58 lines
2.3 KiB
Swift
58 lines
2.3 KiB
Swift
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import Foundation
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/// A `ConnectionSource` backed by repeatedly shelling out to `/usr/bin/nettop`.
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///
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/// Each tick runs a fresh one-shot `nettop` (`-L 1`). Because byte counts are
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/// lifetime-cumulative and stable across invocations, the consumer diffs
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/// successive snapshots to recover per-interval traffic. No elevated privileges
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/// required — that's the whole point of starting here.
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public final class NettopSource: ConnectionSource {
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private let nettopPath: String
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public init(nettopPath: String = "/usr/bin/nettop") {
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self.nettopPath = nettopPath
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}
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public func snapshots(every interval: TimeInterval) -> AsyncStream<ConnectionSnapshot> {
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AsyncStream { continuation in
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let task = Task { [nettopPath] in
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while !Task.isCancelled {
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if let output = try? Self.runNettop(at: nettopPath) {
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let conns = NettopParser.parseConnections(output)
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continuation.yield(ConnectionSnapshot(timestamp: Date(), connections: conns))
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}
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do {
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try await Task.sleep(nanoseconds: UInt64(interval * 1_000_000_000))
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} catch {
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break // cancelled
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}
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}
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continuation.finish()
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}
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continuation.onTermination = { _ in task.cancel() }
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}
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}
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/// Runs one-shot nettop and returns its stdout. Reads the pipe to EOF *before*
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/// waiting on exit so large output can't deadlock a full pipe buffer.
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static func runNettop(at path: String) throws -> String {
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let process = Process()
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process.executableURL = URL(fileURLWithPath: path)
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// -L 1 : one sample then exit -x : raw bytes (no unit suffixes)
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// -n : numeric (skip DNS; we enrich ourselves)
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// -J : pick only the columns we parse
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process.arguments = ["-L", "1", "-x", "-n", "-J", "time,bytes_in,bytes_out"]
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let pipe = Pipe()
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process.standardOutput = pipe
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process.standardError = FileHandle.nullDevice
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try process.run()
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let data = pipe.fileHandleForReading.readDataToEndOfFile()
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process.waitUntilExit()
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return String(decoding: data, as: UTF8.self)
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}
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}
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