/* $OpenBSD: asn_mime.c,v 1.37 2025/06/02 12:18:21 jsg 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/x509.h>

#include "asn1_local.h"
#include "err_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;
}