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Simplify error handling and index file fetch
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@not-an-aardvark
not-an-aardvark committed Dec 5, 2020
1 parent 0000000 commit 0000000
Showing 1 changed file with 68 additions and 78 deletions.
146 changes: 68 additions & 78 deletions main.swift
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Original file line number Diff line number Diff line change
@@ -1,14 +1,40 @@
import CoreWLAN
import Foundation

enum SwitchImportError: Error {
case INTERNAL_ASSERTION_FAILURE
case NO_WIFI_INTERFACE
case HOTSPOT_NOT_FOUND(String)
case MALFORMED_INDEX_FILE(Any)
case BAD_FILENAME_FROM_SWITCH(String)
}

extension URLSession {
func synchronousFetch(url: URL) throws -> Data {
var result: Result<Data, Error> = .failure(SwitchImportError.INTERNAL_ASSERTION_FAILURE)
let semaphore = DispatchSemaphore(value: 0)
let task = dataTask(with: url) { data, _, error in
if let data = data {
result = .success(data)
} else {
result = .failure(error!)
}
semaphore.signal()
}
task.resume()
semaphore.wait()
return try result.get()
}
}

private func printUsage() {
print("""
Usage: switch-album-import -h|-help|--help
switch-album-import -ssid <ssid> -password <password> -output_dir <dir>
""")
}

func main() {
func main() -> Int32 {
let args = Array(CommandLine.arguments.dropFirst())
if (args.contains { arg in arg == "-h" || arg == "-help" || arg == "--help" }) {
printUsage()
Expand All @@ -22,98 +48,62 @@ func main() {
let output_dir = defaults.string(forKey: "output_dir")
else {
printUsage()
exit(1)
return 1
}

var output_dir_is_directory: ObjCBool = true
if !FileManager.default.fileExists(atPath: output_dir, isDirectory: &output_dir_is_directory) {
print("[ERROR] No such directory: \(output_dir)")
exit(1)
}

print("[INFO] Connecting to \(ssid)...")

let client = CWWiFiClient.shared()

guard let interface = client.interface(), let switch_hotspot = (try? interface.scanForNetworks(withName: ssid))?.first else {
print("[ERROR] Failed to find switch hotspot at \(ssid)")
exit(1)
return 1
}

do {
try interface.associate(to: switch_hotspot, password: password)
} catch {
print("[ERROR] Failed to connect to switch hotspot at \(ssid)")
interface.disassociate()
exit(1)
}
print("[INFO] Successfully connected to \(ssid)")

let index_contents = Result {
try Data(contentsOf: URL(string: "http://192.168.0.1/data.json")!)
}
let parsed_index = index_contents.flatMap { contents in
Result { try JSONSerialization.jsonObject(with: contents) }
}

if case let .failure(error) = parsed_index {
print("[ERROR] Failed to download index file from switch: \(error)")
interface.disassociate()
exit(1)
}

guard let parsed_dict = try! parsed_index.get() as? [String: Any],
let console_name = parsed_dict["ConsoleName"] as? String,
let filenames = parsed_dict["FileNames"] as? [String]
else {
print("[ERROR] Failed to parse index file from switch: \(parsed_index)")
interface.disassociate()
exit(1)
}
guard let interface = CWWiFiClient.shared().interface() else {
throw SwitchImportError.NO_WIFI_INTERFACE
}
let matching_networks = try interface.scanForNetworks(withName: ssid)
if matching_networks.count == 0 {
throw SwitchImportError.HOTSPOT_NOT_FOUND(ssid)
}

print("[INFO] Downloading \(filenames.count) file(s) from \(console_name)...")
let semaphore = DispatchSemaphore(value: 0)
for filename in filenames {
// Sanity check to ensure filenames are reasonable and don't contain e.g. path components
if filename.range(of: #"^\w[\w.-]+$"#, options: .regularExpression) == nil {
print("Unexpected filename: \(filename)")
print("[INFO] Connecting to \(ssid)...")
try interface.associate(to: matching_networks.first!, password: password)
defer {
// Disconnect from the Switch hotspot.
// It doesn't seem to be possible to reconnect back to the previous network here. However,
// the OS should do it automatically since it won't be connected to any networks at this
// point. Note that the OS might try to reconnect to the Switch hotspot instead; to prevent
// this, the Switch's SSID should be configured to *not* auto-join in System Preferences.
interface.disassociate()
exit(1)
}

let url = URL(string: "http://192.168.0.1/img/\(filename)")!
print("[INFO] Downloading \(filename)...")
let task = URLSession.shared.dataTask(with: url) { data, _, error in

guard let data = data else {
print("[ERROR] Failed to download \(url): \(String(describing: error))")
interface.disassociate()
exit(1)
let index_contents = try URLSession.shared.synchronousFetch(url: URL(string: "http://192.168.0.1/data.json")!)
let parsed_index = try JSONSerialization.jsonObject(with: index_contents)
guard let parsed_dict = parsed_index as? [String: Any],
let console_name = parsed_dict["ConsoleName"] as? String,
let filenames = parsed_dict["FileNames"] as? [String]
else {
throw SwitchImportError.MALFORMED_INDEX_FILE(parsed_index)
}
print("[INFO] Downloading \(filenames.count) file(s) from \(console_name)...")
for filename in filenames {
// Sanity check to ensure filenames are reasonable and don't contain e.g. path components
if filename.range(of: #"^\w[\w.-]+$"#, options: .regularExpression) == nil {
throw SwitchImportError.BAD_FILENAME_FROM_SWITCH(filename)
}

print("[INFO] Downloading \(filename)...")
let url = URL(string: "http://192.168.0.1/img/\(filename)")!
let data = try URLSession.shared.synchronousFetch(url: url)
let file_url = URL(fileURLWithPath: output_dir).appendingPathComponent(filename)
do {
try data.write(to: file_url)
} catch {
print("[ERROR] Failed to write to \(file_url)")
interface.disassociate()
exit(1)
}
semaphore.signal()
try data.write(to: file_url)
}
task.resume()
}
for _ in filenames {
semaphore.wait()
print("[INFO] Successfully downloaded \(filenames.count) file(s) from \(console_name)")
} catch {
print("[ERROR] \(error)")
return 1
}
print("[INFO] Successfully downloaded \(filenames.count) file(s) from \(console_name)")

// Disconnect from the Switch hotspot.
// It doesn't seem to be possible to reconnect back to the previous network here. However,
// the OS should do it automatically since it won't be connected to any networks at this
// point. Note that the OS might try to reconnect to the Switch hotspot instead; to prevent
// this, the Switch's SSID should be configured to *not* auto-join in System Preferences.
interface.disassociate()
print("[INFO] Disconnected from \(ssid)")
return 0
}

main()
exit(main())

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