asn_mime.c

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/* asn_mime.c */
/* Written by Dr Stephen N Henson ([email protected]) 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
 *    [email protected].
 *
 * 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 <stdio.h>
#include <ctype.h>
#include "cryptlib.h"
#include <openssl/rand.h>
#include <openssl/x509.h>
#include <openssl/asn1.h>
#include <openssl/asn1t.h>
#include "asn1_locl.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)
IMPLEMENT_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)
IMPLEMENT_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
#define mime_debug(x) /* x */

/* 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)
    {
    /* If streaming create stream BIO and copy all content through it */
    if (flags & SMIME_STREAM)
        {
        BIO *bio, *tbio;
        bio = BIO_new_NDEF(out, val, it);
        if (!bio)
            {
            ASN1err(ASN1_F_I2D_ASN1_BIO_STREAM,ERR_R_MALLOC_FAILURE);
            return 0;
            }
        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);
        }
    /* else just write out ASN1 structure which will have all content
     * stored internally
     */
    else
        ASN1_item_i2d_bio(it, out, val);
    return 1;
    }

/* 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)
        {
        ASN1err(ASN1_F_B64_WRITE_ASN1,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()))) {
        ASN1err(ASN1_F_B64_READ_ASN1,ERR_R_MALLOC_FAILURE);
        return 0;
    }
    bio = BIO_push(b64, bio);
    val = ASN1_item_d2i_bio(it, bio, NULL);
    if(!val)
        ASN1err(ASN1_F_B64_READ_ASN1,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);
                OPENSSL_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 */
        RAND_pseudo_bytes((unsigned char *)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 deteched 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)
        {
        ASN1err(ASN1_F_ASN1_OUTPUT_DATA,
                    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))) {
        ASN1err(ASN1_F_SMIME_READ_ASN1,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);
        ASN1err(ASN1_F_SMIME_READ_ASN1, 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);
            ASN1err(ASN1_F_SMIME_READ_ASN1, 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) ) {
            ASN1err(ASN1_F_SMIME_READ_ASN1, 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))) {
            ASN1err(ASN1_F_SMIME_READ_ASN1,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);
            ASN1err(ASN1_F_SMIME_READ_ASN1, ASN1_R_NO_SIG_CONTENT_TYPE);
            return NULL;
        }

        if(strcmp(hdr->value, "application/x-pkcs7-signature") &&
            strcmp(hdr->value, "application/pkcs7-signature")) {
            ASN1err(ASN1_F_SMIME_READ_ASN1,ASN1_R_SIG_INVALID_MIME_TYPE);
            ERR_add_error_data(2, "type: ", 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))) {
            ASN1err(ASN1_F_SMIME_READ_ASN1,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")) {
        ASN1err(ASN1_F_SMIME_READ_ASN1,ASN1_R_INVALID_MIME_TYPE);
        ERR_add_error_data(2, "type: ", 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))) {
        ASN1err(ASN1_F_SMIME_READ_ASN1, 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;
}

/* 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))) {
        ASN1err(ASN1_F_SMIME_TEXT,ASN1_R_MIME_PARSE_ERROR);
        return 0;
    }
    if(!(hdr = mime_hdr_find(headers, "content-type")) || !hdr->value) {
        ASN1err(ASN1_F_SMIME_TEXT,ASN1_R_MIME_NO_CONTENT_TYPE);
        sk_MIME_HEADER_pop_free(headers, mime_hdr_free);
        return 0;
    }
    if (strcmp (hdr->value, "text/plain")) {
        ASN1err(ASN1_F_SMIME_TEXT,ASN1_R_INVALID_MIME_TYPE);
        ERR_add_error_data(2, "type: ", 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;
}

/* 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;
    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) {
            sk_BIO_push(parts, bpart);
            return 1;
        } else if(part) {
            /* Strip CR+LF from linebuf */
            next_eol = strip_eol(linebuf, &len);
            if(first) {
                first = 0;
                if(bpart) sk_BIO_push(parts, bpart);
                bpart = BIO_new(BIO_s_mem());
                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);
        }
    }
    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);
    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 == ';') {
                mime_debug("Found End Value\n");
                *p = 0;
                mhdr = mime_hdr_new(ntmp, strip_ends(q));
                sk_MIME_HEADER_push(headers, mhdr);
                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 == '"') {
                mime_debug("Found Quote\n");
                state = MIME_QUOTE;
            } else if(c == '(') {
                save_state = state;
                state = MIME_COMMENT;
            }
            break;

            case MIME_QUOTE:
            if(c == '"') {
                mime_debug("Found Match Quote\n");
                state = MIME_VALUE;
            }
            break;
        }
    }

    if(state == MIME_TYPE) {
        mhdr = mime_hdr_new(ntmp, strip_ends(q));
        sk_MIME_HEADER_push(headers, mhdr);
    } 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;

}

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, *tmpval, *p;
    int c;
    if(name) {
        if(!(tmpname = BUF_strdup(name))) return NULL;
        for(p = tmpname ; *p; p++) {
            c = (unsigned char)*p;
            if(isupper(c)) {
                c = tolower(c);
                *p = c;
            }
        }
    } else tmpname = NULL;
    if(value) {
        if(!(tmpval = BUF_strdup(value))) return NULL;
        for(p = tmpval ; *p; p++) {
            c = (unsigned char)*p;
            if(isupper(c)) {
                c = tolower(c);
                *p = c;
            }
        }
    } else tmpval = NULL;
    mhdr = (MIME_HEADER *) OPENSSL_malloc(sizeof(MIME_HEADER));
    if(!mhdr) return NULL;
    mhdr->name = tmpname;
    mhdr->value = tmpval;
    if(!(mhdr->params = sk_MIME_PARAM_new(mime_param_cmp))) return NULL;
    return mhdr;
}
        
static int mime_hdr_addparam(MIME_HEADER *mhdr, char *name, char *value)
{
    char *tmpname, *tmpval, *p;
    int c;
    MIME_PARAM *mparam;
    if(name) {
        tmpname = BUF_strdup(name);
        if(!tmpname) return 0;
        for(p = tmpname ; *p; p++) {
            c = (unsigned char)*p;
            if(isupper(c)) {
                c = tolower(c);
                *p = c;
            }
        }
    } else tmpname = NULL;
    if(value) {
        tmpval = BUF_strdup(value);
        if(!tmpval) return 0;
    } else tmpval = NULL;
    /* Parameter values are case sensitive so leave as is */
    mparam = (MIME_PARAM *) OPENSSL_malloc(sizeof(MIME_PARAM));
    if(!mparam) return 0;
    mparam->param_name = tmpname;
    mparam->param_value = tmpval;
    sk_MIME_PARAM_push(mhdr->params, mparam);
    return 1;
}

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)
{
    if(hdr->name) OPENSSL_free(hdr->name);
    if(hdr->value) OPENSSL_free(hdr->value);
    if(hdr->params) sk_MIME_PARAM_pop_free(hdr->params, mime_param_free);
    OPENSSL_free(hdr);
}

static void mime_param_free(MIME_PARAM *param)
{
    if(param->param_name) OPENSSL_free(param->param_name);
    if(param->param_value) OPENSSL_free(param->param_value);
    OPENSSL_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;
    p = linebuf + len - 1;
    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;
    }