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Fix relay file directory decoding and preserve exact RCB options #36

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Merged
masarray merged 8 commits into from
Jul 20, 2026
Merged

Fix relay file directory decoding and preserve exact RCB options #36

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9fdf320
Fix MMS FileDirectory entry decoding and path fidelity
masarray Jul 20, 2026
0432ccb
Cover real MMS FileDirectory list wrappers and paths
masarray Jul 20, 2026
0fe9c7e
Decode live RCB bit strings for exact SCL export
masarray Jul 20, 2026
bfd68b5
Preserve read-only RCB configuration evidence
masarray Jul 20, 2026
df236e5
Merge exact live RCB attributes into selected export model
masarray Jul 20, 2026
7bfda74
Export exact live RCB trigger and optional fields
masarray Jul 20, 2026
9048d1c
Test exact RCB bit-string decoding
masarray Jul 20, 2026
9e429b3
Test exact live RCB option export
masarray Jul 20, 2026
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135 changes: 99 additions & 36 deletions src/AR.Iec61850/Mms/MmsFileDirectory.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -74,16 +74,25 @@ private static bool IsRootFileSpecification(string? value)

private static byte[] EncodeFileNameContent(string value)
{
var normalized = (value ?? string.Empty).Trim().Replace('\\', '/');
var parts = normalized.Split('/', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);
if (parts.Length == 0 && !string.IsNullOrWhiteSpace(normalized))
parts = new[] { normalized };
var normalized = NormalizeFileSpecification(value);

var body = Array.Empty<byte>();
foreach (var part in parts)
body = MmsPresentation.Concat(body, BerWriter.EncodeTlv(0x19, BerWriter.EncodeAscii(part)));
// FileName is a SEQUENCE OF GraphicString. Real IEDs commonly expose the complete
// case-sensitive path in one GraphicString with '/' separators, so preserve that
// representation rather than splitting each directory into a separate element.
return BerWriter.EncodeTlv(0x19, BerWriter.EncodeAscii(normalized));
}

return body;
private static string NormalizeFileSpecification(string value)
{
var segments = (value ?? string.Empty)
.Trim()
.Replace('\\', '/')
.Split('/', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);
if (segments.Length == 0)
throw new ArgumentException("MMS file specification has no usable path segment.", nameof(value));
if (segments.Any(segment => segment is "." or ".."))
throw new ArgumentException("MMS file specification contains a traversal segment.", nameof(value));
return string.Join('/', segments);
}
}

Expand Down Expand Up @@ -137,18 +146,19 @@ public static MmsFileDirectoryResult Decode(
var entries = new List<MmsFileDirectoryEntry>();
var moreFollows = false;
DecodeServiceResponse(service, dir, entries, ref moreFollows);
var distinctEntries = entries
.DistinctBy(x => x.Path, StringComparer.OrdinalIgnoreCase)
.OrderBy(x => x.Path, StringComparer.OrdinalIgnoreCase)
.ToArray();

return new MmsFileDirectoryResult
{
IsSuccess = true,
DirectoryName = dir,
ContinueAfter = continuation,
Entries = entries
.DistinctBy(x => x.Path, StringComparer.OrdinalIgnoreCase)
.OrderBy(x => x.Path, StringComparer.OrdinalIgnoreCase)
.ToArray(),
Entries = distinctEntries,
MoreFollows = moreFollows,
Message = $"MMS FileDirectory decoded {entries.Count} entr(y/ies), moreFollows={moreFollows}.",
Message = $"MMS FileDirectory decoded {distinctEntries.Length} entr(y/ies), moreFollows={moreFollows}.",
ResponseHexPreview = hex
};
}
Expand All @@ -158,26 +168,65 @@ public static MmsFileDirectoryResult Decode(
}
}

private static void DecodeServiceResponse(BerTlv service, string directoryName, List<MmsFileDirectoryEntry> entries, ref bool moreFollows)
private static void DecodeServiceResponse(
BerTlv service,
string directoryName,
List<MmsFileDirectoryEntry> entries,
ref bool moreFollows)
{
foreach (var child in BerReader.ReadChildren(service.Value))
{
if (child.Class == BerClass.ContextSpecific && child.TagNumber == 0 && child.Constructed)
{
foreach (var entry in BerReader.ReadChildren(child.Value))
{
var decoded = DecodeDirectoryEntry(entry, directoryName);
if (decoded != null)
entries.Add(decoded);
}
CollectDirectoryEntries(child, directoryName, entries, depth: 0);
}
else if (child.Class == BerClass.ContextSpecific && child.TagNumber == 1 && child.Value.Length > 0)
{
moreFollows = child.Value.Span[0] != 0;
moreFollows = BerReader.ReadBoolean(child) ?? child.Value.Span[0] != 0;
}
}
}

private static void CollectDirectoryEntries(
BerTlv container,
string directoryName,
List<MmsFileDirectoryEntry> entries,
int depth)
{
if (!container.Constructed || depth > 6)
return;

foreach (var child in BerReader.ReadChildren(container.Value))
{
if (LooksLikeDirectoryEntry(child))
{
var decoded = DecodeDirectoryEntry(child, directoryName);
if (decoded != null)
entries.Add(decoded);
}
else if (child.Constructed)
{
// Some stacks encode listOfDirectoryEntry as [0] -> SEQUENCE ->
// DirectoryEntry SEQUENCE(s), while others place the DirectoryEntry
// SEQUENCE(s) directly under [0]. Accept both without collapsing all
// filenames into one synthetic entry.
CollectDirectoryEntries(child, directoryName, entries, depth + 1);
}
}
}

private static bool LooksLikeDirectoryEntry(BerTlv candidate)
{
if (!candidate.Constructed)
return false;

var fields = BerReader.ReadChildren(candidate.Value);
return fields.Any(field =>
field.Class == BerClass.ContextSpecific &&
field.TagNumber == 0 &&
field.Constructed);
}

private static MmsFileDirectoryEntry? DecodeDirectoryEntry(BerTlv entry, string directoryName)
{
if (!entry.Constructed)
Expand All @@ -189,14 +238,11 @@ private static void DecodeServiceResponse(BerTlv service, string directoryName,

foreach (var field in BerReader.ReadChildren(entry.Value))
{
if (field.EncodedTag == 0x30 || field.Constructed)
if (field.Class == BerClass.ContextSpecific && field.TagNumber == 0 && field.Constructed)
{
var candidate = DecodeFileName(field);
if (!string.IsNullOrWhiteSpace(candidate))
fileName ??= candidate;
fileName = DecodeFileName(field);
}

if (field.Class == BerClass.ContextSpecific && field.TagNumber == 1 && field.Constructed)
else if (field.Class == BerClass.ContextSpecific && field.TagNumber == 1 && field.Constructed)
{
foreach (var attr in BerReader.ReadChildren(field.Value))
{
Expand All @@ -211,10 +257,11 @@ private static void DecodeServiceResponse(BerTlv service, string directoryName,
if (string.IsNullOrWhiteSpace(fileName))
return null;

var path = CombinePath(directoryName, fileName);
var normalizedName = NormalizeReturnedPath(fileName);
var path = CombinePath(directoryName, normalizedName);
return new MmsFileDirectoryEntry
{
Name = fileName,
Name = normalizedName,
Path = path,
SizeBytes = size,
LastModifiedRaw = modified
Expand All @@ -228,7 +275,9 @@ private static string DecodeFileName(BerTlv tlv)

var parts = new List<string>();
CollectGraphicStrings(tlv, parts, depth: 0);
return string.Join('/', parts.Where(x => !string.IsNullOrWhiteSpace(x)));
return string.Join('/', parts
.Select(part => part.Trim().Replace('\\', '/'))
.Where(part => !string.IsNullOrWhiteSpace(part)));
}

private static void CollectGraphicStrings(BerTlv tlv, List<string> parts, int depth)
Expand All @@ -247,14 +296,28 @@ private static void CollectGraphicStrings(BerTlv tlv, List<string> parts, int de

private static string CombinePath(string directoryName, string fileName)
{
if (string.IsNullOrWhiteSpace(directoryName))
return fileName;
var dir = NormalizeReturnedPath(directoryName);
var name = NormalizeReturnedPath(fileName);
if (string.IsNullOrWhiteSpace(dir))
return name;
if (string.IsNullOrWhiteSpace(name))
return dir;

if (name.Equals(dir, StringComparison.OrdinalIgnoreCase) ||
name.StartsWith(dir + "/", StringComparison.OrdinalIgnoreCase))
{
return name;
}

var dir = directoryName.Trim().TrimEnd('/', '\\');
var name = fileName.Trim().TrimStart('/', '\\');
return string.IsNullOrWhiteSpace(dir) ? name : $"{dir}/{name}";
return $"{dir}/{name}";
}

private static string NormalizeReturnedPath(string? value)
=> string.Join('/', (value ?? string.Empty)
.Trim()
.Replace('\\', '/')
.Split('/', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries));

private static MmsFileDirectoryResult Fail(string directoryName, string continueAfter, string message, string hex)
=> new()
{
Expand All @@ -266,4 +329,4 @@ private static MmsFileDirectoryResult Fail(string directoryName, string continue
Message = message,
ResponseHexPreview = hex
};
}
}
10 changes: 9 additions & 1 deletion src/AR.Iec61850/Mms/MmsRcbAvailability.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -38,6 +38,10 @@ public sealed class MmsRcbAvailabilitySnapshot
public string DataSetReference { get; init; } = string.Empty;
public string ReportId { get; init; } = string.Empty;
public string ConfRev { get; init; } = string.Empty;
public string BufferTimeMs { get; init; } = string.Empty;
public string IntegrityPeriodMs { get; init; } = string.Empty;
public string TriggerOptions { get; init; } = string.Empty;
public string OptionalFields { get; init; } = string.Empty;
public string EnabledState { get; init; } = string.Empty;
public string ReservationState { get; init; } = string.Empty;
public string ReservationTimeSeconds { get; init; } = string.Empty;
Expand Down Expand Up @@ -157,6 +161,10 @@ public static MmsRcbAvailabilitySnapshot Evaluate(
DataSetReference = candidate.DataSetReference,
ReportId = candidate.ReportId,
ConfRev = candidate.ConfRev,
BufferTimeMs = candidate.BufferTimeMs,
IntegrityPeriodMs = candidate.IntegrityPeriodMs,
TriggerOptions = candidate.TriggerOptions,
OptionalFields = candidate.OptionalFields,
EnabledState = candidate.EnabledState,
ReservationState = candidate.ReservationState,
ReservationTimeSeconds = candidate.ReservationTimeSeconds,
Expand Down Expand Up @@ -243,4 +251,4 @@ internal static bool HasOwner(string? value)

internal static string NormalizeReference(string? reference)
=> (reference ?? string.Empty).Trim().Replace('$', '.');
}
}
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