Fix panic on empty news path

[rbdr/mobius] / hotline / field.go

diff --git a/hotline/field.go b/hotline/field.go
index 7bba0d709c35da7fa6d5432dc47f196a805f2f8d..65ff39497ad57cf788f5858736785892d298f675 100644 (file)
--- a/hotline/field.go
+++ b/hotline/field.go
@@ -1,6 +1,8 @@
 package hotline
 
 import (
+       "bufio"
+       "bytes"
        "encoding/binary"
        "errors"
        "io"
@@ -62,24 +64,24 @@ var (
        FieldNewsArtData         = [2]byte{0x01, 0x4D} // 333
        FieldNewsArtParentArt    = [2]byte{0x01, 0x4F} // 335
        FieldNewsArt1stChildArt  = [2]byte{0x01, 0x50} // 336
+       FieldNewsArtRecurseDel   = [2]byte{0x01, 0x51} // 337
 
        // These fields are documented, but seemingly unused.
        // FieldUserAlias           = [2]byte{0x00, 0x6F} // 111
        // FieldNewsArtFlags        = [2]byte{0x01, 0x4E} // 334
-       // FieldNewsArtRecurseDel   = [2]byte{0x01, 0x51} // 337
 )
 
 type Field struct {
-       ID        [2]byte // Type of field
-       FieldSize [2]byte // Size of the data part
-       Data      []byte  // Actual field content
+       Type      [2]byte // Type of field
+       FieldSize [2]byte // Size of the data field
+       Data      []byte  // Field data
 
        readOffset int // Internal offset to track read progress
 }
 
-func NewField(id [2]byte, data []byte) Field {
+func NewField(fieldType [2]byte, data []byte) Field {
        f := Field{
-               ID:   id,
+               Type: fieldType,
                Data: make([]byte, len(data)),
        }
 
@@ -90,8 +92,8 @@ func NewField(id [2]byte, data []byte) Field {
        return f
 }
 
-// fieldScanner implements bufio.SplitFunc for parsing byte slices into complete tokens
-func fieldScanner(data []byte, _ bool) (advance int, token []byte, err error) {
+// FieldScanner implements bufio.SplitFunc for parsing byte slices into complete tokens
+func FieldScanner(data []byte, _ bool) (advance int, token []byte, err error) {
        if len(data) < minFieldLen {
                return 0, nil, nil
        }
@@ -105,9 +107,53 @@ func fieldScanner(data []byte, _ bool) (advance int, token []byte, err error) {
        return neededSize, data[0:neededSize], nil
 }
 
+// DecodeInt decodes the field bytes to an int.
+// The official Hotline clients will send uint32s as 2 bytes if possible, but
+// some third party clients such as Frogblast and Heildrun will always send 4 bytes
+func (f *Field) DecodeInt() (int, error) {
+       switch len(f.Data) {
+       case 2:
+               return int(binary.BigEndian.Uint16(f.Data)), nil
+       case 4:
+               return int(binary.BigEndian.Uint32(f.Data)), nil
+       }
+
+       return 0, errors.New("unknown byte length")
+}
+
+func (f *Field) DecodeObfuscatedString() string {
+       return string(EncodeString(f.Data))
+}
+
+// DecodeNewsPath decodes the field data to a news path.
+// Example News Path data for a Category nested under two Bundles:
+// 00000000  00 03 00 00 10 54 6f 70  20 4c 65 76 65 6c 20 42  |.....Top Level B|
+// 00000010  75 6e 64 6c 65 00 00 13  53 65 63 6f 6e 64 20 4c  |undle...Second L|
+// 00000020  65 76 65 6c 20 42 75 6e  64 6c 65 00 00 0f 4e 65  |evel Bundle...Ne|
+// 00000030  73 74 65 64 20 43 61 74  65 67 6f 72 79           |sted Category|
+func (f *Field) DecodeNewsPath() ([]string, error) {
+       if len(f.Data) == 0 {
+               return []string{}, nil
+       }
+
+       pathCount := binary.BigEndian.Uint16(f.Data[0:2])
+
+       scanner := bufio.NewScanner(bytes.NewReader(f.Data[2:]))
+       scanner.Split(newsPathScanner)
+
+       var paths []string
+
+       for i := uint16(0); i < pathCount; i++ {
+               scanner.Scan()
+               paths = append(paths, scanner.Text())
+       }
+
+       return paths, nil
+}
+
 // Read implements io.Reader for Field
 func (f *Field) Read(p []byte) (int, error) {
-       buf := slices.Concat(f.ID[:], f.FieldSize[:], f.Data)
+       buf := slices.Concat(f.Type[:], f.FieldSize[:], f.Data)
 
        if f.readOffset >= len(buf) {
                return 0, io.EOF // All bytes have been read
@@ -125,7 +171,7 @@ func (f *Field) Write(p []byte) (int, error) {
                return 0, errors.New("input slice too short")
        }
 
-       copy(f.ID[:], p[0:2])
+       copy(f.Type[:], p[0:2])
        copy(f.FieldSize[:], p[2:4])
 
        dataSize := int(binary.BigEndian.Uint16(f.FieldSize[:]))
@@ -139,9 +185,9 @@ func (f *Field) Write(p []byte) (int, error) {
        return minFieldLen + dataSize, nil
 }
 
-func getField(id [2]byte, fields *[]Field) *Field {
+func GetField(id [2]byte, fields *[]Field) *Field {
        for _, field := range *fields {
-               if id == field.ID {
+               if id == field.Type {
                        return &field
                }
        }