Is there way to post image captured by splash:png to server?

[telesoho]

I want to capture an image and post the image to a server by multipart/form-data format. The server can only accept binary data of file, so I cannot use base64 to encode it.

I wrote the following code, capture image by splash:png and use base64 encode and decode to get binary data, then try to post data by splash:http_post.

json = require("json")
treat = require("treat")
base64 = require("base64")

function tprint (tbl, indent)
  if not indent then indent = 0 end
  for k, v in pairs(tbl) do
    formatting = string.rep("  ", indent) .. k .. ": "
    if type(v) == "table" then
      print(formatting)
      tprint(v, indent+1)
    elseif type(v) == 'boolean' then
      print(formatting .. tostring(v))      
    else
      print(formatting .. v)
    end
  end
end

local fmt = function(p, ...)
    if select('#', ...) == 0 then
        return p
    else return string.format(p, ...) end
end

local tprintf = function(t, p, ...)
    t[#t+1] = fmt(p, ...)
end

local append_data = function(r, k, data, extra)
    tprintf(r, "content-disposition: form-data; name=\"%s\"", k)
    if extra.filename then
        tprintf(r, "; filename=\"%s\"", extra.filename)
    end
    if extra.content_type then
        tprintf(r, "\r\ncontent-type: %s", extra.content_type)
    end
    if extra.content_transfer_encoding then
        tprintf(
            r, "\r\ncontent-transfer-encoding: %s",
            extra.content_transfer_encoding
        )
    end
    tprintf(r, "\r\n\r\n")
    tprintf(r, data)
    tprintf(r, "\r\n")
end

local gen_boundary = function()
  local t = {"BOUNDARY-"}
  for i=2,17 do t[i] = string.char(math.random(65, 90)) end
  t[18] = "-BOUNDARY"
  return table.concat(t)
end

local encode = function(t, boundary)
    boundary = boundary or gen_boundary()
    local r = {}
    local _t
    for k,v in pairs(t) do
        tprintf(r, "--%s\r\n", boundary)
        _t = type(v)
        if _t == "string" then
            append_data(r, k, v, {})
        elseif _t == "table" then
            assert(v.data, "invalid input")
            local extra = {
                filename = v.filename or v.name,
                content_type = v.content_type or v.mimetype
                    or "application/octet-stream",
                content_transfer_encoding = v.content_transfer_encoding or "binary",
            }
            append_data(r, k, v.data, extra)
        else error(string.format("unexpected type %s", _t)) end
    end
    tprintf(r, "--%s--\r\n", boundary)
    return table.concat(r), boundary
end

local gen_request = function(t)
    local boundary = gen_boundary()
    local s = encode(t, boundary)
    return {
        method = "POST",
        source = s,
        headers = {
            -- ["content-length"] = #s,
            ["content-type"] = fmt("multipart/form-data; boundary=%s", boundary),
        },
    }
end

-- this function adds padding around region
function pad(r, pad)
  return {r[1]-pad, r[2]-pad, r[3]+pad, r[4]+pad}
end

-- this function returns element bounding box
local get_bbox = splash:jsfunc([[
    function(css) {
        var el = document.querySelector(css);
        var r = el.getBoundingClientRect();
        return [r.left, r.top, r.right, r.bottom];
    }
]])

function capture_screenshot(css)
  local region = pad(get_bbox(css), 2)
  return splash:png{region=region}
end

splash:on_request(function(request)
    request:set_header('USER_AGENT', 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.98 Safari/537.36')
end)
splash.resource_timeout = 20.0

assert(splash:go('https://mp.weixin.qq.com/cgi-bin/verifycode'))
assert(splash:wait(0.5))

-- don't crop image by a viewport
splash:set_viewport_full()

local bytes64 = base64.encode(capture_screenshot("img"))
local png_bytes = base64.decode(bytes64)

local rq = gen_request{
    username='xxxxxxx',
    password='xxxx',
    codetype='1004',
    appkey='xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx',
    timeout='60',
    method='upload',
    file={
        name="verify_png",
        content_type="image/png",
        data=png_bytes
    },
}

rq.url="http://api.yundama.com/api.php"

local resp = splash:http_post{
    url=rq.url,
    headers=rq.headers,
    body=rq.source
}

print (base64.decode(resp.info['content']['text']))

But splash:http_post got an error:

SPLASH_LUA_ERROR [input]:148: utf-8

Is there way to post binary data by splash lua? Or I do something wrong?

Thanks in advance!

[Gallaecio]

Did you manage you solve your issue? Have you considered POSTing the image from the code that calls Splash, instead of doing it from the Splash Lua script?

[kasnet]

Did you manage you solve your issue? I have the same problem. @telesoho

[telesoho]

@kasnet @Gallaecio I haven't been able to solve it, so I've given up.