check lab6 ok

.gitignore

@@ -1,2 +1,4 @@
 /build
 /.ccls-cache
+/.vscode
+/.cache

libsponge/router.cc

@@ -1,6 +1,7 @@
 #include "router.hh"
 
 #include <iostream>
+#include <tuple>
 
 using namespace std;
 
@@ -28,15 +29,37 @@ void Router::add_route(const uint32_t route_prefix,
                        const size_t interface_num) {
     cerr << "DEBUG: adding route " << Address::from_ipv4_numeric(route_prefix).ip() << "/" << int(prefix_length)
          << " => " << (next_hop.has_value() ? next_hop->ip() : "(direct)") << " on interface " << interface_num << "\n";
-
-    DUMMY_CODE(route_prefix, prefix_length, next_hop, interface_num);
-    // Your code here.
+    uint32_t mask = 0;
+    if (prefix_length > 0) mask = (1 << 31) >> (prefix_length - 1);
+    _route_table.push_back(std::make_tuple(route_prefix, prefix_length, next_hop, interface_num, mask));
 }
 
 //! \param[in] dgram The datagram to be routed
 void Router::route_one_datagram(InternetDatagram &dgram) {
-    DUMMY_CODE(dgram);
-    // Your code here.
+    auto dst_ip = dgram.header().dst;
+    auto best_match = _route_table.end();
+    int longest_prefix = 0;
+    for (auto rule = _route_table.begin(); rule != _route_table.end(); ++ rule) {
+        auto route_prefix = std::get<0>(*rule);
+        auto prefix_length = std::get<1>(*rule);
+        auto mask = std::get<4>(*rule);
+        if ((mask & route_prefix) == (mask & dst_ip)) {
+            if (longest_prefix <= prefix_length) {
+                longest_prefix = prefix_length;
+                best_match = rule;
+            }
+        }
+    }
+    if (best_match != _route_table.end()) {
+        if (dgram.header().ttl <= 1) {
+            return;
+        }
+        else {
+            dgram.header().ttl --;
+        }
+        auto next_hop = std::get<2>(*best_match).value_or(Address::from_ipv4_numeric(dgram.header().dst));
+        _interfaces[std::get<3>(*best_match)].send_datagram(dgram, next_hop);
+    }
 }
 
 void Router::route() {

libsponge/router.hh

@@ -1,10 +1,13 @@
 #ifndef SPONGE_LIBSPONGE_ROUTER_HH
 #define SPONGE_LIBSPONGE_ROUTER_HH
 
+#include "address.hh"
 #include "network_interface.hh"
 
+#include <cstdint>
 #include <optional>
 #include <queue>
+#include <tuple>
 
 //! \brief A wrapper for NetworkInterface that makes the host-side
 //! interface asynchronous: instead of returning received datagrams
@@ -44,6 +47,9 @@ class Router {
     //! The router's collection of network interfaces
     std::vector<AsyncNetworkInterface> _interfaces{};
 
+    //! Internal routing table. Tuple(prefix, prefix_length, next_hop, interface, mask)
+    std::vector<std::tuple<uint32_t, uint8_t,std::optional<Address>, size_t, uint32_t>> _route_table {};
+
     //! Send a single datagram from the appropriate outbound interface to the next hop,
     //! as specified by the route with the longest prefix_length that matches the
     //! datagram's destination address.