Quoted boundaries doesn't work

[dotMorten]

When looking for the boundary a multipart request, quoted boundaries doesn't seem to be handled.

pion/src/http_parser.cpp

Line 991 in 8553f6f

const std::string boundary = std::string("--") + content_type.substr(pos+9);

     // parse field boundary 
988     std::size_t pos = content_type.find("boundary="); 
989     if (pos == std::string::npos) 
990         return false; 
991     const std::string boundary = std::string("--") + content_type.substr(pos+9);  

However this is allowed, and for instance used by default by .NET Core's HttpClient:
Here's an example from the RFC: http://www.w3.org/Protocols/rfc1341/7_2_Multipart.html

     From: Nathaniel Borenstein <nsb@bellcore.com> 
     To:  Ned Freed <ned@innosoft.com> 
     Subject: Sample message 
     MIME-Version: 1.0 
     Content-type: multipart/mixed; boundary="simple 
     boundary" 

     This is the preamble.  It is to be ignored, though it 
     is a handy place for mail composers to include an 
     explanatory note to non-MIME compliant readers. 
     --simple boundary 

     This is implicitly typed plain ASCII text. 
     It does NOT end with a linebreak. 
     --simple boundary 
     Content-type: text/plain; charset=us-ascii 

     This is explicitly typed plain ASCII text. 
     It DOES end with a linebreak. 

     --simple boundary-- 
     This is the epilogue.  It is also to be ignored.