Fix info_hash url encoding

[YenForYang]

No description provided.

[YenForYang]

Ah after some testing it looks like even PathEscape sometimes uses + instead of %20. I think resorting to strings.Replace() may be the only way. In addition it looks like PathEscape produces non-working results as well sometimes, so I decided to revert back to QueryEscape. It seems to be most reliable when paired with a strings.ReplaceAll(...,"+","%20")

As an aside, I think it's a really good idea to actually log the full announce url (with query parameters) instead of simply the base in debug mode:

torrent/tracker_scraper.go

Lines 145 to 158 in 1d53c17

	me.t.logger.WithDefaultLevel(log.Debug).Printf("announcing to %q: %#v", me.u.String(), req)
	res, err := tracker.Announce{
	Context: ctx,
	HTTPProxy: me.t.cl.config.HTTPProxy,
	UserAgent: me.t.cl.config.HTTPUserAgent,
	TrackerUrl: me.trackerUrl(ip),
	Request: req,
	HostHeader: me.u.Host,
	ServerName: me.u.Hostname(),
	UdpNetwork: me.u.Scheme,
	ClientIp4: krpc.NodeAddr{IP: me.t.cl.config.PublicIp4},
	ClientIp6: krpc.NodeAddr{IP: me.t.cl.config.PublicIp6},
	}.Do()
	me.t.logger.WithDefaultLevel(log.Debug).Printf("announce to %q returned %#v: %v", me.u.String(), res, err)

[anacrolix]

I'm confused, doesn't QueryEscape already encode spaces to %20? You're welcome to add the logging change if it helps.

[anacrolix]

@YenForYang any update on this?

[YenForYang]

Doesn't look like QueryEscape uses %20 consistently -- i.e. only specific parts. I've been doing an explicit strings.Replace and it works great. This issue provides the explanation I believe: golang/go#4013. The issues referencing that issue also may be relevant, for example: hawkular/hawkular-client-go#12

[YenForYang]

I'll submit my current changes, but I doubt you'll like the looks of it. I basically ditched using url.Values and decided to build the string from scratch. I actually find it more readable and it hides less "magic" IMO. I think finer control over building the query is ultimately needed; the url package simply doesn't provide this.

[YenForYang]

Just a side note -- We probably won't get more control of the percent encoding with QueryEscape, given this issue: golang/go#13982

[anacrolix]

@YenForYang what about #591 instead?