lib-mail: Refactor and improve attachment detection

This also adds support for detecting Content-Type->name when Content-Disposition->filename
is not available. This only works in the case of Content-Disposition: attachment.

diff --git a/src/lib-mail/message-part-data.c b/src/lib-mail/message-part-data.c
index 0eeede4fc845b967189d9b03a168a21c6c199c7a..4fe4f9c6cc0265c1c89a3a790aee0db75905e108 100644 (file)
--- a/src/lib-mail/message-part-data.c
+++ b/src/lib-mail/message-part-data.c
@@ -68,32 +68,88 @@ bool message_part_data_is_plain_7bit(const struct message_part *part)
        return TRUE;
 }
 
-bool message_part_data_get_filename(const struct message_part *part,
+/* Returns whether the parameter exists. If a value is requested through
+   value_r, returns it there and return TRUE, otherwise sets *value_r to NULL
+   and returns FALSE. */
+static bool get_param_value(const char *parameter_name,
+                           const struct message_part_param *params_list,
+                           unsigned int params_list_count,
+                           const char **value_r)
+{
+       for (unsigned int i = 0; i < params_list_count; i++) {
+               const struct message_part_param *param = &params_list[i];
+
+               if (strcasecmp(param->name, parameter_name) == 0) {
+                       if (value_r != NULL) {
+                               *value_r = NULL;
+                               if (*param->value != '\0') {
+                                       *value_r = param->value;
+                               }
+                               return *value_r != NULL;
+                       }
+                       return TRUE;
+               }
+       }
+       return FALSE;
+}
+
+static bool message_part_data_find_attachment_filename(
+       const struct message_part_data *data,
+       bool default_return,
+       const char **filename_r)
+{
+       /* The filename might be under Content-Disposition->filename or under
+          Content-Type->name */
+       if (get_param_value("filename", data->content_disposition_params,
+                           data->content_disposition_params_count, filename_r) ||
+           get_param_value("name", data->content_type_params,
+                           data->content_type_params_count, filename_r))
+               return TRUE;
+       return default_return;
+}
+
+/* Returns whether the message has an attachment in accordance with the provided
+   settings. If there is an attachment, the filename is returned in filename_r
+   if it is not NULL. */
+static bool message_part_get_attachment_filename(
+       const struct message_part *part,
+       const struct message_part_attachment_settings *settings,
        const char **filename_r)
 {
        const struct message_part_data *data = part->data;
-       const struct message_part_param *params;
-       unsigned int params_count, i;
 
        i_assert(data != NULL);
 
-       params = data->content_disposition_params;
-       params_count = data->content_disposition_params_count;
-
-       if (data->content_disposition != NULL &&
-               strcasecmp(data->content_disposition, "attachment") != 0) {
+       /* Reject the message if the Content-Type is excluded. */
+       if (settings && settings->content_type_filter != NULL &&
+           !message_part_has_content_types(part, settings->content_type_filter))
                return FALSE;
-       }
-       for (i = 0; i < params_count; i++) {
-               if (strcasecmp(params[i].name, "filename") == 0 &&
-                       params[i].value != NULL) {
-                       *filename_r = params[i].value;
-                       return TRUE;
-               }
-       }
+
+       /* Accept Content-Disposition: attachment, even when it does not have a
+          filename or Content-Type->name parameter */
+       if (null_strcasecmp(data->content_disposition, "attachment") == 0)
+               return message_part_data_find_attachment_filename(data, TRUE, filename_r);
+
+       /* Accept Content-Disposition: inline only when a filename or
+          Content-Type->name is available and if inlined attachments are not
+          excluded */
+       if ((!settings || !settings->exclude_inlined) &&
+           null_strcasecmp(data->content_disposition, "inline") == 0)
+               return message_part_data_find_attachment_filename(data, FALSE, filename_r);
+
        return FALSE;
 }
 
+bool message_part_data_get_filename(const struct message_part *part,
+       const char **filename_r)
+{
+       const struct message_part_data *data = part->data;
+
+       i_assert(data != NULL);
+
+       return message_part_get_attachment_filename(part, NULL, filename_r);
+}
+
 /*
  * Header parsing
  */
@@ -532,7 +588,7 @@ void message_part_data_parse_from_header(pool_t pool,
        }
 }
 
-bool message_part_has_content_types(struct message_part *part,
+bool message_part_has_content_types(const struct message_part *part,
                                    const char *const *types)
 {
        struct message_part_data *data = part->data;
@@ -558,42 +614,9 @@ bool message_part_has_content_types(struct message_part *part,
        return ret;
 }
 
-bool message_part_has_parameter(struct message_part *part, const char *parameter,
-                               bool has_value)
-{
-       struct message_part_data *data = part->data;
-
-       i_assert(data != NULL);
-
-       for (unsigned int i = 0; i < data->content_disposition_params_count; i++) {
-               const struct message_part_param *param =
-                       &data->content_disposition_params[i];
-               if (strcasecmp(param->name, parameter) == 0 &&
-                   (!has_value || *param->value != '\0')) {
-                       return TRUE;
-               }
-       }
-       return FALSE;
-}
-
-bool message_part_is_attachment(struct message_part *part,
-                               const struct message_part_attachment_settings *set)
+bool message_part_is_attachment(
+       struct message_part *part,
+       const struct message_part_attachment_settings *settings)
 {
-       struct message_part_data *data = part->data;
-
-       i_assert(data != NULL);
-
-       /* see if the content-type is excluded */
-       if (set->content_type_filter != NULL &&
-           !message_part_has_content_types(part, set->content_type_filter))
-               return FALSE;
-
-       /* accept any attachment, or any inlined attachment with filename,
-          unless inlined ones are excluded */
-       if (null_strcasecmp(data->content_disposition, "attachment") == 0 ||
-           (!set->exclude_inlined &&
-            null_strcasecmp(data->content_disposition, "inline") == 0 &&
-            message_part_has_parameter(part, "filename", FALSE)))
-               return TRUE;
-       return FALSE;
+       return message_part_get_attachment_filename(part, settings, NULL);
 }

diff --git a/src/lib-mail/message-part-data.h b/src/lib-mail/message-part-data.h
index 9513bfc2f01bebda81457656eff84bf71cf28637..de740419e5b0ede82a53f8501ea7ee952810c7a8 100644 (file)
--- a/src/lib-mail/message-part-data.h
+++ b/src/lib-mail/message-part-data.h
@@ -74,16 +74,13 @@ bool message_part_data_get_filename(const struct message_part *part,
        const char **filename_r);
 
 /* See message_part_attachment_settings */
-bool message_part_has_content_types(struct message_part *part, const char *const *types);
-
-/* Returns TRUE if message part has given parameter, and has non-empty
-   value if has_value is TRUE. */
-bool message_part_has_parameter(struct message_part *part, const char *parameter,
-                               bool has_value);
+bool message_part_has_content_types(const struct message_part *part,
+                                   const char *const *types);
 
 /* Check if part is attachment according to given settings */
-bool message_part_is_attachment(struct message_part *part,
-                               const struct message_part_attachment_settings *set);
+bool message_part_is_attachment(
+       struct message_part *part,
+       const struct message_part_attachment_settings *settings);
 /*
  * Header parsing
  */