fix ios formdata boundary include slash

[li-yechao]

some server not work when upload a file with FromData in ios.
the reason is that there is a slash in boundary, like:

multipart/form-data; boundary=b/QeEbFgqK9PCZo4T/eXv7f.T74SHd5MxCZ846AsTz-yNV0xrRR_Zks4fkNMCzJck9ZE8o

// koa request.js (line 548)
  is(types) {
    if (!types) return typeis(this.req);
    if (!Array.isArray(types)) types = [].slice.call(arguments);
    return typeis(this.req, types);
  }

// type-is index.js (line 237)
function normalizeType (value) {
  // parse the type
  var type = typer.parse(value)

  // remove the parameters
  type.parameters = undefined

  // reformat it
  return typer.format(type)
}

// media-typer
var paramRegExp = /; *([!#$%&'\*\+\-\.0-9A-Z\^_`a-z\|~]+) *= *("(?:[ !\u0023-\u005b\u005d-\u007e\u0080-\u00ff]|\\[\u0020-\u007e])*"|[!#$%&'\*\+\-\.0-9A-Z\^_`a-z\|~]+) */g;

thanks for @dougwilson 's answer.

The / is an illegal character for Content-Type, which is what this module parses. The boundary parameter value needs to be quoted if it contains a / character, for example:

multipart/form-data; boundary="b/QeEbFgqK9PCZo4T/eXv7f.T74SHd5MxCZ846AsTz-yNV0xrRR_Zks4fkNMCzJck9ZE8o"

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[javache]

That will just break #7564 again. Can you instead change the dictionary where we generate the boundary from?

[javache]

react-native/Libraries/Network/RCTNetworking.mm

Line 52 in e1577df

const char *boundaryChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-_./";

[li-yechao]

remove slash from the dictionary of generate boundary

[javache]

@facebook-github-bot shipit

[ivpusic]

I have the same issue. Currently https://golang.org/pkg/mime/#ParseMediaType returns error, because of "/". This is fixing the problem for me.

[jaggerwang]

Same problem, take me a few days to figure this out!!! Before update RN to 0.39, fetch works fine.

[javache]

@unordered Can you sign the CLA so I can pull this?

[li-yechao]

@javache ok

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Thank you for signing our Contributor License Agreement. We can now accept your code for this (and any) Facebook open source project. Thanks!

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@javache has imported this pull request. If you are a Facebook employee, you can view this diff on Phabricator.

[emadicio]

Thanks, finally fixed this issue for me!