/*
 * Copyright (C) 1997-2000 Sensus Consulting Ltd.
 * Matt Newman <matt@sensus.org>
 * Copyright (C) 2023 Brian O'Hagan
 */
#include <tcl.h>
#include <stdio.h>
#include <openssl/bio.h>
#include <openssl/sha.h>
#include <openssl/x509.h>
#include <openssl/x509v3.h>
#include <openssl/x509_vfy.h>
#include <openssl/asn1.h>
#include "tlsInt.h"

/* Define maximum certificate size. Max PEM size 100kB and DER size is 24kB. */
#define CERT_STR_SIZE 32768

/* Common macros */

    if (text != NULL) Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj(text, -1)); \
    Tcl_ListObjAppendElement(interp, obj, listObj); \
}

/*
 * Binary string to hex string
 */
int String_to_Hex(char* input, int len, char *output, int size) {
int String_to_Hex(char* input, int ilen, char *output, int olen) {
    int count = 0;

    for (int i = 0; i < len && count < size - 1; i++, count += 2) {
    for (int i = 0; i < ilen && count < olen - 1; i++, count += 2) {
	sprintf(output + count, "%02X", input[i] & 0xff);
    }
    output[count] = 0;
    return count;
}

/*

    uint32_t usage = X509_get_key_usage(cert);
    Tcl_Obj *listPtr = Tcl_NewListObj(0, NULL);

    if (listPtr == NULL) {
	return NULL;
    }

    if ((xflags & EXFLAG_KUSAGE) && usage < 0xffffff) {
    if ((xflags & EXFLAG_KUSAGE) && usage < UINT32_MAX) {
	if (usage & KU_DIGITAL_SIGNATURE) {
	    Tcl_ListObjAppendElement(interp, listPtr, Tcl_NewStringObj("Digital Signature", -1));
	}
	if (usage & KU_NON_REPUDIATION) {
	    Tcl_ListObjAppendElement(interp, listPtr, Tcl_NewStringObj("Non-Repudiation", -1));
	}
	if (usage & KU_KEY_ENCIPHERMENT) {

	}
	if (usage & KU_ENCIPHER_ONLY) {
	    Tcl_ListObjAppendElement(interp, listPtr, Tcl_NewStringObj("Encipher Only", -1));
	}
	if (usage & KU_DECIPHER_ONLY) {
	    Tcl_ListObjAppendElement(interp, listPtr, Tcl_NewStringObj("Decipher Only", -1));
	}
    } else {
	    Tcl_ListObjAppendElement(interp, listPtr, Tcl_NewStringObj("unrestricted", -1));
    }
    return listPtr;
}

/*
 * Get Certificate Purpose
 */

    uint32_t usage = X509_get_key_usage(cert);
    Tcl_Obj *listPtr = Tcl_NewListObj(0, NULL);

    if (listPtr == NULL) {
	return NULL;
    }

    if (xflags & EXFLAG_XKUSAGE) {
    if ((xflags & EXFLAG_XKUSAGE) && usage < UINT32_MAX) {
	usage = X509_get_extended_key_usage(cert);

	if (usage & XKU_SSL_SERVER) {
	    Tcl_ListObjAppendElement(interp, listPtr, Tcl_NewStringObj("TLS Web Server Authentication", -1));
	}
	if (usage & XKU_SSL_CLIENT) {
	    Tcl_ListObjAppendElement(interp, listPtr, Tcl_NewStringObj("TLS Web Client Authentication", -1));

	}
	if (usage & XKU_DVCS ) {
	    Tcl_ListObjAppendElement(interp, listPtr, Tcl_NewStringObj("DVCS", -1));
	}
	if (usage & XKU_ANYEKU) {
	    Tcl_ListObjAppendElement(interp, listPtr, Tcl_NewStringObj("Any Extended Key Usage", -1));
	}
    } else {
	    Tcl_ListObjAppendElement(interp, listPtr, Tcl_NewStringObj("unrestricted", -1));
    }
    return listPtr;
}

/*
 * Get CRL Distribution Points
 */

    LAPPEND_STR(interp, certPtr, "notAfter", buffer, len);

    /* Subject identifies the entity associated with the public key stored in
	the subject public key field. RFC 5280 section 4.1.2.6 */
    len = BIO_to_Buffer(X509_NAME_print_ex(bio, X509_get_subject_name(cert), 0, flags), bio, buffer, BUFSIZ);
    LAPPEND_STR(interp, certPtr, "subject", buffer, len);

    /* SHA1 Fingerprint of cert - DER representation */
    /* SHA1 Digest (Fingerprint) of cert - DER representation */
    if (X509_digest(cert, EVP_sha1(), md, &len)) {
    len = String_to_Hex(md, len, buffer, BUFSIZ);
	LAPPEND_STR(interp, certPtr, "sha1_hash", buffer, len);
    }

    /* SHA256 Fingerprint of cert - DER representation */
    /* SHA256 Digest (Fingerprint) of cert - DER representation */
    if (X509_digest(cert, EVP_sha256(), md, &len)) {
    len = String_to_Hex(md, len, buffer, BUFSIZ);
	LAPPEND_STR(interp, certPtr, "sha256_hash", buffer, len);
    }

    /* Subject Public Key Info specifies the public key and identifies the
	algorithm with which the key is used. RFC 5280 section 4.1.2.7 */

	len = 0;
	if (X509_pubkey_digest(cert, EVP_get_digestbynid(pknid), md, &n)) {
	    len = String_to_Hex(md, (int)n, buffer, BUFSIZ);
	}
	LAPPEND_STR(interp, certPtr, "publicKeyHash", buffer, len);

	/* digest of the DER representation of the certificate */
	len = 0;
	if (X509_digest(cert, EVP_get_digestbynid(mdnid), md, &n)) {
	    len = String_to_Hex(md, (int)n, buffer, BUFSIZ);
	}
	LAPPEND_STR(interp, certPtr, "signatureHash", buffer, len);
    }

    /* Certificate Purpose. Call before checking for extensions. */
    LAPPEND_STR(interp, certPtr, "purpose", Tls_x509Purpose(cert), -1);
    LAPPEND_OBJ(interp, certPtr, "certificatePurpose", Tls_x509Purposes(interp, cert));

    /* Get extensions flags */
    xflags = X509_get_extension_flags(cert);
    LAPPEND_INT(interp, certPtr, "extFlags", xflags);

	/* Check if cert was issued by CA cert issuer or self signed */
    LAPPEND_BOOL(interp, certPtr, "selfIssued", xflags & EXFLAG_SI);
    LAPPEND_BOOL(interp, certPtr, "selfSigned", xflags & EXFLAG_SS);
    LAPPEND_BOOL(interp, certPtr, "isProxyCert", xflags & EXFLAG_PROXY);
    LAPPEND_BOOL(interp, certPtr, "extInvalid", xflags & EXFLAG_INVALID);
    LAPPEND_BOOL(interp, certPtr, "isCACert", X509_check_ca(cert));

    /* The Unique Ids are used to handle the possibility of reuse of subject
	and/or issuer names over time. RFC 5280 section 4.1.2.8 */
    {
	const ASN1_BIT_STRING *iuid, *suid;
        X509_get0_uids(cert, &iuid, &suid);

    LAPPEND_OBJ(interp, certPtr, "subjectKeyIdentifier",
	Tls_x509Identifier(X509_get0_subject_key_id(cert)));

    /* Key usage extension defines the purpose (e.g., encipherment, signature, certificate
	signing) of the key in the certificate. RFC 5280 section 4.2.1.3, NID_key_usage */
    LAPPEND_OBJ(interp, certPtr, "keyUsage", Tls_x509KeyUsage(interp, cert, xflags));

    /* Certificate Purpose */
    LAPPEND_STR(interp, certPtr, "purpose", Tls_x509Purpose(cert), -1);

    /* Get purposes */
    LAPPEND_OBJ(interp, certPtr, "certificatePurpose", Tls_x509Purposes(interp, cert));

    /* Certificate Policies - indicates the issuing CA considers its issuerDomainPolicy
	equivalent to the subject CA's subjectDomainPolicy. RFC 5280 section 4.2.1.4, NID_certificate_policies */
    if (xflags & EXFLAG_INVALID_POLICY) {
	/* Reject cert */
    }

    /* Policy Mappings - RFC 5280 section 4.2.1.5, NID_policy_mappings */

    LAPPEND_OBJ(interp, certPtr, "issuerAltName", Tls_x509Names(interp, cert, NID_issuer_alt_name, bio));

    /* Subject Directory Attributes provides identification attributes (e.g., nationality)
	of the subject. RFC 5280 section 4.2.1.8 (subjectDirectoryAttributes) */

    /* Basic Constraints identifies whether the subject of the cert is a CA and
	the max depth of valid cert paths for this cert. RFC 5280 section 4.2.1.9, NID_basic_constraints */
    if (xflags & EXFLAG_BCONS) {
    if (!(xflags & EXFLAG_PROXY)) {
	LAPPEND_LONG(interp, certPtr, "pathLen", X509_get_pathlen(cert));
    } else {
	LAPPEND_LONG(interp, certPtr, "pathLen", X509_get_proxy_pathlen(cert));
    }
    LAPPEND_BOOL(interp, certPtr, "basicConstraintsCA", xflags & EXFLAG_CA);
    LAPPEND_BOOL(interp, certPtr, "basicConstraintsCritical", xflags & EXFLAG_CRITICAL);

    /* Name Constraints is only used in CA certs to indicate the name space for
	all subject names in subsequent certificates in a certification path
	MUST be located. RFC 5280 section 4.2.1.10, NID_name_constraints */

    /* Policy Constraints is only used in CA certs to limit the length of a
	cert chain for that CA. RFC 5280 section 4.2.1.11, NID_policy_constraints */

    /* Freshest CRL extension */
    if (xflags & EXFLAG_FRESHEST) {
    }

    /* Authority Information Access indicates how to access info and services
	for the certificate issuer. RFC 5280 section 4.2.2.1, NID_info_access */

    /* Get On-line Certificate Status Protocol (OSCP) URL */
    LAPPEND_OBJ(interp, certPtr, "ocsp", Tls_x509Oscp(interp, cert));
    /* Get On-line Certificate Status Protocol (OSCP) Responders URL */
    LAPPEND_OBJ(interp, certPtr, "ocspResponders", Tls_x509Oscp(interp, cert));

    /* Get Certificate Authority (CA) Issuers URL */
    LAPPEND_OBJ(interp, certPtr, "caIssuers", Tls_x509CaIssuers(interp, cert));

    /* Subject Information Access - RFC 5280 section 4.2.2.2, NID_sinfo_access */

    /* Certificate Alias. If uses a PKCS#12 structure, alias will reflect the