IPv4: Last burst of TCP hacking for today.

Connecting to a test server and exchanging data back and forth works.

Kernel/IPv4Socket.cpp

@@ -245,11 +245,16 @@ void IPv4Socket::send_tcp_packet(NetworkAdapter& adapter, word flags, const void
 
     memcpy(tcp_packet.payload(), payload, payload_size);
     tcp_packet.set_checksum(compute_tcp_checksum(adapter.ipv4_address(), m_destination_address, tcp_packet, payload_size));
-    kprintf("sending tcp packet from %s:%u to %s:%u!\n",
+    kprintf("sending tcp packet from %s:%u to %s:%u with (%s %s) seq_no=%u, ack_no=%u\n",
         adapter.ipv4_address().to_string().characters(),
         source_port(),
         m_destination_address.to_string().characters(),
-        m_destination_port);
+        m_destination_port,
+        tcp_packet.has_syn() ? "SYN" : "",
+        tcp_packet.has_ack() ? "ACK" : "",
+        tcp_packet.sequence_number(),
+        tcp_packet.ack_number()
+    );
     adapter.send_ipv4(MACAddress(), m_destination_address, IPv4Protocol::TCP, move(buffer));
 }
 
@@ -302,7 +307,7 @@ ssize_t IPv4Socket::sendto(const void* data, size_t data_length, int flags, cons
     }
 
     if (type() == SOCK_STREAM) {
-        send_tcp_packet(*adapter, 0, data, data_length);
+        send_tcp_packet(*adapter, TCPFlags::PUSH | TCPFlags::ACK, data, data_length);
         return data_length;
     }
 
@@ -374,7 +379,7 @@ ssize_t IPv4Socket::recvfrom(void* buffer, size_t buffer_length, int flags, sock
 
     if (type() == SOCK_STREAM) {
         auto& tcp_packet = *static_cast<const TCPPacket*>(ipv4_packet.payload());
-        size_t payload_size = packet_buffer.size() - tcp_packet.header_size();
+        size_t payload_size = packet_buffer.size() - sizeof(IPv4Packet) - tcp_packet.header_size();
         ASSERT(buffer_length >= payload_size);
         if (addr) {
             auto& ia = *(sockaddr_in*)addr;
@@ -395,5 +400,4 @@ void IPv4Socket::did_receive(ByteBuffer&& packet)
 #ifdef IPV4_SOCKET_DEBUG
     kprintf("IPv4Socket(%p): did_receive %d bytes, packets in queue: %d\n", this, packet.size(), m_receive_queue.size_slow());
 #endif
-
 }

Kernel/NetworkTask.cpp

@@ -262,8 +262,10 @@ void handle_tcp(const EthernetFrameHeader& eth, int frame_size)
     }
 
     auto& tcp_packet = *static_cast<const TCPPacket*>(ipv4_packet.payload());
+    size_t payload_size = ipv4_packet.payload_size() - tcp_packet.header_size();
+
 #ifdef TCP_DEBUG
-    kprintf("handle_tcp: source=%s:%u, destination=%s:%u seq_no=%u, ack_no=%u, flags=%w (%s %s), window_size=%u\n",
+    kprintf("handle_tcp: source=%s:%u, destination=%s:%u seq_no=%u, ack_no=%u, flags=%w (%s %s), window_size=%u, payload_size=%u\n",
         ipv4_packet.source().to_string().characters(),
         tcp_packet.source_port(),
         ipv4_packet.destination().to_string().characters(),
@@ -273,7 +275,8 @@ void handle_tcp(const EthernetFrameHeader& eth, int frame_size)
         tcp_packet.flags(),
         tcp_packet.has_syn() ? "SYN" : "",
         tcp_packet.has_ack() ? "ACK" : "",
-        tcp_packet.window_size()
+        tcp_packet.window_size(),
+        payload_size
     );
 #endif
 
@@ -293,10 +296,8 @@ void handle_tcp(const EthernetFrameHeader& eth, int frame_size)
     ASSERT(socket->type() == SOCK_STREAM);
     ASSERT(socket->source_port() == tcp_packet.destination_port());
 
-    size_t payload_size = ipv4_packet.payload_size() - tcp_packet.header_size();
-
     if (tcp_packet.ack_number() != socket->tcp_sequence_number()) {
-        kprintf("handle_tcp: ack/seq mismatch: got %u, wanted %u\n", tcp_packet.ack_number(), socket->tcp_sequence_number());
+        kprintf("handle_tcp: ack/seq mismatch: got %u, wanted %u\n",tcp_packet.ack_number(), socket->tcp_sequence_number());
         return;
     }
 
@@ -310,8 +311,8 @@ void handle_tcp(const EthernetFrameHeader& eth, int frame_size)
     }
 
     socket->set_tcp_ack_number(socket->tcp_sequence_number() + payload_size);
-
     socket->send_tcp_packet(*adapter, TCPFlags::ACK);
 
-    socket->did_receive(ByteBuffer::copy((const byte*)&ipv4_packet, sizeof(IPv4Packet) + ipv4_packet.payload_size()));
+    if (payload_size != 0)
+        socket->did_receive(ByteBuffer::copy((const byte*)&ipv4_packet, sizeof(IPv4Packet) + ipv4_packet.payload_size()));
 }

Userland/tc.cpp

@@ -42,30 +42,37 @@ int main(int argc, char** argv)
         return 1;
     }
 
+    printf("Connecting to %s...", addr_str);
+    fflush(stdout);
     rc = connect(fd, (struct sockaddr*)&dst_addr, sizeof(dst_addr));
     if (rc < 0) {
         perror("connect");
         return 1;
     }
+    printf("ok!\n");
 
     char buffer[BUFSIZ];
-    const char* msg = "Test message!\n";
+    const char* msg = "I am a TCP client.";
 
+    printf("Sending a greeting...");
     rc = send(fd, (const char*)msg, strlen(msg), 0);
     if (rc < 0) {
         perror("send");
         return 1;
     }
-    printf("Message sent.\n");
+    printf("ok!\n");
 
+    printf("Waiting for response...");
     ssize_t nrecv = recv(fd, buffer, sizeof(buffer), 0);
     if (nrecv < 0) {
         perror("recvfrom");
         return 1;
     }
     buffer[nrecv] = '\0';
-    printf("Server: %s\n", buffer);
+    printf("ok! Got response:\n");
+    printf("\033[36;1m%s\033[0m", buffer);
 
+    printf("(%d bytes received)\n", nrecv);
     rc = close(fd);
     if (rc < 0) {
         perror("close");