/*
 *  Copyright 2014-2022 The GmSSL Project. All Rights Reserved.
 *
 *  Licensed under the Apache License, Version 2.0 (the License); you may
 *  not use this file except in compliance with the License.
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 */


#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <gmssl/file.h>
#include <gmssl/cms.h>
#include <gmssl/x509.h>
#include <gmssl/rand.h>


static const char *options = "-encrypt (-rcptcert pem)* -in file -out file";


static int get_files_size(int argc, char **argv, const char *option, size_t *len)
{
	char *prog = argv[0];
	char *file = NULL;
	FILE *fp = NULL;

	argc--;
	argv++;

	*len = 0;
	while (argc > 1) {
		if (!strcmp(*argv, option)) {
			size_t fsize;

			if (--argc < 1) {
				fprintf(stderr, "%s: '%s' option value missing\n", prog, *argv);
				return -1;
			}
			file = *(++argv);

			if (!(fp = fopen(file, "rb"))) {
				fprintf(stderr, "%s: open '%s' failed : %s\n", prog, file, strerror(errno));
				return -1;
			}
			if (file_size(fp, &fsize) != 1) {
				fprintf(stderr, "%s: access '%s' failed : %s\n", prog, file, strerror(errno));
				fclose(fp);
				return -1;
			}
			*len += fsize;
			fclose(fp);
		}
		argc--;
		argv++;
	}

	return 1;
}

int cmsencrypt_main(int argc, char **argv)
{
	int ret = 1;
	char *prog = argv[0];
	int op = 0;
	char *infile = NULL;
	char *outfile = NULL;
	FILE *infp = stdin;
	FILE *outfp = stdout;
	uint8_t *rcpt_certs = NULL;
	size_t rcpt_certs_len;
	uint8_t key[16];
	uint8_t iv[16];
	uint8_t *inbuf = NULL;
	size_t inlen;
	uint8_t *cms = NULL;
	size_t cmslen;
	uint8_t *cert;

	if (argc < 2) {
		fprintf(stderr, "usage: %s %s\n", prog, options);
		return 1;
	}
	if (argc == 2 && !strcmp(argv[1], "-help")) {
		printf("usage: %s %s\n", prog, options);
		return 0;
	}

	// prepare cert buffer length?		
	if (get_files_size(argc, argv, "-rcptcert", &rcpt_certs_len) != 1) {
		goto end;
	}
	if (rcpt_certs_len <= 0) {
		fprintf(stderr, "%s: invalid cert length\n", prog);
		goto end;
	}
	rcpt_certs_len = (rcpt_certs_len * 3)/4;
	if (!(rcpt_certs = malloc(rcpt_certs_len))) {
		fprintf(stderr, "%s: malloc failure\n", prog);
		goto end;
	}
	cert = rcpt_certs;

	// FIXME: TOCTOU between file_size measurement and fread. If the file shrinks
	// after measurement, the buffer is oversized but only actual bytes read are
	// encrypted (inlen is updated by fread). If the file grows, data is truncated.
	if (get_files_size(argc, argv, "-in", &inlen) != 1) {
		goto end;
	}
	if (inlen <= 0) {
		fprintf(stderr, "%s: invalid input length\n", prog);
		goto end;
	}
	if (!(inbuf = malloc(inlen))) {
		fprintf(stderr, "%s: %s\n", prog, strerror(errno));
		goto end;
	}

	argc--;
	argv++;

	while (argc > 1) {
		if (!strcmp(*argv, "-help")) {
			printf("usage: %s %s\n", prog, options);
			ret = 0;
			goto end;
		} else if (!strcmp(*argv, "-rcptcert")) {
			char *certfile;
			FILE *certfp;
			size_t certlen;
			if (--argc < 1) goto bad;
			certfile = *(++argv);
			if (!(certfp = fopen(certfile, "rb"))) {
				fprintf(stderr, "%s: open '%s' failure : %s\n", prog, certfile, strerror(errno));
				goto end;
			}
			if (x509_cert_from_pem(cert, &certlen, rcpt_certs_len, certfp) != 1) {
				fprintf(stderr, "%s: error\n", prog);
				fclose(certfp);
				goto end;
			}
			cert += certlen;
			fclose(certfp);
		} else if (!strcmp(*argv, "-in")) {
			if (--argc < 1) goto bad;
			infile = *(++argv);
			if (!(infp = fopen(infile, "rb"))) {
				fprintf(stderr, "%s: open '%s' failure : %s\n", prog, infile, strerror(errno));
				goto end;
			}
			if ((inlen = fread(inbuf, 1, inlen, infp)) <= 0) {
				fprintf(stderr, "%s: read data error: %s\n", prog, strerror(errno));
				goto end;
			}
		} else if (!strcmp(*argv, "-out")) {
			if (--argc < 1) goto bad;
			outfile = *(++argv);
			if (!(outfp = fopen(outfile, "wb"))) {
				fprintf(stderr, "%s: open '%s' failure : %s\n", prog, outfile, strerror(errno));
				goto end;
			}
		} else {
			fprintf(stderr, "%s: illegal option '%s'\n", prog, *argv);
			goto end;
bad:
			fprintf(stderr, "%s: '%s' option value missing\n", prog, *argv);
			goto end;
		}

		argc--;
		argv++;
	}

	rcpt_certs_len = cert - rcpt_certs;

	if (rand_bytes(key, sizeof(key)) != 1
		|| rand_bytes(iv, sizeof(iv)) != 1
		|| cms_envelop(NULL, &cmslen, rcpt_certs, rcpt_certs_len,
			OID_sm4_cbc, key, sizeof(key), iv, sizeof(iv),
			OID_cms_data, inbuf, inlen, NULL, 0, NULL, 0) != 1) {
		fprintf(stderr, "%s: inner error\n", prog);
		goto end;
	}
	if (!(cms = malloc(cmslen))) {
		fprintf(stderr, "%s: malloc failure\n", prog);
		goto end;
	}
	if (cms_envelop(cms, &cmslen, rcpt_certs, rcpt_certs_len,
		OID_sm4_cbc, key, sizeof(key), iv, sizeof(iv),
		OID_cms_data, inbuf, inlen, NULL, 0, NULL, 0) != 1) {
		fprintf(stderr, "%s: inner error\n", prog);
		goto end;
	}
	if (cms_to_pem(cms, cmslen, outfp) != 1) {
		fprintf(stderr, "%s: output CMS failure\n", prog);
		goto end;
	}

	ret = 0;

end:
	if (infile && infp) fclose(infp);
	if (outfile && outfp) fclose(outfp);
	if (rcpt_certs) free(rcpt_certs);
	if (inbuf) free(inbuf);
	if (cms) free(cms);
	return ret;
}
