overthewire - natas/filter.go

     1  package main
     2  
     3  import (
     4  	"net/http"
     5  	"strings"
     6  
     7  	"vimagination.zapto.org/errors"
     8  	xmlpath "gopkg.in/xmlpath.v2"
     9  )
    10  
    11  type Prefixed struct {
    12  	Grabber
    13  	Prefix string
    14  	Length int
    15  }
    16  
    17  func (p Prefixed) Grab(r http.Request) string {
    18  	source := p.Grabber.Grab(r)
    19  	index := strings.Index(source, p.Prefix)
    20  	if index < 0 || len(source) < index+len(p.Prefix)+p.Length {
    21  		panic(errors.Error("failed to get prefixed data"))
    22  	}
    23  	return source[index+len(p.Prefix) : index+len(p.Prefix)+p.Length]
    24  }
    25  
    26  type XPath struct {
    27  	Grabber
    28  	Path string
    29  }
    30  
    31  func (x XPath) Grab(r http.Request) string {
    32  	p := xmlpath.MustCompile(x.Path)
    33  	source := x.Grabber.Grab(r)
    34  	h, err := xmlpath.ParseHTML(strings.NewReader(source))
    35  	e(err)
    36  	str, ok := p.String(h)
    37  	if !ok {
    38  		panic(errors.Error("failed to get xpath data"))
    39  	}
    40  	return str
    41  }