Guard the TCP connections datastructure

kernel/src/net/tcp_layer.cpp

@@ -10,11 +10,14 @@
 #include <list.hpp>
 
 #include "conc/condition_variable.hpp"
+#include "conc/rw_lock.hpp"
 
 #include "net/tcp_layer.hpp"
 #include "net/dns_layer.hpp"
 #include "net/checksum.hpp"
 
+#include "tlib/errors.hpp"
+
 #include "kernel_utils.hpp"
 #include "circular_buffer.hpp"
 #include "timer.hpp"
@@ -37,12 +40,12 @@ using flag_syn         = std::bit_field<uint16_t, uint8_t, 1, 1>;
 using flag_fin         = std::bit_field<uint16_t, uint8_t, 0, 1>;
 
 struct tcp_connection {
-    size_t source_port;
-    size_t target_port;
+    size_t source_port; ///< The source port of the connection
+    size_t target_port; ///< The target port of the connection
 
-    std::atomic<bool> listening;
-    condition_variable queue;
-    circular_buffer<network::ethernet::packet, 8> packets;
+    std::atomic<bool> listening;                           ///< Indicates if a kernel thread is listening on this connection
+    condition_variable queue;                              ///< The listening queue
+    circular_buffer<network::ethernet::packet, 8> packets; ///< The packets for the listening queue
 
     tcp_connection(size_t source_port, size_t target_port)
             : source_port(source_port), target_port(target_port), listening(false) {
@@ -50,24 +53,47 @@ struct tcp_connection {
     }
 };
 
+// The lock used to protect the list of connections
+rw_lock connections_lock;
+
 // Note: We need a list to not invalidate the values during insertions
 std::list<tcp_connection> connections;
 
 tcp_connection* get_connection(size_t source_port, size_t target_port) {
+    auto lock = connections_lock.reader_lock();
+    std::lock_guard<reader_rw_lock> l(lock);
+
+    for(auto& connection : connections){
+        if (connection.source_port == source_port && connection.target_port == target_port) {
+            return &connection;
+        }
+    }
+
+    return nullptr;
+}
+
+tcp_connection& create_connection(size_t target, size_t source){
+    auto lock = connections_lock.writer_lock();
+    std::lock_guard<writer_rw_lock> l(lock);
+
+    return connections.emplace_back(target, source);
+}
+
+void remove_connection(tcp_connection& connection){
+    auto lock = connections_lock.writer_lock();
+    std::lock_guard<writer_rw_lock> l(lock);
+
     auto end = connections.end();
     auto it  = connections.begin();
 
     while (it != end) {
-        auto& connection = *it;
-
-        if (connection.source_port == source_port && connection.target_port == target_port) {
-            return &connection;
+        if (&(*it) == &connection) {
+            connections.erase(it);
+            return;
         }
 
         ++it;
     }
-
-    return nullptr;
 }
 
 void compute_checksum(network::ethernet::packet& packet) {
@@ -154,22 +180,20 @@ void network::tcp::decode(network::interface_descriptor& interface, network::eth
 
     // Propagate to kernel connections
 
-    auto end = connections.end();
-    auto it  = connections.begin();
+    {
+        auto lock = connections_lock.reader_lock();
+        std::lock_guard<reader_rw_lock> l(lock);
 
-    while (it != end) {
-        auto& connection = *it;
+        for (auto& connection : connections) {
+            if (connection.listening.load() && connection.source_port == source_port && connection.target_port == target_port) {
+                auto copy    = packet;
+                copy.payload = new char[copy.payload_size];
+                std::copy_n(packet.payload, packet.payload_size, copy.payload);
 
-        if (connection.listening.load() && connection.source_port == source_port && connection.target_port == target_port) {
-            auto copy    = packet;
-            copy.payload = new char[copy.payload_size];
-            std::copy_n(packet.payload, packet.payload_size, copy.payload);
-
-            connection.packets.push(copy);
-            connection.queue.notify_one();
+                connection.packets.push(copy);
+                connection.queue.notify_one();
+            }
         }
-
-        ++it;
     }
 
     auto seq_number = ack;
@@ -365,7 +389,7 @@ std::expected<void> network::tcp::connect(network::socket& sock, network::interf
 
     // Create the connection
 
-    auto& connection = connections.emplace_back(target, source);
+    auto& connection = create_connection(target, source);
 
     connection.listening = true;
 
@@ -450,7 +474,14 @@ std::expected<void> network::tcp::disconnect(network::socket& sock, network::int
     (flag_ack(&flags)) = 1;
     tcp_header->flags = switch_endian_16(flags);
 
-    auto& connection = connections.emplace_back(target, source);
+    auto connection_ptr = get_connection(target, source);
+
+    if (!connection_ptr) {
+        logging::logf(logging::log_level::ERROR, "tcp: Unable to find connection!\n");
+        return std::make_unexpected<void>(std::ERROR_SOCKET_INVALID_CONNECTION);
+    }
+
+    auto& connection = *connection_ptr;
 
     connection.listening = true;
 
@@ -523,17 +554,7 @@ std::expected<void> network::tcp::disconnect(network::socket& sock, network::int
         tcp::finalize_packet(interface, *packet);
     }
 
-    auto end = connections.end();
-    auto it  = connections.begin();
-
-    while (it != end) {
-        if (&(*it) == &connection) {
-            connections.erase(it);
-            break;
-        }
-
-        ++it;
-    }
+    remove_connection(connection);
 
     return {};
 }

tlib/include/tlib/errors.hpp

@@ -43,6 +43,7 @@ constexpr const size_t ERROR_SOCKET_TIMEOUT                   = 28;
 constexpr const size_t ERROR_SOCKET_INVALID_PACKET_DESCRIPTOR = 29;
 constexpr const size_t ERROR_SOCKET_INVALID_TYPE_PROTOCOL     = 30;
 constexpr const size_t ERROR_SOCKET_NOT_CONNECTED             = 31;
+constexpr const size_t ERROR_SOCKET_INVALID_CONNECTION        = 32;
 
 inline const char* error_message(size_t error){
     switch(error){
@@ -108,6 +109,8 @@ inline const char* error_message(size_t error){
             return "The socket protocol is not vaild with this type";
         case ERROR_SOCKET_NOT_CONNECTED:
             return "The socket is not connected";
+        case ERROR_SOCKET_INVALID_CONNECTION:
+            return "Issue with the internal connection";
         default:
             return "Unknonwn error";
     }