findSipHeader
Find a SIP header in a call.
libSoftphone maintains internally a map of all SIP headers present in the call establishing dialog (incoming INVITE messages and responses). In case the header already exists and a new packet specifies new value for the header, the value in the map is overwritten.
The headers are stored in an internal XML format created when the headers are parsed. Simple and non-standard headers usually have a format of <HeaderName>value</HeaderName>, complex headers like Contact or Via are stored as a non-flat XML tree.
Return
The SIP header in an unspecified format. <HeaderName/> if the header was empty. null if no such header was received.
Parameters
call
The call to search for the SIP header in.
headerName
Name of the header to search for.