move every struct into it's own directory in order to run tests individually.

lib/common/data/string.go

@@ -0,0 +1,123 @@
+package common
+
+/*
+I2P I2PString
+https://geti2p.net/spec/common-structures#string
+Accurate for version 0.9.24
+*/
+
+import (
+	"errors"
+
+	log "github.com/sirupsen/logrus"
+)
+
+// Maximum number of bytes that can be stored in an I2P string
+const (
+	STRING_MAX_SIZE = 255
+)
+
+type I2PString []byte
+
+//
+// Look up the length of the string, reporting errors if the string is
+// invalid or the specified length does not match the provided data.
+//
+func (str I2PString) Length() (length int, err error) {
+	if len(str) == 0 {
+		log.WithFields(log.Fields{
+			"at":     "(I2PString) Length",
+			"reason": "no data",
+		}).Error("error parsing string")
+		err = errors.New("error parsing string: zero length")
+		return
+	}
+	l := Integer([]byte{byte(str[0])})
+	length = l.Int()
+	inferred_len := length + 1
+	str_len := len(str)
+	if inferred_len > str_len {
+		log.WithFields(log.Fields{
+			"at":                    "(I2PString) Length",
+			"string_bytes_length":   str_len,
+			"string_length_field":   length,
+			"expected_bytes_length": inferred_len,
+			"reason":                "data shorter than specified",
+		}).Warn("string format warning")
+		err = errors.New("string parsing warning: string data is shorter than specified by length")
+	} else if str_len > inferred_len {
+		log.WithFields(log.Fields{
+			"at":                    "(I2PString) Length",
+			"string_bytes_length":   str_len,
+			"string_length_field":   length,
+			"expected_bytes_length": inferred_len,
+			"reason":                "data longer than specified",
+		}).Warn("string format warning")
+		err = errors.New("string parsing warning: string contains data beyond length")
+	}
+	return
+}
+
+//
+// Return the string data and any errors encountered by Length.
+//
+func (str I2PString) Data() (data string, err error) {
+	length, err := str.Length()
+	if err != nil {
+		switch err.Error() {
+		case "error parsing string: zero length":
+			return
+		case "string parsing warning: string data is shorter than specified by length":
+			data = string(str[1:])
+			return
+		case "string parsing warning: string contains data beyond length":
+			data = string(str[1 : length+1])
+			return
+		}
+	}
+	data = string(str[1:])
+	return
+}
+
+//
+// This function takes an unformatted Go string and returns a I2PString
+// and any errors encountered during the encoding.
+//
+func ToI2PString(data string) (str I2PString, err error) {
+	data_len := len(data)
+	if data_len > STRING_MAX_SIZE {
+		log.WithFields(log.Fields{
+			"at":         "ToI2PI2PString",
+			"string_len": data_len,
+			"max_len":    STRING_MAX_SIZE,
+			"reason":     "too much data",
+		}).Error("cannot create I2P string")
+		err = errors.New("cannot store that much data in I2P string")
+		return
+	}
+	i2p_string := []byte{byte(data_len)}
+	i2p_string = append(i2p_string, []byte(data)...)
+	str = I2PString(i2p_string)
+	return
+}
+
+//
+// Read a string from a slice of bytes, returning any extra data on the end
+// of the slice and any errors encountered parsing the I2PString.
+//
+func ReadI2PString(data []byte) (str I2PString, remainder []byte, err error) {
+	str = I2PString(data)
+	length, err := I2PString(data).Length()
+	if err != nil && err.Error() == "string parsing warning: string contains data beyond length" {
+		str = I2PString(data[:length+1])
+		remainder = data[length+1:]
+		err = nil
+	}
+	return
+}
+
+func NewI2PString(data []byte) (str *I2PString, remainder []byte, err error) {
+	objstr, remainder, err := ReadI2PString(data)
+	str = &objstr
+	return
+}