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gnupg2/tools/mime-maker.c

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/* mime-maker.c - Create MIME structures
* Copyright (C) 2016 g10 Code GmbH
* Copyright (C) 2016 Bundesamt für Sicherheit in der Informationstechnik
*
* This file is part of GnuPG.
*
* This file is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This file is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, see <https://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "../common/util.h"
#include "../common/zb32.h"
#include "rfc822parse.h"
#include "mime-maker.h"
/* An object to store an header. Also used for a list of headers. */
struct header_s
{
struct header_s *next;
char *value; /* Malloced value. */
char name[1]; /* Name. */
};
typedef struct header_s *header_t;
/* An object to store a MIME part. A part is the header plus the
* content (body). */
struct part_s
{
struct part_s *next; /* Next part in the current container. */
struct part_s *child; /* Child container. */
char *boundary; /* Malloced boundary string. */
header_t headers; /* List of headers. */
header_t *headers_tail;/* Address of last header in chain. */
size_t bodylen; /* Length of BODY. */
char *body; /* Malloced buffer with the body. This is the
* non-encoded value. */
unsigned int partid; /* The part ID. */
};
typedef struct part_s *part_t;
/* Definition of the mime parser object. */
struct mime_maker_context_s
{
void *cookie; /* Cookie passed to all callbacks. */
unsigned int verbose:1; /* Enable verbose mode. */
unsigned int debug:1; /* Enable debug mode. */
part_t mail; /* The MIME tree. */
part_t current_part;
unsigned int partid_counter; /* Counter assign part ids. */
int boundary_counter; /* Used to create easy to read boundaries. */
char *boundary_suffix; /* Random string used in the boundaries. */
struct b64state *b64state; /* NULL or malloced Base64 decoder state. */
/* Helper to convey the output stream to recursive functions. */
estream_t outfp;
};
/* Create a new mime make object. COOKIE is a values woich will be
* used as first argument for all callbacks registered with this
* object. */
gpg_error_t
mime_maker_new (mime_maker_t *r_maker, void *cookie)
{
mime_maker_t ctx;
*r_maker = NULL;
ctx = xtrycalloc (1, sizeof *ctx);
if (!ctx)
return gpg_error_from_syserror ();
ctx->cookie = cookie;
*r_maker = ctx;
return 0;
}
static void
release_parts (part_t part)
{
while (part)
{
part_t partnext = part->next;
while (part->headers)
{
header_t hdrnext = part->headers->next;
xfree (part->headers);
part->headers = hdrnext;
}
release_parts (part->child);
xfree (part->boundary);
xfree (part->body);
xfree (part);
part = partnext;
}
}
/* Release a mime maker object. */
void
mime_maker_release (mime_maker_t ctx)
{
if (!ctx)
return;
release_parts (ctx->mail);
xfree (ctx->boundary_suffix);
xfree (ctx);
}
/* Set verbose and debug mode. */
void
mime_maker_set_verbose (mime_maker_t ctx, int level)
{
if (!level)
{
ctx->verbose = 0;
ctx->debug = 0;
}
else
{
ctx->verbose = 1;
if (level > 10)
ctx->debug = 1;
}
}
static void
dump_parts (part_t part, int level)
{
header_t hdr;
for (; part; part = part->next)
{
log_debug ("%*s[part %u]\n", level*2, "", part->partid);
for (hdr = part->headers; hdr; hdr = hdr->next)
{
log_debug ("%*s%s: %s\n", level*2, "", hdr->name, hdr->value);
}
if (part->body)
log_debug ("%*s[body %zu bytes]\n", level*2, "", part->bodylen);
if (part->child)
{
log_debug ("%*s[container]\n", level*2, "");
dump_parts (part->child, level+1);
}
}
}
/* Dump the mime tree for debugging. */
void
mime_maker_dump_tree (mime_maker_t ctx)
{
dump_parts (ctx->mail, 0);
}
/* Find the parent node for NEEDLE starting at ROOT. */
static part_t
find_parent (part_t root, part_t needle)
{
part_t node, n;
for (node = root->child; node; node = node->next)
{
if (node == needle)
return root;
if ((n = find_parent (node, needle)))
return n;
}
return NULL;
}
/* Find the part node from the PARTID. */
static part_t
find_part (part_t root, unsigned int partid)
{
part_t node, n;
for (node = root->child; node; node = node->next)
{
if (node->partid == partid)
return root;
if ((n = find_part (node, partid)))
return n;
}
return NULL;
}
/* Create a boundary string. Outr codes is aware of the general
* structure of that string (gebins with "=-=") so that
* it can protect against accidentally-used boundaries within the
* content. */
static char *
generate_boundary (mime_maker_t ctx)
{
if (!ctx->boundary_suffix)
{
char buffer[12];
gcry_create_nonce (buffer, sizeof buffer);
ctx->boundary_suffix = zb32_encode (buffer, 8 * sizeof buffer);
if (!ctx->boundary_suffix)
return NULL;
}
ctx->boundary_counter++;
return es_bsprintf ("=-=%02d-%s=-=",
ctx->boundary_counter, ctx->boundary_suffix);
}
/* Ensure that the context has a MAIL and CURRENT_PART object and
* return the parent object if available */
static gpg_error_t
ensure_part (mime_maker_t ctx, part_t *r_parent)
{
if (!ctx->mail)
{
ctx->mail = xtrycalloc (1, sizeof *ctx->mail);
if (!ctx->mail)
{
if (r_parent)
*r_parent = NULL;
return gpg_error_from_syserror ();
}
log_assert (!ctx->current_part);
ctx->current_part = ctx->mail;
ctx->current_part->headers_tail = &ctx->current_part->headers;
}
log_assert (ctx->current_part);
if (r_parent)
*r_parent = find_parent (ctx->mail, ctx->current_part);
return 0;
}
/* Check whether a header with NAME has already been set into PART.
* NAME must be in canonical capitalized format. Return true or
* false. */
static int
have_header (part_t part, const char *name)
{
header_t hdr;
for (hdr = part->headers; hdr; hdr = hdr->next)
if (!strcmp (hdr->name, name))
return 1;
return 0;
}
/* Helper to add a header to a part. */
static gpg_error_t
add_header (part_t part, const char *name, const char *value)
{
gpg_error_t err;
header_t hdr;
size_t namelen;
const char *s;
char *p;
if (!value)
{
s = strchr (name, '=');
if (!s)
return gpg_error (GPG_ERR_INV_ARG);
namelen = s - name;
value = s+1;
}
else
namelen = strlen (name);
hdr = xtrymalloc (sizeof *hdr + namelen);
if (!hdr)
return gpg_error_from_syserror ();
hdr->next = NULL;
memcpy (hdr->name, name, namelen);
hdr->name[namelen] = 0;
/* Check that the header name is valid. */
if (!rfc822_valid_header_name_p (hdr->name))
{
xfree (hdr);
return gpg_error (GPG_ERR_INV_NAME);
}
rfc822_capitalize_header_name (hdr->name);
hdr->value = xtrystrdup (value);
if (!hdr->value)
{
err = gpg_error_from_syserror ();
xfree (hdr);
return err;
}
for (p = hdr->value + strlen (hdr->value) - 1;
(p >= hdr->value
&& (*p == ' ' || *p == '\t' || *p == '\n' || *p == '\r'));
p--)
*p = 0;
if (!(p >= hdr->value))
{
xfree (hdr->value);
xfree (hdr);
return gpg_error (GPG_ERR_INV_VALUE); /* Only spaces. */
}
if (part)
{
*part->headers_tail = hdr;
part->headers_tail = &hdr->next;
}
else
xfree (hdr);
return 0;
}
/* Add a header with NAME and VALUE to the current mail. A LF in the
* VALUE will be handled automagically. If NULL is used for VALUE it
* is expected that the NAME has the format "NAME=VALUE" and VALUE is
* taken from there.
*
* If no container has been added, the header will be used for the
* regular mail headers and not for a MIME part. If the current part
* is in a container and a body has been added, we append a new part
* to the current container. Thus for a non-MIME mail the caller
* needs to call this function followed by a call to add a body. When
* adding a Content-Type the boundary parameter must not be included.
*/
gpg_error_t
mime_maker_add_header (mime_maker_t ctx, const char *name, const char *value)
{
gpg_error_t err;
part_t part, parent;
/* Hack to use this function for a syntax check of NAME and VALUE. */
if (!ctx)
return add_header (NULL, name, value);
err = ensure_part (ctx, &parent);
if (err)
return err;
part = ctx->current_part;
if ((part->body || part->child) && !parent)
{
/* We already have a body but no parent. Adding another part is
* thus not possible. */
return gpg_error (GPG_ERR_CONFLICT);
}
if (part->body || part->child)
{
/* We already have a body and there is a parent. We now append
* a new part to the current container. */
part = xtrycalloc (1, sizeof *part);
if (!part)
return gpg_error_from_syserror ();
part->partid = ++ctx->partid_counter;
part->headers_tail = &part->headers;
log_assert (!ctx->current_part->next);
ctx->current_part->next = part;
ctx->current_part = part;
}
/* If no NAME and no VALUE has been given we do not add a header.
* This can be used to create a new part without any header. */
if (!name && !value)
return 0;
/* If we add Content-Type, make sure that we have a MIME-version
* header first; this simply looks better. */
if (!ascii_strcasecmp (name, "Content-Type")
&& !have_header (ctx->mail, "MIME-Version"))
{
err = add_header (ctx->mail, "MIME-Version", "1.0");
if (err)
return err;
}
return add_header (part, name, value);
}
/* Helper for mime_maker_add_{body,stream}. */
static gpg_error_t
add_body (mime_maker_t ctx, const void *data, size_t datalen)
{
gpg_error_t err;
part_t part, parent;
err = ensure_part (ctx, &parent);
if (err)
return err;
part = ctx->current_part;
if (part->body)
return gpg_error (GPG_ERR_CONFLICT);
part->body = xtrymalloc (datalen? datalen : 1);
if (!part->body)
return gpg_error_from_syserror ();
part->bodylen = datalen;
if (data)
memcpy (part->body, data, datalen);
return 0;
}
/* Add STRING as body to the mail or the current MIME container. A
* second call to this function or mime_make_add_body_data is not
* allowed.
*
* FIXME: We may want to have an append_body to add more data to a body.
*/
gpg_error_t
mime_maker_add_body (mime_maker_t ctx, const char *string)
{
return add_body (ctx, string, strlen (string));
}
/* Add (DATA,DATALEN) as body to the mail or the current MIME
* container. Note that a second call to this function or to
* mime_make_add_body is not allowed. */
gpg_error_t
mime_maker_add_body_data (mime_maker_t ctx, const void *data, size_t datalen)
{
return add_body (ctx, data, datalen);
}
/* This is the same as mime_maker_add_body but takes a stream as
* argument. As of now the stream is copied to the MIME object but
* eventually we may delay that and read the stream only at the time
* it is needed. Note that the address of the stream object must be
* passed and that the ownership of the stream is transferred to this
* MIME object. To indicate the latter the function will store NULL
* at the ADDR_STREAM so that a caller can't use that object anymore
* except for es_fclose which accepts a NULL pointer. */
gpg_error_t
mime_maker_add_stream (mime_maker_t ctx, estream_t *stream_addr)
{
void *data;
size_t datalen;
es_rewind (*stream_addr);
if (es_fclose_snatch (*stream_addr, &data, &datalen))
return gpg_error_from_syserror ();
*stream_addr = NULL;
return add_body (ctx, data, datalen);
}
/* Add a new MIME container. A container can be used instead of a
* body. */
gpg_error_t
mime_maker_add_container (mime_maker_t ctx)
{
gpg_error_t err;
part_t part;
err = ensure_part (ctx, NULL);
if (err)
return err;
part = ctx->current_part;
if (part->body)
return gpg_error (GPG_ERR_CONFLICT); /* There is already a body. */
if (part->child || part->boundary)
return gpg_error (GPG_ERR_CONFLICT); /* There is already a container. */
/* Create a child node. */
part->child = xtrycalloc (1, sizeof *part->child);
if (!part->child)
return gpg_error_from_syserror ();
part->child->headers_tail = &part->child->headers;
part->boundary = generate_boundary (ctx);
if (!part->boundary)
{
err = gpg_error_from_syserror ();
xfree (part->child);
part->child = NULL;
return err;
}
part = part->child;
part->partid = ++ctx->partid_counter;
ctx->current_part = part;
return 0;
}
/* Finish the current container. */
gpg_error_t
mime_maker_end_container (mime_maker_t ctx)
{
gpg_error_t err;
part_t parent;
err = ensure_part (ctx, &parent);
if (err)
return err;
if (!parent)
return gpg_error (GPG_ERR_CONFLICT); /* No container. */
while (parent->next)
parent = parent->next;
ctx->current_part = parent;
return 0;
}
/* Return the part-ID of the current part. */
unsigned int
mime_maker_get_partid (mime_maker_t ctx)
{
if (ensure_part (ctx, NULL))
return 0; /* Ooops. */
return ctx->current_part->partid;
}
/* Write a header and handle emdedded LFs. If BOUNDARY is not NULL it
* is appended to the value. */
/* Fixme: Add automatic line wrapping. */
static gpg_error_t
write_header (mime_maker_t ctx, const char *name, const char *value,
const char *boundary)
{
const char *s;
es_fprintf (ctx->outfp, "%s: ", name);
/* Note that add_header made sure that VALUE does not end with a LF.
* Thus we can assume that a LF is followed by non-whitespace. */
for (s = value; *s; s++)
{
if (*s == '\n')
es_fputs ("\r\n\t", ctx->outfp);
else
es_fputc (*s, ctx->outfp);
}
if (boundary)
{
if (s > value && s[-1] != ';')
es_fputc (';', ctx->outfp);
es_fprintf (ctx->outfp, "\r\n\tboundary=\"%s\"", boundary);
}
es_fputs ("\r\n", ctx->outfp);
return es_ferror (ctx->outfp)? gpg_error_from_syserror () : 0;
}
static gpg_error_t
write_gap (mime_maker_t ctx)
{
es_fputs ("\r\n", ctx->outfp);
return es_ferror (ctx->outfp)? gpg_error_from_syserror () : 0;
}
static gpg_error_t
write_boundary (mime_maker_t ctx, const char *boundary, int last)
{
es_fprintf (ctx->outfp, "\r\n--%s%s\r\n", boundary, last?"--":"");
return es_ferror (ctx->outfp)? gpg_error_from_syserror () : 0;
}
/* Fixme: Apply required encoding. */
static gpg_error_t
write_body (mime_maker_t ctx, const void *body, size_t bodylen)
{
const char *s;
for (s = body; bodylen; s++, bodylen--)
{
if (*s == '\n' && !(s > (const char *)body && s[-1] == '\r'))
es_fputc ('\r', ctx->outfp);
es_fputc (*s, ctx->outfp);
}
return es_ferror (ctx->outfp)? gpg_error_from_syserror () : 0;
}
/* Recursive worker for mime_maker_make. */
static gpg_error_t
write_tree (mime_maker_t ctx, part_t parent, part_t part)
{
gpg_error_t err;
header_t hdr;
for (; part; part = part->next)
{
for (hdr = part->headers; hdr; hdr = hdr->next)
{
if (part->child && !strcmp (hdr->name, "Content-Type"))
err = write_header (ctx, hdr->name, hdr->value, part->boundary);
else
err = write_header (ctx, hdr->name, hdr->value, NULL);
if (err)
return err;
}
err = write_gap (ctx);
if (err)
return err;
if (part->body)
{
err = write_body (ctx, part->body, part->bodylen);
if (err)
return err;
}
if (part->child)
{
log_assert (part->boundary);
err = write_boundary (ctx, part->boundary, 0);
if (!err)
err = write_tree (ctx, part, part->child);
if (!err)
err = write_boundary (ctx, part->boundary, 1);
if (err)
return err;
}
if (part->next)
{
log_assert (parent && parent->boundary);
err = write_boundary (ctx, parent->boundary, 0);
if (err)
return err;
}
}
return 0;
}
/* Add headers we always require. */
static gpg_error_t
add_missing_headers (mime_maker_t ctx)
{
gpg_error_t err;
if (!ctx->mail)
return gpg_error (GPG_ERR_NO_DATA);
if (!have_header (ctx->mail, "MIME-Version"))
{
/* Even if a Content-Type has never been set, we want to
* announce that we do MIME. */
err = add_header (ctx->mail, "MIME-Version", "1.0");
if (err)
goto leave;
}
if (!have_header (ctx->mail, "Date"))
{
char *p = rfctimestamp (make_timestamp ());
if (!p)
err = gpg_error_from_syserror ();
else
err = add_header (ctx->mail, "Date", p);
xfree (p);
if (err)
goto leave;
}
err = 0;
leave:
return err;
}
/* Create message from the tree MIME and write it to FP. Note that
* the output uses only a LF and a later called sendmail(1) is
* expected to convert them to network line endings. */
gpg_error_t
mime_maker_make (mime_maker_t ctx, estream_t fp)
{
gpg_error_t err;
err = add_missing_headers (ctx);
if (err)
return err;
ctx->outfp = fp;
err = write_tree (ctx, NULL, ctx->mail);
ctx->outfp = NULL;
return err;
}
/* Create a stream object from the MIME part identified by PARTID and
* store it at R_STREAM. If PARTID identifies a container the entire
* tree is returned. Using that function may read stream objects
* which have been added as MIME bodies. The caller must close the
* stream object. */
gpg_error_t
mime_maker_get_part (mime_maker_t ctx, unsigned int partid, estream_t *r_stream)
{
gpg_error_t err;
part_t part;
estream_t fp;
*r_stream = NULL;
/* When the entire tree is requested, we make sure that all missing
* headers are applied. We don't do that if only a part is
* requested because the additional headers (like Date:) will only
* be added to part 0 headers anyway. */
if (!partid)
{
err = add_missing_headers (ctx);
if (err)
return err;
part = ctx->mail;
}
else
part = find_part (ctx->mail, partid);
/* For now we use a memory stream object; however it would also be
* possible to create an object created on the fly while the caller
* is reading the returned stream. */
fp = es_fopenmem (0, "w+b");
if (!fp)
return gpg_error_from_syserror ();
ctx->outfp = fp;
err = write_tree (ctx, NULL, part);
ctx->outfp = NULL;
if (!err)
{
es_rewind (fp);
*r_stream = fp;
}
else
es_fclose (fp);
return err;
}
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