Kernel: Start fleshing out an UDP implementation.

Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/b59d588c048

Kernel/IPv4Socket.cpp

@@ -4,9 +4,12 @@
 #include <Kernel/NetworkAdapter.h>
 #include <Kernel/IPv4.h>
 #include <Kernel/ICMP.h>
+#include <Kernel/UDP.h>
 #include <Kernel/ARP.h>
 #include <LibC/errno_numbers.h>
 
+#define IPV4_SOCKET_DEBUG
+
 Lockable<HashTable<IPv4Socket*>>& IPv4Socket::all_sockets()
 {
     static Lockable<HashTable<IPv4Socket*>>* s_table;
@@ -173,9 +176,22 @@ ssize_t IPv4Socket::recvfrom(void* buffer, size_t buffer_length, int flags, cons
     }
     ASSERT(!packet_buffer.is_null());
     auto& ipv4_packet = *(const IPv4Packet*)(packet_buffer.pointer());
-    ASSERT(buffer_length >= ipv4_packet.payload_size());
-    memcpy(buffer, ipv4_packet.payload(), ipv4_packet.payload_size());
-    return ipv4_packet.payload_size();
+
+    if (type() == SOCK_RAW) {
+        ASSERT(buffer_length >= ipv4_packet.payload_size());
+        memcpy(buffer, ipv4_packet.payload(), ipv4_packet.payload_size());
+        return ipv4_packet.payload_size();
+    }
+
+    if (type() == SOCK_DGRAM) {
+        auto& udp_packet = *static_cast<const UDPPacket*>(ipv4_packet.payload());
+        ASSERT(udp_packet.length() >= sizeof(UDPPacket)); // FIXME: This should be rejected earlier.
+        ASSERT(buffer_length >= (udp_packet.length() - sizeof(UDPPacket)));
+        memcpy(buffer, udp_packet.payload(), udp_packet.length() - sizeof(UDPPacket));
+        return udp_packet.length() - sizeof(UDPPacket);
+    }
+
+    ASSERT_NOT_REACHED();
 }
 
 void IPv4Socket::did_receive(ByteBuffer&& packet)

Kernel/IPv4Socket.h

@@ -29,6 +29,9 @@ public:
 
     Lock& lock() { return m_lock; }
 
+    word source_port() const { return m_source_port; }
+    word destination_port() const { return m_destination_port; }
+
 private:
     IPv4Socket(int type, int protocol);
     virtual bool is_ipv4() const override { return true; }
@@ -42,6 +45,9 @@ private:
 
     SinglyLinkedList<ByteBuffer> m_receive_queue;
 
+    word m_source_port { 0 };
+    word m_destination_port { 0 };
+
     Lock m_lock;
     bool m_can_read { false };
 };

Kernel/NetworkTask.cpp

@@ -2,6 +2,7 @@
 #include <Kernel/EthernetFrameHeader.h>
 #include <Kernel/ARP.h>
 #include <Kernel/ICMP.h>
+#include <Kernel/UDP.h>
 #include <Kernel/IPv4.h>
 #include <Kernel/IPv4Socket.h>
 #include <Kernel/Process.h>
@@ -10,10 +11,13 @@
 
 //#define ETHERNET_DEBUG
 //#define IPV4_DEBUG
+//#define ICMP_DEBUG
+#define UDP_DEBUG
 
 static void handle_arp(const EthernetFrameHeader&, int frame_size);
 static void handle_ipv4(const EthernetFrameHeader&, int frame_size);
 static void handle_icmp(const EthernetFrameHeader&, int frame_size);
+static void handle_udp(const EthernetFrameHeader&, int frame_size);
 
 Lockable<HashMap<IPv4Address, MACAddress>>& arp_table()
 {
@@ -146,6 +150,8 @@ void handle_ipv4(const EthernetFrameHeader& eth, int frame_size)
     switch ((IPv4Protocol)packet.protocol()) {
     case IPv4Protocol::ICMP:
         return handle_icmp(eth, frame_size);
+    case IPv4Protocol::UDP:
+        return handle_udp(eth, frame_size);
     default:
         kprintf("handle_ipv4: Unhandled protocol %u\n", packet.protocol());
         break;
@@ -158,7 +164,7 @@ void handle_icmp(const EthernetFrameHeader& eth, int frame_size)
     auto& ipv4_packet = *static_cast<const IPv4Packet*>(eth.payload());
     auto& icmp_header = *static_cast<const ICMPHeader*>(ipv4_packet.payload());
 #ifdef ICMP_DEBUG
-    kprintf("handle_icmp: source=%s, destination=%d type=%b, code=%b\n",
+    kprintf("handle_icmp: source=%s, destination=%s, type=%b, code=%b\n",
         ipv4_packet.source().to_string().characters(),
         ipv4_packet.destination().to_string().characters(),
         icmp_header.type(),
@@ -200,3 +206,37 @@ void handle_icmp(const EthernetFrameHeader& eth, int frame_size)
         adapter->send_ipv4(eth.source(), ipv4_packet.source(), IPv4Protocol::ICMP, move(buffer));
     }
 }
+
+void handle_udp(const EthernetFrameHeader& eth, int frame_size)
+{
+    (void)frame_size;
+    auto& ipv4_packet = *static_cast<const IPv4Packet*>(eth.payload());
+
+    auto* adapter = NetworkAdapter::from_ipv4_address(ipv4_packet.destination());
+    if (!adapter) {
+        kprintf("handle_udp: this packet is not for me, it's for %s\n", ipv4_packet.destination().to_string().characters());
+        return;
+    }
+
+    auto& udp_packet = *static_cast<const UDPPacket*>(ipv4_packet.payload());
+#ifdef UDP_DEBUG
+    kprintf("handle_udp: source=%s:%u, destination=%s:%u length=%u\n",
+        ipv4_packet.source().to_string().characters(),
+        udp_packet.source_port(),
+        ipv4_packet.destination().to_string().characters(),
+        udp_packet.destination_port(),
+        udp_packet.length()
+    );
+#endif
+
+    LOCKER(IPv4Socket::all_sockets().lock());
+    for (RetainPtr<IPv4Socket> socket : IPv4Socket::all_sockets().resource()) {
+        LOCKER(socket->lock());
+        if (socket->protocol() != (unsigned)IPv4Protocol::UDP)
+            continue;
+        if (socket->source_port() != udp_packet.destination_port())
+            continue;
+        socket->did_receive(ByteBuffer::copy((const byte*)&ipv4_packet, sizeof(IPv4Packet) + ipv4_packet.payload_size()));
+        return;
+    }
+}

Kernel/UDP.h

@@ -0,0 +1,32 @@
+#pragma once
+
+#include <Kernel/IPv4.h>
+
+class [[gnu::packed]] UDPPacket {
+public:
+    UDPPacket() { }
+    ~UDPPacket() { }
+
+    word source_port() const { return m_source_port; }
+    void set_source_port(word port) { m_source_port = port; }
+
+    word destination_port() const { return m_destination_port; }
+    void set_destination_port(word port) { m_destination_port = port; }
+
+    word length() const { return m_length; }
+    void set_length(word length) { m_length = length; }
+
+    word checksum() const { return m_checksum; }
+    void set_checksum(word checksum) { m_checksum = checksum; }
+
+    const void* payload() const { return this + 1; }
+    void* payload() { return this + 1; }
+
+private:
+    NetworkOrdered<word> m_source_port;
+    NetworkOrdered<word> m_destination_port;
+    NetworkOrdered<word> m_length;
+    NetworkOrdered<word> m_checksum;
+};
+
+static_assert(sizeof(UDPPacket) == 8);

Kernel/UnixTypes.h

@@ -322,6 +322,7 @@ struct pollfd {
 #define SOCK_TYPE_MASK 0xff
 #define SOCK_STREAM 1
 #define SOCK_RAW 3
+#define SOCK_DGRAM 2
 #define SOCK_NONBLOCK 04000
 #define SOCK_CLOEXEC 02000000
 

LibC/sys/socket.h

@@ -15,6 +15,7 @@ __BEGIN_DECLS
 
 #define SOCK_TYPE_MASK 0xff
 #define SOCK_STREAM 1
+#define SOCK_DGRAM 2
 #define SOCK_RAW 3
 #define SOCK_NONBLOCK 04000
 #define SOCK_CLOEXEC 02000000