Kernel: More work on ICMP support.

We can now kinda sorta respond to ICMP::EchoRequest although there's
still something not entirely right with the packets.

3 files changed, 13 insertions, 18 deletions

diff --git a/Kernel/ICMP.h b/Kernel/ICMP.h
index 0e21b58b5d..6155d431ed 100644
--- a/Kernel/ICMP.h
+++ b/Kernel/ICMP.h
@@ -25,27 +25,22 @@ public:
     word checksum() const { return ntohs(m_checksum); }
     void set_checksum(word w) { m_checksum = htons(w); }
 
-    const void* payload() const { return &m_payload[0]; }
-    void* payload() { return &m_payload[0]; }
+    const void* payload() const { return this + 1; }
+    void* payload() { return this + 1; }
 
 private:
     byte m_type { 0 };
     byte m_code { 0 };
     word m_checksum { 0 };
-    dword m_rest_of_header { 0 };
-    byte m_payload[0];
+    // NOTE: The rest of the header is 4 bytes
 };
 
-static_assert(sizeof(ICMPHeader) == 8);
-
-struct [[gnu::packed]] IPv4ICMPPacket {
-    IPv4Packet ipv4_packet;
-    ICMPHeader icmp_header;
-};
+static_assert(sizeof(ICMPHeader) == 4);
 
 struct [[gnu::packed]] ICMPEchoPacket {
     ICMPHeader header;
     NetworkOrdered<word> identifier;
     NetworkOrdered<word> sequence_number;
-    byte payload[];
+    void* payload() { return this + 1; }
+    const void* payload() const { return this + 1; }
 };
diff --git a/Kernel/IPv4Packet.h b/Kernel/IPv4Packet.h
index 2ff5769002..ae7df3e415 100644
--- a/Kernel/IPv4Packet.h
+++ b/Kernel/IPv4Packet.h
@@ -38,8 +38,8 @@ public:
     const IPv4Address& destination() const { return m_destination; }
     void set_destination(const IPv4Address& address) { m_destination = address; }
 
-    void* payload() { return m_payload; }
-    const void* payload() const { return m_payload; }
+    void* payload() { return this + 1; }
+    const void* payload() const { return this + 1; }
 
 private:
     byte m_version_and_ihl;
@@ -52,7 +52,6 @@ private:
     word m_checksum;
     IPv4Address m_source;
     IPv4Address m_destination;
-    byte m_payload[0];
 };
 
 static_assert(sizeof(IPv4Packet) == 20);
diff --git a/Kernel/NetworkTask.cpp b/Kernel/NetworkTask.cpp
index 41a2d08ca7..6718254a38 100644
--- a/Kernel/NetworkTask.cpp
+++ b/Kernel/NetworkTask.cpp
@@ -156,6 +156,7 @@ void handle_ipv4(const EthernetFrameHeader& eth, int frame_size)
 
 void handle_icmp(const EthernetFrameHeader& eth, int frame_size)
 {
+    (void)frame_size;
     auto& ipv4_packet = *static_cast<const IPv4Packet*>(eth.payload());
     auto& icmp_header = *static_cast<const ICMPHeader*>(ipv4_packet.payload());
     kprintf("handle_icmp: type=%b, code=%b\n", icmp_header.type(), icmp_header.code());
@@ -165,7 +166,7 @@ void handle_icmp(const EthernetFrameHeader& eth, int frame_size)
         // It's for me!
         if (icmp_header.type() == ICMPType::EchoRequest) {
             auto& request = reinterpret_cast<const ICMPEchoPacket&>(icmp_header);
-            kprintf("ICMP echo request: id=%u, seq=%u\n", (int)request.identifier, (int)request.sequence_number);
+            kprintf("ICMP echo request: id=%u, seq=%u, len=%u\n", (int)request.identifier, (int)request.sequence_number, ipv4_packet.length() - sizeof(ICMPEchoPacket));
             byte* response_buffer = (byte*)kmalloc(ipv4_packet.length());
             memset(response_buffer, 0, ipv4_packet.length());
             struct [[gnu::packed]] EchoResponse {
@@ -178,13 +179,13 @@ void handle_icmp(const EthernetFrameHeader& eth, int frame_size)
             response.ipv4.set_source(e1000.ipv4_address());
             response.ipv4.set_destination(ipv4_packet.source());
             response.ipv4.set_protocol(IPv4Protocol::ICMP);
-            response.ipv4.set_length(sizeof(IPv4ICMPPacket));
+            response.ipv4.set_length(ipv4_packet.length());
             response.icmp_echo.header.set_type(ICMPType::EchoReply);
             response.icmp_echo.header.set_code(0);
             response.icmp_echo.identifier = request.identifier;
             response.icmp_echo.sequence_number = request.sequence_number;
-            memcpy(response.icmp_echo.payload, request.payload, ipv4_packet.length() - sizeof(ICMPEchoPacket));
-            e1000.send_ipv4(eth.source(), &response, ipv4_packet.length());
+            memcpy(response.icmp_echo.payload(), request.payload(), ipv4_packet.length() - sizeof(EchoResponse));
+            e1000.send_ipv4(eth.source(), response_buffer, ipv4_packet.length());
             kfree(response_buffer);
         }
     }