Line policy overflow in a header (mime.cpp)

[Displacer]

There is a condition for line.length() in mime.cpp parse_by_line function:

if (line.length() > string::size_type(decoder_line_policy_))
    throw mime_error("Line policy overflow in a header.");

decoder_line_policy_ is set to mailio::codec::line_len_policy_t::RECOMMENDED which equals 73.

In some cases MS Exchange mail server produces lines with larger size, leading to exception thrown.

Can this value be increased to support such messages?

[Displacer]

setting codition to mailio::codec::line_len_policy_t::MANDATORY seems fixing this problem

[karastojko]

Correct, that's the purpose of the line policy.

[Displacer]

Correct, that's the purpose of the line policy.

I have provided pull request https://github.com/karastojko/mailio/pull/167 to quick merge if this is correct changes.

PS: There is also pull request to support boost versions before 1.81 (Ubuntu 22.04 LTS have 1.74)

[Displacer]

It seems decoder_line_policy_ should be set for mailio::codec::line_len_policy_t::MANDATORY in class initialization since there are overflows in mailio::bit8::decode (line 80) in some cases with RECOMMENDED value.

[Displacer]

there seems to be a problem in imap.cpp (line 458): msg.line_policy(line_policy, line_policy); the second parameter of msg.line_policy seems should be MANDATORY also

[Nullarity]

I have the same issue. In my case, the IMAP server is ionos.com. So, to fix it, I need to modify the source and build the project, right? Right now, I am using vcpkg for this library.

[Displacer]

I have the same issue. In my case, the IMAP server is ionos.com. So, to fix it, I need to modify the source and build the project, right? Right now, I am using vcpkg for this library.

You probably could try something like this in client code without rebuilding library:

message msg; msg.line_policy(codec::line_len_policy_t::MANDATORY, codec::line_len_policy_t::MANDATORY); conn.fetch(msg_uid, msg);

I hope this will help.

[karastojko]

@Displacer That's right.

There is also the NONE policy which means unlimited.

[Nullarity]

Thank you, guys, it helped, but unfortunately, while fetching other emails, I get SIGSEGV.

code snippet:

    for (const auto msg_uid : messages) {
      message msg;
      msg.line_policy(codec::line_len_policy_t::NONE,
                      codec::line_len_policy_t::NONE);
      conn.fetch(msg_uid, msg);
      if (!msg.empty()) {
        cout << msg.subject() << endl;
      }
    }

stacktrace.txt

[karastojko]

Thanks for the report. Can you please in the method mime::content_type_t::operator=(const mime::content_type_t&) before the line with to_lower_copy put printing of cont_type.subtype and paste the result here? I am interested to understand the reason of the crash of to_lower_copy() in your case.