Added parameters to add callback function to handle unsupported extensions. Similar to how the callback functions work when parsing certificates. Also added new test cases.

Signed-off-by: Matthias Schulz <mschulz@hilscher.com>

include/mbedtls/x509_csr.h

@@ -102,6 +102,64 @@ mbedtls_x509write_csr;
 int mbedtls_x509_csr_parse_der(mbedtls_x509_csr *csr,
                                const unsigned char *buf, size_t buflen);
 
+/**
+ * \brief          The type of certificate extension callbacks.
+ *
+ *                 Callbacks of this type are passed to and used by the
+ *                 mbedtls_x509_csr_parse_der_with_ext_cb() routine when
+ *                 it encounters either an unsupported extension.
+ *                 Future versions of the library may invoke the callback
+ *                 in other cases, if and when the need arises.
+ *
+ * \param p_ctx    An opaque context passed to the callback.
+ * \param csr      The CSR being parsed.
+ * \param oid      The OID of the extension.
+ * \param critical Whether the extension is critical.
+ * \param p        Pointer to the start of the extension value
+ *                 (the content of the OCTET STRING).
+ * \param end      End of extension value.
+ *
+ * \note           The callback must fail and return a negative error code
+ *                 if it can not parse or does not support the extension.
+ *                 When the callback fails to parse a critical extension
+ *                 mbedtls_x509_csr_parse_der_with_ext_cb() also fails.
+ *                 When the callback fails to parse a non critical extension
+ *                 mbedtls_x509_csr_parse_der_with_ext_cb() simply skips
+ *                 the extension and continues parsing.
+ *
+ * \return         \c 0 on success.
+ * \return         A negative error code on failure.
+ */
+typedef int (*mbedtls_x509_csr_ext_cb_t)(void *p_ctx,
+                                         mbedtls_x509_csr const *csr,
+                                         mbedtls_x509_buf const *oid,
+                                         int critical,
+                                         const unsigned char *p,
+                                         const unsigned char *end);
+
+/**
+ * \brief          Load a Certificate Signing Request (CSR) in DER format
+ *
+ * \note           CSR attributes (if any) are currently silently ignored.
+ *
+ * \note           If #MBEDTLS_USE_PSA_CRYPTO is enabled, the PSA crypto
+ *                 subsystem must have been initialized by calling
+ *                 psa_crypto_init() before calling this function.
+ *
+ * \param csr      CSR context to fill
+ * \param buf      buffer holding the CRL data
+ * \param buflen   size of the buffer
+ * \param cb       A callback invoked for every unsupported certificate
+ *                 extension.
+ * \param p_ctx    An opaque context passed to the callback.
+ *
+ * \return         0 if successful, or a specific X509 error code
+ */
+int mbedtls_x509_csr_parse_der_with_ext_cb(mbedtls_x509_csr *csr,
+                               const unsigned char *buf, size_t buflen,
+                               mbedtls_x509_csr_ext_cb_t cb,
+                               void *p_ctx);
+
 /**
  * \brief          Load a Certificate Signing Request (CSR), DER or PEM format
  *