parseHttpHeaders crashes on malformed header

[polonevitch]

Program terminated with signal SIGABRT, Aborted.
...
#5  std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::operator[] (this=<optimized out>, __pos=<optimized out>)
    at /usr/src/debug/gcc-11.4.1-3.el9.x86_64/obj-x86_64-redhat-linux/x86_64-redhat-linux/libstdc++-v3/include/bits/basic_string.h:1055
#6  0x000000000060366f in ix::parseHttpHeaders[abi:cxx11](std::unique_ptr<ix::Socket, std::default_delete<ix::Socket> >&, std::function<bool ()> const&) ()
#7  0x00000000005f3c65 in ix::Http::parseRequest[abi:cxx11](std::unique_ptr<ix::Socket, std::default_delete<ix::Socket> >&, int) ()
#8  0x00000000005de3e9 in ix::HttpServer::handleConnection(std::unique_ptr<ix::Socket, std::default_delete<ix::Socket> >, std::shared_ptr<ix::ConnectionState>) ()

There is no sanitizer for the received bytes. When a sequence like "...\0:..." is received, the lineStr is constructed with a size smaller than i, which triggers a crash upon accessing lineStr[start].