From 6d8161de7353ecb636f895656d1c1f3610fb7f99 Mon Sep 17 00:00:00 2001
From: Pol Henarejos <pol.henarejos@cttc.es>
Date: Wed, 8 Jun 2022 17:34:17 +0200
Subject: [PATCH] Added functions to retrieve CAR and CHR from certs.

Signed-off-by: Pol Henarejos <pol.henarejos@cttc.es>
---
 src/hsm/cvc.c | 31 +++++++++++++++++++++++++++++++
 src/hsm/cvc.h |  3 +++
 2 files changed, 34 insertions(+)

diff --git a/src/hsm/cvc.c b/src/hsm/cvc.c
index da5539d..8ab2682 100644
--- a/src/hsm/cvc.c
+++ b/src/hsm/cvc.c
@@ -240,3 +240,34 @@ size_t asn1_cvc_aut(void *rsa_ecdsa, uint8_t key_type, uint8_t *buf, size_t buf_
     mbedtls_mpi_free(&s);
     return p-buf;
 }
+
+uint8_t *cvc_get_field(uint8_t *data, size_t len, size_t *olen, uint16_t tag) {
+    uint8_t *rdata = NULL;
+    if (data == NULL || len == 0)
+        return NULL;
+    if (asn1_find_tag(data, len, tag, olen, &rdata) == false)
+        return NULL;
+    return rdata;
+}
+
+uint8_t *cvc_get_car(uint8_t *data, size_t len, size_t *olen) {
+    uint8_t *bkdata = data;
+    if ((data = cvc_get_field(data, len, olen, 0x67)) == NULL) /* Check for CSR */
+        data = bkdata;
+    if ((data = cvc_get_field(data, len, olen, 0x7F21)) != NULL) {
+        if ((data = cvc_get_field(data, len, olen, 0x7F4E)) != NULL)
+            return cvc_get_field(data, len, olen, 0x42);
+    }
+    return NULL;
+}
+
+uint8_t *cvc_get_chr(uint8_t *data, size_t len, size_t *olen) {
+    uint8_t *bkdata = data;
+    if ((data = cvc_get_field(data, len, olen, 0x67)) == NULL) /* Check for CSR */
+        data = bkdata;
+    if ((data = cvc_get_field(data, len, olen, 0x7F21)) != NULL) {
+        if ((data = cvc_get_field(data, len, olen, 0x7F4E)) != NULL)
+            return cvc_get_field(data, len, olen, 0x5F20);
+    }
+    return NULL;
+}
diff --git a/src/hsm/cvc.h b/src/hsm/cvc.h
index 9cef0fd..2f13c1c 100644
--- a/src/hsm/cvc.h
+++ b/src/hsm/cvc.h
@@ -23,5 +23,8 @@
 
 extern size_t asn1_cvc_cert(void *rsa_ecdsa, uint8_t key_type, uint8_t *buf, size_t buf_len);
 extern size_t asn1_cvc_aut(void *rsa_ecdsa, uint8_t key_type, uint8_t *buf, size_t buf_len);
+extern uint8_t *cvc_get_field(uint8_t *data, size_t len, size_t *olen, uint16_t tag);
+extern uint8_t *cvc_get_car(uint8_t *data, size_t len, size_t *olen);
+extern uint8_t *cvc_get_chr(uint8_t *data, size_t len, size_t *olen);
 
 #endif