DHCPClient: Resend DHCP packets when we don't receive an answer

Previously we'd only only send one DHCP request for network interfaces
which were up when DHCPClient started. If that packet was lost we'd
never send another request for those interfaces.

Also, if an interface were to appear after DHCPClient started (not
that that is possible at the moment) we wouldn't send requests for
that interface either.

3 files changed, 30 insertions, 42 deletions

diff --git a/Userland/Services/DHCPClient/DHCPv4Client.cpp b/Userland/Services/DHCPClient/DHCPv4Client.cpp
index 78039b2f69..f3edc2d3f2 100644
--- a/Userland/Services/DHCPClient/DHCPv4Client.cpp
+++ b/Userland/Services/DHCPClient/DHCPv4Client.cpp
@@ -112,9 +112,7 @@ static void set_params(const InterfaceDescriptor& iface, const IPv4Address& ipv4
     }
 }
 
-DHCPv4Client::DHCPv4Client(Vector<InterfaceDescriptor> ifnames_for_immediate_discover, Vector<InterfaceDescriptor> ifnames_for_later)
-    : m_ifnames_for_immediate_discover(move(ifnames_for_immediate_discover))
-    , m_ifnames_for_later(move(ifnames_for_later))
+DHCPv4Client::DHCPv4Client()
 {
     m_server = Core::UDPServer::construct(this);
     m_server->on_ready_to_receive = [this] {
@@ -133,36 +131,37 @@ DHCPv4Client::DHCPv4Client(Vector<InterfaceDescriptor> ifnames_for_immediate_dis
         VERIFY_NOT_REACHED();
     }
 
-    for (auto& iface : m_ifnames_for_immediate_discover)
-        dhcp_discover(iface);
+    m_check_timer = Core::Timer::create_repeating(
+        1000, [this] { try_discover_ifs(); }, this);
 
-    m_fail_check_timer = Core::Timer::create_repeating(
-        1000, [this] { try_discover_deferred_ifs(); }, this);
+    m_check_timer->start();
 
-    m_fail_check_timer->start();
+    try_discover_ifs();
 }
 
-void DHCPv4Client::try_discover_deferred_ifs()
+void DHCPv4Client::try_discover_ifs()
 {
-    auto current_interval = m_fail_check_timer->interval();
-    if (current_interval < m_max_timer_backoff_interval)
-        current_interval *= 1.9f;
-    m_fail_check_timer->set_interval(current_interval);
-
-    if (m_ifnames_for_later.is_empty())
-        return;
-
-    // See if any of them are now up.
     auto ifs_result = get_discoverable_interfaces();
     if (ifs_result.is_error())
         return;
 
+    bool sent_discover_request = false;
     Interfaces& ifs = ifs_result.value();
     for (auto& iface : ifs.ready) {
-        if (!m_ifnames_for_later.remove_first_matching([&](auto& if_) { return if_.m_ifname == iface.m_ifname; }))
+        if (iface.m_current_ip_address != IPv4Address { 0, 0, 0, 0 })
             continue;
 
-        deferred_invoke([this, iface](auto&) { dhcp_discover(iface); });
+        dhcp_discover(iface);
+        sent_discover_request = true;
+    }
+
+    if (sent_discover_request) {
+        auto current_interval = m_check_timer->interval();
+        if (current_interval < m_max_timer_backoff_interval)
+            current_interval *= 1.9f;
+        m_check_timer->set_interval(current_interval);
+    } else {
+        m_check_timer->set_interval(1000);
     }
 }
 
@@ -192,12 +191,14 @@ Result<DHCPv4Client::Interfaces, String> DHCPv4Client::get_discoverable_interfac
         auto name = if_object.get("name").to_string();
         auto mac = if_object.get("mac_address").to_string();
         auto is_up = if_object.get("link_up").to_bool();
+        auto ipv4_addr_maybe = IPv4Address::from_string(if_object.get("ipv4_address").to_string());
+        auto ipv4_addr = ipv4_addr_maybe.has_value() ? ipv4_addr_maybe.value() : IPv4Address { 0, 0, 0, 0 };
         if (is_up) {
             dbgln_if(DHCPV4_DEBUG, "Found adapter '{}' with mac {}, and it was up!", name, mac);
-            ifnames_to_immediately_discover.empend(name, mac_from_string(mac));
+            ifnames_to_immediately_discover.empend(name, mac_from_string(mac), ipv4_addr);
         } else {
             dbgln_if(DHCPV4_DEBUG, "Found adapter '{}' with mac {}, but it was down", name, mac);
-            ifnames_to_attempt_later.empend(name, mac_from_string(mac));
+            ifnames_to_attempt_later.empend(name, mac_from_string(mac), ipv4_addr);
         }
     });
 
@@ -344,10 +345,8 @@ void DHCPv4Client::dhcp_discover(const InterfaceDescriptor& iface)
     auto& dhcp_packet = builder.build();
 
     // broadcast the discover request
-    if (!send(iface, dhcp_packet, this)) {
-        m_ifnames_for_later.append(iface);
+    if (!send(iface, dhcp_packet, this))
         return;
-    }
     m_ongoing_transactions.set(transaction_id, make<DHCPv4Transaction>(iface));
 }
 
@@ -373,9 +372,7 @@ void DHCPv4Client::dhcp_request(DHCPv4Transaction& transaction, const DHCPv4Pack
     auto& dhcp_packet = builder.build();
 
     // broadcast the "request" request
-    if (!send(iface, dhcp_packet, this)) {
-        m_ifnames_for_later.append(iface);
+    if (!send(iface, dhcp_packet, this))
         return;
-    }
     transaction.accepted_offer = true;
 }
diff --git a/Userland/Services/DHCPClient/DHCPv4Client.h b/Userland/Services/DHCPClient/DHCPv4Client.h
index f7fcf1ea65..72af9d2d33 100644
--- a/Userland/Services/DHCPClient/DHCPv4Client.h
+++ b/Userland/Services/DHCPClient/DHCPv4Client.h
@@ -21,7 +21,7 @@
 struct InterfaceDescriptor {
     String m_ifname;
     MACAddress m_mac_address;
-    IPv4Address m_current_ip_address { 0, 0, 0, 0 };
+    IPv4Address m_current_ip_address;
 };
 
 struct DHCPv4Transaction {
@@ -40,7 +40,7 @@ class DHCPv4Client final : public Core::Object {
     C_OBJECT(DHCPv4Client)
 
 public:
-    explicit DHCPv4Client(Vector<InterfaceDescriptor> ifnames_for_immediate_discover, Vector<InterfaceDescriptor> ifnames_for_later);
+    explicit DHCPv4Client();
     virtual ~DHCPv4Client() override;
 
     void dhcp_discover(const InterfaceDescriptor& ifname);
@@ -57,13 +57,11 @@ public:
     static Result<Interfaces, String> get_discoverable_interfaces();
 
 private:
-    void try_discover_deferred_ifs();
+    void try_discover_ifs();
 
     HashMap<u32, OwnPtr<DHCPv4Transaction>> m_ongoing_transactions;
-    Vector<InterfaceDescriptor> m_ifnames_for_immediate_discover;
-    Vector<InterfaceDescriptor> m_ifnames_for_later;
     RefPtr<Core::UDPServer> m_server;
-    RefPtr<Core::Timer> m_fail_check_timer;
+    RefPtr<Core::Timer> m_check_timer;
     int m_max_timer_backoff_interval { 600000 }; // 10 minutes
 
     void handle_offer(const DHCPv4Packet&, const ParsedDHCPv4Options&);
diff --git a/Userland/Services/DHCPClient/main.cpp b/Userland/Services/DHCPClient/main.cpp
index a150b07e4a..6d55e675b1 100644
--- a/Userland/Services/DHCPClient/main.cpp
+++ b/Userland/Services/DHCPClient/main.cpp
@@ -34,14 +34,7 @@ int main([[maybe_unused]] int argc, [[maybe_unused]] char** argv)
 
     unveil(nullptr, nullptr);
 
-    auto ifs_result = DHCPv4Client::get_discoverable_interfaces();
-    if (ifs_result.is_error()) {
-        warnln("Error: {}", ifs_result.error());
-        return 1;
-    }
-
-    auto ifs = ifs_result.release_value();
-    auto client = DHCPv4Client::construct(move(ifs.ready), move(ifs.not_ready));
+    auto client = DHCPv4Client::construct();
 
     if (pledge("stdio inet cpath rpath", nullptr) < 0) {
         perror("pledge");