Implement updating a client Pub+PSK when editing a client (#401)

This covers the normal use-case where clients generate keys
locally on their device and notify the server of their new/updated keys.

The server verifies Preshared and Public keys independently of each
other. Should a client generate a new tunnel which lacks a PSK and send
only a Public key to the server (admin) where the earlier server created
profile has a Preshared key, the server admin/user must determine the
course of action:
keep or remove the PSK.

handler/routes.go

@@ -567,6 +567,45 @@ func UpdateClient(db store.IStore) echo.HandlerFunc {
 			return c.JSON(http.StatusBadRequest, jsonHTTPResponse{false, "Extra Allowed IPs must be in CIDR format"})
 		}
 
+		// update Wireguard Client PublicKey
+		if client.PublicKey != _client.PublicKey && _client.PublicKey != "" {
+			_, err := wgtypes.ParseKey(_client.PublicKey)
+			if err != nil {
+				log.Error("Cannot verify provided Wireguard public key: ", err)
+				return c.JSON(http.StatusInternalServerError, jsonHTTPResponse{false, "Cannot verify provided Wireguard public key"})
+			}
+			// check for duplicates
+			clients, err := db.GetClients(false)
+			if err != nil {
+				log.Error("Cannot get client list for duplicate public key check")
+				return c.JSON(http.StatusInternalServerError, jsonHTTPResponse{false, "Cannot get client list for duplicate public key check"})
+			}
+			for _, other := range clients {
+				if other.Client.PublicKey == _client.PublicKey {
+					log.Error("Duplicate Public Key")
+					return c.JSON(http.StatusInternalServerError, jsonHTTPResponse{false, "Duplicate Public Key"})
+				}
+			}
+
+			// When replacing any PublicKey, discard any locally stored Wireguard Client PrivateKey
+			// Client PubKey no longer corresponds to locally stored PrivKey.
+			// QR code (needs PrivateKey) for this client is no longer possible now.
+
+			if client.PrivateKey != "" {
+				client.PrivateKey = ""
+			}
+
+		}
+
+		// update Wireguard Client PresharedKey
+		if client.PresharedKey != _client.PresharedKey && _client.PresharedKey != "" {
+			_, err := wgtypes.ParseKey(_client.PresharedKey)
+			if err != nil {
+				log.Error("Cannot verify provided Wireguard preshared key: ", err)
+				return c.JSON(http.StatusInternalServerError, jsonHTTPResponse{false, "Cannot verify provided Wireguard preshared key"})
+			}
+		}
+
 		// map new data
 		client.Name = _client.Name
 		client.Email = _client.Email
@@ -575,6 +614,8 @@ func UpdateClient(db store.IStore) echo.HandlerFunc {
 		client.AllocatedIPs = _client.AllocatedIPs
 		client.AllowedIPs = _client.AllowedIPs
 		client.ExtraAllowedIPs = _client.ExtraAllowedIPs
+		client.PublicKey = _client.PublicKey
+		client.PresharedKey = _client.PresharedKey
 		client.UpdatedAt = time.Now().UTC()
 
 		// write to the database

templates/clients.html

@@ -129,6 +129,26 @@ Wireguard Clients
                             </label>
                         </div>
                     </div>
+                    <details>
+                        <summary><strong>Public and Preshared Keys</strong>
+                            <i class="fas fa-info-circle" data-toggle="tooltip"
+                               data-original-title="Update the server stored
+                               client Public and Preshared keys.">
+                            </i>
+                        </summary>
+                        <div class="form-group" style="margin-top: 1rem">
+                            <label for="_client_public_key" class="control-label">
+                                Public Key
+                            </label>
+                            <input type="text" class="form-control" id="_client_public_key" name="_client_public_key" aria-invalid="false">
+                        </div>
+                        <div class="form-group">
+                            <label for="_client_preshared_key" class="control-label">
+                                Preshared Key
+                            </label>
+                            <input type="text" class="form-control" id="_client_preshared_key" name="_client_preshared_key">
+                        </div>
+                    </details>
                 </div>
                 <div class="modal-footer justify-content-between">
                     <button type="button" class="btn btn-default" data-dismiss="modal">Cancel</button>
@@ -388,6 +408,7 @@ Wireguard Clients
 
 
         // Edit client modal event
+        // This fills the modal dialogue with data from the DB when we open the edit menu
         $(document).ready(function () {
             $("#modal_edit_client").on('show.bs.modal', function (event) {
                 let modal = $(this);
@@ -458,6 +479,9 @@ Wireguard Clients
 
                         modal.find("#_use_server_dns").prop("checked", client.use_server_dns);
                         modal.find("#_enabled").prop("checked", client.enabled);
+
+                        modal.find("#_client_public_key").val(client.public_key);
+                        modal.find("#_client_preshared_key").val(client.preshared_key);
                     },
                     error: function (jqXHR, exception) {
                         const responseJson = jQuery.parseJSON(jqXHR.responseText);
@@ -523,6 +547,8 @@ Wireguard Clients
         }
 
         // submitEditClient function for updating an existing client
+        // This sends dialogue data to the back-end when user presses "Save"
+        // See e.g. routes.go:UpdateClient for where data is processed/verified.
         function submitEditClient() {
             const client_id = $("#_client_id").val();
             const name = $("#_client_name").val();
@@ -531,6 +557,8 @@ Wireguard Clients
             const allowed_ips = $("#_client_allowed_ips").val().split(",");
             let use_server_dns = false;
             let extra_allowed_ips = [];
+            const public_key = $("#_client_public_key").val();
+            const preshared_key = $("#_client_preshared_key").val();
 
             if( $("#_client_extra_allowed_ips").val() !== "" ) {
                 extra_allowed_ips = $("#_client_extra_allowed_ips").val().split(",");
@@ -547,7 +575,7 @@ Wireguard Clients
             }
 
             const data = {"id": client_id, "name": name, "email": email, "allocated_ips": allocated_ips,
-                "allowed_ips": allowed_ips, "extra_allowed_ips": extra_allowed_ips, "use_server_dns": use_server_dns, "enabled": enabled};
+                "allowed_ips": allowed_ips, "extra_allowed_ips": extra_allowed_ips, "use_server_dns": use_server_dns, "enabled": enabled, "public_key": public_key, "preshared_key": preshared_key};
 
             $.ajax({
                 cache: false,