From: Stefan Schantl Date: Thu, 4 Aug 2022 17:56:54 +0000 (+0200) Subject: general-functions.pl: Add LWP-based flexible downloader function. X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=e19baf70ddb6c1de85e8390457e6087e101cd6a6;p=people%2Fstevee%2Fipfire-2.x.git general-functions.pl: Add LWP-based flexible downloader function. This function can be used to grab content and/or store it into files. Signed-off-by: Stefan Schantl --- diff --git a/config/cfgroot/general-functions.pl b/config/cfgroot/general-functions.pl index d871025eb6..027ab55332 100644 --- a/config/cfgroot/general-functions.pl +++ b/config/cfgroot/general-functions.pl @@ -19,6 +19,22 @@ use Socket; use IO::Socket; use Net::SSLeay; use Net::IPv4Addr qw(:all); + +# Load module to move files. +use File::Copy; + +# Load module to get file stats. +use File::stat; + +# Load module to deal with temporary files. +use File::Temp; + +# Load module to deal with the date formats used by the HTTP protocol. +use HTTP::Date; + +# Load the libwwwperl User Agent module. +use LWP::UserAgent; + $|=1; # line buffering $General::version = 'VERSION'; @@ -1417,6 +1433,251 @@ sub generateProtoTransHash () { return %protocols; } +# Function to grab a given URL content or to download and store it on disk. +# +# The function requires a configuration hash to be passed. +# +# The following options (hash keys) are supported: +# +# URL -> The URL to the content or file. REQUIRED! +# FILE -> The filename as fullpath where the content/file should be stored on disk. +# ETAGSFILE -> A filename again as fullpath where Etags should be stored and read. +# ETAGPREFIX -> In case a custom etag name should be used, otherwise it defaults to the given URL. +# MAXSIZE -> In bytes until the downloader will abort downloading. (example: 10_485_760 for 10MB) +# +# If a file is given an If-Modified-Since header will be generated from the last modified timestamp +# of an already stored file. In case an Etag file is specified an If-None-Match header will be added to +# the request - Both can be used at the same time. +# +# In case no FILE option has been passed to the function, the content of the requested URL will be returned. +# +# Return codes (if FILE is used): +# +# nothing - On success +# no url - If no URL has been specified. +# not_modified - In case the servers responds with "Not modified" (304) +# dl_error - If the requested URL cannot be accessed. +# incomplete download - In case the size of the local file does not match the remote content_lenght. +# +sub downloader (%) { + my (%args) = @_; + + # Remap args hash and convert all keys into upper case format. + %args = map { uc $_ => $args{$_} } keys %args; + + # The amount of download attempts before giving up and + # logging an error. + my $max_dl_attempts = 3; + + # Temporary directory to download the files. + my $tmp_dl_directory = "/var/tmp"; + + # Assign hash values. + my $url = $args{"URL"} if (exists($args{"URL"})); + my $file = $args{"FILE"} if (exists($args{"FILE"})); + my $etags_file = $args{"ETAGSFILE"} if (exists($args{"ETAGSFILE"})); + my $etagprefix = $url; + $etagprefix = $args{"ETAGPREFIX"} if (exists($args{"ETAGPREFIX"})); + my $max_size = $args{"MAXSIZE"} if (exists($args{"MAXSIZE"})); + + # Abort with error "no url", if no URL has been given. + return "no url" unless ($url); + + my %etags = (); + my $tmpfile; + + # Read-in proxysettings. + my %proxysettings=(); + &readhash("${General::swroot}/proxy/settings", \%proxysettings); + + # Create a user agent instance. + # + # Request SSL hostname verification and specify path + # to the CA file. + my $ua = LWP::UserAgent->new( + ssl_opts => { + SSL_ca_file => '/etc/ssl/cert.pem', + verify_hostname => 1, + }, + ); + + # Set timeout to 10 seconds. + $ua->timeout(10); + + # Assign maximum download size if set. + $ua->max_size($max_size) if ($max_size); + + # Generate UserAgent. + my $agent = &MakeUserAgent(); + + # Set the generated UserAgent. + $ua->agent($agent); + + # Check if an upstream proxy is configured. + if ($proxysettings{'UPSTREAM_PROXY'}) { + my $proxy_url; + + $proxy_url = "http://"; + + # Check if the proxy requires authentication. + if (($proxysettings{'UPSTREAM_USER'}) && ($proxysettings{'UPSTREAM_PASSWORD'})) { + $proxy_url .= "$proxysettings{'UPSTREAM_USER'}\:$proxysettings{'UPSTREAM_PASSWORD'}\@"; + } + + # Add proxy server address and port. + $proxy_url .= $proxysettings{'UPSTREAM_PROXY'}; + + # Append proxy settings. + $ua->proxy(['http', 'https'], $proxy_url); + } + + # Create a HTTP request element and pass the given URL to it. + my $request = HTTP::Request->new(GET => $url); + + # Check if a file to store the output has been provided. + if ($file) { + # Check if the given file already exits, because it has been downloaded in the past. + # + # In this case we are requesting the server if the remote file has been changed or not. + # This will be done by sending the modification time in a special HTTP header. + if (-f $file) { + # Call stat on the file. + my $stat = stat($file); + + # Omit the mtime of the existing file. + my $mtime = $stat->mtime; + + # Convert the timestamp into right format. + my $http_date = time2str($mtime); + + # Add the If-Modified-Since header to the request to ask the server if the + # file has been modified. + $request->header( 'If-Modified-Since' => "$http_date" ); + } + + # Generate temporary file name, located in the tempoary download directory and with a suffix of ".tmp". + # The downloaded file will be stored there until some sanity checks are performed. + my $tmp = File::Temp->new( SUFFIX => ".tmp", DIR => "$tmp_dl_directory/", UNLINK => 0 ); + $tmpfile = $tmp->filename(); + } + + # Check if an file for etags has been given. + if ($etags_file) { + # Read-in Etags file for known Etags if the file is present. + &readhash("$etags_file", \%etags) if (-f $etags_file); + + # Check if an Etag for the current provider is stored. + if ($etags{$etagprefix}) { + # Grab the stored tag. + my $etag = $etags{$etagprefix}; + + # Add an "If-None-Match header to the request to ask the server if the + # file has been modified. + $request->header( 'If-None-Match' => $etag ); + } + } + + my $dl_attempt = 1; + my $response; + + # Download and retry on failure. + while ($dl_attempt <= $max_dl_attempts) { + # Perform the request and save the output into the tmpfile if requested. + $response = $ua->request($request, $tmpfile); + + # Check if the download was successfull. + if($response->is_success) { + # Break loop. + last; + + # Check if the server responds with 304 (Not Modified). + } elsif ($response->code == 304) { + # Remove temporary file, if one exists. + unlink("$tmpfile") if (-e "$tmpfile"); + + # Return "not modified". + return "not modified"; + + # Check if we ran out of download re-tries. + } elsif ($dl_attempt eq $max_dl_attempts) { + # Obtain error. + my $error = $response->content; + + # Remove temporary file, if one exists. + unlink("$tmpfile") if (-e "$tmpfile"); + + # Return the error message from response.. + return "$error"; + } + + # Remove temporary file, if one exists. + unlink("$tmpfile") if (-e "$tmpfile"); + + # Increase download attempt counter. + $dl_attempt++; + } + + # Obtain the connection headers. + my $headers = $response->headers; + + # Check if an Etag file has been provided. + if ($etags_file) { + # Grab the Etag from the response if the server provides one. + if ($response->header('Etag')) { + # Add the provided Etag to the hash of tags. + $etags{$etagprefix} = $response->header('Etag'); + + # Write the etags file. + &writehash($etags_file, \%etags); + } + } + + # Check if the response should be stored on disk. + if ($file) { + # Get the remote size of the content. + my $remote_size = $response->header('Content-Length'); + + # Perform a stat on the temporary file. + my $stat = stat($tmpfile); + + # Grab the size of the stored temporary file. + my $local_size = $stat->size; + + # Check if both sizes are equal. + if(($remote_size) && ($remote_size ne $local_size)) { + # Delete the temporary file. + unlink("$tmpfile"); + + # Abort and return "incomplete download" as error. + return "incomplete download"; + } + + # Move the temporaray file to the desired file by overwriting a may + # existing one. + move("$tmpfile", "$file"); + + # Omit the timestamp from response header, when the file has been modified the + # last time. + my $last_modified = $headers->last_modified; + + # Check if we got a last-modified value from the server. + if ($last_modified) { + # Assign the last-modified timestamp as mtime to the + # stored file. + utime(time(), "$last_modified", "$file"); + } + + # Delete temporary file. + unlink("$tmpfile"); + + # If we got here, everything worked fine. Return nothing. + return; + } else { + # Decode the response content and return it. + return $response->decoded_content; + } +} + # Cloud Stuff sub running_in_cloud() {