[evolution-data-server] I#23 - [IMAPx] Fails to parse some BODYSTRUCTURE responses

[Milan Crha <mcrha src gnome org>]

commit 79493ca9c4ef37573dc3b758747533115eafcb5c
Author: Milan Crha <mcrha redhat com>
Date:   Tue Aug 21 17:04:49 2018 +0200

    I#23 - [IMAPx] Fails to parse some BODYSTRUCTURE responses
    
    Closes https://gitlab.gnome.org/GNOME/evolution-data-server/issues/23

 src/camel/providers/imapx/camel-imapx-utils.c | 63 +++++++++++++++++++++++----
 1 file changed, 55 insertions(+), 8 deletions(-)
---
diff --git a/src/camel/providers/imapx/camel-imapx-utils.c b/src/camel/providers/imapx/camel-imapx-utils.c
index 3f3326464..4b6c45533 100644
--- a/src/camel/providers/imapx/camel-imapx-utils.c
+++ b/src/camel/providers/imapx/camel-imapx-utils.c
@@ -947,12 +947,14 @@ imapx_parse_body_fields (CamelIMAPXInputStream *stream,
                          GCancellable *cancellable,
                          GError **error)
 {
+       gint tok;
+       guint len;
        guchar *token;
        gchar  *type;
        gsize type_len;
        guint64 number;
        struct _CamelMessageContentInfo *cinfo;
-       gboolean success;
+       gboolean success, is_broken_response = FALSE;
 
        /* body_fields     ::= body_fld_param SPACE body_fld_id SPACE
         * body_fld_desc SPACE body_fld_enc SPACE
@@ -971,12 +973,27 @@ imapx_parse_body_fields (CamelIMAPXInputStream *stream,
        type = alloca (type_len);
        g_strlcpy (type, (gchar *) token, type_len);
 
-       success = camel_imapx_input_stream_astring (
-               stream, &token, cancellable, error);
+       /* Peek what follows, as Gmail can return invalid multipart/mixed response
+          when it contains another multipart/mixed with the same boundary. */
+       tok = camel_imapx_input_stream_token (stream, &token, &len, cancellable, error);
 
-       if (!success)
+       if (tok == IMAPX_TOK_ERROR)
                goto error;
 
+       camel_imapx_input_stream_ungettoken (stream, tok, token, len);
+
+       if (tok == '(') {
+               /* Broken response, has missing 'type', contains only 'subtype' */
+               is_broken_response = TRUE;
+               token = (guchar *) type;
+               type = (gchar *) "multipart";
+       } else {
+               success = camel_imapx_input_stream_astring (stream, &token, cancellable, error);
+
+               if (!success)
+                       goto error;
+       }
+
        cinfo->type = camel_content_type_new (type, (gchar *) token);
 
        success = imapx_parse_param_list (
@@ -985,6 +1002,36 @@ imapx_parse_body_fields (CamelIMAPXInputStream *stream,
        if (!success)
                goto error;
 
+       if (is_broken_response) {
+               gint nested_level = 0;
+
+               /* Ignore everything until the last ')' */
+               do {
+                       tok = camel_imapx_input_stream_token (stream, &token, &len, cancellable, error);
+
+                       if (tok == IMAPX_TOK_ERROR)
+                               goto error;
+
+                       if (tok == '(') {
+                               nested_level++;
+                       } else if (tok == ')' && nested_level > 0) {
+                               tok = 0; /* To not be used as the stop condition */
+                               nested_level--;
+                       } else if (tok == IMAPX_TOK_LITERAL) {
+                               camel_imapx_input_stream_set_literal (stream, len);
+
+                               do {
+                                       tok = camel_imapx_input_stream_getl (stream, &token, &len, 
cancellable, error);
+                               } while (tok > 0);
+                       }
+               } while ((nested_level > 0 || tok != ')') && tok != IMAPX_TOK_ERROR);
+
+               if (tok == ')')
+                       camel_imapx_input_stream_ungettoken (stream, tok, token, len);
+
+               return cinfo;
+       }
+
        /* body_fld_id     ::= nstring */
        success = camel_imapx_input_stream_nstring (
                stream, &token, cancellable, error);
@@ -1402,8 +1449,8 @@ imapx_parse_body (CamelIMAPXInputStream *stream,
                                stream, tok, token, len);
 
                        if (tok == '(' || tok == IMAPX_TOK_TOKEN) {
-                               dinfo = imapx_parse_ext_optional (
-                                       stream, cancellable, &local_error);
+                               if (tok == '(')
+                                       dinfo = imapx_parse_ext_optional (stream, cancellable, &local_error);
 
                                if (local_error)
                                        goto error;
@@ -1505,8 +1552,8 @@ imapx_parse_body (CamelIMAPXInputStream *stream,
                        camel_imapx_input_stream_ungettoken (
                                stream, tok, token, len);
                        if (tok == '(' || tok == IMAPX_TOK_TOKEN) {
-                               dinfo = imapx_parse_ext_optional (
-                                       stream, cancellable, &local_error);
+                               if (tok == '(')
+                                       dinfo = imapx_parse_ext_optional (stream, cancellable, &local_error);
 
                                if (local_error)
                                        goto error;