minio/cmd/httprange.go

175 lines
5.2 KiB
Go

/*
* MinIO Cloud Storage, (C) 2015, 2016 MinIO, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package cmd
import (
"errors"
"fmt"
"strconv"
"strings"
)
const (
byteRangePrefix = "bytes="
)
// HTTPRangeSpec represents a range specification as supported by S3 GET
// object request.
//
// Case 1: Not present -> represented by a nil RangeSpec
// Case 2: bytes=1-10 (absolute start and end offsets) -> RangeSpec{false, 1, 10}
// Case 3: bytes=10- (absolute start offset with end offset unspecified) -> RangeSpec{false, 10, -1}
// Case 4: bytes=-30 (suffix length specification) -> RangeSpec{true, -30, -1}
type HTTPRangeSpec struct {
// Does the range spec refer to a suffix of the object?
IsSuffixLength bool
// Start and end offset specified in range spec
Start, End int64
}
// GetLength - get length of range
func (h *HTTPRangeSpec) GetLength(resourceSize int64) (rangeLength int64, err error) {
switch {
case resourceSize < 0:
return 0, errors.New("Resource size cannot be negative")
case h == nil:
rangeLength = resourceSize
case h.IsSuffixLength:
specifiedLen := -h.Start
rangeLength = specifiedLen
if specifiedLen > resourceSize {
rangeLength = resourceSize
}
case h.Start >= resourceSize:
return 0, errInvalidRange
case h.End > -1:
end := h.End
if resourceSize <= end {
end = resourceSize - 1
}
rangeLength = end - h.Start + 1
case h.End == -1:
rangeLength = resourceSize - h.Start
default:
return 0, errors.New("Unexpected range specification case")
}
return rangeLength, nil
}
// GetOffsetLength computes the start offset and length of the range
// given the size of the resource
func (h *HTTPRangeSpec) GetOffsetLength(resourceSize int64) (start, length int64, err error) {
if h == nil {
// No range specified, implies whole object.
return 0, resourceSize, nil
}
length, err = h.GetLength(resourceSize)
if err != nil {
return 0, 0, err
}
start = h.Start
if h.IsSuffixLength {
start = resourceSize + h.Start
if start < 0 {
start = 0
}
}
return start, length, nil
}
// Parse a HTTP range header value into a HTTPRangeSpec
func parseRequestRangeSpec(rangeString string) (hrange *HTTPRangeSpec, err error) {
// Return error if given range string doesn't start with byte range prefix.
if !strings.HasPrefix(rangeString, byteRangePrefix) {
return nil, fmt.Errorf("'%s' does not start with '%s'", rangeString, byteRangePrefix)
}
// Trim byte range prefix.
byteRangeString := strings.TrimPrefix(rangeString, byteRangePrefix)
// Check if range string contains delimiter '-', else return error. eg. "bytes=8"
sepIndex := strings.Index(byteRangeString, "-")
if sepIndex == -1 {
return nil, fmt.Errorf("'%s' does not have a valid range value", rangeString)
}
offsetBeginString := byteRangeString[:sepIndex]
offsetBegin := int64(-1)
// Convert offsetBeginString only if its not empty.
if len(offsetBeginString) > 0 {
if offsetBeginString[0] == '+' {
return nil, fmt.Errorf("Byte position ('%s') must not have a sign", offsetBeginString)
} else if offsetBegin, err = strconv.ParseInt(offsetBeginString, 10, 64); err != nil {
return nil, fmt.Errorf("'%s' does not have a valid first byte position value", rangeString)
} else if offsetBegin < 0 {
return nil, fmt.Errorf("First byte position is negative ('%d')", offsetBegin)
}
}
offsetEndString := byteRangeString[sepIndex+1:]
offsetEnd := int64(-1)
// Convert offsetEndString only if its not empty.
if len(offsetEndString) > 0 {
if offsetEndString[0] == '+' {
return nil, fmt.Errorf("Byte position ('%s') must not have a sign", offsetEndString)
} else if offsetEnd, err = strconv.ParseInt(offsetEndString, 10, 64); err != nil {
return nil, fmt.Errorf("'%s' does not have a valid last byte position value", rangeString)
} else if offsetEnd < 0 {
return nil, fmt.Errorf("Last byte position is negative ('%d')", offsetEnd)
}
}
switch {
case offsetBegin > -1 && offsetEnd > -1:
if offsetBegin > offsetEnd {
return nil, errInvalidRange
}
return &HTTPRangeSpec{false, offsetBegin, offsetEnd}, nil
case offsetBegin > -1:
return &HTTPRangeSpec{false, offsetBegin, -1}, nil
case offsetEnd > -1:
if offsetEnd == 0 {
return nil, errInvalidRange
}
return &HTTPRangeSpec{true, -offsetEnd, -1}, nil
default:
// rangeString contains first and last byte positions missing. eg. "bytes=-"
return nil, fmt.Errorf("'%s' does not have valid range value", rangeString)
}
}
// String returns stringified representation of range for a particular resource size.
func (h *HTTPRangeSpec) String(resourceSize int64) string {
if h == nil {
return ""
}
off, length, err := h.GetOffsetLength(resourceSize)
if err != nil {
return ""
}
return fmt.Sprintf("%d-%d", off, off+length-1)
}