[PATCH 2/4] Introduce a generic tree-like abstraction for MIME traversal.
Austin Clements
amdragon at MIT.EDU
Sun Dec 4 11:31:38 PST 2011
This wraps all of the complex MIME part handling in a single, simple
function that gets part N from *any* MIME object, so traversing a MIME
part tree becomes a two-line for loop. Furthermore, the MIME node
structure provides easy access to envelopes for message parts as well
as cryptographic information.
This code is directly derived from the current show_message_body code
(much of it is identical), but the control relation is inverted:
instead of show_message_body controlling the traversal of the MIME
structure and invoking callbacks, the caller controls the traversal of
the MIME structure.
---
Makefile.local | 1 +
mime-node.c | 234 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
notmuch-client.h | 80 ++++++++++++++++++
3 files changed, 315 insertions(+), 0 deletions(-)
create mode 100644 mime-node.c
diff --git a/Makefile.local b/Makefile.local
index c94402b..c46ed26 100644
--- a/Makefile.local
+++ b/Makefile.local
@@ -312,6 +312,7 @@ notmuch_client_srcs = \
notmuch-time.c \
query-string.c \
show-message.c \
+ mime-node.c \
json.c
notmuch_client_modules = $(notmuch_client_srcs:.c=.o)
diff --git a/mime-node.c b/mime-node.c
new file mode 100644
index 0000000..a8e4a59
--- /dev/null
+++ b/mime-node.c
@@ -0,0 +1,234 @@
+/* notmuch - Not much of an email program, (just index and search)
+ *
+ * Copyright © 2009 Carl Worth
+ * Copyright © 2009 Keith Packard
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see http://www.gnu.org/licenses/ .
+ *
+ * Authors: Carl Worth <cworth at cworth.org>
+ * Keith Packard <keithp at keithp.com>
+ * Austin Clements <aclements at csail.mit.edu>
+ */
+
+#include "notmuch-client.h"
+
+/* Context that gets inherited from the root node. */
+typedef struct mime_node_context {
+ /* Per-message resources. These are allocated internally and must
+ * be destroyed. */
+ FILE *file;
+ GMimeStream *stream;
+ GMimeParser *parser;
+ GMimeMessage *mime_message;
+
+ /* Context provided by the caller. */
+ GMimeCipherContext *cryptoctx;
+ notmuch_bool_t decrypt;
+} mime_node_context_t;
+
+static int
+_mime_node_context_free (mime_node_context_t *res)
+{
+ if (res->mime_message)
+ g_object_unref (res->mime_message);
+
+ if (res->parser)
+ g_object_unref (res->parser);
+
+ if (res->stream)
+ g_object_unref (res->stream);
+
+ if (res->file)
+ fclose (res->file);
+
+ return 0;
+}
+
+notmuch_status_t
+mime_node_open (const void *ctx, notmuch_message_t *message,
+ GMimeCipherContext *cryptoctx, notmuch_bool_t decrypt,
+ mime_node_t **root_out)
+{
+ const char *filename = notmuch_message_get_filename (message);
+ mime_node_context_t *mctx;
+ mime_node_t *root;
+ notmuch_status_t status;
+
+ root = talloc_zero (ctx, mime_node_t);
+ if (root == NULL) {
+ fprintf (stderr, "Out of memory.\n");
+ status = NOTMUCH_STATUS_OUT_OF_MEMORY;
+ goto DONE;
+ }
+
+ /* Create the tree-wide context */
+ mctx = talloc_zero (root, mime_node_context_t);
+ if (mctx == NULL) {
+ fprintf (stderr, "Out of memory.\n");
+ status = NOTMUCH_STATUS_OUT_OF_MEMORY;
+ goto DONE;
+ }
+ talloc_set_destructor (mctx, _mime_node_context_free);
+
+ mctx->file = fopen (filename, "r");
+ if (! mctx->file) {
+ fprintf (stderr, "Error opening %s: %s\n", filename, strerror (errno));
+ status = NOTMUCH_STATUS_FILE_ERROR;
+ goto DONE;
+ }
+
+ mctx->stream = g_mime_stream_file_new (mctx->file);
+ g_mime_stream_file_set_owner (GMIME_STREAM_FILE (mctx->stream), FALSE);
+
+ mctx->parser = g_mime_parser_new_with_stream (mctx->stream);
+
+ mctx->mime_message = g_mime_parser_construct_message (mctx->parser);
+
+ mctx->cryptoctx = cryptoctx;
+ mctx->decrypt = decrypt;
+
+ /* Create the root node */
+ root->part = GMIME_OBJECT (mctx->mime_message);
+ root->envelope_file = message;
+ root->children = 1;
+ root->ctx = mctx;
+
+ *root_out = root;
+ return NOTMUCH_STATUS_SUCCESS;
+
+DONE:
+ talloc_free (root);
+ return status;
+}
+
+static int
+_signature_validity_free (GMimeSignatureValidity **proxy)
+{
+ g_mime_signature_validity_free (*proxy);
+ return 0;
+}
+
+static mime_node_t *
+_mime_node_create (const mime_node_t *parent, GMimeObject *part)
+{
+ mime_node_t *out = talloc_zero (parent, mime_node_t);
+ GError *err = NULL;
+
+ /* Set basic node properties */
+ out->part = part;
+ out->ctx = parent->ctx;
+ if (!talloc_reference (out, out->ctx)) {
+ fprintf (stderr, "Out of memory.\n");
+ talloc_free (out);
+ return NULL;
+ }
+
+ /* Deal with the different types of parts */
+ if (GMIME_IS_PART (part)) {
+ out->children = 0;
+ } else if (GMIME_IS_MULTIPART (part)) {
+ out->children = g_mime_multipart_get_count (GMIME_MULTIPART (part));
+ } else if (GMIME_IS_MESSAGE_PART (part)) {
+ /* Promote part to an envelope and open it */
+ GMimeMessagePart *message_part = GMIME_MESSAGE_PART (part);
+ GMimeMessage *message = g_mime_message_part_get_message (message_part);
+ out->envelope_part = message_part;
+ out->part = GMIME_OBJECT (message);
+ out->children = 1;
+ } else {
+ fprintf (stderr, "Warning: Unknown mime part type: %s.\n",
+ g_type_name (G_OBJECT_TYPE (part)));
+ talloc_free (out);
+ return NULL;
+ }
+
+ /* Handle PGP/MIME parts */
+ if (GMIME_IS_MULTIPART_ENCRYPTED (part) && out->ctx->decrypt) {
+ if (out->children != 2) {
+ /* this violates RFC 3156 section 4, so we won't bother with it. */
+ fprintf (stderr, "Error: %d part(s) for a multipart/encrypted "
+ "message (should be exactly 2)\n",
+ out->children);
+ } else {
+ out->is_encrypted = TRUE;
+ GMimeMultipartEncrypted *encrypteddata =
+ GMIME_MULTIPART_ENCRYPTED (part);
+ out->decrypted_child = g_mime_multipart_encrypted_decrypt
+ (encrypteddata, out->ctx->cryptoctx, &err);
+ if (out->decrypted_child) {
+ out->decrypt_success = TRUE;
+ out->is_signed = TRUE;
+ out->sig_validity = g_mime_multipart_encrypted_get_signature_validity (encrypteddata);
+ } else {
+ fprintf (stderr, "Failed to decrypt part: %s\n",
+ (err ? err->message : "no error explanation given"));
+ }
+ }
+ } else if (GMIME_IS_MULTIPART_SIGNED (part) && out->ctx->cryptoctx) {
+ if (out->children != 2) {
+ /* this violates RFC 3156 section 5, so we won't bother with it. */
+ fprintf (stderr, "Error: %d part(s) for a multipart/signed message "
+ "(should be exactly 2)\n",
+ out->children);
+ } else {
+ out->is_signed = TRUE;
+ /* For some reason the GMimeSignatureValidity returned
+ * here is not a const (inconsistent with that
+ * returned by
+ * g_mime_multipart_encrypted_get_signature_validity,
+ * and therefore needs to be properly disposed of.
+ * Hopefully the API will become more consistent. */
+ GMimeSignatureValidity *sig_validity = g_mime_multipart_signed_verify
+ (GMIME_MULTIPART_SIGNED (part), out->ctx->cryptoctx, &err);
+ out->sig_validity = sig_validity;
+ if (sig_validity) {
+ GMimeSignatureValidity **proxy =
+ talloc (out, GMimeSignatureValidity *);
+ *proxy = sig_validity;
+ talloc_set_destructor (proxy, _signature_validity_free);
+ }
+ }
+ }
+
+ if (out->is_signed && !out->sig_validity)
+ fprintf (stderr, "Failed to verify signed part: %s\n",
+ (err ? err->message : "no error explanation given"));
+
+ if (err)
+ g_error_free (err);
+
+ return out;
+}
+
+mime_node_t *
+mime_node_child (const mime_node_t *parent, int child)
+{
+ if (!parent || child < 0 || child >= parent->children)
+ return NULL;
+
+ if (GMIME_IS_MULTIPART (parent->part)) {
+ GMimeMultipart *multipart = GMIME_MULTIPART (parent->part);
+ if (child == 1 && parent->decrypted_child)
+ return _mime_node_create (parent, parent->decrypted_child);
+ return _mime_node_create (parent, g_mime_multipart_get_part (multipart, child));
+ } else if (GMIME_IS_MESSAGE (parent->part)) {
+ GMimeMessage *message = GMIME_MESSAGE (parent->part);
+ GMimeObject *child = g_mime_message_get_mime_part (message);
+ return _mime_node_create (parent, child);
+ } else {
+ /* This should have been caught by message_part_create */
+ INTERNAL_ERROR ("Unexpected GMimeObject type: %s",
+ g_type_name (G_OBJECT_TYPE (parent->part)));
+ }
+}
diff --git a/notmuch-client.h b/notmuch-client.h
index d7fb6ee..752c234 100644
--- a/notmuch-client.h
+++ b/notmuch-client.h
@@ -238,4 +238,84 @@ notmuch_config_set_maildir_synchronize_flags (notmuch_config_t *config,
notmuch_bool_t
debugger_is_active (void);
+/* mime-node.c */
+
+/* mime_node_t represents a single node in a MIME tree. A MIME tree
+ * abstracts the different ways of traversing different types of MIME
+ * parts, allowing a MIME message to be viewed as a generic tree of
+ * parts. Message-type parts have one child, multipart-type parts
+ * have multiple children, and leaf parts have zero children.
+ */
+typedef struct mime_node {
+ /* The MIME object of this part. This will be a GMimeMessage,
+ * GMimePart, GMimeMultipart, or a subclass of one of these.
+ *
+ * This will never be a GMimeMessagePart because GMimeMessagePart
+ * is structurally redundant with GMimeMessage. If this part is a
+ * message (that is, 'part' is a GMimeMessage), then either
+ * envelope_file will be set to a notmuch_message_t (for top-level
+ * messages) or envelope_part will be set to a GMimeMessagePart
+ * (for embedded message parts).
+ */
+ GMimeObject *part;
+
+ /* If part is a GMimeMessage, these record the envelope of the
+ * message: either a notmuch_message_t representing a top-level
+ * message, or a GMimeMessagePart representing a MIME part
+ * containing a message.
+ */
+ notmuch_message_t *envelope_file;
+ GMimeMessagePart *envelope_part;
+
+ /* The number of children of this part. */
+ int children;
+
+ /* True if this is the container for an encrypted or signed part.
+ * This does *not* mean that decryption or signature verification
+ * succeeded. */
+ notmuch_bool_t is_encrypted, is_signed;
+ /* True if decryption of this part's child succeeded. In this
+ * case, the decrypted part is substituted for the second child of
+ * this part (which would usually be the encrypted data). */
+ notmuch_bool_t decrypt_success;
+ /* For signed or encrypted containers, the validity of the
+ * signature. May be NULL if signature verification failed. */
+ const GMimeSignatureValidity *sig_validity;
+
+ /* Internal: Context inherited from the root iterator. */
+ struct mime_node_context *ctx;
+
+ /* Internal: For successfully decrypted multipart parts, the
+ * decrypted part to substitute for the second child. */
+ GMimeObject *decrypted_child;
+} mime_node_t;
+
+/* Construct a new MIME node pointing to the root message part of
+ * message. If cryptoctx is non-NULL, it will be used to verify
+ * signatures on any child parts. If decrypt is true, then cryptoctx
+ * will additionally be used to decrypt any encrypted child parts.
+ *
+ * Return value:
+ *
+ * NOTMUCH_STATUS_SUCCESS: Root node is returned in *node_out.
+ *
+ * NOTMUCH_STATUS_FILE_ERROR: Failed to open message file.
+ *
+ * NOTMUCH_STATUS_OUT_OF_MEMORY: Out of memory.
+ */
+notmuch_status_t
+mime_node_open (const void *ctx, notmuch_message_t *message,
+ GMimeCipherContext *cryptoctx, notmuch_bool_t decrypt,
+ mime_node_t **node_out);
+
+/* Return a new MIME node for the requested child part of parent.
+ * parent will be used as the talloc context for the returned child
+ * node.
+ *
+ * In case of any failure, this function returns NULL, (after printing
+ * an error message on stderr).
+ */
+mime_node_t *
+mime_node_child (const mime_node_t *parent, int child);
+
#endif
--
1.7.5.4
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