE %d] started dropping packets!\n", InstanceID);
+    //     first = false;
+    //     dropping = true;
+    // }
+
     // TODO: check if the FIFO is full!
 
     MPPacketHeader pktheader;
@@ -466,11 +467,30 @@ int SendPacketGeneric(u32 type, u8* packet, int len, u64 timestamp)
     pktheader.Length = len;
     pktheader.Timestamp = timestamp;
 
+    std::vector<uint8_t> buf;
+
     type &= 0xFFFF;
     int nfifo = (type == 2) ? 1 : 0;
+    // NOTE: this is the ni-fi packet header, altering this header in any way
+    // seems to consistently trigger PACKET FIFO OVERFLOW errors
     FIFOWrite(nfifo, &pktheader, sizeof(pktheader));
+    buf.insert(buf.end(), (uint8_t*) &pktheader, (uint8_t*) &pktheader + sizeof(pktheader));
     if (len)
+    {
+        // // replace packet content with random noise while dropping
+        // if (dropping)
+        //     for (size_t i = 0; i < len; i++)
+        //         packet[i] = rand();
+
+        buf.insert(buf.end(), (uint8_t*) packet, (uint8_t*) packet + len);
         FIFOWrite(nfifo, packet, len);
+    }
+
+    struct pcap_pkthdr p;
+    p.len = buf.size();
+    p.caplen = buf.size();
+    gettimeofday(&p.ts, NULL);
+    pcap_dump((u_char*) dumper, &p, buf.data());
 
     if (type == 1)
     {
-- 
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