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Diffstat (limited to 'tools/mime-maker.c')
| -rw-r--r-- | tools/mime-maker.c | 777 |
1 files changed, 777 insertions, 0 deletions
diff --git a/tools/mime-maker.c b/tools/mime-maker.c new file mode 100644 index 0000000..91eab82 --- /dev/null +++ b/tools/mime-maker.c @@ -0,0 +1,777 @@ +/* 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; +} |