#! /usr/bin/env crystal
require "openssl"
require "openssl/digest"
require "http/client"
require "file.cr"
#
# Crystal 0.10 has a bug in the OpenSSL::Digest.update method, rewrite it here.
#
module OpenSSL
module DigestBase
def update(io : IO)
buffer :: UInt8[2048]
while (read_bytes = io.read(buffer.to_slice)) > 0
self << buffer.to_slice[0, read_bytes]
end
self
end
end
end
private def getHashInformation(hashMethod : String) : Hash
begin
hashData = OpenSSL::Digest.new(hashMethod)
rescue
raise "Unacceptable hashing algorithm: #{hashMethod}"
end
returnValue = {
length: hashData.digest_size
}
return returnValue
end
private def validateFile(fileName, hashMethod, hashValue) : Bool
checkHash = OpenSSL::Digest.new(hashMethod)
checkHash.file(fileName)
if checkHash.hexdigest === hashValue
return true
end
return false
end
private def fetchFile(url : String, cacheFileName, hashMethod, hashValue)
if (url =~ /^https?:\/\//).nil?
raise "Invalid URL scheme\nWe only support HTTP, and HTTPS transports for origin URLs. The URL must begin with one of: http://, https://"
end
tempFileName = "#{cacheFileName}-#{Random.rand}-#{Random.rand}-#{Random.rand}"
Dir.mkdir_p(File.dirname(cacheFileName), mode = 0o755);
HTTP::Client.get(url) { |result|
if result.status_code != 200
raise "Unable to fetch remote file, HTTP status code: #{result.status_code}"
end
if ! result.body_io?
raise "Unable to fetch remote file, no body"
end
begin
tempFile = File.open(tempFileName, "w");
IO.copy(result.body_io, tempFile.to_fd_io);
ensure
if tempFile
tempFile.close
end
end
}
if ! validateFile(tempFileName, hashMethod, hashValue)
if File.exists?(tempFileName)
File.delete(tempFileName)
end
raise "Unable to fetch remote file, validation failed"
end
File.rename(tempFileName, cacheFileName)
end
private def deliverFile(fileName)
file = File.open(fileName)
IO.copy(file, STDOUT)
file.close
end
private def handleRequest(hashMethod, hashValue, upstreamURL = Nil)
hashInfo = getHashInformation(hashMethod)
if (hashValue.size != (hashInfo[:length] * 2))
raise "Hash length is incorrect, it should be #{hashInfo[:length] * 2} hex digits long"
end
if (hashValue =~ /^[0-9a-f]*$/).nil?
raise "Hash value is incorrect, it should contain only hex digits"
end
cacheFileName = hashMethod + "/" + hashValue
if File.exists?(cacheFileName)
return cacheFileName
end
if upstreamURL.is_a?(Nil)
raise "Contents are not locally cached and no upstream URL has been provided"
end
fetchFile(upstreamURL, cacheFileName, hashMethod, hashValue)
return cacheFileName
end
private def parseURL(url : String)
urlParts = url.split("/")
case urlParts.size
when 1
raise "No hash method or hash value specified."
when 2
raise "No hash value specified"
when 3
hashMethod = urlParts[1];
hashValue = urlParts[2];
else
raise "Too many components specified in pathname"
end
return [hashMethod, hashValue]
end
private def createURL : String
host = Nil
["HTTP_HOST", "SERVER_NAME"].each { |hostEntry|
if ENV[hostEntry]?
host = ENV[hostEntry]
break
end
}
if host.is_a?(Nil)
return "<unknown>"
end
if ENV["HTTPS"]? && ENV["HTTPS"] === "on"
scheme = "https"
else
scheme = "http"
end
addPort = ""
if ENV["SERVER_PORT"]?
defaultPort = if scheme == "https"
443
else
80
end
if ENV["SERVER_PORT"].to_i != defaultPort
addPort = ":#{ENV["SERVER_PORT"]}"
end
end
return "#{scheme}://#{host}#{addPort}/"
end
private def cgiInterface
if ENV["HTTP_X_CACHE_URL"]?
upstreamURL = ENV["HTTP_X_CACHE_URL"]
end
begin
hashMethod, hashValue = parseURL(ENV["REQUEST_URI"])
outputFile = handleRequest(hashMethod, hashValue, upstreamURL)
rescue reason
puts "Status: 400 Not OK"
puts "Content-type: text/plain"
puts ""
puts "Usage: #{createURL()}<hashMethod>/<hashValue>"
puts " Supply X-Cache-URL header with the origin URL to cache, it will be fetched and cached if the contents are not already available"
puts ""
puts "Example: curl --fail --header 'X-Cache-URL: http://www.rkeene.org/' http://hashcache.rkeene.org/sha1/dfc00e1a9ad78225527028db113d72c0ec8c12f8"
puts ""
puts "Error:"
reason.to_s.split("\n").each { |line|
puts "\t#{line}"
}
return
end
if outputFile.is_a?(String)
if File.exists?(outputFile)
puts "Status: 200 OK"
puts "Content-type: application/octet-stream"
puts ""
deliverFile(outputFile)
return
end
end
puts "Status: 400 Not OK"
puts "Content-type: text/plain"
puts ""
puts "Something went terribly wrong"
end
private def httpInterface
puts "No HTTP interface yet"
exit 1
end
if ENV["GATEWAY_INTERFACE"]?
cgiInterface
else
httpInterface
end
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