# NOTE: Setup lowercase URI scheme prefixes used within this procedure
    #       to detect and/or change the URI scheme used.  By default, this
    #       procedure will always attempt to force HTTPS use when the "tls"
    #       package is available -AND- it disallows redirects from HTTPS to
    #       HTTP -AND- it disallows using HTTP when the "tls" package is
    #       unavailable.
    #
    set http http://; set https https://
    set http http://
    set httpLen [string length $http]
    set httpEnd [expr {$httpLen - 1}]

    set https https://
    set httpsLen [string length $https]
    set httpsEnd [expr {$httpsLen - 1}]

    #
    # 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} error] == 0} then {
      ::http::register https 443 [list ::tls::socket -tls1 true]

      if {$forceSecureUri} then {
        if {[string tolower [string range $uri 0 6]] eq $http} then {
          set uri [appendArgs $https [string range $uri 7 end]]
        if {[string tolower [string range $uri 0 $httpEnd]] eq $http} then {
          set uri [appendArgs $https [string range $uri $httpLen end]]
        }
      }
    } else {
      if {$mustHaveTls} then {
        error [appendArgs \
            "the \"tls\" package cannot be loaded: " $error]
      }

      if {$allowInsecureUri} then {
        if {[string tolower [string range $uri 0 7]] eq $https} then {
          set uri [appendArgs $http [string range $uri 8 end]]
        if {[string tolower [string range $uri 0 $httpsEnd]] eq $https} then {
          set uri [appendArgs $http [string range $uri $httpsLen end]]
        }
      }
    }

    #
    # NOTE: Unless the caller forbids it, display progress messages during
    #       the download.

      #       this platform.  So far, this issue has only been seen
      #       with the tls 1.6.1 package that shipped with macOS.
      #
      if {[string length $code] == 0} then {
        error [appendArgs \
            "received empty HTTP response code for URL \"" $uri \
            "\", the \"tls\" (and/or \"http\") package(s) may be " \
            "broken for this platform"]
            "broken for this Tcl installation (or platform)"]
      }

      #
      # NOTE: Check the HTTP response code, in order to follow any HTTP
      #       redirect responses.
      #
      switch -glob -- $code {

          #
          # NOTE: We hit another HTTP redirect.  Stop if there are more
          #       than X.
          #
          incr redirectCount

          #
          # TODO: Maybe make this limit more configurable?
          # TODO: Maybe make this limit more configurable?  The caller
          #       can pass any negative integer to disable it entirely
          #       -OR- zero to completely disallow any redirects.
          #
          if {$redirectLimit >= 0 && \
          if {$redirectCount > $redirectLimit} then {
              $redirectCount > $redirectLimit} then {
            #
            # NOTE: Just "give up" and raise a script error.
            #
            ::http::cleanup $token; error [appendArgs \
                "redirection limit of " $redirectLimit " exceeded"]
          }

            #
            # NOTE: For security, by default, do NOT follow an HTTP
            #       redirect if it attempts to redirect from HTTPS
            #       to HTTP.
            #
            if {!$allowInsecureRedirect && \
                [string tolower [string range $uri 0 7]] eq $https && \
                [string tolower [string range $location 0 7]] ne $https} then {
                [string tolower [string range \
                    $uri 0 $httpsEnd]] eq $https && \
                [string tolower [string range \
                    $location 0 $httpsEnd]] ne $https} then {
              #
              # NOTE: Just "give up" and raise a script error.
              #
              ::http::cleanup $token; error [appendArgs \
                  "refused insecure redirect from \"" $uri "\" to \"" \
                  $location \"]
                  "refused (insecure) redirect from \"" $uri \
                  "\" to \"" $location \
                  "\" with HTTP response status code " $code]
            }

            #
            # NOTE: Replace the original URI with the new one, for
            #       use in the next HTTP request.
            #
            set uri $location

            #
            # NOTE: Cleanup the current HTTP token now beause a new
            #       one will be created for the next request.
            #
            ::http::cleanup $token
          } else {
            #
            # NOTE: Just "give up" and raise a script error.
            #
            ::http::cleanup $token; error [appendArgs \
                "redirect from \"" $uri "\" missing location, code " \
                "redirect from \"" $uri \
                "\" missing location, HTTP response status code " \
                $code ", data: " $data]
          }
        }
        300 -
        304 -
        305 -
        306 {
          ::http::cleanup $token; error [appendArgs \
              "unsupported redirection HTTP response status code " $code \
              ", data: " $data]
              "unsupported redirection HTTP response status code " \
              $code ", data: " $data]
        }
        4?? {
          ::http::cleanup $token; error [appendArgs \
              "client error HTTP response status code " $code ", data: " \
              $data]
        }
        5?? {

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