54a3dff1c2
- Implement TNEF extraction and recursive parsing in new `tnef_reader.go` and associated tests. - Create tests for TNEF extraction scenarios in `tnef_diag_test.go`, `tnef_diag7_test.go`, and `tnef_diag8_test.go`.
48 lines
1.2 KiB
Go
48 lines
1.2 KiB
Go
package internal
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import (
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"bytes"
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"os"
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)
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// EmailFormat represents the detected format of an email file.
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type EmailFormat string
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const (
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FormatEML EmailFormat = "eml"
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FormatMSG EmailFormat = "msg"
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FormatUnknown EmailFormat = "unknown"
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)
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// msgMagic is the OLE2/CFB compound file header signature used by .msg files.
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var msgMagic = []byte{0xD0, 0xCF, 0x11, 0xE0, 0xA1, 0xB1, 0x1A, 0xE1}
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// DetectEmailFormat identifies the email file format by inspecting the file's
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// binary magic bytes, regardless of the file extension.
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//
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// Supported formats:
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// - "msg": Microsoft Outlook MSG (OLE2/CFB compound file)
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// - "eml": Standard MIME email (RFC 5322)
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// - "unknown": Could not determine format
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func DetectEmailFormat(filePath string) (EmailFormat, error) {
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f, err := os.Open(filePath)
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if err != nil {
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return FormatUnknown, err
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}
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defer f.Close()
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buf := make([]byte, 8)
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n, err := f.Read(buf)
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if err != nil || n < 1 {
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return FormatUnknown, nil
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}
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// MSG files start with the OLE2 Compound File Binary magic bytes.
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if n >= 8 && bytes.Equal(buf[:8], msgMagic) {
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return FormatMSG, nil
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}
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// EML files are plain-text MIME messages; assume EML for anything else.
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return FormatEML, nil
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}
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