54 lines
1.9 KiB
Crystal
54 lines
1.9 KiB
Crystal
alias SigProc = Proc(Array(String), Int32, Array(String))
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def fetch_decrypt_function(id = "CvFH_6DNRCY")
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document = YT_POOL.client &.get("/watch?v=#{id}&gl=US&hl=en&disable_polymer=1").body
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url = document.match(/src="(?<url>\/yts\/jsbin\/player_ias-[^\/]+\/en_US\/base.js)"/).not_nil!["url"]
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player = YT_POOL.client &.get(url).body
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function_name = player.match(/^(?<name>[^=]+)=function\(\w\){\w=\w\.split\(""\);[^\. ]+\.[^( ]+/m).not_nil!["name"]
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function_body = player.match(/^#{Regex.escape(function_name)}=function\(\w\){(?<body>[^}]+)}/m).not_nil!["body"]
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function_body = function_body.split(";")[1..-2]
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var_name = function_body[0][0, 2]
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var_body = player.delete("\n").match(/var #{Regex.escape(var_name)}={(?<body>(.*?))};/).not_nil!["body"]
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operations = {} of String => SigProc
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var_body.split("},").each do |operation|
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op_name = operation.match(/^[^:]+/).not_nil![0]
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op_body = operation.match(/\{[^}]+/).not_nil![0]
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case op_body
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when "{a.reverse()"
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operations[op_name] = ->(a : Array(String), b : Int32) { a.reverse }
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when "{a.splice(0,b)"
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operations[op_name] = ->(a : Array(String), b : Int32) { a.delete_at(0..(b - 1)); a }
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else
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operations[op_name] = ->(a : Array(String), b : Int32) { c = a[0]; a[0] = a[b % a.size]; a[b % a.size] = c; a }
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end
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end
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decrypt_function = [] of {SigProc, Int32}
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function_body.each do |function|
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function = function.lchop(var_name).delete("[].")
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op_name = function.match(/[^\(]+/).not_nil![0]
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value = function.match(/\(\w,(?<value>[\d]+)\)/).not_nil!["value"].to_i
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decrypt_function << {operations[op_name], value}
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end
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return decrypt_function
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end
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def decrypt_signature(fmt, op)
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return "" if !fmt["s"]? || !fmt["sp"]?
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sp = fmt["sp"]
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sig = fmt["s"].split("")
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op.each do |proc, value|
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sig = proc.call(sig, value)
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end
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return "&#{sp}=#{sig.join("")}"
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end
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