Class: Gem::S3URISigner

# File 'lib/rubygems/s3_uri_signer.rb', line 168

def create_request_pool(uri)
  proxy_uri = Gem::Request.proxy_uri(Gem::Request.get_proxy_from_env(uri.scheme))
  certs = Gem::Request.get_cert_files
  Gem::Request::ConnectionPools.new(proxy_uri, certs).pool_for(uri)
end

# File 'lib/rubygems/s3_uri_signer.rb', line 142

def ec2_metadata_credentials_json
  require_relative "vendored_net_http"
  require_relative "request"
  require_relative "request/connection_pools"
  require "json"

  iam_info = ec2_metadata_request(EC2_IAM_INFO)
  # Expected format: arn:aws:iam::<id>:instance-profile/<role_name>
  role_name = iam_info["InstanceProfileArn"].split("/").last
  ec2_metadata_request(EC2_IAM_SECURITY_CREDENTIALS + role_name)
end

# File 'lib/rubygems/s3_uri_signer.rb', line 154

def ec2_metadata_request(url)
  uri = Gem::URI(url)
  @request_pool ||= create_request_pool(uri)
  request = Gem::Request.new(uri, Gem::Net::HTTP::Get, nil, @request_pool)
  response = request.fetch

  case response
  when Gem::Net::HTTPOK then
    JSON.parse(response.body)
  else
    raise InstanceProfileError.new("Unable to fetch AWS metadata from #{uri}: #{response.message} #{response.code}")
  end
end

# File 'lib/rubygems/s3_uri_signer.rb', line 105

def fetch_s3_config
  return S3Config.new(uri.user, uri.password, nil, "us-east-1") if uri.user && uri.password

  s3_source = Gem.configuration[:s3_source] || Gem.configuration["s3_source"]
  host = uri.host
  raise ConfigurationError.new("no s3_source key exists in .gemrc") unless s3_source

  auth = s3_source[host] || s3_source[host.to_sym]
  raise ConfigurationError.new("no key for host #{host} in s3_source in .gemrc") unless auth

  provider = auth[:provider] || auth["provider"]
  case provider
  when "env"
    id = ENV["AWS_ACCESS_KEY_ID"]
    secret = ENV["AWS_SECRET_ACCESS_KEY"]
    security_token = ENV["AWS_SESSION_TOKEN"]
  when "instance_profile"
    credentials = ec2_metadata_credentials_json
    id = credentials["AccessKeyId"]
    secret = credentials["SecretAccessKey"]
    security_token = credentials["Token"]
  else
    id = auth[:id] || auth["id"]
    secret = auth[:secret] || auth["secret"]
    security_token = auth[:security_token] || auth["security_token"]
  end

  raise ConfigurationError.new("s3_source for #{host} missing id or secret") unless id && secret

  region = auth[:region] || auth["region"] || "us-east-1"
  S3Config.new(id, secret, security_token, region)
end

# File 'lib/rubygems/s3_uri_signer.rb', line 59

def generate_canonical_query_params(s3_config, date_time, credential_info, expiration)
  canonical_params = {}
  canonical_params["X-Amz-Algorithm"] = "AWS4-HMAC-SHA256"
  canonical_params["X-Amz-Credential"] = "#{s3_config.access_key_id}/#{credential_info}"
  canonical_params["X-Amz-Date"] = date_time
  canonical_params["X-Amz-Expires"] = expiration.to_s
  canonical_params["X-Amz-SignedHeaders"] = "host"
  canonical_params["X-Amz-Security-Token"] = s3_config.security_token if s3_config.security_token

  # Sorting is required to generate proper signature
  canonical_params.sort.to_h.map do |key, value|
    "#{base64_uri_escape(key)}=#{base64_uri_escape(value)}"
  end.join("&")
end

# File 'lib/rubygems/s3_uri_signer.rb', line 74

def generate_canonical_request(canonical_host, query_params)
  [
    "GET",
    uri.path,
    query_params,
    "host:#{canonical_host}",
    "", # empty params
    "host",
    "UNSIGNED-PAYLOAD",
  ].join("\n")
end

# File 'lib/rubygems/s3_uri_signer.rb', line 95

def generate_signature(s3_config, date, string_to_sign)
  date_key = OpenSSL::HMAC.digest("sha256", "AWS4" + s3_config.secret_access_key, date)
  date_region_key = OpenSSL::HMAC.digest("sha256", date_key, s3_config.region)
  date_region_service_key = OpenSSL::HMAC.digest("sha256", date_region_key, "s3")
  signing_key = OpenSSL::HMAC.digest("sha256", date_region_service_key, "aws4_request")
  OpenSSL::HMAC.hexdigest("sha256", signing_key, string_to_sign)
end

# File 'lib/rubygems/s3_uri_signer.rb', line 86

def generate_string_to_sign(date_time, credential_info, canonical_request)
  [
    "AWS4-HMAC-SHA256",
    date_time,
    credential_info,
    OpenSSL::Digest::SHA256.hexdigest(canonical_request),
  ].join("\n")
end

# File 'lib/rubygems/s3_uri_signer.rb', line 37

def sign(expiration = 86_400)
  s3_config = fetch_s3_config

  current_time = Time.now.utc
  date_time = current_time.strftime("%Y%m%dT%H%m%SZ")
  date = date_time[0,8]

  credential_info = "#{date}/#{s3_config.region}/s3/aws4_request"
  canonical_host = "#{uri.host}.s3.#{s3_config.region}.amazonaws.com"

  query_params = generate_canonical_query_params(s3_config, date_time, credential_info, expiration)
  canonical_request = generate_canonical_request(canonical_host, query_params)
  string_to_sign = generate_string_to_sign(date_time, credential_info, canonical_request)
  signature = generate_signature(s3_config, date, string_to_sign)

  Gem::URI.parse("https://#{canonical_host}#{uri.path}?#{query_params}&X-Amz-Signature=#{signature}")
end