Add service fee to specific wallet (#2050)

* add service fee to specific wallet

* add to .env.example

* Added service fee wallet to manage server

* cleaned

* prettier

* Added badge for service fee

* Added tooltip

* Added service fee max

* allow ignoring service fee for internal transactions

* add fee_reserve_total helper funciton that includes service_fee

* html for admin ui

* typo

* Update .env.example

Co-authored-by: Pavol Rusnak <pavol@rusnak.io>

* fix .env.template comment

* bundle

* WIP: expose fee reserve endpoint

---------

Co-authored-by: Arc <ben@arc.wales>
Co-authored-by: dni ⚡ <office@dnilabs.com>
Co-authored-by: Pavol Rusnak <pavol@rusnak.io>

.env.example

@@ -78,7 +78,13 @@ LNBITS_EXTENSIONS_DEFAULT_INSTALL="tpos"
 LNBITS_DATA_FOLDER="./data"
 # LNBITS_DATABASE_URL="postgres://user:password@host:port/databasename"
 
-LNBITS_SERVICE_FEE="0.0"
+# Value in percent
+LNBITS_SERVICE_FEE=0.0
+# Max fee to charge per transaction (in satoshi), 0 will leave no max and use LNBITS_SERVICE_FEE %
+LNBITS_SERVICE_FEE_MAX=0
+# The wallet where the service fee will be sent to
+LNBITS_SERVICE_FEE_WALLET=""
+
 # value in millisats
 LNBITS_RESERVE_FEE_MIN=2000
 # value in percent

lnbits/app.py

@@ -426,6 +426,8 @@ def log_server_info():
     logger.info(f"Data folder: {settings.lnbits_data_folder}")
     logger.info(f"Database: {get_db_vendor_name()}")
     logger.info(f"Service fee: {settings.lnbits_service_fee}")
+    logger.info(f"Service fee max: {settings.lnbits_service_fee_max}")
+    logger.info(f"Service fee wallet: {settings.lnbits_service_fee_wallet}")
 
 
 def get_db_vendor_name():

lnbits/core/services.py

@@ -185,7 +185,6 @@ async def pay_invoice(
     if max_sat and invoice.amount_msat > max_sat * 1000:
         raise ValueError("Amount in invoice is too high.")
 
-    fee_reserve_msat = fee_reserve(invoice.amount_msat)
     async with db.reuse_conn(conn) if conn else db.connect() as conn:
         temp_id = invoice.payment_hash
         internal_id = f"internal_{invoice.payment_hash}"
@@ -228,6 +227,9 @@ async def pay_invoice(
         # (pending only)
         internal_checking_id = await check_internal(invoice.payment_hash, conn=conn)
         if internal_checking_id:
+            fee_reserve_total_msat = fee_reserve_total(
+                invoice.amount_msat, internal=True
+            )
             # perform additional checks on the internal payment
             # the payment hash is not enough to make sure that this is the same invoice
             internal_invoice = await get_standalone_payment(
@@ -244,19 +246,22 @@ async def pay_invoice(
             # create a new payment from this wallet
             new_payment = await create_payment(
                 checking_id=internal_id,
-                fee=0,
+                fee=0 + abs(fee_reserve_total_msat),
                 pending=False,
                 conn=conn,
                 **payment_kwargs,
             )
         else:
+            fee_reserve_total_msat = fee_reserve_total(
+                invoice.amount_msat, internal=False
+            )
             logger.debug(f"creating temporary payment with id {temp_id}")
             # create a temporary payment here so we can check if
             # the balance is enough in the next step
             try:
                 new_payment = await create_payment(
                     checking_id=temp_id,
-                    fee=-fee_reserve_msat,
+                    fee=-abs(fee_reserve_total_msat),
                     conn=conn,
                     **payment_kwargs,
                 )
@@ -270,14 +275,18 @@ async def pay_invoice(
         assert wallet, "Wallet for balancecheck could not be fetched"
         if wallet.balance_msat < 0:
             logger.debug("balance is too low, deleting temporary payment")
-            if not internal_checking_id and wallet.balance_msat > -fee_reserve_msat:
+            if (
+                not internal_checking_id
+                and wallet.balance_msat > -fee_reserve_total_msat
+            ):
                 raise PaymentFailure(
-                    f"You must reserve at least ({round(fee_reserve_msat/1000)} sat) to"
+                    f"You must reserve at least ({round(fee_reserve_total_msat/1000)}"
-                    " cover potential routing fees."
+                    "  sat) to cover potential routing fees."
                 )
             raise PermissionError("Insufficient balance.")
 
     if internal_checking_id:
+        service_fee_msat = service_fee(invoice.amount_msat, internal=True)
         logger.debug(f"marking temporary payment as not pending {internal_checking_id}")
         # mark the invoice from the other side as not pending anymore
         # so the other side only has access to his new money when we are sure
@@ -294,6 +303,8 @@ async def pay_invoice(
         logger.debug(f"enqueuing internal invoice {internal_checking_id}")
         await internal_invoice_queue.put(internal_checking_id)
     else:
+        fee_reserve_msat = fee_reserve(invoice.amount_msat, internal=False)
+        service_fee_msat = service_fee(invoice.amount_msat, internal=False)
         logger.debug(f"backend: sending payment {temp_id}")
         # actually pay the external invoice
         WALLET = get_wallet_class()
@@ -315,7 +326,10 @@ async def pay_invoice(
                 await update_payment_details(
                     checking_id=temp_id,
                     pending=payment.ok is not True,
-                    fee=payment.fee_msat,
+                    fee=-(
+                        abs(payment.fee_msat if payment.fee_msat else 0)
+                        + abs(service_fee_msat)
+                    ),
                     preimage=payment.preimage,
                     new_checking_id=payment.checking_id,
                     conn=conn,
@@ -343,6 +357,18 @@ async def pay_invoice(
                 f" database: {temp_id}"
             )
 
+    # credit service fee wallet
+    if settings.lnbits_service_fee_wallet and service_fee_msat:
+        new_payment = await create_payment(
+            wallet_id=settings.lnbits_service_fee_wallet,
+            fee=0,
+            amount=abs(service_fee_msat),
+            memo="service fee",
+            checking_id="service_fee" + temp_id,
+            payment_request=payment_request,
+            payment_hash=invoice.payment_hash,
+            pending=False,
+        )
     return invoice.payment_hash
 
 
@@ -496,12 +522,31 @@ async def check_transaction_status(
 
 # WARN: this same value must be used for balance check and passed to
 # WALLET.pay_invoice(), it may cause a vulnerability if the values differ
-def fee_reserve(amount_msat: int) -> int:
+def fee_reserve(amount_msat: int, internal: bool = False) -> int:
     reserve_min = settings.lnbits_reserve_fee_min
     reserve_percent = settings.lnbits_reserve_fee_percent
     return max(int(reserve_min), int(amount_msat * reserve_percent / 100.0))
 
 
+def service_fee(amount_msat: int, internal: bool = False) -> int:
+    service_fee_percent = settings.lnbits_service_fee
+    fee_max = settings.lnbits_service_fee_max * 1000
+    if settings.lnbits_service_fee_wallet:
+        if internal and settings.lnbits_service_fee_ignore_internal:
+            return 0
+        fee_percentage = int(amount_msat / 100 * service_fee_percent)
+        if fee_max > 0 and fee_percentage > fee_max:
+            return fee_max
+        else:
+            return fee_percentage
+    else:
+        return 0
+
+
+def fee_reserve_total(amount_msat: int, internal: bool = False) -> int:
+    return fee_reserve(amount_msat, internal) + service_fee(amount_msat, internal)
+
+
 async def send_payment_notification(wallet: Wallet, payment: Payment):
     await websocketUpdater(
         wallet.id,

lnbits/core/templates/admin/_tab_funding.html

@@ -85,6 +85,64 @@
           </div>
         </div>
       </div>
+      <h6 class="q-mt-xl q-mb-md">Service Fees</h6>
+      <div class="row q-col-gutter-md">
+        <div class="col-12 col-md-6">
+          <p>Service Fee</p>
+          <q-input
+            filled
+            type="number"
+            v-model.number="formData.lnbits_service_fee"
+            label="Service fee (%)"
+            step="0.1"
+            hint="Fee charged per tx (%)"
+          ></q-input>
+          <br />
+        </div>
+        <div class="col-12 col-md-6">
+          <p>Service fee max</p>
+          <q-input
+            filled
+            type="number"
+            v-model.number="formData.lnbits_service_fee_max"
+            label="Service fee max (sats)"
+            hint="Max service fee to charge in (sats)"
+          ></q-input>
+          <br />
+        </div>
+        <div class="col-12 col-md-6">
+          <p>Fee Wallet</p>
+          <q-input
+            filled
+            v-model="formData.lnbits_service_fee_wallet"
+            label="Fee wallet (wallet ID)"
+            hint="Wallet ID to send funds to"
+          ></q-input>
+          <br />
+        </div>
+        <div class="col-12 col-md-6">
+          <p>Disable Service Fee for Internal Payments</p>
+          <q-item tag="label" v-ripple>
+            <q-item-section>
+              <q-item-label>Disable Fee</q-item-label>
+              <q-item-label caption
+                >Disable Service Fee for Internal Lightning
+                Payments</q-item-label
+              >
+            </q-item-section>
+            <q-item-section avatar>
+              <q-toggle
+                size="md"
+                v-model="formData.lnbits_service_fee_ignore_internal"
+                checked-icon="check"
+                color="green"
+                unchecked-icon="clear"
+              />
+            </q-item-section>
+          </q-item>
+          <br />
+        </div>
+      </div>
       <div v-if="isSuperUser">
         <lnbits-funding-sources
           :form-data="formData"

lnbits/core/templates/admin/_tab_server.html

@@ -19,41 +19,6 @@
           <br />
         </div>
       </div>
-      <div class="row q-col-gutter-md">
-        <div class="col-12 col-md-6">
-          <p>Service Fee</p>
-          <q-input
-            filled
-            type="number"
-            v-model.number="formData.lnbits_service_fee"
-            label="Service fee (%)"
-            step="0.1"
-            hint="Fee charged per tx (%)"
-          ></q-input>
-          <br />
-        </div>
-        <div class="col-12 col-md-6">
-          <p>Miscellaneous</p>
-          <q-item tag="label" v-ripple>
-            <q-item-section>
-              <q-item-label>Hide API</q-item-label>
-              <q-item-label caption
-                >Hides wallet api, extensions can choose to honor</q-item-label
-              >
-            </q-item-section>
-            <q-item-section avatar>
-              <q-toggle
-                size="md"
-                v-model="formData.lnbits_hide_api"
-                checked-icon="check"
-                color="green"
-                unchecked-icon="clear"
-              />
-            </q-item-section>
-          </q-item>
-          <br />
-        </div>
-      </div>
       <div class="row q-col-gutter-md">
         <div class="col-12 col-md-6">
           <p>Allowed currencies</p>
@@ -93,6 +58,27 @@
           ></q-select>
           <br />
         </div>
+        <div class="col-12 col-md-6">
+          <p>Miscellaneous</p>
+          <q-item tag="label" v-ripple>
+            <q-item-section>
+              <q-item-label>Hide API</q-item-label>
+              <q-item-label caption
+                >Hides wallet api, extensions can choose to honor</q-item-label
+              >
+            </q-item-section>
+            <q-item-section avatar>
+              <q-toggle
+                size="md"
+                v-model="formData.lnbits_hide_api"
+                checked-icon="check"
+                color="green"
+                unchecked-icon="clear"
+              />
+            </q-item-section>
+          </q-item>
+          <br />
+        </div>
       </div>
 
       <div>

lnbits/core/views/api.py

@@ -104,6 +104,7 @@ from ..services import (
     PaymentFailure,
     check_transaction_status,
     create_invoice,
+    fee_reserve_total,
     pay_invoice,
     perform_lnurlauth,
     websocketManager,
@@ -386,6 +387,21 @@ async def api_payments_create(
         )
 
 
+@api_router.get("/api/v1/payments/fee-reserve")
+async def api_payments_fee_reserve(invoice: str = Query("invoice")) -> JSONResponse:
+    invoice_obj = bolt11.decode(invoice)
+    if invoice_obj.amount_msat:
+        response = {
+            "fee_reserve": fee_reserve_total(invoice_obj.amount_msat),
+        }
+        return JSONResponse(response)
+    else:
+        raise HTTPException(
+            status_code=HTTPStatus.BAD_REQUEST,
+            detail="Invoice has no amount.",
+        )
+
+
 @api_router.post("/api/v1/payments/lnurl")
 async def api_payments_pay_lnurl(
     data: CreateLnurl, wallet: WalletTypeInfo = Depends(require_admin_key)

lnbits/core/views/generic.py

@@ -214,6 +214,7 @@ async def wallet(
             "user": user.dict(),
             "wallet": userwallet.dict(),
             "service_fee": settings.lnbits_service_fee,
+            "service_fee_max": settings.lnbits_service_fee_max,
             "web_manifest": f"/manifest/{user.id}.webmanifest",
         },
     )

lnbits/helpers.py

@@ -59,6 +59,9 @@ def template_renderer(additional_folders: Optional[List] = None) -> Jinja2Templa
     t.env.globals["LNBITS_VERSION"] = settings.version
     t.env.globals["LNBITS_NEW_ACCOUNTS_ALLOWED"] = settings.new_accounts_allowed
     t.env.globals["LNBITS_ADMIN_UI"] = settings.lnbits_admin_ui
+    t.env.globals["LNBITS_SERVICE_FEE"] = settings.lnbits_service_fee
+    t.env.globals["LNBITS_SERVICE_FEE_MAX"] = settings.lnbits_service_fee_max
+    t.env.globals["LNBITS_SERVICE_FEE_WALLET"] = settings.lnbits_service_fee_wallet
     t.env.globals["LNBITS_NODE_UI"] = (
         settings.lnbits_node_ui and get_node_class() is not None
     )

lnbits/settings.py

@@ -99,6 +99,9 @@ class OpsSettings(LNbitsSettings):
     lnbits_reserve_fee_min: int = Field(default=2000)
     lnbits_reserve_fee_percent: float = Field(default=1.0)
     lnbits_service_fee: float = Field(default=0)
+    lnbits_service_fee_ignore_internal: bool = Field(default=True)
+    lnbits_service_fee_max: int = Field(default=0)
+    lnbits_service_fee_wallet: str = Field(default=None)
     lnbits_hide_api: bool = Field(default=False)
     lnbits_denomination: str = Field(default="sats")
 

lnbits/static/i18n/en.js

@@ -54,6 +54,10 @@ window.localisation.en = {
   view_github: 'View on GitHub',
   voidwallet_active: 'VoidWallet is active! Payments disabled',
   use_with_caution: 'USE WITH CAUTION - %{name} wallet is still in BETA',
+  service_fee: 'Service fee: %{amount} % per transaction',
+  service_fee_max: 'Service fee: %{amount} % per transaction (max %{max} sats)',
+  service_fee_tooltip:
+    'Service fee charged by the LNbits server admin per outgoing transaction',
   toggle_darkmode: 'Toggle Dark Mode',
   view_swagger_docs: 'View LNbits Swagger API docs',
   api_docs: 'API docs',

lnbits/static/js/service-worker.js

@@ -1,6 +1,6 @@
 // update cache version every time there is a new deployment
 // so the service worker reinitializes the cache
-const CACHE_VERSION = 72
+const CACHE_VERSION = 82
 const CURRENT_CACHE = `lnbits-${CACHE_VERSION}-`
 
 const getApiKey = request => {

lnbits/templates/base.html

@@ -74,7 +74,29 @@
               v-text='$t("use_with_caution", { name: "{{ SITE_TITLE }}" })'
             ></span>
           </q-badge>
-          {% endblock %}
+          {% if LNBITS_SERVICE_FEE > 0 %}
+          <q-badge
+            v-show="$q.screen.gt.sm"
+            v-if="g.user"
+            color="green"
+            text-color="black"
+            class="q-mr-md"
+          >
+            {% if LNBITS_SERVICE_FEE_MAX > 0 %}
+            <span
+              v-text='$t("service_fee_max", { amount: "{{ LNBITS_SERVICE_FEE }}", max: "{{ LNBITS_SERVICE_FEE_MAX }}"})'
+            ></span>
+            {%else%}
+            <span
+              v-text='$t("service_fee", { amount: "{{ LNBITS_SERVICE_FEE }}" })'
+            ></span>
+            {%endif%}
+            <q-tooltip
+              ><span v-text='$t("service_fee_tooltip")'></span
+            ></q-tooltip>
+          </q-badge>
+
+          {%endif%} {% endblock %}
           <q-badge
             v-if="g.offline"
             color="red"

tests/core/views/test_api.py

@@ -6,6 +6,7 @@ import pytest
 from lnbits import bolt11
 from lnbits.core.crud import get_standalone_payment, update_payment_details
 from lnbits.core.models import CreateInvoice, Payment
+from lnbits.core.services import fee_reserve_total
 from lnbits.core.views.admin_api import api_auditor
 from lnbits.core.views.api import api_payment
 from lnbits.settings import settings
@@ -14,6 +15,7 @@ from lnbits.wallets import get_wallet_class
 from ...helpers import (
     cancel_invoice,
     get_random_invoice_data,
+    get_real_invoice,
     is_fake,
     is_regtest,
     pay_real_invoice,
@@ -845,3 +847,32 @@ async def test_receive_real_invoice_set_pending_and_check_state(
     assert payment_by_checking_id.pending is False
     assert payment_by_checking_id.bolt11 == payment_not_pending.bolt11
     assert payment_by_checking_id.payment_hash == payment_not_pending.payment_hash
+
+
+@pytest.mark.asyncio
+async def test_check_fee_reserve(client, adminkey_headers_from):
+    # if regtest, create a real invoice, otherwise create an internal invoice
+    # call /api/v1/payments/fee-reserve?invoice=... with it and check if the fee reserve
+    # is correct
+    payment_request = ""
+    if is_regtest:
+        real_invoice = get_real_invoice(1000)
+        payment_request = real_invoice["payment_request"]
+
+    else:
+        create_invoice = CreateInvoice(out=False, amount=1000, memo="test")
+        response = await client.post(
+            "/api/v1/payments",
+            json=create_invoice.dict(),
+            headers=adminkey_headers_from,
+        )
+        assert response.status_code < 300
+        invoice = response.json()
+        payment_request = invoice["payment_request"]
+
+    response = await client.get(
+        f"/api/v1/payments/fee-reserve?invoice={payment_request}",
+    )
+    assert response.status_code < 300
+    fee_reserve = response.json()
+    assert fee_reserve["fee_reserve"] == fee_reserve_total(1000_000)