// Copyright (C) 2004-2021 Artifex Software, Inc.
//
// This file is part of MuPDF.
//
// MuPDF is free software: you can redistribute it and/or modify it under the
// terms of the GNU Affero General Public License as published by the Free
// Software Foundation, either version 3 of the License, or (at your option)
// any later version.
//
// MuPDF is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
// FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
// details.
//
// You should have received a copy of the GNU Affero General Public License
// along with MuPDF. If not, see <https://www.gnu.org/licenses/agpl-3.0.en.html>
//
// Alternative licensing terms are available from the licensor.
// For commercial licensing, see <https://www.artifex.com/> or contact
// Artifex Software, Inc., 1305 Grant Avenue - Suite 200, Novato,
// CA 94945, U.S.A., +1(415)492-9861, for further information.

#include "mupdf/fitz.h"
#include "mupdf/pdf.h"

#include "mupdf/helpers/pkcs7-openssl.h"

#ifndef HAVE_LIBCRYPTO

pdf_pkcs7_signer *
pkcs7_openssl_read_pfx(fz_context *ctx, const char *pfile, const char *pw)
{
	fz_throw(ctx, FZ_ERROR_GENERIC, "No OpenSSL support.");
}

pdf_pkcs7_verifier *
pkcs7_openssl_new_verifier(fz_context *ctx)
{
	fz_throw(ctx, FZ_ERROR_GENERIC, "No OpenSSL support.");
}

#else

#include <limits.h>
#include <string.h>

/* Generated from resources/certs/AdobeCA.p7c */
static const char AdobeCA_p7c[] = {
48,130,4,208,6,9,42,134,72,134,247,13,1,7,2,160,130,4,193,48,130,4,189,2,
1,1,49,0,48,11,6,9,42,134,72,134,247,13,1,7,1,160,130,4,165,48,130,4,161,
48,130,3,137,160,3,2,1,2,2,4,62,28,189,40,48,13,6,9,42,134,72,134,247,13,
1,1,5,5,0,48,105,49,11,48,9,6,3,85,4,6,19,2,85,83,49,35,48,33,6,3,85,4,10,
19,26,65,100,111,98,101,32,83,121,115,116,101,109,115,32,73,110,99,111,114,
112,111,114,97,116,101,100,49,29,48,27,6,3,85,4,11,19,20,65,100,111,98,101,
32,84,114,117,115,116,32,83,101,114,118,105,99,101,115,49,22,48,20,6,3,85,
4,3,19,13,65,100,111,98,101,32,82,111,111,116,32,67,65,48,30,23,13,48,51,
48,49,48,56,50,51,51,55,50,51,90,23,13,50,51,48,49,48,57,48,48,48,55,50,51,
90,48,105,49,11,48,9,6,3,85,4,6,19,2,85,83,49,35,48,33,6,3,85,4,10,19,26,
65,100,111,98,101,32,83,121,115,116,101,109,115,32,73,110,99,111,114,112,
111,114,97,116,101,100,49,29,48,27,6,3,85,4,11,19,20,65,100,111,98,101,32,
84,114,117,115,116,32,83,101,114,118,105,99,101,115,49,22,48,20,6,3,85,4,
3,19,13,65,100,111,98,101,32,82,111,111,116,32,67,65,48,130,1,34,48,13,6,
9,42,134,72,134,247,13,1,1,1,5,0,3,130,1,15,0,48,130,1,10,2,130,1,1,0,204,
79,84,132,247,167,162,231,51,83,127,63,156,18,136,107,44,153,71,103,126,15,
30,185,173,20,136,249,195,16,216,29,240,240,213,159,105,10,47,89,53,176,204,
108,169,76,156,21,160,159,206,32,191,160,207,84,226,224,32,102,69,63,57,134,
56,126,156,196,142,7,34,198,36,246,1,18,176,53,223,85,234,105,144,176,219,
133,55,30,226,78,7,178,66,161,106,19,105,160,102,234,128,145,17,89,42,155,
8,121,90,32,68,45,201,189,115,56,139,60,47,224,67,27,93,179,11,240,175,53,
26,41,254,239,166,146,221,129,76,157,61,89,142,173,49,60,64,126,155,145,54,
6,252,226,92,141,209,141,38,213,92,69,207,175,101,63,177,170,210,98,150,244,
168,56,234,186,96,66,244,244,28,74,53,21,206,248,78,34,86,15,149,24,197,248,
150,159,159,251,176,183,120,37,233,128,107,189,214,10,240,198,116,148,157,
243,15,80,219,154,119,206,75,112,131,35,141,160,202,120,32,68,92,60,84,100,
241,234,162,48,25,159,234,76,6,77,6,120,75,94,146,223,34,210,201,103,179,
122,210,1,2,3,1,0,1,163,130,1,79,48,130,1,75,48,17,6,9,96,134,72,1,134,248,
66,1,1,4,4,3,2,0,7,48,129,142,6,3,85,29,31,4,129,134,48,129,131,48,129,128,
160,126,160,124,164,122,48,120,49,11,48,9,6,3,85,4,6,19,2,85,83,49,35,48,
33,6,3,85,4,10,19,26,65,100,111,98,101,32,83,121,115,116,101,109,115,32,73,
110,99,111,114,112,111,114,97,116,101,100,49,29,48,27,6,3,85,4,11,19,20,65,
100,111,98,101,32,84,114,117,115,116,32,83,101,114,118,105,99,101,115,49,
22,48,20,6,3,85,4,3,19,13,65,100,111,98,101,32,82,111,111,116,32,67,65,49,
13,48,11,6,3,85,4,3,19,4,67,82,76,49,48,43,6,3,85,29,16,4,36,48,34,128,15,
50,48,48,51,48,49,48,56,50,51,51,55,50,51,90,129,15,50,48,50,51,48,49,48,
57,48,48,48,55,50,51,90,48,11,6,3,85,29,15,4,4,3,2,1,6,48,31,6,3,85,29,35,
4,24,48,22,128,20,130,183,56,74,147,170,155,16,239,128,187,217,84,226,241,
15,251,128,156,222,48,29,6,3,85,29,14,4,22,4,20,130,183,56,74,147,170,155,
16,239,128,187,217,84,226,241,15,251,128,156,222,48,12,6,3,85,29,19,4,5,48,
3,1,1,255,48,29,6,9,42,134,72,134,246,125,7,65,0,4,16,48,14,27,8,86,54,46,
48,58,52,46,48,3,2,4,144,48,13,6,9,42,134,72,134,247,13,1,1,5,5,0,3,130,1,
1,0,50,218,159,67,117,193,250,111,201,111,219,171,29,54,55,62,188,97,25,54,
183,2,60,29,35,89,152,108,158,238,77,133,231,84,200,32,31,167,212,187,226,
191,0,119,125,36,107,112,47,92,193,58,118,73,181,211,224,35,132,42,113,106,
34,243,193,39,41,152,21,246,53,144,228,4,76,195,141,188,159,97,28,231,253,
36,140,209,68,67,140,22,186,155,77,165,212,53,47,188,17,206,189,247,81,55,
141,159,144,228,20,241,24,63,190,233,89,18,53,249,51,146,243,158,224,213,
107,154,113,155,153,75,200,113,195,225,177,97,9,196,229,250,145,240,66,58,
55,125,52,249,114,232,205,170,98,28,33,233,213,244,130,16,227,123,5,182,45,
104,86,11,126,126,146,44,111,77,114,130,12,237,86,116,178,157,185,171,45,
43,29,16,95,219,39,117,112,143,253,29,215,226,2,160,121,229,28,229,255,175,
100,64,81,45,158,155,71,219,66,165,124,31,194,166,72,176,215,190,146,105,
77,164,246,41,87,197,120,17,24,220,135,81,202,19,178,98,157,79,43,50,189,
49,165,193,250,82,171,5,136,200,49,0
};

#include "openssl/err.h"
#include "openssl/bio.h"
#include "openssl/asn1.h"
#include "openssl/x509.h"
#include "openssl/x509v3.h"
#include "openssl/err.h"
#include "openssl/objects.h"
#include "openssl/pem.h"
#include "openssl/pkcs7.h"
#include "openssl/pkcs12.h"
#include "openssl/opensslv.h"

#ifndef OPENSSL_VERSION_NUMBER
#warning detect version of openssl at compile time
#endif

#if defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x3060000fL

static inline const STACK_OF(PKCS12_SAFEBAG) *
PKCS12_SAFEBAG_get0_safes(const PKCS12_SAFEBAG *bag)
{
	return (OBJ_obj2nid(bag->type) == NID_safeContentsBag) ? bag->value.safes : NULL;
}

static inline const PKCS8_PRIV_KEY_INFO *
PKCS12_SAFEBAG_get0_p8inf(const PKCS12_SAFEBAG *bag)
{
	return (OBJ_obj2nid(bag->type) == NID_keyBag) ? bag->value.keybag : NULL;
}

#endif

typedef struct
{
	fz_context *ctx;
	fz_stream *stm;
} BIO_stream_data;

static int stream_read(BIO *b, char *buf, int size)
{
	BIO_stream_data *data = (BIO_stream_data *)BIO_get_data(b);
	size_t read = 0;

	fz_try(data->ctx)
		read = fz_read(data->ctx, data->stm, (unsigned char *) buf, size);
	fz_catch(data->ctx)
		return -1;

	return (int)read;
}

static long stream_ctrl(BIO *b, int cmd, long arg1, void *arg2)
{
	BIO_stream_data *data = (BIO_stream_data *)BIO_get_data(b);
	long ret;
	switch (cmd)
	{
	case BIO_C_FILE_SEEK:
		fz_try(data->ctx)
		{
			fz_seek(data->ctx, data->stm, arg1, SEEK_SET);
			ret = fz_tell(data->ctx, data->stm);
		}
		fz_catch(data->ctx)
			return -1;
		return ret;
	default:
		return 1;
	}
}

static int stream_new(BIO *b)
{
	BIO_stream_data *data = (BIO_stream_data *)malloc(sizeof(BIO_stream_data));
	if (!data)
		return 0;

	data->ctx = NULL;
	data->stm = NULL;

	BIO_set_init(b, 1);
	BIO_set_data(b, data);
	BIO_clear_flags(b, INT_MAX);

	return 1;
}

static int stream_free(BIO *b)
{
	if (b == NULL)
		return 0;

	free(BIO_get_data(b));
	BIO_set_data(b, NULL);
	BIO_set_init(b, 0);
	BIO_clear_flags(b, INT_MAX);

	return 1;
}

static long stream_callback_ctrl(BIO *b, int cmd, bio_info_cb *fp)
{
	return 1;
}

static BIO *BIO_new_stream(fz_context *ctx, fz_stream *stm)
{
	static BIO_METHOD *methods = NULL;
	BIO *bio;
	BIO_stream_data *data;

	if (!methods)
	{
		methods = BIO_meth_new(BIO_TYPE_NONE, "segment reader");
		if (!methods)
			return NULL;

		BIO_meth_set_read(methods, stream_read);
		BIO_meth_set_ctrl(methods, stream_ctrl);
		BIO_meth_set_create(methods, stream_new);
		BIO_meth_set_destroy(methods, stream_free);
		BIO_meth_set_callback_ctrl(methods, stream_callback_ctrl);
	}

	bio = BIO_new(methods);
	data = BIO_get_data(bio);
	data->ctx = ctx;
	data->stm = stm;

	return bio;
}

static int verify_callback(int ok, X509_STORE_CTX *ctx)
{
	int err, depth;

	err = X509_STORE_CTX_get_error(ctx);
	depth = X509_STORE_CTX_get_error_depth(ctx);

	if (!ok && depth >= 6)
	{
		X509_STORE_CTX_set_error(ctx, X509_V_ERR_CERT_CHAIN_TOO_LONG);
	}

	switch (err)
	{
	case X509_V_ERR_INVALID_PURPOSE:
	case X509_V_ERR_CERT_HAS_EXPIRED:
	case X509_V_ERR_KEYUSAGE_NO_CERTSIGN:
		X509_STORE_CTX_set_error(ctx, X509_V_OK);
		ok = 1;
		break;

	default:
		break;
	}

	return ok;
}

/* Get the certificates from a PKCS7 object */
static STACK_OF(X509) *pk7_certs(PKCS7 *pk7)
{
	if (pk7 == NULL || pk7->d.ptr == NULL)
		return NULL;

	if (PKCS7_type_is_signed(pk7))
		return pk7->d.sign->cert;
	else if (PKCS7_type_is_signedAndEnveloped(pk7))
		return pk7->d.signed_and_enveloped->cert;
	else
		return NULL;
}

/* Get the signing certificate from a PKCS7 object */
static X509 *pk7_signer(STACK_OF(X509) *certs, PKCS7_SIGNER_INFO *si)
{
	PKCS7_ISSUER_AND_SERIAL *ias = si->issuer_and_serial;
	if (certs == NULL)
		return NULL;

	return X509_find_by_issuer_and_serial(certs, ias->issuer, ias->serial);
}

static pdf_signature_error pk7_verify_sig(PKCS7 *p7, BIO *detached)
{
	BIO *p7bio=NULL;
	char readbuf[1024*4];
	int res = PDF_SIGNATURE_ERROR_UNKNOWN;
	int i;
	STACK_OF(PKCS7_SIGNER_INFO) *sk;

	ERR_clear_error();

	p7bio = PKCS7_dataInit(p7, detached);
	if (!p7bio)
		goto exit;

	/* We now have to 'read' from p7bio to calculate digests etc. */
	while (BIO_read(p7bio, readbuf, sizeof(readbuf)) > 0)
		;

	/* We can now verify signatures */
	sk = PKCS7_get_signer_info(p7);
	if (sk == NULL || sk_PKCS7_SIGNER_INFO_num(sk) <= 0)
	{
		/* there are no signatures on this data */
		res = PDF_SIGNATURE_ERROR_NO_SIGNATURES;
		goto exit;
	}

	for (i=0; i<sk_PKCS7_SIGNER_INFO_num(sk); i++)
	{
		int rc;
		PKCS7_SIGNER_INFO *si = sk_PKCS7_SIGNER_INFO_value(sk, i);
		X509 *x509 = pk7_signer(pk7_certs(p7), si);

		/* were we able to find the cert in passed to us */
		if (x509 == NULL)
			goto exit;

		rc = PKCS7_signatureVerify(p7bio, p7, si, x509);
		if (rc > 0)
		{
			res = PDF_SIGNATURE_ERROR_OKAY;
		}
		else
		{
			long err = ERR_GET_REASON(ERR_get_error());
			switch (err)
			{
			case PKCS7_R_DIGEST_FAILURE:
				res = PDF_SIGNATURE_ERROR_DIGEST_FAILURE;
				break;
			default:
				break;
			}
			goto exit;
		}
	}

exit:
	BIO_free(p7bio);
	ERR_free_strings();

	return res;
}

static pdf_signature_error pk7_verify_cert(X509_STORE *cert_store, PKCS7 *p7)
{
	int res = PDF_SIGNATURE_ERROR_OKAY;
	int i;
	STACK_OF(PKCS7_SIGNER_INFO) *sk;
	X509_STORE_CTX *ctx;

	ctx = X509_STORE_CTX_new();
	if (!ctx)
		return PDF_SIGNATURE_ERROR_UNKNOWN;

	ERR_clear_error();

	X509_STORE_set_verify_cb_func(cert_store, verify_callback);

	/* We can now verify signatures */
	sk = PKCS7_get_signer_info(p7);
	if (sk == NULL)
	{
		/* there are no signatures on this data */
		res = PDF_SIGNATURE_ERROR_NO_SIGNATURES;
		goto exit;
	}

	for (i=0; i<sk_PKCS7_SIGNER_INFO_num(sk); i++)
	{
		int ctx_err;
		PKCS7_SIGNER_INFO *si = sk_PKCS7_SIGNER_INFO_value(sk, i);
		STACK_OF(X509) *certs = pk7_certs(p7);
		X509 *cert = pk7_signer(certs, si);
		if (cert == NULL)
		{
			res = PDF_SIGNATURE_ERROR_NO_CERTIFICATE;
			goto exit;
		}

		/* Acrobat reader creates self-signed certificates that don't list
		 * certificate signing within the key usage parameters. openssl does
		 * not recognise those as self signed. We work around this by removing
		 * the key usage parameters before the verification check */
		{
			int i = X509_get_ext_by_NID(cert, NID_key_usage, -1);
			if (i >= 0)
			{
				X509_EXTENSION *ext = X509_get_ext(cert, i);
				X509_delete_ext(cert, i);
				X509_EXTENSION_free(ext);
			}
		}

		if (!X509_STORE_CTX_init(ctx, cert_store, cert, certs))
		{
			res = PDF_SIGNATURE_ERROR_UNKNOWN;
			goto exit;
		}

		if (!X509_STORE_CTX_set_purpose(ctx, X509_PURPOSE_SMIME_SIGN))
		{
			res = PDF_SIGNATURE_ERROR_UNKNOWN;
			goto exit;
		}

		/* X509_verify_cert may return an error, but in all such cases
		 * it sets a context error */
		X509_verify_cert(ctx);
		X509_STORE_CTX_cleanup(ctx);
		ctx_err = X509_STORE_CTX_get_error(ctx);
		switch (ctx_err)
		{
		case X509_V_OK:
			break;
		case X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT:
			res = PDF_SIGNATURE_ERROR_SELF_SIGNED;
			goto exit;
		case X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN:
			res = PDF_SIGNATURE_ERROR_SELF_SIGNED_IN_CHAIN;
			goto exit;
		default:
			res = PDF_SIGNATURE_ERROR_UNKNOWN;
			goto exit;
		}
	}

exit:
	X509_STORE_CTX_free(ctx);
	ERR_free_strings();

	return res;
}

static pdf_signature_error
check_digest(fz_context *ctx, pdf_pkcs7_verifier *verifier, fz_stream *stm, unsigned char *sig, size_t sig_len)
{
	PKCS7 *pk7sig = NULL;
	BIO *bsig = NULL;
	BIO *bdata = NULL;
	int res = PDF_SIGNATURE_ERROR_UNKNOWN;

	if (sig_len > INT_MAX)
		fz_throw(ctx, FZ_ERROR_GENERIC, "Signature length too large");

	bsig = BIO_new_mem_buf(sig, (int)sig_len);
	pk7sig = d2i_PKCS7_bio(bsig, NULL);
	if (pk7sig == NULL)
		goto exit;

	bdata = BIO_new_stream(ctx, stm);
	if (bdata == NULL)
		goto exit;

	res = pk7_verify_sig(pk7sig, bdata);

exit:
	BIO_free(bdata);
	PKCS7_free(pk7sig);
	BIO_free(bsig);

	return res;
}

static pdf_signature_error
check_certificate(fz_context *ctx, pdf_pkcs7_verifier *verifier, unsigned char *sig, size_t sig_len)
{
	PKCS7 *pk7sig = NULL;
	PKCS7 *pk7cert = NULL;
	X509_STORE *st = NULL;
	BIO *bsig = NULL;
	BIO *bcert = NULL;
	STACK_OF(X509) *certs = NULL;
	int res = PDF_SIGNATURE_ERROR_UNKNOWN;

	if (sig_len > INT_MAX)
		return res;

	bsig = BIO_new_mem_buf(sig, (int)sig_len);
	pk7sig = d2i_PKCS7_bio(bsig, NULL);
	if (pk7sig == NULL)
		goto exit;

	/* Find the certificates in the pk7 file */
	bcert = BIO_new_mem_buf((void*)AdobeCA_p7c, sizeof AdobeCA_p7c);
	pk7cert = d2i_PKCS7_bio(bcert, NULL);
	if (pk7cert == NULL)
		goto exit;

	certs = pk7_certs(pk7cert);

	st = X509_STORE_new();
	if (st == NULL)
		goto exit;

	/* Add the certificates to the store */
	if (certs != NULL)
	{
		int i, n = sk_X509_num(certs);

		for (i = 0; i < n; i++)
		{
			X509 *c = sk_X509_value(certs, i);
			X509_STORE_add_cert(st, c);
		}
	}

	res = pk7_verify_cert(st, pk7sig);

exit:
	X509_STORE_free(st);
	PKCS7_free(pk7cert);
	BIO_free(bcert);
	PKCS7_free(pk7sig);
	BIO_free(bsig);

	return res;
}

typedef struct
{
	pdf_pkcs7_distinguished_name base;
	char buf[8192];
} pdf_pkcs7_distinguished_name_openssl;

typedef struct
{
	pdf_pkcs7_signer base;
	int refs;
	X509 *x509;
	EVP_PKEY *pkey;
} openssl_signer;

typedef struct
{
	pdf_pkcs7_verifier base;
} openssl_verifier;

static void add_from_bags(X509 **pX509, EVP_PKEY **pPkey, const STACK_OF(PKCS12_SAFEBAG) *bags, const char *pw);

static void add_from_bag(X509 **pX509, EVP_PKEY **pPkey, PKCS12_SAFEBAG *bag, const char *pw)
{
	EVP_PKEY *pkey = NULL;
	X509 *x509 = NULL;
	switch (M_PKCS12_bag_type(bag))
	{
	case NID_keyBag:
		{
			const PKCS8_PRIV_KEY_INFO *p8 = PKCS12_SAFEBAG_get0_p8inf(bag);
			pkey = EVP_PKCS82PKEY(p8);
		}
		break;

	case NID_pkcs8ShroudedKeyBag:
		{
			PKCS8_PRIV_KEY_INFO *p8 = PKCS12_decrypt_skey(bag, pw, (int)strlen(pw));
			if (p8)
			{
				pkey = EVP_PKCS82PKEY(p8);
				PKCS8_PRIV_KEY_INFO_free(p8);
			}
		}
		break;

	case NID_certBag:
		if (M_PKCS12_cert_bag_type(bag) == NID_x509Certificate)
			x509 = PKCS12_certbag2x509(bag);
		break;

	case NID_safeContentsBag:
		add_from_bags(pX509, pPkey, PKCS12_SAFEBAG_get0_safes(bag), pw);
		break;
	}

	if (pkey)
	{
		if (!*pPkey)
			*pPkey = pkey;
		else
			EVP_PKEY_free(pkey);
	}

	if (x509)
	{
		if (!*pX509)
			*pX509 = x509;
		else
			X509_free(x509);
	}
}

static void add_from_bags(X509 **pX509, EVP_PKEY **pPkey, const STACK_OF(PKCS12_SAFEBAG) *bags, const char *pw)
{
	int i;

	for (i = 0; i < sk_PKCS12_SAFEBAG_num(bags); i++)
		add_from_bag(pX509, pPkey, sk_PKCS12_SAFEBAG_value(bags, i), pw);
}

static pdf_pkcs7_signer *keep_signer(fz_context *ctx, pdf_pkcs7_signer *signer)
{
	openssl_signer *osigner = (openssl_signer *)signer;
	return fz_keep_imp(ctx, osigner, &osigner->refs);
}

static void drop_signer(fz_context *ctx, pdf_pkcs7_signer *signer)
{
	openssl_signer *osigner = (openssl_signer *)signer;
	if (fz_drop_imp(ctx, osigner, &osigner->refs))
	{
		X509_free(osigner->x509);
		EVP_PKEY_free(osigner->pkey);
		fz_free(ctx, osigner);
	}
}

static char *x509_get_name_entry_string(fz_context *ctx, X509_NAME *name, int nid)
{
	int idx = X509_NAME_get_index_by_NID(name, nid, -1);
	X509_NAME_ENTRY *entry = X509_NAME_get_entry(name, idx);
	ASN1_STRING *data = X509_NAME_ENTRY_get_data(entry);
	return data ? fz_strdup(ctx, (const char *)ASN1_STRING_get0_data(data)) : NULL;
}

static pdf_pkcs7_distinguished_name *x509_distinguished_name(fz_context *ctx, X509 *x509)
{
	pdf_pkcs7_distinguished_name *dn = fz_malloc_struct(ctx, pdf_pkcs7_distinguished_name);

	fz_try(ctx)
	{
		X509_NAME *subj = X509_get_subject_name(x509);
		dn->cn = x509_get_name_entry_string(ctx, subj, NID_commonName);
		dn->o = x509_get_name_entry_string(ctx, subj, NID_organizationName);
		dn->ou = x509_get_name_entry_string(ctx, subj, NID_organizationalUnitName);
		dn->email = x509_get_name_entry_string(ctx, subj, NID_pkcs9_emailAddress);
		dn->c = x509_get_name_entry_string(ctx, subj, NID_countryName);
	}
	fz_catch(ctx)
	{
		pdf_signature_drop_distinguished_name(ctx, dn);
		fz_rethrow(ctx);
	}

	return (pdf_pkcs7_distinguished_name *)dn;
}

static pdf_pkcs7_distinguished_name *signer_distinguished_name(fz_context *ctx, pdf_pkcs7_signer *signer)
{
	openssl_signer *osigner = (openssl_signer *)signer;
	X509 *x509 = osigner->x509;
	pdf_pkcs7_distinguished_name *dn = fz_malloc_struct(ctx, pdf_pkcs7_distinguished_name);

	fz_try(ctx)
	{
		X509_NAME *subj = X509_get_subject_name(x509);
		dn->cn = x509_get_name_entry_string(ctx, subj, NID_commonName);
		dn->o = x509_get_name_entry_string(ctx, subj, NID_organizationName);
		dn->ou = x509_get_name_entry_string(ctx, subj, NID_organizationalUnitName);
		dn->email = x509_get_name_entry_string(ctx, subj, NID_pkcs9_emailAddress);
		dn->c = x509_get_name_entry_string(ctx, subj, NID_countryName);
	}
	fz_catch(ctx)
	{
		pdf_signature_drop_distinguished_name(ctx, dn);
		fz_rethrow(ctx);
	}

	return dn;
}

static int signer_create_digest(fz_context *ctx, pdf_pkcs7_signer *signer, fz_stream *in, unsigned char *digest, size_t digest_len)
{
	openssl_signer *osigner = (openssl_signer *)signer;
	int res = 0;
	BIO *bdata = NULL;
	BIO *bp7in = NULL;
	BIO *bp7 = NULL;
	PKCS7 *p7 = NULL;
	PKCS7_SIGNER_INFO *si;

	unsigned char *p7_ptr;
	size_t p7_len;

	if (in != NULL)
	{
		bdata = BIO_new_stream(ctx, in);
		if (bdata == NULL)
			goto exit;
	}

	p7 = PKCS7_new();
	if (p7 == NULL)
		goto exit;

	PKCS7_set_type(p7, NID_pkcs7_signed);
	si = PKCS7_add_signature(p7, osigner->x509, osigner->pkey, EVP_sha1());
	if (si == NULL)
		goto exit;

	PKCS7_add_signed_attribute(si, NID_pkcs9_contentType, V_ASN1_OBJECT, OBJ_nid2obj(NID_pkcs7_data));
	PKCS7_add_certificate(p7, osigner->x509);

	PKCS7_content_new(p7, NID_pkcs7_data);
	PKCS7_set_detached(p7, 1);

	bp7in = PKCS7_dataInit(p7, NULL);
	if (bp7in == NULL)
		goto exit;

	while(bdata) /* bdata knowingly not changed in the loop */
	{
		char buf[4096];
		int n = BIO_read(bdata, buf, sizeof(buf));
		if (n <= 0)
			break;
		BIO_write(bp7in, buf, n);
	}

	if (!PKCS7_dataFinal(p7, bp7in))
		goto exit;

	BIO_free(bdata);
	bdata = NULL;

	bp7 = BIO_new(BIO_s_mem());
	if (bp7 == NULL || !i2d_PKCS7_bio(bp7, p7))
		goto exit;

	p7_len = (size_t)BIO_get_mem_data(bp7, &p7_ptr);
	if (digest && p7_len > digest_len)
		goto exit;

	if (digest)
		memcpy(digest, p7_ptr, p7_len);

	res = p7_len;

exit:
	BIO_free(bp7);
	BIO_free_all(bp7in);
	PKCS7_free(p7);
	BIO_free(bdata);

	return res;
}

static size_t max_digest_size(fz_context *ctx, pdf_pkcs7_signer *signer)
{
	/* Perform a test digest generation to find the required size. Size
	 * is assumed independent of data being hashed */
	return signer_create_digest(ctx, signer, NULL, NULL, 0);
}

pdf_pkcs7_signer *pkcs7_openssl_read_pfx(fz_context *ctx, const char *pfile, const char *pw)
{
	BIO *pfxbio = NULL;
	PKCS12 *p12 = NULL;
	STACK_OF(PKCS7) *asafes;
	openssl_signer *signer = NULL;
	int i;

	fz_var(pfxbio);
	fz_var(p12);
	fz_var(signer);
	fz_try(ctx)
	{
		signer = fz_malloc_struct(ctx, openssl_signer);
		signer->base.keep = keep_signer;
		signer->base.drop = drop_signer;
		signer->base.get_signing_name = signer_distinguished_name;
		signer->base.max_digest_size = max_digest_size;
		signer->base.create_digest = signer_create_digest;
		signer->refs = 1;

		OpenSSL_add_all_algorithms();

		EVP_add_digest(EVP_md5());
		EVP_add_digest(EVP_sha1());

		ERR_load_crypto_strings();

		ERR_clear_error();

		pfxbio = BIO_new_file(pfile, "rb");
		if (pfxbio == NULL)
			fz_throw(ctx, FZ_ERROR_GENERIC, "Can't open pfx file: %s", pfile);

		p12 = d2i_PKCS12_bio(pfxbio, NULL);
		if (p12 == NULL)
			fz_throw(ctx, FZ_ERROR_GENERIC, "Invalid pfx file: %s", pfile);

		asafes = PKCS12_unpack_authsafes(p12);
		if (asafes == NULL)
			fz_throw(ctx, FZ_ERROR_GENERIC, "Invalid pfx file: %s", pfile);

		/* Nothing in this for loop can fz_throw */
		for (i = 0; i < sk_PKCS7_num(asafes); i++)
		{
			PKCS7 *p7;
			STACK_OF(PKCS12_SAFEBAG) *bags;
			int bagnid;

			p7 = sk_PKCS7_value(asafes, i);
			bagnid = OBJ_obj2nid(p7->type);
			switch (bagnid)
			{
			case NID_pkcs7_data:
				bags = PKCS12_unpack_p7data(p7);
				break;
			case NID_pkcs7_encrypted:
				bags = PKCS12_unpack_p7encdata(p7, pw, (int)strlen(pw));
				break;
			default:
				continue;
			}

			if (bags)
			{
				add_from_bags(&signer->x509, &signer->pkey, bags, pw);
				sk_PKCS12_SAFEBAG_pop_free(bags, PKCS12_SAFEBAG_free);
			}
		}
		sk_PKCS7_pop_free (asafes, PKCS7_free);

		if (signer->pkey == NULL)
			fz_throw(ctx, FZ_ERROR_GENERIC, "Failed to obtain public key");

		if (signer->x509 == NULL)
			fz_throw(ctx, FZ_ERROR_GENERIC, "Failed to obtain certificate");
	}
	fz_always(ctx)
	{
		PKCS12_free(p12);
		BIO_free(pfxbio);
	}
	fz_catch(ctx)
	{
		drop_signer(ctx, &signer->base);
		fz_rethrow(ctx);
	}

	return &signer->base;
}

pdf_pkcs7_distinguished_name *get_signatory(fz_context *ctx, pdf_pkcs7_verifier *verifier, unsigned char *sig, size_t sig_len)
{
	pdf_pkcs7_distinguished_name *name = NULL;
	PKCS7 *pk7sig = NULL;
	BIO *bsig = NULL;
	STACK_OF(PKCS7_SIGNER_INFO) *sk = NULL;
	X509 *x509 = NULL;

	if (sig_len > INT_MAX)
		fz_throw(ctx, FZ_ERROR_GENERIC, "Signature length too large");

	bsig = BIO_new_mem_buf(sig, (int)sig_len);
	pk7sig = d2i_PKCS7_bio(bsig, NULL);
	if (pk7sig == NULL)
		goto exit;

	sk = PKCS7_get_signer_info(pk7sig);
	if (sk == NULL || sk_PKCS7_SIGNER_INFO_num(sk) <= 0)
		goto exit;

	x509 = pk7_signer(pk7_certs(pk7sig), sk_PKCS7_SIGNER_INFO_value(sk, 0));

	fz_try(ctx)
		name = x509_distinguished_name(ctx, x509);
	fz_catch(ctx)
	{
		PKCS7_free(pk7sig);
		BIO_free(bsig);
		fz_rethrow(ctx);
	}

exit:
	PKCS7_free(pk7sig);
	BIO_free(bsig);

	return name;
}

static void
drop_openssl_verifier(fz_context *ctx, pdf_pkcs7_verifier *verifier)
{
	fz_free(ctx, verifier);
}

pdf_pkcs7_verifier *
pkcs7_openssl_new_verifier(fz_context *ctx)
{
	openssl_verifier *verifier = NULL;

	verifier = fz_malloc_struct(ctx, openssl_verifier);
	verifier->base.drop = drop_openssl_verifier;
	verifier->base.check_digest = check_digest;
	verifier->base.check_certificate = check_certificate;
	verifier->base.get_signatory = get_signatory;

	return &verifier->base;
}

#endif
