Parse a multipart SOAP response in Swift

Question

I'm trying to download a file from a soap service and I'm getting the following after a successful request

the response header

multipart/related; type="application/xop+xml"; boundary="uuid:917b60a9-3089-43ad-a8c2-b4a3c62db98c"; start="<[email protected]>"; start-info="text/xml"

response body

--uuid:0a679f64-0753-44fe-b627-2267b5b72b1d
Content-Type: application/xop+xml; charset=UTF-8; type="text/xml"
Content-Transfer-Encoding: binary
Content-ID: <[email protected]>

<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"><soap:Body><ns2:leseDokumentResponse xmlns:ns2="http://webservice/"><return><status>OK</status><dokument><xop:Include xmlns:xop="http://www.w3.org/2004/08/xop/include" href="cid:[email protected]"/></dokument></return></ns2:leseDokumentResponse></soap:Body></soap:Envelope>
--uuid:0a679f64-0753-44fe-b627-2267b5b72b1d
Content-Type: application/octet-stream
Content-Transfer-Encoding: binary
Content-ID: <[email protected]>

... binary data ...
--uuid:0a679f64-0753-44fe-b627-2267b5b72b1d--

How can I parse the file binary data?

I tried these questions but nothing works Parsing http-multipart response Parse multipart response for image download in ios

From Reponse header: `boundary="uuid:917b60a9-3089-43ad-a8c2-b4a3c62db98c"` is different from the bounday you get in the body. Is that normal? Or you printed 2 different one? Else, with `.firstRange(of:)` method of `Data`, and iterating to find all `--uuid:0a679f64-0753-44fe-b627-2267b5b72b1d`, you can find the binary data. — Larme, Apr 28 '20 at 16:05
Note tested, but could Vapor code (https://github.com/vapor/multipart-kit) be useful for that? — Larme, Apr 28 '20 at 16:27
The uuid should be taken as example and not as is because it’s different from one request to another — zombie, Apr 28 '20 at 16:42

score 1 · Accepted Answer · answered May 27 '20 at 08:20

Parsing a multi-part SOAP response can be easily done by using MultipartKit

I created an extension on Alamofire's DataResponse to handle the response

import Alamofire
import MultipartKit
import Swime

extension DataResponse where Success == Data {

    var boundary: String? {

        let header = response?.allHeaderFields.first(where: {
            $0.key as? String == "Content-Type"
        })

        let scanner = Scanner(string: header?.value as? String ?? "")

        _ = scanner.scanUpToString("boundary=\"")
        _ = scanner.scanString("boundary=\"")
        let boundary = scanner.scanUpToString("\";")

        return boundary
    }

    func multipartParts() -> [MultipartPart] {

        guard let boundary = boundary else { return [] }

        guard let data = try? result.get() else { return [] }

        let parser = MultipartParser(boundary: boundary)

        var parts: [MultipartPart] = []
        var headers: HTTPHeaders = [:]
        var body: Data = Data()

        parser.onHeader = { (field, value) in
            headers.replaceOrAdd(name: field, value: value)
        }
        parser.onBody = { new in
            body.append(contentsOf: new.readableBytesView)
        }
        parser.onPartComplete = {
            let part = MultipartPart(headers: headers, body: body)
            headers = [:]
            body = Data()
            parts.append(part)
        }

        do {
            try parser.execute(data)
        } catch {
            print(error.localizedDescription)
        }

        return parts
    }

    func parseMultipart() -> (message: String, files: [Data])? {

        let parts = multipartParts()

        let message = parts.first(where: { $0.id == "<[email protected]>" })?.body.string ?? ""

        let dataPart = parts.filter { $0.id != "<[email protected]>" }

        let files = dataPart.compactMap { Data(multipart: $0) }

        return (message, files)
    }
}

extension ByteBuffer {
    var string: String {
        return String(decoding: self.readableBytesView, as: UTF8.self)
    }
}

extension MultipartPart {

    /// Gets or sets the `name` attribute from the part's `"Content-ID"` header.
    public var id: String? {
        get { self.headers.first(name: "Content-ID") }
    }
}

which then can be used on a data response like this:

let request = SessionManager.request(urlRequest).responseData(completionHandler: { response in

    switch response.result {
        case .failure(let error):
            self.alert(error)

        case .success:

            guard let parts = response.parseMultipart() else { return }

            DispatchQueue.main.async {

                self.loadResponse(message: parts.message, files: parts.files)
        }
    }
})

the message id can be different so I would maybe suggest checking the type too

Hope this will help someone.

Parse a multipart SOAP response in Swift

1 Answers1