From 1b37347422f00edb648dfa78cd83083a2f80a9e8 Mon Sep 17 00:00:00 2001
From: Christian Grothoff <christian@grothoff.org>
Date: Fri, 11 Aug 2023 16:30:32 +0200
Subject: add STEFAN support to exchange

---
 src/exchange/taler-exchange-httpd.c      | 71 ++++++++++++++++++++++++++++++++
 src/exchange/taler-exchange-httpd.h      | 21 ++++++++++
 src/exchange/taler-exchange-httpd_keys.c |  8 ++++
 3 files changed, 100 insertions(+)

(limited to 'src/exchange')

diff --git a/src/exchange/taler-exchange-httpd.c b/src/exchange/taler-exchange-httpd.c
index 7d5992935..194ec6dae 100644
--- a/src/exchange/taler-exchange-httpd.c
+++ b/src/exchange/taler-exchange-httpd.c
@@ -149,6 +149,27 @@ struct TALER_AttributeEncryptionKeyP TEH_attribute_key;
  */
 struct TALER_EXCHANGEDB_Plugin *TEH_plugin;
 
+/**
+ * Absolute STEFAN parameter.
+ */
+struct TALER_Amount TEH_stefan_abs;
+
+/**
+ * Logarithmic STEFAN parameter.
+ */
+struct TALER_Amount TEH_stefan_log;
+
+/**
+ * Linear STEFAN parameter.
+ */
+struct TALER_Amount TEH_stefan_lin;
+
+/**
+ * Default number of fractional digits to render
+ * amounts with.
+ */
+unsigned int TEH_currency_fraction_digits;
+
 /**
  * Our currency.
  */
@@ -1925,6 +1946,25 @@ exchange_serve_process_config (void)
                                "CURRENCY");
     return GNUNET_SYSERR;
   }
+  {
+    unsigned long long cfd;
+
+    if (GNUNET_OK !=
+        GNUNET_CONFIGURATION_get_value_number (TEH_cfg,
+                                               "exchange",
+                                               "CURRENCY_FRACTION_DIGITS",
+                                               &cfd))
+      cfd = 0;
+    if (cfd > 8)
+    {
+      GNUNET_log_config_invalid (GNUNET_ERROR_TYPE_ERROR,
+                                 "taler",
+                                 "CURRENCY_FRACTION_DIGITS",
+                                 "Value must be below 8");
+      return GNUNET_SYSERR;
+    }
+    TEH_currency_fraction_digits = (unsigned int) cfd;
+  }
   if (GNUNET_OK !=
       TALER_config_get_amount (TEH_cfg,
                                "exchange",
@@ -1935,6 +1975,37 @@ exchange_serve_process_config (void)
                 "Need amount in section `exchange' under `AML_THRESHOLD'\n");
     return GNUNET_SYSERR;
   }
+  if (GNUNET_OK !=
+      TALER_config_get_amount (TEH_cfg,
+                               "exchange",
+                               "STEFAN_ABS",
+                               &TEH_stefan_abs))
+  {
+    GNUNET_assert (GNUNET_OK ==
+                   TALER_amount_set_zero (TEH_currency,
+                                          &TEH_stefan_abs));
+  }
+  if (GNUNET_OK !=
+      TALER_config_get_amount (TEH_cfg,
+                               "exchange",
+                               "STEFAN_LOG",
+                               &TEH_stefan_log))
+  {
+    GNUNET_assert (GNUNET_OK ==
+                   TALER_amount_set_zero (TEH_currency,
+                                          &TEH_stefan_log));
+  }
+  if (GNUNET_OK !=
+      TALER_config_get_amount (TEH_cfg,
+                               "exchange",
+                               "STEFAN_LIN",
+                               &TEH_stefan_lin))
+  {
+    GNUNET_assert (GNUNET_OK ==
+                   TALER_amount_set_zero (TEH_currency,
+                                          &TEH_stefan_lin));
+  }
+
   if (0 != strcmp (TEH_currency,
                    TEH_aml_threshold.currency))
   {
diff --git a/src/exchange/taler-exchange-httpd.h b/src/exchange/taler-exchange-httpd.h
index 9fcfcd6c1..9e18f9e69 100644
--- a/src/exchange/taler-exchange-httpd.h
+++ b/src/exchange/taler-exchange-httpd.h
@@ -97,6 +97,27 @@ extern struct TALER_AttributeEncryptionKeyP TEH_attribute_key;
  */
 extern struct TALER_EXCHANGEDB_Plugin *TEH_plugin;
 
+/**
+ * Absolute STEFAN parameter.
+ */
+extern struct TALER_Amount TEH_stefan_abs;
+
+/**
+ * Logarithmic STEFAN parameter.
+ */
+extern struct TALER_Amount TEH_stefan_log;
+
+/**
+ * Linear STEFAN parameter.
+ */
+extern struct TALER_Amount TEH_stefan_lin;
+
+/**
+ * Default number of fractional digits to render
+ * amounts with.
+ */
+extern unsigned int TEH_currency_fraction_digits;
+
 /**
  * Our currency.
  */
diff --git a/src/exchange/taler-exchange-httpd_keys.c b/src/exchange/taler-exchange-httpd_keys.c
index 9623a5a30..0bb5c8138 100644
--- a/src/exchange/taler-exchange-httpd_keys.c
+++ b/src/exchange/taler-exchange-httpd_keys.c
@@ -2525,6 +2525,14 @@ create_krd (struct TEH_KeyStateHandle *ksh,
                              TEH_base_url),
     GNUNET_JSON_pack_string ("currency",
                              TEH_currency),
+    GNUNET_JSON_pack_uint64 ("currency_fraction_digits",
+                             TEH_currency_fraction_digits),
+    TALER_JSON_pack_amount ("stefan_abs",
+                            &TEH_stefan_abs),
+    TALER_JSON_pack_amount ("stefan_log",
+                            &TEH_stefan_log),
+    TALER_JSON_pack_amount ("stefan_lin",
+                            &TEH_stefan_lin),
     GNUNET_JSON_pack_string ("asset_type",
                              asset_type),
     // FIXME: legacy, remove soon!
-- 
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