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• xpath evaluting error in andorid

  - by R_Dhorawat

  i'm running one application in android browser which contain the following code.. [ if (typeof XPathResult != "undefined") { //use build in xpath support for Safari 3.0 //alert("xpathExpr"+xpathExpr); //alert("doc"+doc); var xmlDocument = doc; if (doc.nodeType != 9) { xmlDocument = doc.ownerDocument; } results = xmlDocument.evaluate(xpathExpr,doc, function(prefix) { return namespaces[prefix] || null;}, XPathResult.ANY_TYPE, null ); var thisResult; result = []; var len = 0; do { thisResult = results.iterateNext(); if (thisResult) { result[len] = thisResult; len++; } } while ( thisResult ); } else { try{ if (doc.selectNodes) { result = doc.selectNodes(xpathExpr); } }catch(ex){} } return result; ] but when i run this app in Firefox control come in if statement and everything works fine.. but in android browser it's giving error ... XPathResult undefined... this time control come to else statement and even here it's showing that selectNodes is undefind and. so the result come as null whereas in Firefox it's giving list of nodes.. realy need it to be done ... help needed.. thanks...

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• How to encrypt a RSAKey using another RSAKey?

  - by Tom Brito

  I know its not the usual thing to do. But the specification I'm implementing is discribed this way, and I cannot run out. I was trying to encrypt the modulus and exponent of the private key, but the following test code raises an exception because the byte array is 1 byte larger then the maximum allowed by RSA block: import java.security.KeyPair; import java.security.KeyPairGenerator; import java.security.NoSuchAlgorithmException; import java.security.NoSuchProviderException; import java.security.interfaces.RSAPrivateKey; import java.security.interfaces.RSAPublicKey; import javax.crypto.Cipher; import org.apache.commons.lang.ArrayUtils; public class TEST { public static KeyPair generateKeyPair() throws NoSuchAlgorithmException, NoSuchProviderException { KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA", "BC"); keyPairGenerator.initialize(1024); return keyPairGenerator.generateKeyPair(); } public static void main(String[] args) throws Exception { KeyPair keyPair = generateKeyPair(); RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate(); System.out.println("Priv modulus len = " + privateKey.getModulus().bitLength()); System.out.println("Priv exponent len = " + privateKey.getPrivateExponent().bitLength()); System.out.println("Priv modulus toByteArray len = " + privateKey.getModulus().toByteArray().length); byte[] byteArray = privateKey.getModulus().toByteArray(); // the byte at index 0 have no value (in every generation it is always zero) byteArray = ArrayUtils.subarray(byteArray, 1, byteArray.length); System.out.println("byteArray size: " + byteArray.length); RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic(); Cipher cipher = Cipher.getInstance("RSA", "BC"); cipher.init(Cipher.ENCRYPT_MODE, publicKey); byte[] encryptedBytes = cipher.doFinal(byteArray); System.out.println("Success!"); } } (obs. its just a test, i would never encrypt the private key with its pair public key) The byte array is 128 bytes, the exactly maximum allowed by a RSA block, so why the exception? And how to fix it?

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• Filtering string in Python

  - by Ecce_Homo

  I am making algorithm for checking the string (e-mail) - like "E-mail addres is valid" but their are rules. First part of e-mail has to be string that has 1-8 characters (can contain alphabet, numbers, underscore [ _ ]...all the parts that e-mail contains) and after @ the second part of e-mail has to have string that has 1-12 characters (also containing all legal expressions) and it has to end with top level domain .com EDIT email = raw_input ("Enter the e-mail address:") length = len (email) if length > 20 print "Address is too long" elif lenght < 5: print "Address is too short" if not email.endswith (".com"): print "Address doesn't contain correct domain ending" first_part = len (splitting[0]) second_part = len(splitting[1]) account = splitting[0] domain = splitting[1] for c in account: if c not in "abcdefghijklmopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_.": print "Invalid char", "->", c,"<-", "in account name of e-mail" for c in domain: if c not in "abcdefghijklmopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_.": print "Invalid char", "->", c,"<-", "in domain of e-mail" if first_part == 0: print "You need at least 1 character before the @" elif first_part> 8: print "The first part is too long" if second_part == 4: print "You need at least 1 character after the @" elif second_part> 16: print "The second part is too long" else: # if everything is fine return this print "E-mail addres is valid" EDIT: After reproting what is wrong with our input, now I need to make Python recognize valid address and return ("E-mail adress is valid") This is the best i can do with my knowledge....and we cant use regular expressions, teacher said we are going to learn them later.

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• How can I convert a byte array into a double and back?

  - by user350005

  For converting a byte array to a double I found this: //convert 8 byte array to double int start=0;//??? int i = 0; int len = 8; int cnt = 0; byte[] tmp = new byte[len]; for (i = start; i < (start + len); i++) { tmp[cnt] = arr[i]; //System.out.println(java.lang.Byte.toString(arr[i]) + " " + i); cnt++; } long accum = 0; i = 0; for ( int shiftBy = 0; shiftBy < 64; shiftBy += 8 ) { accum |= ( (long)( tmp[i] & 0xff ) ) << shiftBy; i++; } return Double.longBitsToDouble(accum); But I could not find anything which would convert a double into a byte array.

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• singledispatch in class, how to dispatch self type

  - by yanxinyou

  Using python3.4. Here I want use singledispatch to dispatch different type in __mul__ method . The code like this : class Vector(object): ## some code not paste @functools.singledispatch def __mul__(self, other): raise NotImplementedError("can't mul these type") @__mul__.register(int) @__mul__.register(object) # Becasue can't use Vector , I have to use object def _(self, other): result = Vector(len(self)) # start with vector of zeros for j in range(len(self)): result[j] = self[j]*other return result @__mul__.register(Vector) # how can I use the self't type @__mul__.register(object) # def _(self, other): pass # need impl As you can see the code , I want support Vector*Vertor , This has Name error Traceback (most recent call last): File "p_algorithms\vector.py", line 6, in <module> class Vector(object): File "p_algorithms\vector.py", line 84, in Vector @__mul__.register(Vector) # how can I use the self't type NameError: name 'Vector' is not defined The question may be How Can I use class Name a Type in the class's method ? I know c++ have font class statement . How python solve my problem ? And it is strange to see result = Vector(len(self)) where the Vector can be used in method body .

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• printSoln module problem

  - by dingo_d

  Hi I found in book:Numerical Methods in engineering with Python the module run_kut5, but for that module I need module printSoln, all provided in the book. Now I cp the code, made necessary line adjustments and so. The code looks like: # -*- coding: cp1250 -*- ## module printSoln ''' printSoln(X,Y,freq). Prints X and Y returned from the differential equation solvers using printput frequency ’freq’. freq = n prints every nth step. freq = 0 prints initial and final values only. ''' def printSoln(X,Y,freq): def printHead(n): print "\n x ", for i in range (n): print " y[",i,"] ", print def printLine(x,y,n): print "%13.4e"% x,f for i in range (n): print "%13.4e"% y[i], print m = len(Y) try: n = len(Y[0]) except TypeError: n = 1 if freq == 0: freq = m printHead(n) for i in range(0,m,freq): printLine(X[i],Y[i],n) if i != m - 1: printLine(X[m - 1],Y[m - 1],n) Now, when I run the program it says: line 24, in <module> m = len(Y) NameError: name 'Y' is not defined But I cp'd from the book :\ So now when I call the run_kut module I get the same error, no Y defined in printSoln... I'm trying to figure this out but I suck :( Help, please...

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• Dynamic programming Approach- Knapsack Puzzle

  - by idalsin

  I'm trying to solve the Knapsack problem with the dynamical programming(DP) approach, with Python 3.x. My TA pointed us towards this code for a head start. I've tried to implement it, as below: def take_input(infile): f_open = open(infile, 'r') lines = [] for line in f_open: lines.append(line.strip()) f_open.close() return lines def create_list(jewel_lines): #turns the jewels into a list of lists jewels_list = [] for x in jewel_lines: weight = x.split()[0] value = x.split()[1] jewels_list.append((int(value), int(weight))) jewels_list = sorted(jewels_list, key = lambda x : (-x[0], x[1])) return jewels_list def dynamic_grab(items, max_weight): table = [[0 for weight in range(max_weight+1)] for j in range(len(items)+1)] for j in range(1,len(items)+1): val= items[j-1][0] wt= items[j-1][1] for weight in range(1, max_weight+1): if wt > weight: table[j][weight] = table[j-1][weight] else: table[j][weight] = max(table[j-1][weight],table[j-1][weight-wt] + val) result = [] weight = max_weight for j in range(len(items),0,-1): was_added = table[j][weight] != table[j-1][weight] if was_added: val = items[j-1][0] wt = items[j-1][1] result.append(items[j-1]) weight -= wt return result def totalvalue(comb): #total of a combo of items totwt = totval = 0 for val, wt in comb: totwt += wt totval += val return (totval, -totwt) if totwt <= max_weight else (0,0) #required setup of variables infile = "JT_test1.txt" given_input = take_input(infile) max_weight = int(given_input[0]) given_input.pop(0) jewels_list = create_list(given_input) #test lines print(jewels_list) print(greedy_grab(jewels_list, max_weight)) bagged = dynamic_grab(jewels_list, max_weight) print(totalvalue(bagged)) The sample case is below. It is in the format line[0] = bag_max, line[1:] is in form(weight, value): 575 125 3000 50 100 500 6000 25 30 I'm confused as to the logic of this code in that it returns me a tuple and I'm not sure what the output tuple represents. I've been looking at this for a while and just don't understand what the code is pointing me at. Any help would be appreciated.

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• Shell halts while looping and 'transforming' values in dictionary (Python 2.7.5)

  - by Gus

  I'm building a program that will sum digits in a given list in a recursive way. Say, if the source list has 10 elements, the second list will have 9, the third 8 and so on until the last list that will have only one element. This is done by adding the first element to the second, then the second to the third and so on. I'm stuck without feedback from the shell. It halts without throwing any errors, then in a couple of seconds the fan is spinning like crazy. I've read quite a few posts here and changed my approach, but I'm not sure that what have so far can produce the results I'm looking for. Thanks in advance: #--------------------------------------------------- #functions #--------------------------------------------------- #sum up pairs in a list def reduce(inputList): i = 0 while (i < len(inputList)): #ref to current and next item j = i + 1 #don't go for the last item if j != len(inputList): #new number eq current + next number newNumber = inputList[i] + inputList[j] if newNumber >= 10: #reduce newNumber to single digit newNumber = sum(map(int, str(newNumber))) #collect into temp list outputList.append(newNumber) i = i + 1 return outputList; #--------------------------------------------------- #program starts here #--------------------------------------------------- outputList = [] sourceList = [7, 3, 1, 2, 1, 4, 6] counter = len(sourceList) dict = {} dict[0] = sourceList print '-------------' print 'Level 0:', dict[0] for i in range(counter): j = i + 1 if j != counter: baseList = dict.get(i) #check function to understand what it does newList = reduce(baseList) #new key and value from previous/transformed value dict[j] = newList print 'Level %d: %s' % (j, dict[j])

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• Alert visualization recipe: Get out your blender, drop in some sp_send_dbmail, Google Charts API, add your favorite colors and sprinkle with html. Blend till it’s smooth and looks pretty enough to taste.

  - by Maria Zakourdaev

    I really like database monitoring. My email inbox have a constant flow of different types of alerts coming from our production servers with all kinds of information, sometimes more useful and sometimes less useful. Usually database alerts look really simple, it’s usually a plain text email saying “Prod1 Database data file on Server X is 80% used. You’d better grow it manually before some query triggers the AutoGrowth process”. Imagine you could have received email like the one below.  In addition to the alert description it could have also included the the database file growth chart over the past 6 months. Wouldn’t it give you much more information whether the data growth is natural or extreme? That’s truly what data visualization is for. Believe it or not, I have sent the graph below from SQL Server stored procedure without buying any additional data monitoring/visualization tool.   Would you like to visualize your database alerts like I do? Then like myself, you’d love the Google Charts. All you need to know is a little HTML and have a mail profile configured on your SQL Server instance regardless of the SQL Server version. First of all, I hope you know that the sp_send_dbmail procedure has a great parameter @body_format = ‘HTML’, which allows us to send rich and colorful messages instead of boring black and white ones. All that we need is to dynamically create HTML code. This is how, for instance, you can create a table and populate it with some data: DECLARE @html varchar(max) SET @html = '<html>' + '<H3><font id="Text" style='color: Green;'>Top Databases: </H3>' + '<table border="1" bordercolor="#3300FF" style='background-color:#DDF8CC' width='70%' cellpadding='3' cellspacing='3'>' + '<tr><font color="Green"><th>Database Name</th><th>Size</th><th>Physical Name</th></tr>' + CAST( (SELECT TOP 10                             td = name,'',                             td = size * 8/1024 ,'',                             td = physical_name              FROM sys.master_files               ORDER BY size DESC             FOR XML PATH ('tr'),TYPE ) AS VARCHAR(MAX)) + '</table>' EXEC msdb.dbo.sp_send_dbmail @recipients = '[email protected]', @subject ='Top databases', @body = @html, @body_format = 'HTML' This is the result:   If you want to add more visualization effects, you can use Google Charts Tools https://google-developers.appspot.com/chart/interactive/docs/index which is a free and rich library of data visualization charts, they’re also easy to populate and embed. There are two versions of the Google Charts Image based charts: https://google-developers.appspot.com/chart/image/docs/gallery/chart_gall This is an old version, it’s officially deprecated although it will be up for a next few years or so. I really enjoy using this one because it can be viewed within the email body. For mobile devices you need to change the “Load remote images” property in your email application configuration.           Charts based on JavaScript classes: https://google-developers.appspot.com/chart/interactive/docs/gallery This API is newer, with rich and highly interactive charts, and it’s much more easier to understand and configure. The only downside of it is that they cannot be viewed within the email body. Outlook, Gmail and many other email clients, as part of their security policy, do not run any JavaScript that’s placed within the email body. However, you can still enjoy this API by sending the report as an email attachment. Here is an example of the old version of Google Charts API, sending the same top databases report as in the previous example but instead of a simple table, this script is using a pie chart right from  the T-SQL code DECLARE @html  varchar(8000) DECLARE @Series  varchar(800),@Labels  varchar(8000),@Legend  varchar(8000);     SET @Series = ''; SET @Labels = ''; SET @Legend = ''; SELECT TOP 5 @Series = @Series + CAST(size * 8/1024 as varchar) + ',',                         @Labels = @Labels +CAST(size * 8/1024 as varchar) + 'MB'+'|',                         @Legend = @Legend + name + '|' FROM sys.master_files ORDER BY size DESC SELECT @Series = SUBSTRING(@Series,1,LEN(@Series)-1),         @Labels = SUBSTRING(@Labels,1,LEN(@Labels)-1),         @Legend = SUBSTRING(@Legend,1,LEN(@Legend)-1) SET @html =   '<H3><font color="Green"> '+@@ServerName+' top 5 databases : </H3>'+    '<br>'+    '<img src="http://chart.apis.google.com/chart?'+    'chf=bg,s,DDF8CC&'+    'cht=p&'+    'chs=400x200&'+    'chco=3072F3|7777CC|FF9900|FF0000|4A8C26&'+    'chd=t:'+@Series+'&'+    'chl='+@Labels+'&'+    'chma=0,0,0,0&'+    'chdl='+@Legend+'&'+    'chdlp=b"'+    'alt="'+@@ServerName+' top 5 databases" />'              EXEC msdb.dbo.sp_send_dbmail @recipients = '[email protected]',                             @subject = 'Top databases',                             @body = @html,                             @body_format = 'HTML' This is what you get. Isn’t it great? Chart parameters reference: chf     Gradient fill  bg - backgroud ; s- solid cht     chart type  ( p - pie) chs        chart size width/height chco    series colors chd        chart data string        1,2,3,2 chl        pir chart labels        a|b|c|d chma    chart margins chdl    chart legend            a|b|c|d chdlp    chart legend text        b - bottom of chart   Line graph implementation is also really easy and powerful DECLARE @html varchar(max) DECLARE @Series varchar(max) DECLARE @HourList varchar(max) SET @Series = ''; SET @HourList = ''; SELECT @HourList = @HourList + SUBSTRING(CONVERT(varchar(13),last_execution_time,121), 12,2)  + '|' ,              @Series = @Series + CAST( COUNT(1) as varchar) + ',' FROM sys.dm_exec_query_stats s     CROSS APPLY sys.dm_exec_sql_text(plan_handle) t WHERE last_execution_time > = getdate()-1 GROUP BY CONVERT(varchar(13),last_execution_time,121) ORDER BY CONVERT(varchar(13),last_execution_time,121) SET @Series = SUBSTRING(@Series,1,LEN(@Series)-1) SET @html = '<img src="http://chart.apis.google.com/chart?'+ 'chco=CA3D05,87CEEB&'+ 'chd=t:'+@Series+'&'+ 'chds=1,350&'+ 'chdl= Proc executions from cache&'+ 'chf=bg,s,1F1D1D|c,lg,0,363433,1.0,2E2B2A,0.0&'+ 'chg=25.0,25.0,3,2&'+ 'chls=3|3&'+ 'chm=d,CA3D05,0,-1,12,0|d,FFFFFF,0,-1,8,0|d,87CEEB,1,-1,12,0|d,FFFFFF,1,-1,8,0&'+ 'chs=600x450&'+ 'cht=lc&'+ 'chts=FFFFFF,14&'+ 'chtt=Executions for from' +(SELECT CONVERT(varchar(16),min(last_execution_time),121)          FROM sys.dm_exec_query_stats          WHERE last_execution_time > = getdate()-1) +' till '+ +(SELECT CONVERT(varchar(16),max(last_execution_time),121)     FROM sys.dm_exec_query_stats) + '&'+ 'chxp=1,50.0|4,50.0&'+ 'chxs=0,FFFFFF,12,0|1,FFFFFF,12,0|2,FFFFFF,12,0|3,FFFFFF,12,0|4,FFFFFF,14,0&'+ 'chxt=y,y,x,x,x&'+ 'chxl=0:|1|350|1:|N|2:|'+@HourList+'3:|Hour&'+ 'chma=55,120,0,0" alt="" />' EXEC msdb.dbo.sp_send_dbmail @recipients = '[email protected]', @subject ='Daily number of executions', @body = @html, @body_format = 'HTML' Chart parameters reference: chco    series colors chd        series data chds    scale format chdl    chart legend chf        background fills chg        grid line chls    line style chm        line fill chs        chart size cht        chart type chts    chart style chtt    chart title chxp    axis label positions chxs    axis label styles chxt    axis tick mark styles chxl    axis labels chma    chart margins If you don’t mind to get your charts as an email attachment, you can enjoy the Java based Google Charts which are even easier to configure, and have much more advanced graphics. In the example below, the sp_send_email procedure uses the parameter @query which will be executed at the time that sp_send_dbemail is executed and the HTML result of this execution will be attached to the email. DECLARE @html varchar(max),@query varchar(max) DECLARE @SeriesDBusers  varchar(800);     SET @SeriesDBusers = ''; SELECT @SeriesDBusers = @SeriesDBusers +  ' ["'+DB_NAME(r.database_id) +'", ' +cast(count(1) as varchar)+'],' FROM sys.dm_exec_requests r GROUP BY DB_NAME(database_id) ORDER BY count(1) desc; SET @SeriesDBusers = SUBSTRING(@SeriesDBusers,1,LEN(@SeriesDBusers)-1) SET @query = ' PRINT '' <html>   <head>     <script type="text/javascript" src="https://www.google.com/jsapi"></script>     <script type="text/javascript">       google.load("visualization", "1", {packages:["corechart"]});        google.setOnLoadCallback(drawChart);       function drawChart() {                      var data = google.visualization.arrayToDataTable([                        ["Database Name", "Active users"],                        '+@SeriesDBusers+'                      ]);                        var options = {                        title: "Active users",                        pieSliceText: "value"                      };                        var chart = new google.visualization.PieChart(document.getElementById("chart_div"));                      chart.draw(data, options);       };     </script>   </head>   <body>     <table>     <tr><td>         <div id="chart_div" style='width: 800px; height: 300px;'></div>         </td></tr>     </table>   </body> </html> ''' EXEC msdb.dbo.sp_send_dbmail    @recipients = '[email protected]',    @subject ='Active users',    @body = @html,    @body_format = 'HTML',    @query = @Query,     @attach_query_result_as_file = 1,     @query_attachment_filename = 'Results.htm' After opening the email attachment in the browser you are getting this kind of report: In fact, the above is not only for database alerts. It can be used for applicative reports if you need high levels of customization that you cannot achieve using standard methods like SSRS. If you need more information on how to customize the charts, you can try the following: Image Based Charts wizard https://google-developers.appspot.com/chart/image/docs/chart_wizard  Live Image Charts Playground https://google-developers.appspot.com/chart/image/docs/chart_playground Image Based Charts Parameters List https://google-developers.appspot.com/chart/image/docs/chart_params Java Script Charts Playground https://code.google.com/apis/ajax/playground/?type=visualization Use the above examples as a starting point for your procedures and I’d be more than happy to hear of your implementations of the above techniques. Yours, Maria

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• Confusion about TCP packet analysis terms

  - by Berkay

  I'm analyzing our network and have some confusion about the terms: this is the 2-packet output from source to destination. from these i have to get some features as describe, pls make me clear... packets with at least a bytes of TCP data payload: it seems tcp.len0; The minimum segment size (confusion is headers are included or or not) The average segment size observed during the lifetime of the connection, the definition: is calculated as the value reported in the actual data bytes divided by the actual data pkts reported. Total bytes in IP packets, should be ip_len value. Total bytes in (Ethernet) The total number of bytes sent probably related to frame.len and frame.cap_len these two terms are describes as, also make me clear about these two terms. frame.cap_len: Frame length stored into the capture file frame.len: Frame length on the wire

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• mystery Internet traffic to port 445

  - by Ben Collver

  Recently, I noticed traffic from the office network to TCP port 445 on the Internet [a]. Below are the Linux firewall log entries to Facebook's network [b] and Google's network [c]. I would like to identify the source of this traffic. My first guess is that Facebook and Google might be using multiple TCP ports for SSL load balancing. However, I could not confirm this based on the web proxy logs. What else might it be? [a] http://support.microsoft.com/kb/204279 [b] Sep 4 08:30:03 firewall01 kernel: IN=eth0 OUT=eth2 SRC=10.0.0.131 DST=69.171.237.34 LEN=52 TOS=0x00 PREC=0x00 TTL=127 ID=14287 DF PROTO=TCP SPT=51711 DPT=445 WINDOW=8192 RES=0x00 SYN URGP=0 [c] Aug 28 06:02:41 firewall01 kernel: IN=eth0 OUT=eth2 SRC=10.0.0.115 DST=173.194.33.47 LEN=52 TOS=0x00 PREC=0x00 TTL=127 ID=4558 DF PROTO=TCP SPT=49294 DPT=445 WINDOW=8192 RES=0x00 SYN URGP=0

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• Tracing out going connections

  - by Tiffany Walker

  Jan 24 07:00:49 HOST kernel: [875997.380464] Firewall: *TCP_OUT Blocked* IN= OUT=eth0 SRC=108.60.11.15 DST=74.80.225.32 LEN=52 TOS=0x00 PREC=0x00 TTL=64 ID=18789 DF PROTO=TCP SPT=64823 DPT=81 WINDOW=14600 RES=0x00 SYN URGP=0 Jan 24 07:00:50 HOST kernel: [875998.378321] Firewall: *TCP_OUT Blocked* IN= OUT=eth0 SRC=108.60.11.15 DST=74.80.225.32 LEN=52 TOS=0x00 PREC=0x00 TTL=64 ID=18790 DF PROTO=TCP SPT=64823 DPT=81 WINDOW=14600 RES=0x00 SYN URGP=0 I run fcgid so everything runs as a user. But is there a way to trace and figure out who is running an out going script? The sites all share the same IP so it's hard to know which site it is or where the script is located at.

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• Android: OutOfMemoryError while uploading video...

  - by AP257

  Hi all, I have the same problem as described here, but I will supply a few more details. While trying to upload a video in Android, I'm reading it into memory, and if the video is large I get an OutOfMemoryError. Here's my code: // get bytestream to upload videoByteArray = getBytesFromFile(cR, fileUriString); public static byte[] getBytesFromFile(ContentResolver cR, String fileUriString) throws IOException { Uri tempuri = Uri.parse(fileUriString); InputStream is = cR.openInputStream(tempuri); byte[] b3 = readBytes(is); is.close(); return b3; } public static byte[] readBytes(InputStream inputStream) throws IOException { ByteArrayOutputStream byteBuffer = new ByteArrayOutputStream(); // this is storage overwritten on each iteration with bytes int bufferSize = 1024; byte[] buffer = new byte[bufferSize]; int len = 0; while ((len = inputStream.read(buffer)) != -1) { byteBuffer.write(buffer, 0, len); } return byteBuffer.toByteArray(); } And here's the traceback (the error is thrown on the byteBuffer.write(buffer, 0, len) line): 04-08 11:56:20.456: ERROR/dalvikvm-heap(6088): Out of memory on a 16775184-byte allocation. 04-08 11:56:20.456: INFO/dalvikvm(6088): "IntentService[UploadService]" prio=5 tid=17 RUNNABLE 04-08 11:56:20.456: INFO/dalvikvm(6088): | group="main" sCount=0 dsCount=0 s=N obj=0x449a3cf0 self=0x38d410 04-08 11:56:20.456: INFO/dalvikvm(6088): | sysTid=6119 nice=0 sched=0/0 cgrp=default handle=4010416 04-08 11:56:20.456: INFO/dalvikvm(6088): at java.io.ByteArrayOutputStream.expand(ByteArrayOutputStream.java:~93) 04-08 11:56:20.456: INFO/dalvikvm(6088): at java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java:218) 04-08 11:56:20.456: INFO/dalvikvm(6088): at com.android.election2010.UploadService.readBytes(UploadService.java:199) 04-08 11:56:20.456: INFO/dalvikvm(6088): at com.android.election2010.UploadService.getBytesFromFile(UploadService.java:182) 04-08 11:56:20.456: INFO/dalvikvm(6088): at com.android.election2010.UploadService.doUploadinBackground(UploadService.java:118) 04-08 11:56:20.456: INFO/dalvikvm(6088): at com.android.election2010.UploadService.onHandleIntent(UploadService.java:85) 04-08 11:56:20.456: INFO/dalvikvm(6088): at android.app.IntentService$ServiceHandler.handleMessage(IntentService.java:30) 04-08 11:56:20.456: INFO/dalvikvm(6088): at android.os.Handler.dispatchMessage(Handler.java:99) 04-08 11:56:20.456: INFO/dalvikvm(6088): at android.os.Looper.loop(Looper.java:123) 04-08 11:56:20.456: INFO/dalvikvm(6088): at android.os.HandlerThread.run(HandlerThread.java:60) 04-08 11:56:20.467: WARN/dalvikvm(6088): threadid=17: thread exiting with uncaught exception (group=0x4001b180) 04-08 11:56:20.467: ERROR/AndroidRuntime(6088): Uncaught handler: thread IntentService[UploadService] exiting due to uncaught exception 04-08 11:56:20.467: ERROR/AndroidRuntime(6088): java.lang.OutOfMemoryError 04-08 11:56:20.467: ERROR/AndroidRuntime(6088): at java.io.ByteArrayOutputStream.expand(ByteArrayOutputStream.java:93) 04-08 11:56:20.467: ERROR/AndroidRuntime(6088): at java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java:218) 04-08 11:56:20.467: ERROR/AndroidRuntime(6088): at com.android.election2010.UploadService.readBytes(UploadService.java:199) 04-08 11:56:20.467: ERROR/AndroidRuntime(6088): at com.android.election2010.UploadService.getBytesFromFile(UploadService.java:182) 04-08 11:56:20.467: ERROR/AndroidRuntime(6088): at com.android.election2010.UploadService.doUploadinBackground(UploadService.java:118) 04-08 11:56:20.467: ERROR/AndroidRuntime(6088): at com.android.election2010.UploadService.onHandleIntent(UploadService.java:85) 04-08 11:56:20.467: ERROR/AndroidRuntime(6088): at android.app.IntentService$ServiceHandler.handleMessage(IntentService.java:30) 04-08 11:56:20.467: ERROR/AndroidRuntime(6088): at android.os.Handler.dispatchMessage(Handler.java:99) 04-08 11:56:20.467: ERROR/AndroidRuntime(6088): at android.os.Looper.loop(Looper.java:123) 04-08 11:56:20.467: ERROR/AndroidRuntime(6088): at android.os.HandlerThread.run(HandlerThread.java:60) 04-08 11:56:20.496: INFO/Process(4657): Sending signal. PID: 6088 SIG: 3 I guess that as @DroidIn suggests, I need to upload it in chunks. But (newbie question alert) does that mean that I should make multiple PostMethod requests, and glue the file together at the server end? Or can I load the bytestream into memory in chunks, and glue it together in the Android code? If anyone could give me a clue as to the best approach, I would be very grateful.

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• Android: OutOfMemoryError while uploading video - how best to chunk?

  - by AP257

  Hi all, I have the same problem as described here, but I will supply a few more details. While trying to upload a video in Android, I'm reading it into memory, and if the video is large I get an OutOfMemoryError. Here's my code: // get bytestream to upload videoByteArray = getBytesFromFile(cR, fileUriString); public static byte[] getBytesFromFile(ContentResolver cR, String fileUriString) throws IOException { Uri tempuri = Uri.parse(fileUriString); InputStream is = cR.openInputStream(tempuri); byte[] b3 = readBytes(is); is.close(); return b3; } public static byte[] readBytes(InputStream inputStream) throws IOException { ByteArrayOutputStream byteBuffer = new ByteArrayOutputStream(); // this is storage overwritten on each iteration with bytes int bufferSize = 1024; byte[] buffer = new byte[bufferSize]; int len = 0; while ((len = inputStream.read(buffer)) != -1) { byteBuffer.write(buffer, 0, len); } return byteBuffer.toByteArray(); } And here's the traceback (the error is thrown on the byteBuffer.write(buffer, 0, len) line): 04-08 11:56:20.456: ERROR/dalvikvm-heap(6088): Out of memory on a 16775184-byte allocation. 04-08 11:56:20.456: INFO/dalvikvm(6088): "IntentService[UploadService]" prio=5 tid=17 RUNNABLE 04-08 11:56:20.456: INFO/dalvikvm(6088): | group="main" sCount=0 dsCount=0 s=N obj=0x449a3cf0 self=0x38d410 04-08 11:56:20.456: INFO/dalvikvm(6088): | sysTid=6119 nice=0 sched=0/0 cgrp=default handle=4010416 04-08 11:56:20.456: INFO/dalvikvm(6088): at java.io.ByteArrayOutputStream.expand(ByteArrayOutputStream.java:~93) 04-08 11:56:20.456: INFO/dalvikvm(6088): at java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java:218) 04-08 11:56:20.456: INFO/dalvikvm(6088): at com.android.election2010.UploadService.readBytes(UploadService.java:199) 04-08 11:56:20.456: INFO/dalvikvm(6088): at com.android.election2010.UploadService.getBytesFromFile(UploadService.java:182) 04-08 11:56:20.456: INFO/dalvikvm(6088): at com.android.election2010.UploadService.doUploadinBackground(UploadService.java:118) 04-08 11:56:20.456: INFO/dalvikvm(6088): at com.android.election2010.UploadService.onHandleIntent(UploadService.java:85) 04-08 11:56:20.456: INFO/dalvikvm(6088): at android.app.IntentService$ServiceHandler.handleMessage(IntentService.java:30) 04-08 11:56:20.456: INFO/dalvikvm(6088): at android.os.Handler.dispatchMessage(Handler.java:99) 04-08 11:56:20.456: INFO/dalvikvm(6088): at android.os.Looper.loop(Looper.java:123) 04-08 11:56:20.456: INFO/dalvikvm(6088): at android.os.HandlerThread.run(HandlerThread.java:60) 04-08 11:56:20.467: WARN/dalvikvm(6088): threadid=17: thread exiting with uncaught exception (group=0x4001b180) 04-08 11:56:20.467: ERROR/AndroidRuntime(6088): Uncaught handler: thread IntentService[UploadService] exiting due to uncaught exception 04-08 11:56:20.467: ERROR/AndroidRuntime(6088): java.lang.OutOfMemoryError 04-08 11:56:20.467: ERROR/AndroidRuntime(6088): at java.io.ByteArrayOutputStream.expand(ByteArrayOutputStream.java:93) 04-08 11:56:20.467: ERROR/AndroidRuntime(6088): at java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java:218) 04-08 11:56:20.467: ERROR/AndroidRuntime(6088): at com.android.election2010.UploadService.readBytes(UploadService.java:199) 04-08 11:56:20.467: ERROR/AndroidRuntime(6088): at com.android.election2010.UploadService.getBytesFromFile(UploadService.java:182) 04-08 11:56:20.467: ERROR/AndroidRuntime(6088): at com.android.election2010.UploadService.doUploadinBackground(UploadService.java:118) 04-08 11:56:20.467: ERROR/AndroidRuntime(6088): at com.android.election2010.UploadService.onHandleIntent(UploadService.java:85) 04-08 11:56:20.467: ERROR/AndroidRuntime(6088): at android.app.IntentService$ServiceHandler.handleMessage(IntentService.java:30) 04-08 11:56:20.467: ERROR/AndroidRuntime(6088): at android.os.Handler.dispatchMessage(Handler.java:99) 04-08 11:56:20.467: ERROR/AndroidRuntime(6088): at android.os.Looper.loop(Looper.java:123) 04-08 11:56:20.467: ERROR/AndroidRuntime(6088): at android.os.HandlerThread.run(HandlerThread.java:60) 04-08 11:56:20.496: INFO/Process(4657): Sending signal. PID: 6088 SIG: 3 I guess that as @DroidIn suggests, I need to upload it in chunks. But (newbie question alert) does that mean that I should make multiple PostMethod requests, and glue the file together at the server end? Or can I load the bytestream into memory in chunks, and glue it together in the Android code? If anyone could give me a clue as to the best approach, I would be very grateful.

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• CryptoExcercise Encryption/Decryption Problem

  - by venkat

  I am using apples "cryptoexcercise" (Security.Framework) in my application to encrypt and decrypt a data of numeric value. When I give the input 950,128 the values got encrypted, but it is not getting decrypted and exists with the encrypted value only. This happens only with the mentioned numeric values. Could you please check this issue and give the solution to solve this problem? here is my code (void)testAsymmetricEncryptionAndDecryption { uint8_t *plainBuffer; uint8_t *cipherBuffer; uint8_t *decryptedBuffer; const char inputString[] = "950"; int len = strlen(inputString); if (len > BUFFER_SIZE) len = BUFFER_SIZE-1; plainBuffer = (uint8_t *)calloc(BUFFER_SIZE, sizeof(uint8_t)); cipherBuffer = (uint8_t *)calloc(CIPHER_BUFFER_SIZE, sizeof(uint8_t)); decryptedBuffer = (uint8_t *)calloc(BUFFER_SIZE, sizeof(uint8_t)); strncpy( (char *)plainBuffer, inputString, len); NSLog(@"plain text : %s", plainBuffer); [self encryptWithPublicKey:(UInt8 *)plainBuffer cipherBuffer:cipherBuffer]; NSLog(@"encrypted data: %s", cipherBuffer); [self decryptWithPrivateKey:cipherBuffer plainBuffer:decryptedBuffer]; NSLog(@"decrypted data: %s", decryptedBuffer); free(plainBuffer); free(cipherBuffer); free(decryptedBuffer); } (void)encryptWithPublicKey:(uint8_t *)plainBuffer cipherBuffer:(uint8_t *)cipherBuffer { OSStatus status = noErr; size_t plainBufferSize = strlen((char *)plainBuffer); size_t cipherBufferSize = CIPHER_BUFFER_SIZE; NSLog(@"SecKeyGetBlockSize() public = %d", SecKeyGetBlockSize([self getPublicKeyRef])); // Error handling // Encrypt using the public. status = SecKeyEncrypt([self getPublicKeyRef], PADDING, plainBuffer, plainBufferSize, &cipherBuffer[0], &cipherBufferSize ); NSLog(@"encryption result code: %d (size: %d)", status, cipherBufferSize); NSLog(@"encrypted text: %s", cipherBuffer); } (void)decryptWithPrivateKey:(uint8_t *)cipherBuffer plainBuffer:(uint8_t *)plainBuffer { OSStatus status = noErr; size_t cipherBufferSize = strlen((char *)cipherBuffer); NSLog(@"decryptWithPrivateKey: length of buffer: %d", BUFFER_SIZE); NSLog(@"decryptWithPrivateKey: length of input: %d", cipherBufferSize); // DECRYPTION size_t plainBufferSize = BUFFER_SIZE; // Error handling status = SecKeyDecrypt([self getPrivateKeyRef], PADDING, &cipherBuffer[0], cipherBufferSize, &plainBuffer[0], &plainBufferSize ); NSLog(@"decryption result code: %d (size: %d)", status, plainBufferSize); NSLog(@"FINAL decrypted text: %s", plainBuffer); } (SecKeyRef)getPublicKeyRef { OSStatus sanityCheck = noErr; SecKeyRef publicKeyReference = NULL; if (publicKeyRef == NULL) { NSMutableDictionary *queryPublicKey = [[NSMutableDictionary alloc] init]; // Set the public key query dictionary. [queryPublicKey setObject:(id)kSecClassKey forKey:(id)kSecClass]; [queryPublicKey setObject:publicTag forKey:(id)kSecAttrApplicationTag]; [queryPublicKey setObject:(id)kSecAttrKeyTypeRSA forKey:(id)kSecAttrKeyType]; [queryPublicKey setObject:[NSNumber numberWithBool:YES] forKey:(id)kSecReturnRef]; // Get the key. sanityCheck = SecItemCopyMatching((CFDictionaryRef)queryPublicKey, (CFTypeRef *)&publicKeyReference); if (sanityCheck != noErr) { publicKeyReference = NULL; } [queryPublicKey release]; } else { publicKeyReference = publicKeyRef; } return publicKeyReference; } (SecKeyRef)getPrivateKeyRef { OSStatus resultCode = noErr; SecKeyRef privateKeyReference = NULL; if(privateKeyRef == NULL) { NSMutableDictionary * queryPrivateKey = [[NSMutableDictionary alloc] init]; // Set the private key query dictionary. [queryPrivateKey setObject:(id)kSecClassKey forKey:(id)kSecClass]; [queryPrivateKey setObject:privateTag forKey:(id)kSecAttrApplicationTag]; [queryPrivateKey setObject:(id)kSecAttrKeyTypeRSA forKey:(id)kSecAttrKeyType]; [queryPrivateKey setObject:[NSNumber numberWithBool:YES] forKey:(id)kSecReturnRef]; // Get the key. resultCode = SecItemCopyMatching((CFDictionaryRef)queryPrivateKey, (CFTypeRef *)&privateKeyReference); NSLog(@"getPrivateKey: result code: %d", resultCode); if(resultCode != noErr) { privateKeyReference = NULL; } [queryPrivateKey release]; } else { privateKeyReference = privateKeyRef; } return privateKeyReference; }

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• How to use pipes for nonblocking IPC (UART emulation)

  - by codebauer

  I would like to write some test/emulation code that emulates a serial port connection. The real code looks like this: DUT <- UART - testtool.exe My plan is to use create a test application (CodeUnderTest.out) on linux that forks to launch testool.out with two (read & write) named pipes as arguments. But I cannot figure out how to make all the pipe IO non-blocking! The setup would look like this:. CodeUnderTest.out <- named pipes - testTool.out (lauched from CodeUnderTest.out) I have tried opening the pipes as following: open(wpipe,O_WRONLY|O_NONBLOCK); open(rpipe,O_RDONLY|O_NONBLOCK); But the write blocks until the reader opens the wpipe. Next I tried the following: open(wpipe,O_RDWR|O_NONBLOCK); open(rpipe,O_RDONLY|O_NONBLOCK); But then the reader of the first message never gets any data (doesn't block though) I also tried adding open and close calls around each message, but that didn't work either... Here is some test code: #include <stdio.h> #include <sys/types.h> #include <unistd.h> #include <fcntl.h> pid_t pid; char* rpipe, *wpipe,*x; FILE *rh,*wh; int rfd,wfd; void openrpipe( void ) { rfd = open(rpipe,O_RDONLY|O_NONBLOCK); rh = fdopen(rfd,"rb"); printf("%sopeningr %x\n",x,rh); } void openwpipe( void ) { //Fails when reader not already opened //wfd = open(wpipe,O_WRONLY|O_NONBLOCK); wfd = open(wpipe,O_RDWR|O_NONBLOCK); wh = fdopen(wfd,"wb"); printf("%sopeningw %x\n",x,wh); } void closerpipe( void ) { int i; i = fclose(rh); printf("%sclosingr %d\n",x,i); } void closewpipe( void ) { int i; i = fclose(wh); printf("%sclosingw %d\n",x,i); } void readpipe( char* expect, int len) { char buf[1024]; int i=0; printf("%sreading\n",x); while(i==0) { //printf("."); i = fread(buf,1,len,rh); } printf("%sread (%d) %s\n",x,i,buf); } void writepipe( char* data, int len) { int i,j; printf("%swriting\n",x); i = fwrite(data,1,len,rh); j = fflush(rh); //No help! printf("%sflush %d\n",x,j); printf("%swrite (%d) %s\n",x,i,data); } int main(int argc, char **argv) { rpipe = "readfifo"; wpipe = "writefifo"; x = ""; pid = fork(); if( pid == 0) { wpipe = "readfifo"; rpipe = "writefifo"; x = " "; openrpipe(); openwpipe(); writepipe("paul",4); readpipe("was",3); writepipe("here",4); closerpipe(); closewpipe(); exit(0); } openrpipe(); openwpipe(); readpipe("paul",4); writepipe("was",3); readpipe("here",4); closerpipe(); closewpipe(); return( -1 ); } BTW: To use the testocd above you need to pipes in the cwd: mkfifo ./readfifo mkfifo ./writefifo

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• Best style for Python programs: what do you suggest?

  - by Noctis Skytower

  A friend of mine wanted help learning to program, so he gave me all the programs that he wrote for his previous classes. The last program that he wrote was an encryption program, and after rewriting all his programs in Python, this is how his encryption program turned out (after adding my own requirements). #! /usr/bin/env python ################################################################################ """\ CLASS INFORMATION ----------------- Program Name: Program 11 Programmer: Stephen Chappell Instructor: Stephen Chappell for CS 999-0, Python Due Date: 17 May 2010 DOCUMENTATION ------------- This is a simple encryption program that can encode and decode messages.""" ################################################################################ import sys KEY_FILE = 'Key.txt' BACKUP = '''\ !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNO\ PQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~ _@/6-UC'GzaV0%5Mo9g+yNh8b">Bi=<Lx [sQn#^R.D2Xc(\ Jm!4e${lAEWud&t7]H\`}pvPw)FY,Z~?qK|3SOfk*:1;jTrI''' ################################################################################ def main(): "Run the program: loads key, runs processing loop, and saves key." encode_map, decode_map = load_key(KEY_FILE) try: run_interface_loop(encode_map, decode_map) except SystemExit: pass save_key(KEY_FILE, encode_map) def run_interface_loop(encode_map, decode_map): "Shows the menu and runs the appropriate command." print('This program handles encryption via a customizable key.') while True: print('''\ MENU ==== (1) Encode (2) Decode (3) Custom (4) Finish''') switch = get_character('Select: ', tuple('1234')) FUNC[switch](encode_map, decode_map) def get_character(prompt, choices): "Gets a valid menu option and returns it." while True: sys.stdout.write(prompt) sys.stdout.flush() line = sys.stdin.readline()[:-1] if not line: sys.exit() if line in choices: return line print(repr(line), 'is not a valid choice.') ################################################################################ def load_key(filename): "Gets the key file data and returns encoding/decoding dictionaries." plain, cypher = open_file(filename) return dict(zip(plain, cypher)), dict(zip(cypher, plain)) def open_file(filename): "Load the keys and tries to create it when not available." while True: try: with open(filename) as file: plain, cypher = file.read().split('\n') return plain, cypher except: with open(filename, 'w') as file: file.write(BACKUP) def save_key(filename, encode_map): "Dumps the map into two buffers and saves them to the key file." plain = cypher = str() for p, c in encode_map.items(): plain += p cypher += c with open(filename, 'w') as file: file.write(plain + '\n' + cypher) ################################################################################ def encode(encode_map, decode_map): "Encodes message for the user." print('Enter your message to encode (EOF when finished).') message = get_message() for char in message: sys.stdout.write(encode_map[char] if char in encode_map else char) def decode(encode_map, decode_map): "Decodes message for the user." print('Enter your message to decode (EOF when finished).') message = get_message() for char in message: sys.stdout.write(decode_map[char] if char in decode_map else char) def custom(encode_map, decode_map): "Allows user to edit the encoding/decoding dictionaries." plain, cypher = get_new_mapping() for p, c in zip(plain, cypher): encode_map[p] = c decode_map[c] = p ################################################################################ def get_message(): "Gets and returns text entered by the user (until EOF)." buffer = [] while True: line = sys.stdin.readline() if line: buffer.append(line) else: return ''.join(buffer) def get_new_mapping(): "Prompts for strings to edit encoding/decoding maps." while True: plain = get_unique_chars('What do you want to encode from?') cypher = get_unique_chars('What do you want to encode to?') if len(plain) == len(cypher): return plain, cypher print('Both lines should have the same length.') def get_unique_chars(prompt): "Gets strings that only contain unique characters." print(prompt) while True: line = input() if len(line) == len(set(line)): return line print('There were duplicate characters: please try again.') ################################################################################ # This map is used for dispatching commands in the interface loop. FUNC = {'1': encode, '2': decode, '3': custom, '4': lambda a, b: sys.exit()} ################################################################################ if __name__ == '__main__': main() For all those Python programmers out there, your help is being requested. How should the formatting (not necessarily the coding by altered to fit Python's style guide? My friend does not need to be learning things that are not correct. If you have suggestions on the code, feel free to post them to this wiki as well.

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• Differing styles in Python program: what do you suggest?

  - by Noctis Skytower

  A friend of mine wanted help learning to program, so he gave me all the programs that he wrote for his previous classes. The last program that he wrote was an encryption program, and after rewriting all his programs in Python, this is how his encryption program turned out (after adding my own requirements). #! /usr/bin/env python ################################################################################ """\ CLASS INFORMATION ----------------- Program Name: Program 11 Programmer: Stephen Chappell Instructor: Stephen Chappell for CS 999-0, Python Due Date: 17 May 2010 DOCUMENTATION ------------- This is a simple encryption program that can encode and decode messages.""" ################################################################################ import sys KEY_FILE = 'Key.txt' BACKUP = '''\ !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNO\ PQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~ _@/6-UC'GzaV0%5Mo9g+yNh8b">Bi=<Lx [sQn#^R.D2Xc(\ Jm!4e${lAEWud&t7]H\`}pvPw)FY,Z~?qK|3SOfk*:1;jTrI''' ################################################################################ def main(): "Run the program: loads key, runs processing loop, and saves key." encode_map, decode_map = load_key(KEY_FILE) try: run_interface_loop(encode_map, decode_map) except SystemExit: pass save_key(KEY_FILE, encode_map) def run_interface_loop(encode_map, decode_map): "Shows the menu and runs the appropriate command." print('This program handles encryption via a customizable key.') while True: print('''\ MENU ==== (1) Encode (2) Decode (3) Custom (4) Finish''') switch = get_character('Select: ', tuple('1234')) FUNC[switch](encode_map, decode_map) def get_character(prompt, choices): "Gets a valid menu option and returns it." while True: sys.stdout.write(prompt) sys.stdout.flush() line = sys.stdin.readline()[:-1] if not line: sys.exit() if line in choices: return line print(repr(line), 'is not a valid choice.') ################################################################################ def load_key(filename): "Gets the key file data and returns encoding/decoding dictionaries." plain, cypher = open_file(filename) return dict(zip(plain, cypher)), dict(zip(cypher, plain)) def open_file(filename): "Load the keys and tries to create it when not available." while True: try: with open(filename) as file: plain, cypher = file.read().split('\n') return plain, cypher except: with open(filename, 'w') as file: file.write(BACKUP) def save_key(filename, encode_map): "Dumps the map into two buffers and saves them to the key file." plain = cypher = str() for p, c in encode_map.items(): plain += p cypher += c with open(filename, 'w') as file: file.write(plain + '\n' + cypher) ################################################################################ def encode(encode_map, decode_map): "Encodes message for the user." print('Enter your message to encode (EOF when finished).') message = get_message() for char in message: sys.stdout.write(encode_map[char] if char in encode_map else char) def decode(encode_map, decode_map): "Decodes message for the user." print('Enter your message to decode (EOF when finished).') message = get_message() for char in message: sys.stdout.write(decode_map[char] if char in decode_map else char) def custom(encode_map, decode_map): "Allows user to edit the encoding/decoding dictionaries." plain, cypher = get_new_mapping() for p, c in zip(plain, cypher): encode_map[p] = c decode_map[c] = p ################################################################################ def get_message(): "Gets and returns text entered by the user (until EOF)." buffer = [] while True: line = sys.stdin.readline() if line: buffer.append(line) else: return ''.join(buffer) def get_new_mapping(): "Prompts for strings to edit encoding/decoding maps." while True: plain = get_unique_chars('What do you want to encode from?') cypher = get_unique_chars('What do you want to encode to?') if len(plain) == len(cypher): return plain, cypher print('Both lines should have the same length.') def get_unique_chars(prompt): "Gets strings that only contain unique characters." print(prompt) while True: line = input() if len(line) == len(set(line)): return line print('There were duplicate characters: please try again.') ################################################################################ # This map is used for dispatching commands in the interface loop. FUNC = {'1': encode, '2': decode, '3': custom, '4': lambda a, b: sys.exit()} ################################################################################ if __name__ == '__main__': main() For all those Python programmers out there, your help is being requested. How should the formatting (not necessarily the coding by altered to fit Python's style guide? My friend does not need to be learning things that are not correct. If you have suggestions on the code, feel free to post them to this wiki as well.

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• Want to Receive dynamic length data from a message queue in IPC?

  - by user1089679

  Here I have to send and receive dynamic data using a SysV message queue. so in structure filed i have dynamic memory allocation char * because its size may be varies. so how can i receive this type of message at receiver side. Please let me know how can i send dynamic length of data with message queue. I am getting problem in this i posted my code below. send.c /*filename : send.c *To compile : gcc send.c -o send */ #include <stdio.h> #include <stdlib.h> #include <errno.h> #include <string.h> #include <sys/types.h> #include <sys/ipc.h> #include <sys/msg.h> struct my_msgbuf { long mtype; char *mtext; }; int main(void) { struct my_msgbuf buf; int msqid; key_t key; static int count = 0; char temp[5]; int run = 1; if ((key = ftok("send.c", 'B')) == -1) { perror("ftok"); exit(1); } printf("send.c Key is = %d\n",key); if ((msqid = msgget(key, 0644 | IPC_CREAT)) == -1) { perror("msgget"); exit(1); } printf("Enter lines of text, ^D to quit:\n"); buf.mtype = 1; /* we don't really care in this case */ int ret = -1; while(run) { count++; buf.mtext = malloc(50); strcpy(buf.mtext,"Hi hello test message here"); snprintf(temp, sizeof (temp), "%d",count); strcat(buf.mtext,temp); int len = strlen(buf.mtext); /* ditch newline at end, if it exists */ if (buf.mtext[len-1] == '\n') buf.mtext[len-1] = '\0'; if (msgsnd(msqid, &buf, len+1, IPC_NOWAIT) == -1) /* +1 for '\0' */ perror("msgsnd"); if(count == 100) run = 0; usleep(1000000); } if (msgctl(msqid, IPC_RMID, NULL) == -1) { perror("msgctl"); exit(1); } return 0; } receive.c /* filename : receive.c * To compile : gcc receive.c -o receive */ #include <stdio.h> #include <stdlib.h> #include <errno.h> #include <sys/types.h> #include <sys/ipc.h> #include <sys/msg.h> struct my_msgbuf { long mtype; char *mtext; }; int main(void) { struct my_msgbuf buf; int msqid; key_t key; if ((key = ftok("send.c", 'B')) == -1) { /* same key as send.c */ perror("ftok"); exit(1); } if ((msqid = msgget(key, 0644)) == -1) { /* connect to the queue */ perror("msgget"); exit(1); } printf("test: ready to receive messages, captain.\n"); for(;;) { /* receive never quits! */ buf.mtext = malloc(50); if (msgrcv(msqid, &buf, 50, 0, 0) == -1) { perror("msgrcv"); exit(1); } printf("test: \"%s\"\n", buf.mtext); } return 0; }

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• (This is for a project, so yes it is homework) How would I finish this java code?

  - by user2924318

  The task is to create arrays using user input (which I was able to do), then for the second part, use a separate method to sort the array in ascending order then output it. I have gotten it to do everything I need except I don't know how I would get it to sort. The directions say to use a while loop from 0 to the length to find the minimum value then swap that with the 1st, but I don't know how to do this. This is what I have so far: public static void main(String[] args) { Scanner in = new Scanner(System.in); int storage = getNumDigits(in); if(storage == 0){ System.out.print("No digits to store? OK, goodbye!"); System.exit(0); } int []a = new int [storage]; a = getDigits(a, in); displayDigits(a); selectionSort(a); } private static int getNumDigits(Scanner inScanner) { System.out.print("Please enter the number of digits to be stored: "); int stored = inScanner.nextInt(); while(stored < 0){ System.out.println("ERROR! You must enter a non-negative number of digits!"); System.out.println(); System.out.print("Please enter the number of digits to be stored: "); stored = inScanner.nextInt(); } return stored; } private static int[] getDigits(int[] digits, Scanner inScanner) { int length = digits.length; int count = 0; int toBeStored = 0; while(count < length){ System.out.print("Enter integer " +count +": "); toBeStored = inScanner.nextInt(); digits[count] = toBeStored; count++; } return digits; } private static void displayDigits(int[] digits) { int len = digits.length; System.out.println(); System.out.println("Array before sorting:"); System.out.println("Number of digits in array: " +len); System.out.print("Digits in array: "); for(int cnt = 0; cnt < len-1; cnt++){ System.out.print(digits[cnt] + ", "); } System.out.println(digits[len-1]); } private static void selectionSort(int[] digits) { int l = digits.length; System.out.println(); System.out.println("Array after sorting:"); System.out.println("Number of digits in array: " +l); System.out.print("Digits in array: "); int index = 0; int value = digits[0]; int indVal = digits[index]; while(index < l){ indVal = digits[index]; if(indVal <= value){ indVal = value; digits[index] = value; index++; } else if(value < indVal){ index++; } System.out.print(value); //This is where I don't know what to do. } }

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• Function currying in Javascript

  - by kerry

  Do you catch yourself doing something like this often? 1: Ajax.request('/my/url', {'myParam': paramVal}, function() { myCallback(paramVal); }); Creating a function which calls another function asynchronously is a bad idea because the value of paramVal may change before it is called.  Enter the curry function: 1: Function.prototype.curry = function(scope) { 2: var args = []; 3: for (var i=1, len = arguments.length; i < len; ++i) { 4: args.push(arguments[i]); 5: } 6: var m = this; 7: return function() { 8: m.apply(scope, args); 9: }; 10: } This function creates a wrapper around the function and ‘locks in’ the method parameters.  The first parameter is the scope of the function call (usually this or window).  Any remaining parameters will be passed to the method call.  Using the curry method the above call changes to: 1: Ajax.request('/my/url', {'myParam': paramVal}, myCallback.curry(window,paramVal)); Remember when passing objects to the curry method that the objects members may still change.

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• Correct For Loop Design

  - by Yttrill

  What is the correct design for a for loop? Felix currently uses if len a > 0 do for var i in 0 upto len a - 1 do println a.[i]; done done which is inclusive of the upper bound. This is necessary to support the full range of values of a typical integer type. However the for loop shown does not support zero length arrays, hence the special test, nor will the subtraction of 1 work convincingly if the length of the array is equal to the number of integers. (I say convincingly because it may be that 0 - 1 = maxval: this is true in C for unsigned int, but are you sure it is true for unsigned char without thinking carefully about integral promotions?) The actual implementation of the for loop by my compiler does correctly handle 0 but this requires two tests to implement the loop: continue: if not (i <= bound) goto break body if i == bound goto break ++i goto continue break: Throw in the hand coded zero check in the array example and three tests are needed. If the loop were exclusive it would handle zero properly, avoiding the special test, but there'd be no way to express the upper bound of an array with maximum size. Note the C way of doing this: for(i=0; predicate(i); increment(i)) has the same problem. The predicate is tested after the increment, but the terminating increment is not universally valid! There is a general argument that a simple exclusive loop is enough: promote the index to a large type to prevent overflow, and assume no one will ever loop to the maximum value of this type.. but I'm not entirely convinced: if you promoted to C's size_t and looped from the second largest value to the largest you'd get an infinite loop!

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• Shuffling algorithm with no "self-mapping"?

  - by OregonTrail

  To randomly shuffle an array, with no bias towards any particular permutation, there is the Knuth Fischer-Yeats algorithm. In Python: #!/usr/bin/env python import sys from random import randrange def KFYShuffle(items): i = len(items) - 1 while i > 0: j = randrange(i+1) # 0 <= j <= i items[j], items[i] = items[i], items[j] i = i - 1 return items print KFYShuffle(range(int(sys.argv[1]))) There is also Sattolo's algorithm, which produces random cycles. In Python: #!/usr/bin/env python import sys from random import randrange def SattoloShuffle(items): i = len(items) while i > 1: i = i - 1 j = randrange(i) # 0 <= j <= i-1 items[j], items[i] = items[i], items[j] return items print SattoloShuffle(range(int(sys.argv[1]))) I'm currently writing a simulation with the following specifications for a shuffling algorithm: The algorithm is unbiased. If a true random number generator was used, no permutation would be more likely than any other. No number ends up at its original index. The input to the shuffle will always be A[i] = i for i from 0 to N-1 Permutations are produced that are not cycles, but still meet specification 2. The cycles produced by Sattolo's algorithm meet specification 2, but not specification 1 or 3. I've been working at creating an algorithm that meets these specifications, what I came up with was equivalent to Sattolo's algorithm. Does anyone have an algorithm for this problem?

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• check what process was causing the problem of high cpu load

  - by linuxk

  I'm running nginx wordpress server in KVM using 12.04 server x86. It was running very well about 4 month until 2 hours ago. I found that my website is down and no ping response. Virt-manager logged high cpu load(plz see the picture below) before unexpected shut down. I want to know what process caused unexpected shutdown. The following log files make me think my server is attacked. Any suggestions and help would be appreciated. kern.log and syslog showed me same output. Nov 11 03:54:11 www kernel: [1344541.156239] [UFW BLOCK] IN=eth0 OUT= MAC= SRC=0.0.0.0 DST=224.0. 0.1 LEN=32 TOS=0x00 PREC=0xC0 TTL=1 ID=0 DF PROTO=2 Nov 11 03:54:11 www kernel: [1344541.156315] [UFW BLOCK] IN=eth0 OUT= MAC= SRC=0101:080a:2334:c90 0:0100:0000:0000:0000 DST=ff02:0000:0000:0000:0000:0000:0000:0001 LEN=72 TC=0 HOPLIMIT=1 FLOWLBL=0 PROTO=ICMPv6 TYPE=130 CODE=0 /nginx/access.log showed me 119.235.237.17 - - [11/Nov/2012:03:45:29 +0900] "GET /blog HTTP/1.1" 200 30493 "-" "Yeti/1.0 (NHN Corp.; http://help.naver.com/robots/)" my-server-ip - - [11/Nov/2012:11:05:30 +0900] "POST /wp-cron.php?doing_wp_cron=13 HTTP/1.0" 499 0 "-" "WordPress/3.4.2; http://mywebsite.com" Server turned on in here. 119.235.237.16 - - [11/Nov/2012:11:05:30 +0900] "GET /blog HTTP/1.1" 200 32935 "-" "Yeti/1.0 (NHN Corp.; http://help.naver.com/robots/)"

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• Linear Search in Python? [closed]

  - by POTUS

  def find_interval(mesh,x): '''This function finds the interval containing x according to the following rules, mesh is an ordered list with n numbers return 0 if x < mesh[0] return n if mesh[n-1] < x return k if mesh[k-1] <= x < mesh[k] return n-1 if mesh[n-2] <= x <= mesh[n-1] This function does a Linear search. 08/29/2012 ''' for n in range(len(mesh)): for k in range(len(mesh)): if x == mesh[n]: print "Found x at index:" return n elif x<mesh[n]: return 0 elif mesh[n-1]<x: return n elif mesh[n-2]<=x<=mesh[n-1]: return n-1 elif mesh[k-1]<=x<mesh[k]: return k mesh = [0, 0.1, 0.25, 0.5, 0.6, 0.75, 0.9, 1] print mesh print find_interval(mesh, -1) print find_interval(mesh, 0) print find_interval(mesh, 0.1) print find_interval(mesh, 0.8) print find_interval(mesh, 0.9) print find_interval(mesh, 1) print find_interval(mesh, 1.01) Output: [0, 0.100000000000000, 0.250000000000000, 0.500000000000000, 0.600000000000000, 0.750000000000000, 0.900000000000000, 1] 0 Found x at index: 0 2 6 -1 -1 0 I don't think the output is correct. Can anyone help me fix it? Thanks.

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