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bencode.go
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bencode.go
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package bencode
import "strconv"
import "bytes"
import "fmt"
import "container/list"
import "os"
import "bufio"
/*
string: number:chars
int: i numbers e
dict: d string:|int|list|dict|string e
list: l string|int|list|dicte
*/
const (
Bestr = iota;
Beint;
Bedict;
Belist;
Beend;
)
/*
Just a way to split them up,
*/
func NextToken(input *bufio.Reader)(encoded []byte, betype int, err os.Error){
/*
dict returns just d
list returns just l
string returns encoded string
int returns encoded int
*/
c, err := input.ReadByte();
if err == os.EOF {
return nil, 0,err
}
if err != nil {
//print(err.String());
return nil, 0,err;
}
switch {
case c == 'i': // it's an integer i..e
//i:= 0;
number := make([]byte,1,10);
c, err = input.ReadByte();
if err != nil {
return nil, 0,err
}
for c != 'e' {
number = bytes.AddByte(number, c);
if c, err = input.ReadByte(); err != nil {
return;
}
}
return number,Beint,nil;
case c == 'l': //it's a list l...e
alist := make([]byte,1,1);
alist = bytes.AddByte(alist,c);
return alist,Belist,nil;
case c == 'e': // the end of a dict or list
end := make([]byte,1,1);
end = bytes.AddByte(end,c);
return end,Beend,nil
case c >= '0' && c <= '9': // it's a string and c is the size
str := make([]byte,1,10);
strSize := make([]byte,1,10);
strSize = bytes.AddByte(strSize, c);
str = bytes.AddByte(str, c);
var c1 uint8;
c1, err = input.ReadByte();
if err != nil {
return nil, 0,err
}
for c1 >= '0' && c1 <= '9' {
strSize = bytes.AddByte(strSize, c1);
str= bytes.AddByte(str, c1);
c1, err = input.ReadByte();
if err != nil {
return nil, 0, err
}
}
strLen, err := strconv.Atoi(string(strSize));
if err != nil {
return nil, 0, os.NewError("strlength doesn't convert to int")
}
for i := 0; i < strLen; i++ {
c2, err := input.ReadByte();
if err != nil {
return nil, 0, err
}
//fmt.Printf("the c is: %s\n",string(c1));
str = bytes.AddByte(str, c2);
}
return str,Bestr,nil;
case c == 'd': //it's a dict
dict := make( []byte,1,1);
dict = bytes.AddByte(dict,c);
return dict,Bedict,nil;
}
//shouldn't get here
return nil,0,os.NewError("error, shouldn't be here");
}
type BeString []byte
type BeNode struct {
Betype int;
Bestr string;
Beint int;
Bedict map[string]*BeNode;
Belist *list.List;
}
/*finds the info dict and returns a hash of it*/
/*infohash := sha1.New();Write(strings.Bytes(str));
encode each item in be.Bedict["info"] and write to infohash
be.Bedict["info_hash"] = infohash.Sum();
thing := sha1.New();
str := "pizza";
thing.Write(strings.Bytes(str));*/
func (this *BeNode) Encode() (output string, err os.Error) {
buffer := new(bytes.Buffer);
switch this.Betype {
case Bestr:
if _, err = buffer.WriteString(strconv.Itoa(len(this.Bestr))); err != nil {
return
}
if _, err = buffer.WriteString(":"); err != nil {
return
}
if _, err = buffer.WriteString(this.Bestr); err != nil {
return
}
case Beint:
if _, err = buffer.WriteString("i"); err != nil {
return
}
if _, err = buffer.WriteString(strconv.Itoa(this.Beint)); err != nil {
return
}
if _, err = buffer.WriteString("e"); err != nil {
return
}
case Bedict:
if _, err = buffer.WriteString("d"); err != nil {
return
}
for key, item := range this.Bedict {
var encoded string;
if _, err = buffer.WriteString(strconv.Itoa(len(key))); err != nil {
return
}
if _, err = buffer.WriteString(":"); err != nil {
return
}
if _, err := buffer.WriteString(key); err != nil {
return
}
if encoded, err = item.Encode(); err != nil {
return
}
if _, err = buffer.WriteString(encoded); err != nil {
return
}
}
if _, err = buffer.WriteString("e"); err != nil {
return
}
case Belist:
if _, err = buffer.WriteString("l"); err != nil {
return
}
for item := range this.Belist.Iter() {
var encoded string;
if encoded, err = item.(*BeNode).Encode(); err != nil {
return
}
if _, err := buffer.WriteString(encoded); err != nil {
return
}
}
if _, err = buffer.WriteString("e"); err != nil {
return
}
}
output = buffer.String();
return;
}
func (this *BeNode) Print() {
switch this.Betype {
case Bestr:
//print("this is string:");
fmt.Printf("%s\n", this.Bestr)
case Beint:
fmt.Printf("%d\n", this.Beint)
case Belist:
listchan := this.Belist.Iter();
for i := range (listchan) {
i.(*BeNode).Print()
}
case Bedict:
//print("this is a dict");
for i, j := range this.Bedict {
fmt.Printf("%s=", i);
j.Print();
fmt.Printf("\n");
}
default:
fmt.Printf("error")
}
return;
}