Fixes fingerprints.json: too many open files Error

[zeknox]

While running the tool with the following arguments the script would error due to a condition where too many open files occurred.

$ subjack -w targets.txt -t 100 -timeout 30 -o results.json -a

...

2020/02/04 02:33:04 open /go//src/github.com/haccer/subjack/fingerprints.json: too many open files

After review, it appears that each goroutine within subjack.dns() would read the fingerprints file. Refactored the code to read the fingerprints.json file once and then pass the []Fingerprints struct into the goroutines.

This appears to be working well for me and likely has some performance gains as well.

• fixes fingerprints.json: too many open files condition by reading the file once and passing data into the goroutine functions

[AnotherWayIn]

Thanks for fixing this. After adding the fixes manually, is there an easier way to compile these changes? I'm getting:

../../../src/subjack/dns.go:8:2: cannot find package "github.com/haccer/available" in any of:
        /usr/lib/go-1.13/src/github.com/haccer/available (from $GOROOT)
        /root/go/src/src/github.com/haccer/available (from $GOPATH)
../../../src/subjack/dns.go:9:2: cannot find package "github.com/miekg/dns" in any of:
        /usr/lib/go-1.13/src/github.com/miekg/dns (from $GOROOT)
        /root/go/src/src/github.com/miekg/dns (from $GOPATH)
../../../src/subjack/requests.go:5:2: cannot find package "github.com/valyala/fasthttp" in any of:
        /usr/lib/go-1.13/src/github.com/valyala/fasthttp (from $GOROOT)
        /root/go/src/src/github.com/valyala/fasthttp (from $GOPATH)

[zeknox]

Navigate into the $GOPATH/src/github.com/haccer/subjack/ directory or wherever you pulled it down too. Execute go get . to install the dependency packages, and then try to go build or go run

This PR does not fully fix the too many files issue, but likely helps.