flutter app connect to ip camera with digest auth - flutter

Question

I'm trying to pass digest auth on my ip camera
I do it on Flutter but actually it doesn't matter.
I got http response from camera with status code 401 Not Authorized
and Headers:
{content-type: text/html, pragma: no-cache, cache-control: no-cache, www-authenticate: Digest
realm="goAhead", domain=":13237",qop="auth", nonce="a98326cc6022c2a2b7cc7e57a5956f77",
opaque="5ccc069c403ebaf9f0171e9517f40e41",algorithm="MD5", stale="FALSE", date: Thu Dec 26 16:31:43
2019, server: GoAhead-Webs}
from this source here I've found the needed Response constructor view like this:
var mResponse = "Digest username=\"$username\", realm=\"$realm\", nonce=\"$nonce\", uri=\"$uri\",
response=\"$_response\", cnonce=\"$cnonce\", nc=$nc, qop=\"$qop\"";
I create this:
Digest username="admin", realm="goAhead", nonce="a98326cc6022c2a2b7cc7e57a5956f77",
uri="/onvif/device_service", response="5313fe5265efcd3da37cec322d92ebd7", cnonce="1234567890",
nc=00000001, qop="auth"
and send http request to camera:
Future<http.Response> new_response = http.post(snapshotUrl, headers: {"Content-Type":"text/xml; charset=utf-8", "Authorization": mResponse }, body: mGetSnapshotUriAuth);
new_response.then((resp){
print(resp.statusCode);
});
and getting this error:
[ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: Invalid header field name
When I remove "Authorization" field of headers, camera response with 401 code.
I'm trying to get snapshot from ip camera works on Onvif protocol. I am not sure in Uri parameter.
The same error when I try send this http request via http Client on desktop machine screenshot
Question 2:
When I try to change uri param to something else e.g:
String uri = http://www.onvif.org/ver10/media/wsdl/GetSnapshotUri";
My camera stops reply to me. The same behaviour I can see when I start use Http sniffer or change Digest's response's field name. Sometimes reset camera helps(or even hard reset) and it start working(return 401 error) again, sometimes it's start working by itself. But by the way the camera continues working via others Camera Viewer Apps.
My screenshot from http sniffer
PS After many tests to solve this problem I think my param values are correct, because If change something e.g username, password and etc (except cnonce. When I change сnonce the result the same), I got other error: 401.
screenshot of Android studio with error

Answer 1

Writing SOAP requests by hand is BAD PRACTICE. I know nothing about dart, but I invite you to look for a tool like gsoap for generating the functions from thw WSDL files you can find here.
Don't write requests by hand, you'll end up in a mess when parsing the responses.