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Allow to choose IP resolution strategy (#446) 

Haven't seen any reports of the `arp` vs DHCP issues so I think it's reasonable to remove the warning and allow to customize the resolution strategy.
This commit is contained in:
Fedor Korotkov 2023-03-16 09:41:54 -04:00 committed by GitHub
parent 94e9425db7
commit 4a454a3115
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GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 33 additions and 38 deletions
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56
Sources/tart/Commands/IP.swift
View File

@ -4,6 +4,12 @@ import Network
import SystemConfiguration
import Sentry
enum IPResolutionStrategy: String, ExpressibleByArgument, CaseIterable {
case dhcp, arp
private(set) static var allValueStrings: [String] = Format.allCases.map { "\($0)"}
}
struct IP: AsyncParsableCommand {
static var configuration = CommandConfiguration(abstract: "Get VM's IP address")
@ -13,46 +19,40 @@ struct IP: AsyncParsableCommand {
@Option(help: "Number of seconds to wait for a potential VM booting")
var wait: UInt16 = 0
@Option(help: ArgumentHelp("Strategy for resolving IP address: dhcp or arp",
discussion: """
By default, Tart is looking up and parsing DHCP lease file to determine the IP of the VM.\n
This method is fast and the most reliable but only returns local IP adresses.\n
Alternatively, Tart can call external `arp` executable and parse it's output.\n
In case of enabled Bridged Networking this method will return VM's IP address on the network interface used for Bridged Networking.\n
Note that `arp` strategy won't work for VMs using `--net-softnet`.
"""))
var resolver: IPResolutionStrategy = .dhcp
func run() async throws {
let vmDir = try VMStorageLocal().open(name)
let vmConfig = try VMConfig.init(fromURL: vmDir.configURL)
let vmMACAddress = MACAddress(fromString: vmConfig.macAddress.string)!
guard let ipViaDHCP = try await IP.resolveIP(vmMACAddress, secondsToWait: wait) else {
guard let ip = try await IP.resolveIP(vmMACAddress, resolutionStrategy: resolver, secondsToWait: wait) else {
throw RuntimeError.NoIPAddressFound("no IP address found, is your VM running?")
}
let arpCache = try ARPCache()
if let ipViaARP = try arpCache.ResolveMACAddress(macAddress: vmMACAddress), ipViaARP != ipViaDHCP {
// Capture the warning into Sentry
SentrySDK.capture(message: "DHCP lease and ARP cache entries for a single MAC address differ") { scope in
scope.setLevel(.warning)
scope.setContext(value: [
"MAC address": vmMACAddress,
"IP via ARP": ipViaARP,
"IP via DHCP": ipViaDHCP,
], key: "Address conflict details")
scope.add(Attachment(path: "/var/db/dhcpd_leases", filename: "dhcpd_leases.txt", contentType: "text/plain"))
scope.add(Attachment(data: arpCache.arpCommandOutput, filename: "arp-an-output.txt", contentType: "text/plain"))
}
fputs("WARNING: DHCP lease and ARP cache entries for MAC address \(vmMACAddress) differ: "
+ "got \(ipViaDHCP) and \(ipViaARP) respectively, consider reporting this case to"
+ " https://github.com/cirruslabs/tart/issues/172\n", stderr)
}
print(ipViaDHCP)
print(ip)
}
static public func resolveIP(_ vmMACAddress: MACAddress, secondsToWait: UInt16) async throws -> IPv4Address? {
static public func resolveIP(_ vmMACAddress: MACAddress, resolutionStrategy: IPResolutionStrategy = .dhcp, secondsToWait: UInt16 = 0) async throws -> IPv4Address? {
let waitUntil = Calendar.current.date(byAdding: .second, value: Int(secondsToWait), to: Date.now)!
repeat {
if let leases = try Leases(), let ip = try leases.resolveMACAddress(macAddress: vmMACAddress) {
return ip
switch resolutionStrategy {
case .arp:
if let ip = try ARPCache().ResolveMACAddress(macAddress: vmMACAddress) {
return ip
}
case .dhcp:
if let leases = try Leases(), let ip = try leases.ResolveMACAddress(macAddress: vmMACAddress) {
return ip
}
}
// wait a second

7
Sources/tart/MACAddressResolver/ARPCache.swift
View File

@ -67,7 +67,7 @@ struct ARPCache {
self.arpCommandOutput = arpCommandOutput
}
func ResolveMACAddress(macAddress: MACAddress, bridgeOnly: Bool = true) throws -> IPv4Address? {
func ResolveMACAddress(macAddress: MACAddress) throws -> IPv4Address? {
let lines = String(decoding: arpCommandOutput, as: UTF8.self)
.trimmingCharacters(in: .whitespacesAndNewlines)
.components(separatedBy: "\n")
@ -95,11 +95,6 @@ struct ARPCache {
throw ARPCommandYieldedInvalidOutputError(explanation: "failed to parse MAC address \(rawMAC)")
}
let interface = try match.getCaptureGroup(name: "interface", for: line)
if bridgeOnly && !interface.starts(with: "bridge") {
continue
}
if macAddress == mac {
return ip
}

2
Sources/tart/MACAddressResolver/Leases.swift
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@ -107,7 +107,7 @@ class Leases {
return rawLeases
}
func resolveMACAddress(macAddress: MACAddress) throws -> IPv4Address? {
func ResolveMACAddress(macAddress: MACAddress) throws -> IPv4Address? {
leases[macAddress]?.ip
}
}

6
Tests/TartTests/MACAddressResolverTests.swift
View File

@ -12,7 +12,7 @@ final class MACAddressResolverTests: XCTestCase {
""")
XCTAssertEqual(IPv4Address("1.2.3.4"),
try leases.resolveMACAddress(macAddress: MACAddress(fromString: "00:11:22:33:44:55")!))
try leases.ResolveMACAddress(macAddress: MACAddress(fromString: "00:11:22:33:44:55")!))
}
func testMultipleEntries() throws {
@ -28,8 +28,8 @@ final class MACAddressResolverTests: XCTestCase {
""")
XCTAssertEqual(IPv4Address("1.2.3.4"),
try leases.resolveMACAddress(macAddress: MACAddress(fromString: "00:11:22:33:44:55")!))
try leases.ResolveMACAddress(macAddress: MACAddress(fromString: "00:11:22:33:44:55")!))
XCTAssertEqual(IPv4Address("5.6.7.8"),
try leases.resolveMACAddress(macAddress: MACAddress(fromString: "AA:BB:CC:DD:EE:FF")!))
try leases.ResolveMACAddress(macAddress: MACAddress(fromString: "AA:BB:CC:DD:EE:FF")!))
}
}