xref: /openbsd-src/lib/libcrypto/asn1/asn_mime.c (revision c5925a468152d12d66256ed11ca00607b9563fa3)

/* $OpenBSD: asn_mime.c,v 1.35 2025/01/17 05:02:18 tb Exp $ */
/* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
 * project.
 */
/* ====================================================================
 * Copyright (c) 1999-2008 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    licensing@OpenSSL.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 */

#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <openssl/asn1.h>
#include <openssl/asn1t.h>
#include <openssl/err.h>
#include <openssl/x509.h>

#include "asn1_local.h"
#include "evp_local.h"

/* Generalised MIME like utilities for streaming ASN1. Although many
 * have a PKCS7/CMS like flavour others are more general purpose.
 */

/* MIME format structures
 * Note that all are translated to lower case apart from
 * parameter values. Quotes are stripped off
 */

typedef struct {
	char *param_name;		/* Param name e.g. "micalg" */
	char *param_value;		/* Param value e.g. "sha1" */
} MIME_PARAM;

DECLARE_STACK_OF(MIME_PARAM)

typedef struct {
	char *name;			/* Name of line e.g. "content-type" */
	char *value;			/* Value of line e.g. "text/plain" */
	STACK_OF(MIME_PARAM) *params;	/* Zero or more parameters */
} MIME_HEADER;

DECLARE_STACK_OF(MIME_HEADER)

static int asn1_output_data(BIO *out, BIO *data, ASN1_VALUE *val, int flags,
    const ASN1_ITEM *it);
static char * strip_ends(char *name);
static char * strip_start(char *name);
static char * strip_end(char *name);
static MIME_HEADER *mime_hdr_new(char *name, char *value);
static int mime_hdr_addparam(MIME_HEADER *mhdr, char *name, char *value);
static STACK_OF(MIME_HEADER) *mime_parse_hdr(BIO *bio);
static int mime_hdr_cmp(const MIME_HEADER * const *a,
    const MIME_HEADER * const *b);
static int mime_param_cmp(const MIME_PARAM * const *a,
    const MIME_PARAM * const *b);
static void mime_param_free(MIME_PARAM *param);
static int mime_bound_check(char *line, int linelen, char *bound, int blen);
static int multi_split(BIO *bio, char *bound, STACK_OF(BIO) **ret);
static int strip_eol(char *linebuf, int *plen);
static MIME_HEADER *mime_hdr_find(STACK_OF(MIME_HEADER) *hdrs, char *name);
static MIME_PARAM *mime_param_find(MIME_HEADER *hdr, char *name);
static void mime_hdr_free(MIME_HEADER *hdr);

#define MAX_SMLEN 1024

/* Output an ASN1 structure in BER format streaming if necessary */

int
i2d_ASN1_bio_stream(BIO *out, ASN1_VALUE *val, BIO *in, int flags,
    const ASN1_ITEM *it)
{
	BIO *bio, *tbio;
	int ret;

	/* Without streaming, write out the ASN.1 structure's content. */
	if ((flags & SMIME_STREAM) == 0)
		return ASN1_item_i2d_bio(it, out, val);

	/* If streaming, create a stream BIO and copy all content through it. */
	if ((bio = BIO_new_NDEF(out, val, it)) == NULL) {
		ASN1error(ERR_R_MALLOC_FAILURE);
		return 0;
	}

	ret = SMIME_crlf_copy(in, bio, flags);
	(void)BIO_flush(bio);

	/* Free up successive BIOs until we hit the old output BIO. */
	do {
		tbio = BIO_pop(bio);
		BIO_free(bio);
		bio = tbio;
	} while (bio != out);

	return ret;
}

/* Base 64 read and write of ASN1 structure */

static int
B64_write_ASN1(BIO *out, ASN1_VALUE *val, BIO *in, int flags,
    const ASN1_ITEM *it)
{
	BIO *b64;
	int r;

	b64 = BIO_new(BIO_f_base64());
	if (!b64) {
		ASN1error(ERR_R_MALLOC_FAILURE);
		return 0;
	}
	/* prepend the b64 BIO so all data is base64 encoded.
	 */
	out = BIO_push(b64, out);
	r = i2d_ASN1_bio_stream(out, val, in, flags, it);
	(void)BIO_flush(out);
	BIO_pop(out);
	BIO_free(b64);
	return r;
}

/* Streaming ASN1 PEM write */

int
PEM_write_bio_ASN1_stream(BIO *out, ASN1_VALUE *val, BIO *in, int flags,
    const char *hdr, const ASN1_ITEM *it)
{
	int r;

	BIO_printf(out, "-----BEGIN %s-----\n", hdr);
	r = B64_write_ASN1(out, val, in, flags, it);
	BIO_printf(out, "-----END %s-----\n", hdr);
	return r;
}

static ASN1_VALUE *
b64_read_asn1(BIO *bio, const ASN1_ITEM *it)
{
	BIO *b64;
	ASN1_VALUE *val;
	if (!(b64 = BIO_new(BIO_f_base64()))) {
		ASN1error(ERR_R_MALLOC_FAILURE);
		return 0;
	}
	bio = BIO_push(b64, bio);
	val = ASN1_item_d2i_bio(it, bio, NULL);
	if (!val)
		ASN1error(ASN1_R_DECODE_ERROR);
	(void)BIO_flush(bio);
	bio = BIO_pop(bio);
	BIO_free(b64);
	return val;
}

/* Generate the MIME "micalg" parameter from RFC3851, RFC4490 */

static int
asn1_write_micalg(BIO *out, STACK_OF(X509_ALGOR) *mdalgs)
{
	const EVP_MD *md;
	int i, have_unknown = 0, write_comma, ret = 0, md_nid;

	have_unknown = 0;
	write_comma = 0;
	for (i = 0; i < sk_X509_ALGOR_num(mdalgs); i++) {
		if (write_comma)
			BIO_write(out, ",", 1);
		write_comma = 1;
		md_nid = OBJ_obj2nid(sk_X509_ALGOR_value(mdalgs, i)->algorithm);
		md = EVP_get_digestbynid(md_nid);
		if (md && md->md_ctrl) {
			int rv;
			char *micstr;
			rv = md->md_ctrl(NULL, EVP_MD_CTRL_MICALG, 0, &micstr);
			if (rv > 0) {
				BIO_puts(out, micstr);
				free(micstr);
				continue;
			}
			if (rv != -2)
				goto err;
		}
		switch (md_nid) {
		case NID_sha1:
			BIO_puts(out, "sha1");
			break;

		case NID_md5:
			BIO_puts(out, "md5");
			break;

		case NID_sha256:
			BIO_puts(out, "sha-256");
			break;

		case NID_sha384:
			BIO_puts(out, "sha-384");
			break;

		case NID_sha512:
			BIO_puts(out, "sha-512");
			break;

		case NID_id_GostR3411_94:
			BIO_puts(out, "gostr3411-94");
			goto err;
			break;

		default:
			if (have_unknown)
				write_comma = 0;
			else {
				BIO_puts(out, "unknown");
				have_unknown = 1;
			}
			break;

		}
	}

	ret = 1;

 err:
	return ret;
}

/* SMIME sender */

int
SMIME_write_ASN1(BIO *bio, ASN1_VALUE *val, BIO *data, int flags,
    int ctype_nid, int econt_nid, STACK_OF(X509_ALGOR) *mdalgs,
    const ASN1_ITEM *it)
{
	char bound[33], c;
	int i;
	const char *mime_prefix, *mime_eol, *cname = "smime.p7m";
	const char *msg_type = NULL;

	if (flags & SMIME_OLDMIME)
		mime_prefix = "application/x-pkcs7-";
	else
		mime_prefix = "application/pkcs7-";

	if (flags & SMIME_CRLFEOL)
		mime_eol = "\r\n";
	else
		mime_eol = "\n";
	if ((flags & SMIME_DETACHED) && data) {
		/* We want multipart/signed */
		/* Generate a random boundary */
		arc4random_buf(bound, 32);
		for (i = 0; i < 32; i++) {
			c = bound[i] & 0xf;
			if (c < 10)
				c += '0';
			else
				c += 'A' - 10;
			bound[i] = c;
		}
		bound[32] = 0;
		BIO_printf(bio, "MIME-Version: 1.0%s", mime_eol);
		BIO_printf(bio, "Content-Type: multipart/signed;");
		BIO_printf(bio, " protocol=\"%ssignature\";", mime_prefix);
		BIO_puts(bio, " micalg=\"");
		asn1_write_micalg(bio, mdalgs);
		BIO_printf(bio, "\"; boundary=\"----%s\"%s%s",
		    bound, mime_eol, mime_eol);
		BIO_printf(bio, "This is an S/MIME signed message%s%s",
		    mime_eol, mime_eol);
		/* Now write out the first part */
		BIO_printf(bio, "------%s%s", bound, mime_eol);
		if (!asn1_output_data(bio, data, val, flags, it))
			return 0;
		BIO_printf(bio, "%s------%s%s", mime_eol, bound, mime_eol);

		/* Headers for signature */

		BIO_printf(bio, "Content-Type: %ssignature;", mime_prefix);
		BIO_printf(bio, " name=\"smime.p7s\"%s", mime_eol);
		BIO_printf(bio, "Content-Transfer-Encoding: base64%s",
		    mime_eol);
		BIO_printf(bio, "Content-Disposition: attachment;");
		BIO_printf(bio, " filename=\"smime.p7s\"%s%s",
		    mime_eol, mime_eol);
		B64_write_ASN1(bio, val, NULL, 0, it);
		BIO_printf(bio, "%s------%s--%s%s", mime_eol, bound,
		    mime_eol, mime_eol);
		return 1;
	}

	/* Determine smime-type header */

	if (ctype_nid == NID_pkcs7_enveloped)
		msg_type = "enveloped-data";
	else if (ctype_nid == NID_pkcs7_signed) {
		if (econt_nid == NID_id_smime_ct_receipt)
			msg_type = "signed-receipt";
		else if (sk_X509_ALGOR_num(mdalgs) >= 0)
			msg_type = "signed-data";
		else
			msg_type = "certs-only";
	} else if (ctype_nid == NID_id_smime_ct_compressedData) {
		msg_type = "compressed-data";
		cname = "smime.p7z";
	}
	/* MIME headers */
	BIO_printf(bio, "MIME-Version: 1.0%s", mime_eol);
	BIO_printf(bio, "Content-Disposition: attachment;");
	BIO_printf(bio, " filename=\"%s\"%s", cname, mime_eol);
	BIO_printf(bio, "Content-Type: %smime;", mime_prefix);
	if (msg_type)
		BIO_printf(bio, " smime-type=%s;", msg_type);
	BIO_printf(bio, " name=\"%s\"%s", cname, mime_eol);
	BIO_printf(bio, "Content-Transfer-Encoding: base64%s%s",
	    mime_eol, mime_eol);
	if (!B64_write_ASN1(bio, val, data, flags, it))
		return 0;
	BIO_printf(bio, "%s", mime_eol);
	return 1;
}

/* Handle output of ASN1 data */


static int
asn1_output_data(BIO *out, BIO *data, ASN1_VALUE *val, int flags,
    const ASN1_ITEM *it)
{
	BIO *tmpbio;
	const ASN1_AUX *aux = it->funcs;
	ASN1_STREAM_ARG sarg;
	int rv = 1;

	/*
	 * If data is not detached or resigning then the output BIO is
	 * already set up to finalise when it is written through.
	 */
	if (!(flags & SMIME_DETACHED) || (flags & PKCS7_REUSE_DIGEST)) {
		SMIME_crlf_copy(data, out, flags);
		return 1;
	}

	if (!aux || !aux->asn1_cb) {
		ASN1error(ASN1_R_STREAMING_NOT_SUPPORTED);
		return 0;
	}

	sarg.out = out;
	sarg.ndef_bio = NULL;
	sarg.boundary = NULL;

	/* Let ASN1 code prepend any needed BIOs */

	if (aux->asn1_cb(ASN1_OP_DETACHED_PRE, &val, it, &sarg) <= 0)
		return 0;

	/* Copy data across, passing through filter BIOs for processing */
	SMIME_crlf_copy(data, sarg.ndef_bio, flags);

	/* Finalize structure */
	if (aux->asn1_cb(ASN1_OP_DETACHED_POST, &val, it, &sarg) <= 0)
		rv = 0;

	/* Now remove any digests prepended to the BIO */

	while (sarg.ndef_bio != out) {
		tmpbio = BIO_pop(sarg.ndef_bio);
		BIO_free(sarg.ndef_bio);
		sarg.ndef_bio = tmpbio;
	}

	return rv;
}

/* SMIME reader: handle multipart/signed and opaque signing.
 * in multipart case the content is placed in a memory BIO
 * pointed to by "bcont". In opaque this is set to NULL
 */

ASN1_VALUE *
SMIME_read_ASN1(BIO *bio, BIO **bcont, const ASN1_ITEM *it)
{
	BIO *asnin;
	STACK_OF(MIME_HEADER) *headers = NULL;
	STACK_OF(BIO) *parts = NULL;
	MIME_HEADER *hdr;
	MIME_PARAM *prm;
	ASN1_VALUE *val;
	int ret;

	if (bcont)
		*bcont = NULL;

	if (!(headers = mime_parse_hdr(bio))) {
		ASN1error(ASN1_R_MIME_PARSE_ERROR);
		return NULL;
	}

	if (!(hdr = mime_hdr_find(headers, "content-type")) || !hdr->value) {
		sk_MIME_HEADER_pop_free(headers, mime_hdr_free);
		ASN1error(ASN1_R_NO_CONTENT_TYPE);
		return NULL;
	}

	/* Handle multipart/signed */

	if (!strcmp(hdr->value, "multipart/signed")) {
		/* Split into two parts */
		prm = mime_param_find(hdr, "boundary");
		if (!prm || !prm->param_value) {
			sk_MIME_HEADER_pop_free(headers, mime_hdr_free);
			ASN1error(ASN1_R_NO_MULTIPART_BOUNDARY);
			return NULL;
		}
		ret = multi_split(bio, prm->param_value, &parts);
		sk_MIME_HEADER_pop_free(headers, mime_hdr_free);
		if (!ret || (sk_BIO_num(parts) != 2) ) {
			ASN1error(ASN1_R_NO_MULTIPART_BODY_FAILURE);
			sk_BIO_pop_free(parts, BIO_vfree);
			return NULL;
		}

		/* Parse the signature piece */
		asnin = sk_BIO_value(parts, 1);

		if (!(headers = mime_parse_hdr(asnin))) {
			ASN1error(ASN1_R_MIME_SIG_PARSE_ERROR);
			sk_BIO_pop_free(parts, BIO_vfree);
			return NULL;
		}

		/* Get content type */

		if (!(hdr = mime_hdr_find(headers, "content-type")) ||
		    !hdr->value) {
			sk_MIME_HEADER_pop_free(headers, mime_hdr_free);
			sk_BIO_pop_free(parts, BIO_vfree);
			ASN1error(ASN1_R_NO_SIG_CONTENT_TYPE);
			return NULL;
		}

		if (strcmp(hdr->value, "application/x-pkcs7-signature") &&
		    strcmp(hdr->value, "application/pkcs7-signature")) {
			ASN1error(ASN1_R_SIG_INVALID_MIME_TYPE);
			ERR_asprintf_error_data("type: %s", hdr->value);
			sk_MIME_HEADER_pop_free(headers, mime_hdr_free);
			sk_BIO_pop_free(parts, BIO_vfree);
			return NULL;
		}
		sk_MIME_HEADER_pop_free(headers, mime_hdr_free);
		/* Read in ASN1 */
		if (!(val = b64_read_asn1(asnin, it))) {
			ASN1error(ASN1_R_ASN1_SIG_PARSE_ERROR);
			sk_BIO_pop_free(parts, BIO_vfree);
			return NULL;
		}

		if (bcont) {
			*bcont = sk_BIO_value(parts, 0);
			BIO_free(asnin);
			sk_BIO_free(parts);
		} else sk_BIO_pop_free(parts, BIO_vfree);
			return val;
	}

	/* OK, if not multipart/signed try opaque signature */

	if (strcmp (hdr->value, "application/x-pkcs7-mime") &&
	    strcmp (hdr->value, "application/pkcs7-mime")) {
		ASN1error(ASN1_R_INVALID_MIME_TYPE);
		ERR_asprintf_error_data("type: %s", hdr->value);
		sk_MIME_HEADER_pop_free(headers, mime_hdr_free);
		return NULL;
	}

	sk_MIME_HEADER_pop_free(headers, mime_hdr_free);

	if (!(val = b64_read_asn1(bio, it))) {
		ASN1error(ASN1_R_ASN1_PARSE_ERROR);
		return NULL;
	}
	return val;
}

/* Copy text from one BIO to another making the output CRLF at EOL */
int
SMIME_crlf_copy(BIO *in, BIO *out, int flags)
{
	BIO *bf;
	char eol;
	int len;
	char linebuf[MAX_SMLEN];

	/* Buffer output so we don't write one line at a time. This is
	 * useful when streaming as we don't end up with one OCTET STRING
	 * per line.
	 */
	bf = BIO_new(BIO_f_buffer());
	if (!bf)
		return 0;
	out = BIO_push(bf, out);
	if (flags & SMIME_BINARY) {
		while ((len = BIO_read(in, linebuf, MAX_SMLEN)) > 0)
			BIO_write(out, linebuf, len);
	} else {
		if (flags & SMIME_TEXT)
			BIO_printf(out, "Content-Type: text/plain\r\n\r\n");
		while ((len = BIO_gets(in, linebuf, MAX_SMLEN)) > 0) {
			eol = strip_eol(linebuf, &len);
			if (len)
				BIO_write(out, linebuf, len);
			if (eol)
				BIO_write(out, "\r\n", 2);
		}
	}
	(void)BIO_flush(out);
	BIO_pop(out);
	BIO_free(bf);
	return 1;
}
LCRYPTO_ALIAS(SMIME_crlf_copy);

/* Strip off headers if they are text/plain */
int
SMIME_text(BIO *in, BIO *out)
{
	char iobuf[4096];
	int len;
	STACK_OF(MIME_HEADER) *headers;
	MIME_HEADER *hdr;

	if (!(headers = mime_parse_hdr(in))) {
		ASN1error(ASN1_R_MIME_PARSE_ERROR);
		return 0;
	}
	if (!(hdr = mime_hdr_find(headers, "content-type")) || !hdr->value) {
		ASN1error(ASN1_R_MIME_NO_CONTENT_TYPE);
		sk_MIME_HEADER_pop_free(headers, mime_hdr_free);
		return 0;
	}
	if (strcmp (hdr->value, "text/plain")) {
		ASN1error(ASN1_R_INVALID_MIME_TYPE);
		ERR_asprintf_error_data("type: %s", hdr->value);
		sk_MIME_HEADER_pop_free(headers, mime_hdr_free);
		return 0;
	}
	sk_MIME_HEADER_pop_free(headers, mime_hdr_free);
	while ((len = BIO_read(in, iobuf, sizeof(iobuf))) > 0)
		BIO_write(out, iobuf, len);
	if (len < 0)
		return 0;
	return 1;
}
LCRYPTO_ALIAS(SMIME_text);

/*
 * Split a multipart/XXX message body into component parts: result is
 * canonical parts in a STACK of bios
 */
static int
multi_split(BIO *bio, char *bound, STACK_OF(BIO) **ret)
{
	char linebuf[MAX_SMLEN];
	int len, blen;
	int eol = 0, next_eol = 0;
	BIO *bpart = NULL;
	STACK_OF(BIO) *parts;
	char state, part, first;

	blen = strlen(bound);
	part = 0;
	state = 0;
	first = 1;
	parts = sk_BIO_new_null();
	*ret = parts;
	if (parts == NULL)
		return 0;
	while ((len = BIO_gets(bio, linebuf, MAX_SMLEN)) > 0) {
		state = mime_bound_check(linebuf, len, bound, blen);
		if (state == 1) {
			first = 1;
			part++;
		} else if (state == 2) {
			if (sk_BIO_push(parts, bpart) == 0)
				return 0;
			return 1;
		} else if (part) {
			/* Strip CR+LF from linebuf */
			next_eol = strip_eol(linebuf, &len);
			if (first) {
				first = 0;
				if (bpart != NULL) {
					if (sk_BIO_push(parts, bpart) == 0)
						return 0;
				}
				bpart = BIO_new(BIO_s_mem());
				if (bpart == NULL)
					return 0;
				BIO_set_mem_eof_return(bpart, 0);
			} else if (eol)
				BIO_write(bpart, "\r\n", 2);
			eol = next_eol;
			if (len)
				BIO_write(bpart, linebuf, len);
		}
	}
	BIO_free(bpart);
	return 0;
}

/* This is the big one: parse MIME header lines up to message body */

#define MIME_INVALID	0
#define MIME_START	1
#define MIME_TYPE	2
#define MIME_NAME	3
#define MIME_VALUE	4
#define MIME_QUOTE	5
#define MIME_COMMENT	6

static STACK_OF(MIME_HEADER) *
mime_parse_hdr(BIO *bio)
{
	char *p, *q, c;
	char *ntmp;
	char linebuf[MAX_SMLEN];
	MIME_HEADER *mhdr = NULL;
	STACK_OF(MIME_HEADER) *headers;
	int len, state, save_state = 0;

	headers = sk_MIME_HEADER_new(mime_hdr_cmp);
	if (!headers)
		return NULL;
	while ((len = BIO_gets(bio, linebuf, MAX_SMLEN)) > 0) {
		/* If whitespace at line start then continuation line */
		if (mhdr && isspace((unsigned char)linebuf[0]))
			state = MIME_NAME;
		else
			state = MIME_START;
		ntmp = NULL;

		/* Go through all characters */
		for (p = linebuf, q = linebuf;
		    (c = *p) && (c != '\r') && (c != '\n'); p++) {

			/* State machine to handle MIME headers
			 * if this looks horrible that's because it *is*
			 */

			switch (state) {
			case MIME_START:
				if (c == ':') {
					state = MIME_TYPE;
					*p = 0;
					ntmp = strip_ends(q);
					q = p + 1;
				}
				break;

			case MIME_TYPE:
				if (c == ';') {
					*p = 0;
					mhdr = mime_hdr_new(ntmp,
					    strip_ends(q));
					if (mhdr == NULL)
						goto merr;
					if (sk_MIME_HEADER_push(headers,
					    mhdr) == 0)
						goto merr;
					ntmp = NULL;
					q = p + 1;
					state = MIME_NAME;
				} else if (c == '(') {
					save_state = state;
					state = MIME_COMMENT;
				}
				break;

			case MIME_COMMENT:
				if (c == ')') {
					state = save_state;
				}
				break;

			case MIME_NAME:
				if (c == '=') {
					state = MIME_VALUE;
					*p = 0;
					ntmp = strip_ends(q);
					q = p + 1;
				}
				break;

			case MIME_VALUE:
				if (c == ';') {
					state = MIME_NAME;
					*p = 0;
					mime_hdr_addparam(mhdr, ntmp,
					    strip_ends(q));
					ntmp = NULL;
					q = p + 1;
				} else if (c == '"') {
					state = MIME_QUOTE;
				} else if (c == '(') {
					save_state = state;
					state = MIME_COMMENT;
				}
				break;

			case MIME_QUOTE:
				if (c == '"') {
					state = MIME_VALUE;
				}
				break;
			}
		}

		if (state == MIME_TYPE) {
			mhdr = mime_hdr_new(ntmp, strip_ends(q));
			if (mhdr == NULL)
				goto merr;
			if (sk_MIME_HEADER_push(headers, mhdr) == 0)
				goto merr;
		} else if (state == MIME_VALUE)
			mime_hdr_addparam(mhdr, ntmp, strip_ends(q));

		if (p == linebuf)
			break;	/* Blank line means end of headers */
	}

	return headers;

 merr:
	if (mhdr != NULL)
		mime_hdr_free(mhdr);
	sk_MIME_HEADER_pop_free(headers, mime_hdr_free);
	return NULL;
}

static char *
strip_ends(char *name)
{
	return strip_end(strip_start(name));
}

/* Strip a parameter of whitespace from start of param */
static char *
strip_start(char *name)
{
	char *p, c;

	/* Look for first non white space or quote */
	for (p = name; (c = *p); p++) {
		if (c == '"') {
			/* Next char is start of string if non null */
			if (p[1])
				return p + 1;
			/* Else null string */
			return NULL;
		}
		if (!isspace((unsigned char)c))
			return p;
	}
	return NULL;
}

/* As above but strip from end of string : maybe should handle brackets? */
static char *
strip_end(char *name)
{
	char *p, c;

	if (!name)
		return NULL;

	/* Look for first non white space or quote */
	for (p = name + strlen(name) - 1; p >= name; p--) {
		c = *p;
		if (c == '"') {
			if (p - 1 == name)
				return NULL;
			*p = 0;
			return name;
		}
		if (isspace((unsigned char)c))
			*p = 0;
		else
			return name;
	}
	return NULL;
}

static MIME_HEADER *
mime_hdr_new(char *name, char *value)
{
	MIME_HEADER *mhdr;
	char *tmpname = NULL, *tmpval = NULL, *p;

	if (name) {
		if (!(tmpname = strdup(name)))
			goto err;
		for (p = tmpname; *p; p++)
			*p = tolower((unsigned char)*p);
	}
	if (value) {
		if (!(tmpval = strdup(value)))
			goto err;
		for (p = tmpval; *p; p++)
			*p = tolower((unsigned char)*p);
	}
	mhdr = malloc(sizeof(MIME_HEADER));
	if (!mhdr)
		goto err;
	mhdr->name = tmpname;
	mhdr->value = tmpval;
	if (!(mhdr->params = sk_MIME_PARAM_new(mime_param_cmp))) {
		free(mhdr);
		goto err;
	}
	return mhdr;
 err:
	free(tmpname);
	free(tmpval);
	return NULL;
}

static int
mime_hdr_addparam(MIME_HEADER *mhdr, char *name, char *value)
{
	char *tmpname = NULL, *tmpval = NULL, *p;
	MIME_PARAM *mparam;

	if (name) {
		tmpname = strdup(name);
		if (!tmpname)
			goto err;
		for (p = tmpname; *p; p++)
			*p = tolower((unsigned char)*p);
	}
	if (value) {
		tmpval = strdup(value);
		if (!tmpval)
			goto err;
	}
	/* Parameter values are case sensitive so leave as is */
	mparam = malloc(sizeof(MIME_PARAM));
	if (!mparam)
		goto err;
	mparam->param_name = tmpname;
	mparam->param_value = tmpval;
	if (sk_MIME_PARAM_push(mhdr->params, mparam) == 0) {
		free(mparam);
		goto err;
	}
	return 1;
 err:
	free(tmpname);
	free(tmpval);
	return 0;
}

static int
mime_hdr_cmp(const MIME_HEADER * const *a, const MIME_HEADER * const *b)
{
	if (!(*a)->name || !(*b)->name)
		return !!(*a)->name - !!(*b)->name;
	return (strcmp((*a)->name, (*b)->name));
}

static int
mime_param_cmp(const MIME_PARAM * const *a, const MIME_PARAM * const *b)
{
	if (!(*a)->param_name || !(*b)->param_name)
		return !!(*a)->param_name - !!(*b)->param_name;
	return (strcmp((*a)->param_name, (*b)->param_name));
}

/* Find a header with a given name (if possible) */

static MIME_HEADER *
mime_hdr_find(STACK_OF(MIME_HEADER) *hdrs, char *name)
{
	MIME_HEADER htmp;
	int idx;
	htmp.name = name;
	idx = sk_MIME_HEADER_find(hdrs, &htmp);
	if (idx < 0)
		return NULL;
	return sk_MIME_HEADER_value(hdrs, idx);
}

static MIME_PARAM *
mime_param_find(MIME_HEADER *hdr, char *name)
{
	MIME_PARAM param;
	int idx;
	param.param_name = name;
	idx = sk_MIME_PARAM_find(hdr->params, &param);
	if (idx < 0)
		return NULL;
	return sk_MIME_PARAM_value(hdr->params, idx);
}

static void
mime_hdr_free(MIME_HEADER *hdr)
{
	free(hdr->name);
	free(hdr->value);
	if (hdr->params)
		sk_MIME_PARAM_pop_free(hdr->params, mime_param_free);
	free(hdr);
}

static void
mime_param_free(MIME_PARAM *param)
{
	free(param->param_name);
	free(param->param_value);
	free(param);
}

/* Check for a multipart boundary. Returns:
 * 0 : no boundary
 * 1 : part boundary
 * 2 : final boundary
 */
static int
mime_bound_check(char *line, int linelen, char *bound, int blen)
{
	if (linelen == -1)
		linelen = strlen(line);
	if (blen == -1)
		blen = strlen(bound);
	/* Quickly eliminate if line length too short */
	if (blen + 2 > linelen)
		return 0;
	/* Check for part boundary */
	if (!strncmp(line, "--", 2) && !strncmp(line + 2, bound, blen)) {
		if (!strncmp(line + blen + 2, "--", 2))
			return 2;
		else
			return 1;
	}
	return 0;
}

static int
strip_eol(char *linebuf, int *plen)
{
	int len = *plen;
	char *p, c;
	int is_eol = 0;

	for (p = linebuf + len - 1; len > 0; len--, p--) {
		c = *p;
		if (c == '\n')
			is_eol = 1;
		else if (c != '\r')
			break;
	}
	*plen = len;
	return is_eol;
}