From ecfd07dfc8b8de76866f5f5756be8f949b86859e Mon Sep 17 00:00:00 2001
From: Leon Lynch <lynch.leon@gmail.com>
Date: Thu, 1 Feb 2024 19:30:33 +0100
Subject: [PATCH] Stringify Account Type (field 5F57)

---
 src/emv_fields.h  |  7 +++++++
 src/emv_strings.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++
 src/emv_strings.h | 13 ++++++++++++
 src/emv_tags.h    |  3 +++
 4 files changed, 76 insertions(+)

diff --git a/src/emv_fields.h b/src/emv_fields.h
index 517f556..bfb7629 100644
--- a/src/emv_fields.h
+++ b/src/emv_fields.h
@@ -205,6 +205,13 @@ __BEGIN_DECLS
 #define EMV_AUC_INTERNATIONAL_CASHBACK                          (0x40) ///< Application Usage Control: International cashback allowed
 #define EMV_AUC_RFU                                             (0x3F) ///< Application Usage Control: RFU
 
+// Account Type (field 5F57)
+// See EMV 4.4 Book 3, Annex G, Table 56
+#define EMV_ACCOUNT_TYPE_DEFAULT                                (0x00) ///< Account Type: Default
+#define EMV_ACCOUNT_TYPE_SAVINGS                                (0x10) ///< Account Type: Savings
+#define EMV_ACCOUNT_TYPE_CHEQUE_OR_DEBIT                        (0x20) ///< Account Type: Cheque/Debit
+#define EMV_ACCOUNT_TYPE_CREDIT                                 (0x30) ///< Account Type: Credit
+
 // Cardholder Verification (CV) Rule byte 1, CVM Codes
 // See EMV 4.4 Book 3, Annex C3, Table 43
 #define EMV_CV_RULE_APPLY_NEXT_IF_UNSUCCESSFUL                  (0x40) ///< Apply succeeding CV Rule if this CVM is unsuccessful
diff --git a/src/emv_strings.c b/src/emv_strings.c
index 29285de..1201200 100644
--- a/src/emv_strings.c
+++ b/src/emv_strings.c
@@ -487,6 +487,20 @@ int emv_tlv_get_info(
 			}
 			return 0;
 
+		case EMV_TAG_5F57_ACCOUNT_TYPE:
+			info->tag_name = "Account Type";
+			info->tag_desc =
+				"Indicates the type of account selected on the "
+				"terminal, coded as specified in Annex G";
+			info->format = EMV_FORMAT_N;
+			if (!tlv->value) {
+				// Cannot use tlv->value[0], even if value_str is NULL.
+				// This is typically for Data Object List (DOL) entries that
+				// have been packed into TLV entries for this function to use.
+				return 0;
+			}
+			return emv_account_type_get_string(tlv->value[0], value_str, value_str_len);
+
 		case EMV_TAG_9F01_ACQUIRER_IDENTIFIER:
 			info->tag_name = "Acquirer Identifier";
 			info->tag_desc =
@@ -3004,6 +3018,45 @@ int emv_language_preference_get_string_list(
 	return 0;
 }
 
+int emv_account_type_get_string(
+	uint8_t account_type,
+	char* str,
+	size_t str_len
+)
+{
+	if (!str || !str_len) {
+		// Caller didn't want the value string
+		return 0;
+	}
+
+	// Account Type (field 5F57)
+	// See EMV 4.4 Book 3, Annex G, Table 56
+	switch (account_type) {
+		case EMV_ACCOUNT_TYPE_DEFAULT:
+			strncpy(str, "Default", str_len);
+			str[str_len - 1] = 0;
+			return 0;
+
+		case EMV_ACCOUNT_TYPE_SAVINGS:
+			strncpy(str, "Savings", str_len);
+			str[str_len - 1] = 0;
+			return 0;
+
+		case EMV_ACCOUNT_TYPE_CHEQUE_OR_DEBIT:
+			strncpy(str, "Cheque/Debit", str_len);
+			str[str_len - 1] = 0;
+			return 0;
+
+		case EMV_ACCOUNT_TYPE_CREDIT:
+			strncpy(str, "Credit", str_len);
+			str[str_len - 1] = 0;
+			return 0;
+
+		default:
+			return 1;
+	}
+}
+
 static const char* emv_cvm_code_get_string(uint8_t cvm_code)
 {
 	const char* cvm_str;
diff --git a/src/emv_strings.h b/src/emv_strings.h
index 45b4595..57fa9bb 100644
--- a/src/emv_strings.h
+++ b/src/emv_strings.h
@@ -492,6 +492,19 @@ int emv_language_preference_get_string_list(
 	size_t str_len
 );
 
+/**
+ * Stringify Account Type (field 5F57)
+ * @param account_type Account Type field
+ * @param str String buffer output
+ * @param str_len Length of string buffer in bytes
+ * @return Zero for success. Less than zero for internal error. Greater than zero for parse error.
+ */
+int emv_account_type_get_string(
+	uint8_t account_type,
+	char* str,
+	size_t str_len
+);
+
 /**
  * Stringify Cardholder Verification Method (CVM) List (field 8E)
  * @note Strings in output buffer are delimited using "\n", including the last string
diff --git a/src/emv_tags.h b/src/emv_tags.h
index af9def7..f8fa29b 100644
--- a/src/emv_tags.h
+++ b/src/emv_tags.h
@@ -178,6 +178,9 @@ __BEGIN_DECLS
 /// EMV tag 5F56 Issuer Country Code (alpha3 format). Template BF0C or 73.
 #define EMV_TAG_5F56_ISSUER_COUNTRY_CODE_ALPHA3                 (0x5F56)
 
+/// EMV tag 5F57 Account Type
+#define EMV_TAG_5F57_ACCOUNT_TYPE                               (0x5F57)
+
 /// EMV tag 9F01 Acquirer Identifier
 #define EMV_TAG_9F01_ACQUIRER_IDENTIFIER                        (0x9F01)