#
  # NOTE: This procedure returns non-zero if the specified package can be
  #       downloaded, i.e. because it is not required for the downloading
  #       process itself to be functional, etc.  The package argument is
  #       the name of the package to check.
  #
  proc canDownloadPackage { package } {
    #
    # NOTE: Since all the functionality needed by this package is built-in
    #       to Eagle, there are no download restrictions when it is being
    #       used.
    #
    if {[isEagle]} then {
      return true
    }

    #
    # NOTE: Since the "http" and "tls" packages are required from within
    #       the custom [package unknown] itself, in order to locate and
    #       download the requested package, we must return false here to
    #       prevent needless recursion.
    #
    if {[lsearch -exact [list http tls] $package] != -1} then {


  #
  # NOTE: This procedure sets up the default values for all configuration
  #       parameters used by the package repository client.  There are no
  #       arguments.
  #
  proc setupPackageUnknownVars {} {
    #
    # NOTE: Should the HTTP request processor attempt to force the use of
    #       HTTPS for URIs that were originally HTTP?  This setting is only
    #       applicable to native Tcl.
    #
    variable forceSecureHttps; # DEFAULT: true

    if {![info exists forceSecureHttps]} then {
      set forceSecureHttps true
    }

    #
    # NOTE: Is this HTTP request processor allowed to use plain HTTP if/when
    #       the "tls" package is not available?  This should only be changed
    #       if the "tls" package cannot be easily installed for use with the
    #       native Tcl interpreter in use.  It should be noted here that the
    #       official package repository server reserves the right to refuse
    #       plain HTTP connections, which means that changing this setting

    #       designed to process a single HTTP request, including any HTTP
    #       3XX redirects (up to the specified limit), and return the raw
    #       HTTP response data.  It does not contain special code to handle
    #       HTTP status codes other than 3XX (e.g. 4XX, 5XX, etc).
    #
    # <public>
    proc getFileViaHttp { uri redirectLimit channel quiet args } {
      #
      # NOTE: This variable is used to determine if plain HTTP URIs should be
      #       converted to HTTPS, if the "tls" package is available.
      #
      variable forceSecureHttps

      #
      # NOTE: This variable is used to determine if plain HTTP is allowed if
      #       the "tls" package is not available.
      #
      variable allowInsecureHttp

      #

      #
      # NOTE: If the 'tls' package is available, always attempt to use HTTPS;
      #       otherwise, only attempt to use HTTP if explicitly allowed.
      #
      if {[catch {package require tls}] == 0} then {
        ::http::register https 443 [list ::tls::socket -tls1 true]

        if {$forceSecureHttps} then {
          if {[string range $uri 0 6] eq "http://"} then {
            set uri [appendArgs https:// [string range $uri 7 end]]
          }
        }
      } elseif {$allowInsecureHttp} then {
        if {[string range $uri 0 7] eq "https://"} then {
          set uri [appendArgs http:// [string range $uri 8 end]]
        }
      }