scusi / bpjm.go

// go library to scope with the BPjM Censorship list package Bpjm import ( "net/url" "regexp" "crypto/md5" "strings" "bytes" "io/ioutil" "encoding/binary" "io" ) // BpjmEntry is a datastructure for BPjM List Entries type BpjmEntry struct { DomainMd5 []byte // Md5 sum of domain, with a leading http PathMd5 []byte Depth int32 } // parseURL - takes an URL string as input and returns a pointer to an url.URL object func ParseURL(ustr string) (u *url.URL, err error) { u, err = url.Parse(ustr) return u, err } // XtrctHost - takes a url object and returns the host func XtrctHost(u *url.URL) (host string) { return u.Host } // XtrctPath - takes an url object and returns the path func XtrctPath(u *url.URL) (path string) { return u.Path } // FilterHost - Filters host according to BPjM Host Filters // effectivley it cuts away a leading 'www.' subdomain, if existing func FilterHost(host string) (fhost string) { re := regexp.MustCompile("^www.") fhost = re.ReplaceAllString(host, "") return fhost } // FilterPath - Filters path according to BPjM Path Filters // effectivley cuts away the root directory from path, if existing func FilterPath(path string) (fpath string) { re := regexp.MustCompile("^/") fpath = re.ReplaceAllString(path, "") return fpath } // GenMd5 - Generates n MD5 checksum of a given string and returns the md5sum as array of bytes func GenMd5(in string) (md5sum []byte) { inb := []byte(in) md5 := md5.Sum(inb) for _, c := range md5 { md5sum = append(md5sum, c) } return md5sum } // check - is a general error checking routine that panics on error func check(err error) { if err != nil { panic(err) } } // enumerate depth of a given URL func EnumerateDepth(u *url.URL) (depth int32) { path := XtrctPath(u) i := len(strings.Split(path, "/")) return int32(i) } // UrlToBpjmEntry - takes an URL string as input and returns a BpjmEntry object func UrlToBpjmEntry(ustr string) (entry BpjmEntry) { u, err := ParseURL(ustr) check(err) host := FilterHost( XtrctHost(u) ) path := FilterPath( XtrctPath(u) ) depth := EnumerateDepth(u) e := BpjmEntry{ GenMd5("http://" + host), GenMd5(path), depth, } return e } // Load a binary BPjM ListFile from a Fritzbox func LoadFritzBoxFile(filename string)(data []byte) { data, _ = ioutil.ReadFile(filename) return data } // FritzBoxFile - datastructure to describe an Fritzbox BPjM File type FritzBoxFile struct { Magick []byte EmbedFileName string Size int Records int Entries []BpjmEntry } func ParseFritzBoxFile(data []byte)(FBF FritzBoxFile){ // set up a buffer we can work with buffer := bytes.NewBuffer(data) // get magick; first 5 bytes magick := buffer.Next(5) // get embedded filename; next 59 bytes; cut out the null bytes and make it a string embedFileName := string( bytes.Trim(buffer.Next(59), string(0x00)) ) // get size of file in bytes size := buffer.Len() // prepager a list to store entries var Entries []BpjmEntry // init counter n := 0 // for each entry in list... for { // ... read domain hash d := make([]byte, 16) _, err := buffer.Read(d) if err != nil { if err == io.EOF { break } panic(err) } // ...read path hash p := make([]byte, 16) _, err = buffer.Read(p) if err != nil { if err == io.EOF { break } panic(err) } //...read depth i, err := binary.ReadUvarint(buffer) if err != nil { if err == io.EOF { break } panic(err) } // parse read data into an BpjmEntry object e := BpjmEntry{ d, p, int32(i), } // append object to list of objects Entries = append(Entries, e) // count n++ } // parse collected data into a FirtzBoxFile Object FBF = FritzBoxFile{ magick, embedFileName, size, n, Entries, } // return the FBF Object return FBF }