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39 lines
793 B
39 lines
793 B
package ber
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import (
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"errors"
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"fmt"
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"io"
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)
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func readHeader(reader io.Reader) (identifier Identifier, length int, read int, err error) {
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var (
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c, l int
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i Identifier
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)
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if i, c, err = readIdentifier(reader); err != nil {
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return Identifier{}, 0, read, err
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}
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identifier = i
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read += c
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if l, c, err = readLength(reader); err != nil {
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return Identifier{}, 0, read, err
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}
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length = l
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read += c
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// Validate length type with identifier (x.600, 8.1.3.2.a)
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if length == LengthIndefinite && identifier.TagType == TypePrimitive {
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return Identifier{}, 0, read, errors.New("indefinite length used with primitive type")
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}
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if length < LengthIndefinite {
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err = fmt.Errorf("length cannot be less than %d", LengthIndefinite)
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return
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}
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return identifier, length, read, nil
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}
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