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ReadWrite

The Noonification: Here Comes Web3: Chris Dixon’s Read Write Own (3/15/2024)

The World Wide Web, thank you Sir Tim, was conceived as a technology designed to be “ ” It has devolved from that into a (cyber)space of moated castles, Disneylandish . a powerful source for social change and individual creativity. cathedrals, not bazaars While very entertaining and very useful in many ways the hegemonic Web platforms present as artificial rather than organic, hierarchical rather than egalitarian. The Big Platforms are owned and managed by a handful of dominant, supervalued, companies. Prominent are Alphabet (Google’s parent) and Meta (Facebook’s parent). Low cost and high profit, they are great at informing and entertaining us. Meanwhile, however, in consequential ways they are beggaring those who provide the content and the users who consume that content. The top platforms are richly paid to channel advertising. To us. The Web has evolved into a massive, and massively profitable, advertising engine. As such, the Web now might be (and is becoming) seen as a form of de facto feudalism, digital imperialism, and digerati aristocracy. The attention of us billions of serfs is the product sold to advertisers. No coercion there. More like… seduction. Note, this critique does not imply a call for legislation or government regulation. Both tend to be blunt instruments that land much harder on startups than on the hegemons of the digital megaverse. It calls for transformation. Which will come, as always, , as Microsoft dethroned IBM, Google (partially) dethroned Microsoft, Facebook (partially) dethroned Google, Apple (partially) dethroned Facebook, and so forth. from more innovation How did we get here? Can we, and if so how can we, once again unleash the imprisoned lighting ( ) of the colonized Web to create a new golden age of innovation and equitable prosperity? h/t Emma Lazarus Enter the blockchain. First, though, who am I to judge? I am one of the few surviving Original Gangsters of the Supply Side/Reaganomics revolution. We, relentlessly mocked by the right (“voodoo economics”) and the left (“trickle-down economics”), got policies enacted that, over time , pushed the Dow from 814 (on that day in November 1979 that Reagan officially declared his candidacy for the presidency) to its current flirtation with 40,000. Our voodoo doubled real per capita GDP (from $30,000 to $60,000). It raised nominal American and world GDP by a factor of ten. Pretty good voodoo. That said, what’s the next act? The juice from the original equitable prosperity policy formula -- of stabilizing the dollar (slaying the inflation dragon for two generations and cutting the top marginal income tax rate from 70% to, initially, 28%) -- got wrung out around the time Bill Clinton left the building. I was and am enthusiastic about reducing counterproductively high marginal tax rates across-the-board. Yet much of what ensued in the name of supply-side during the 21st century is a cargo-cult version of supply-side’s successes of the ‘80s and ‘90s. The post-Reagan/Clinton grotesque caricature of authentic supply-side economics has left the economy limping for a generation. Cumulatively, over 20+ years, sub-par growth rates are crippling. They leave us with an economy, both national and personal, far lower than what consistent 3+% supply-side growth rates would have delivered over time. As , compound interest is the eighth wonder of the world.  A one or two percent differential compounded over 20 years makes a huge difference. Einstein probably never said Is there a new, plausible, way to re-ignite vibrant, widely shared, rising living standards? As Nobel Prize winner Paul Romer has pointed out, the secret sauce is innovation. Tech. Enter A16z’s , “a General Partner and has been at Andreessen Horowitz since 2012. He founded and leads a16z crypto, which invests in web3 technologies through four dedicated funds with more than $7 billion under management.” Chris Dixon Dixon has delivered a splendid new book . It lays out in clear, practical terms how the wild wild Web was lost. And how to set it right in such a way that everyone, including us serfs, can prosper. Read Write Own: Building the Next Era of the Internet As , prosperity is too important to be left to the economists. Enter Dixon. war is too important to be left to the generals How to restore sizzling, equitable, prosperity? The blockchain. The blockchain is a revolutionary form of software which, when more fully developed, portends to allow most of the value created by the community and by its cultural creatives to be enjoyed by the full community and its cultural creatives. Not (as now) exclusively, or at least primarily, by the corporate royalty and tech aristocracy. At long last, Dixon gives us a presentation of the blockchain and its properties imbued with an enthusiasm leavened with shrewd practical insight devoid of hype. Dixon is one of the Masters of the Digital Universe (as coder, entrepreneur, and investor). He knows whereof he writes and has written the first really great, comprehensive, book on the blockchain, . Read Write Own: Building the Next Era of the Internet Eureka! Dixon provides an overview in his introduction. He there provides us a World-Wide-Webb-telescopic-eye view of the three eras of the internet, of a new movement, of seeing the truth and determining the internet’s future. Part One, “Read Write”—treats the early internet, which was effectively read only, and Web2, allowing us surfers to write and post through websites, blogs, podcasts, social media and so forth. He explains why networks matter and lays out a trenchant taxonomy of the two dominant incumbent networks (protocol, like the internet and email, and corporate, such as Google and Facebook) and their properties. In Part Two, “Own,” Dixon then goes on to explain what blockchains are, what “tokens” are, and what the – radically great – properties of blockchain networks are… or could and can be. “Own” is a short word with huge implications. Ownership is what has been lost, and which can be restored via a (better) blockchain. In Part Three, “A New Era,” Dixon explains and explores the fundamentals of the business model, community-created software, and take rates (meaning the vigorish that the corporate network proprietors extract from their communities, a process he aptly calls “attract and extract”). He lays out how building networks with token incentives can dramatically change the way the world works for the better, making it more prosperous, cultured, and equitable. He presents vividly the attendant “tokenomics” … and how to restore popular, rather than corporate-autocratic, governance. In Part Four, “Here and Now”, he contrasts the culture of the computer (blockchain as compute platform) with the casino (cryptocurrency), concluding with “What’s Next” … showing how mobile computing, starting with the iPhone, changed everything. He then lays out “some promising applications.” Dixon concludes with a pragmatic vision of the reinvention of the internet… and what grounds his cause for optimism. Until Dixon, in many years of my searching, like Diogenes with his lantern, I had encountered not one single really good, comprehensive, book on the blockchain. (I may have missed one, admittedly, for instance, not yet having gotten to Alex Tapscott’s critically acclaimed .) Web3 There I rested, baffled. So much sizzle. So little steak. So, together with a brilliant acquaintance, I helped write one: . That said, it mainly was focused on the potential finance applications of the blockchain, not the Big Picture. Redefining the Future of the Economy: Governance Blocks and Economic Architecture I thereafter co-authored a second book on this subject, , a compilation of ten superior policies designed to let the sector thrive while protecting the public. Blockchain With American Character It took a long odyssey to arrive at Dixon. I wandered around for years asking people vastly smarter than me what the blockchain was good for and seeking examples of killer applications (“use cases” in the prevailing jargon). In response, I got oodles of hype. And almost no satisfying answers … with one exception, though a largely unpublished one. noteworthy Cometh now Chris Dixon. I am not the only one impressed. Sam Altman, the godfather of ChatGPT, blurbs Read Write Own: “Read this book to understand a compelling vision of where the Internet should go and how to get there.” Shark Tank’s Mark Cuban: “Chris Dixon succeeds at explaining how crypto technology is vital to our technological future and how we all can benefit much as we have from the internet.” And many more captains of industry, tech titans, and nouveau billionaires discovered Dixon’s writings before I did. My own modest credentials? I have been working within and with the Blockchain ecosystem for, well, eons. One of my LinkedIn verticals is aggregating some of the most interesting stories about NFTs. Ralph Benko’s Cryptozoic Eon Geology nerds will recognize the original to be the pre-Cambrian era … before the trilobites and dinosaurs... comprising 80% of Earth’s geo-history. Are we trembling at the verge of the blockchain’s equivalent of the ? Cryptozoic Eon Cambrian explosion Dixon thinks so. So do I. Call me yet my odyssey through the blockchain ecosystem has brought me into contact with creatures and cultures as exotically beautiful and, sometimes, as weird as those encountered by Odysseus during his long return to Ithaka. Nobody My own pilgrimage: Senior advisor to the fabulous Perianne Boring’s Chamber of Digital Commerce, one of the sector’s earliest and most distinguished cheerleaders. Long-time active member of the Federal Blockchain Working Group. Privileged to present more than once at the conferences of the , the preeminent association of officials and international career civil servants. Government Blockchain Association Serving, for two years, as the senior counselor to the American Blockchain PAC, with its advisory board chaired by who generously contributed the introduction to . The breakthrough nature of Stornetta and Haber’s discovery is decisively evidenced by the fact that three of Satoshi’s eight footnotes referenced his and Stuart Haber’s . blockchain-co-inventor Dr. W. Scott Stornetta Blockchain With American Character seminal paper The high privilege of working with one of Satoshi’s earliest Bitcoin core devs (and major contributor to the Android OS) in establishing a DC think tank devoted to smart energy policy, . Jeff Garzik Washington Power and Light Voted Contributor of the Year in 2022 at for my blockchain writings in six categories: politics, economics, science, art, philosophy, and (with Greg Meredith) scaling. HackerNoon My blockchain-related efforts have migrated primarily to the , rather than policy, side. enterprise My primary focus is on the use of rho calculus (a refinement of Robin Milner’s Turing Award-winning pi-calculus) to deploy a blockchain that, unlike the dominant platforms, scales. Bitcoin does a mere 7 transactions per second, Ethereum, 70 transactions per second. Inadequate for practical utility. And expensive to operate. And storable. (Currently it costs almost half a million dollars to store one iTune on the dominant incumbent chains, hence the referenced data are mostly stashed behind someone else’s firewall, not at all optimal.) And searchable. (Currently the dominant blockchains are largely opaque, like the Web before search engines.) And secure. So … now what? Dixon is a true Master of the Blockchain Universe. Not (like me) a practiced propagandist. Thus he buries his lede on page 179: “The stakes are high. As I’ve argued here, blockchain networks are the only known technology that can re-establish an open, democratic internet.” Hello Congress my old friend, I’ve come to talk to you again…. This re-establishment is a very big deal indeed. What’s next? For the tantalizing promise of the blockchain to be realized we need smart policy that protects the public while not stifling innovation or exporting this cutting-edge tech, and the potentially trillions of associated dollars, to Berlin, Singapore or Zug. Imagine how worse off America would be today if Congress and our regulators had effectively deported the headquarters of the big Web success stories, like Google, to Europe or the Pacific? The need for a savvy legal and regulatory environment is something that legislators, regulators, and the ethical actors within the industry (like Dixon) all agree upon. Yet Washington has thus far proved mostly thrown, acting like the primates upon encountering the monolith at the beginning of . 2001: a Space Odyssey We’re at the precipice of deporting Web3 and its associated power, prestige and wealth. That may be about to change. The blockchain’s thought leaders are at long last gearing up to help guide the footsteps of the Washington elite back onto the Paths of Righteousness via smart policy, smart legislation, and smart regulation. Some very smart leaders of the blockchain ecosystem are now promising to , a modest investment in support a multi-billion dollar sector. invest $78M in lobbying and advocacy in 2024 The open question? Will they deploy their resources effectively? Or be taken in by the wily Beltway Bandits? What to do? Those of us who remember C.P. Snow’s seminal understand that the “physical scientists” (which would include software engineers, notwithstanding that software is, so to speak, metaphysical) among whom I count myself as a very lesser figure do not really understand the “literary intellectuals” (among whom I also count myself in a very minor way). The Two Cultures And The Scientific Revolution This misunderstanding causes a terrible disconnect. As Snow reported, in 1959: “They have a curious distorted image of each other. Their attitudes are so different that, even at the level of emotion, they can’t find much common ground.” This can be countered… if the blockchain thought leaders know how to adopt an effective approach. There is abundant potential common ground. Dixon’s book offers a “ ” – the brain’s bridge connecting the left (logical, dominating the physical scientists) and right (narrative-based, dominating the literary intellectuals) hemispheres – to enable both sides to understand each other. corpus callosum To their mutual, and our, great benefit. There’s a simple way to expedite this process, one with a high ROI. Were the thought leaders of the $78M blockchain advocacy effort to allocate an absurdly small fraction (less than 1%) of their dedicated resources to distributing two copies (one for the Congressperson or Senator, one for his or her most relevant legislative aide) of Read Write Own, the impact almost surely will be disproportionately valuable compared to the low cost of such an operation. How do I know? I’ve pretty much single-handedly gotten (non-blockchain related) legislation passed through the House. Twice. There are a lot of smart, idealistic, people working on Capitol Hill, many actively interested in the blockchain and in its tantalizing potential. Put Read Write Own in front of them! The power of can hardly be overestimated: Joseph Pulitzer’s principles “…put it before them briefly so that they will read it, clearly so that they will understand it, forcibly so that they will appreciate it, picturesquely so that they will remember it, and, above all, accurately so that they may be wisely guided by its light.” The late supply-side chief propagandist Jude Wanniski’s book “The Way the World Works” played an outsized role in igniting the worldwide wave of unprecedented equitable prosperity driven by supply-side economics. This arcane fact is mostly long forgotten. That said, I was there and remember. In the , “And I only am escaped alone to tell thee.” words of Ishmael Read Write Own, properly deployed, very well could catalyze a comparably magnificent equitable prosperity transformation. Putting Dixon’s Read Write Own in front of the right eyeballs in the right way on Capitol Hill, could very well release the djinn of “the only known technology that can re-establish an open, democratic internet” from its lamp. Which eyeballs? Don’t try to guess. Simply trust the process known as “ as described by James Surowiecki. the wisdom of crowds” Flood the zone and let the implicate order take it from there. And then … let a new golden age of equitable prosperity, via the road thereto so ably mapped out by Dixon, foment well-designed policy and thereby foster the next great manifestation of equitable prosperity for America. And the world. Read. Write. Own.

Here Comes Web3: Chris Dixon’s Read Write Own

এখানে আসে ওয়েব 3: ক্রিস ডিক্সনের পড়া লেখা নিজস্ব

Hier kommt Web3: Chris Dixons Read Write Own

Aquí viene Web3: Lectura y escritura propia de Chris Dixon

Voici le Web3 : Lire, écrire et posséder de Chris Dixon

यहाँ आता है वेब3: क्रिस डिक्सन का पढ़ें लिखें अपना

Web3 の登場: Chris Dixon の Read Write Own

Web3 출시: Chris Dixon의 읽기 쓰기

Aí vem a Web3: Read Write Own de Chris Dixon

А вот и Web3: книга Криса Диксона «Читайте, пишите сами»

İşte Web3 Geliyor: Chris Dixon'ın Oku Yaz Kendin Yaz

Đây là Web3: Tự đọc và viết của Chris Dixon

Web3 来了：Chris Dixon 的 Read Write Own

Read/write splitting is a technique to route reads and writes to multiple database servers, allowing you to perform query-based load balancing. Implementing this at the application level is hard because it couples code or configuration parameters to the underlying database topology. For example, you might have to define different for each server in the database cluster. connection pools MariaDB MaxScale is an advanced database proxy that can be used as a read/write splitter that routes statements to replica nodes and / / statements to primary nodes. This happens automatically without having to change your application code or even configuration—with MaxScale, the database looks like a single-node database to your application. SELECT INSERT UPDATE DELETE In this hands-on tutorial, you’ll learn how to configure MariaDB database replication with one primary and two replica nodes, as well as how to set up MaxScale to hide the complexity of the underlying . The best part: you’ll learn all this without leaving your web browser! topology The Play With Docker Website (PWD) is a website that allows you to create virtual machines with preinstalled and interact with them directly in your browser. Log in and start a new session. Play With Docker Docker You will use a total of 5 nodes: : Primary server node1 : Replica server A node2 : Replica server B node3 : MaxScale database proxy node4 : Test machine (equivalent to a web server, for example) node5 : Even though are a good fit for the most simple scenarios and for development environments, it might not be the best option for production environments. MariaDB Corporation does not currently offer support for Docker deployments in production environments. For production environments, it is recommended to use MariaDB Enterprise (on the cloud or on-premise) or MariaDB SkySQL (currently available on AWS and GCP). Note databases on Docker containers Running the Primary Server Add a new instance using the corresponding button: On , run a MariaDB primary server as follows: node1 docker run --name mariadb-primary \
  -d \
  --net=host \
  -e MARIADB_ROOT_PASSWORD=password \
  -e MARIADB_DATABASE=demo \
  -e MARIADB_USER=user \
  -e MARIADB_PASSWORD=password \
  -e MARIADB_REPLICATION_MODE=master \
  -e MARIADB_REPLICATION_USER=replication_user \
  -e MARIADB_REPLICATION_PASSWORD=password \
  bitnami/mariadb:latest This configures a container running MariaDB Community Server with a database user for replication ( ). Replicas will use this user to connect to the primary. replication_user Running the Replica Servers Create two new instances ( and ) and run the following command on both of them: node2 node3 docker run --name mariadb-replica \
  -d \
  --net=host \
  -e MARIADB_MASTER_ROOT_PASSWORD=password \
  -e MARIADB_REPLICATION_MODE=slave \
  -e MARIADB_REPLICATION_USER=replication_user \
  -e MARIADB_REPLICATION_PASSWORD=password \
  -e MARIADB_MASTER_HOST=<PRIMARY_IP_ADDRESS> \
  bitnami/mariadb:latest Replace with the IP address of . You can find the IP address in the instances list. <PRIMARY_IP_ADDRESS> node1 Now you have a cluster formed by one primary node and two replicas. All the writes you perform on the primary node ( ) are automatically replicated to all replica nodes ( and ). node1 node1 node2 Running MaxScale MaxScale is a that understands . This allows it to route write operations to the master node and read operations to the replicas in a load-balanced fashion. Your application can connect to MaxScale using a single endpoint as if it was a one-node database. database proxy SQL Create a new instance ( ) and run as follows: node4 MaxScale docker run --name maxscale \
  -d  \
  --publish 4000:4000 \
  mariadb/maxscale:latest You can configure MaxScale through config files, but in this tutorial, we’ll use the command line to make sure you understand each step. In less ephemeral environments you should use config files, especially in orchestrated deployments such as and . Docker Swarm Kubernetes Launch a new shell in : node4 docker exec -it maxscale bash You need to create objects in MaxScale. These are the MariaDB databases to which MaxScale routes reads and writes. Replace , , and with the IP addresses of the corresponding nodes ( , , and ) and execute the following: server <NODE_1_IP_ADDRESS> <NODE_2_IP_ADDRESS> <NODE_3_IP_ADDRESS> node1 node2 node3 maxctrl create server node1 <NODE_1_IP_ADDRESS>
maxctrl create server node2 <NODE_2_IP_ADDRESS>
maxctrl create server node3 <NODE_3_IP_ADDRESS> Next, you need to create a MaxScale to check the state of the cluster. Run the following command: monitor maxctrl create monitor mdb_monitor mariadbmon \
    --monitor-user root --monitor-password 'password' \
    --servers node1 node2 node3 Don’t use the user in production environments! It’s okay in this ephemeral lab environment, but in other cases and give it the appropriate grants. Note: root create a new database user for MaxScale Now that MaxScale is monitoring the servers and making this information available to other modules, you can create a MaxScale . In this case, the service uses a MaxScale router to make reads and writes go to the correct type of server in the cluster (primary or replica). Run the following to create a new service: service maxctrl create service query_router_service readwritesplit \
    user=root \
    password=password \
    --servers node1 node2 node3 Finally, you need to create a MaxScale . This kind of object defines a port that MaxScale uses to receive requests. You have to associate the listener with the router. Run the following to create a new listener: listener maxctrl create listener \
    query_router_service query_router_listener 4000 \
    --protocol=MariaDBClient Notice how the listener is configured to use port . This is the same port you published when you run the Docker container. 4000 Check that the servers are up and running: maxctrl list servers You should see something like the following: Testing the Setup To test the cluster, create a new instance ( ) and start an Ubuntu container: node5 docker run --name ubuntu -itd ubuntu This container is equivalent to, for example, a machine that hosts a web application that connects to the database. Run a new Bash session in the machine: docker exec -it ubuntu bash Update the package catalog: apt update Install the MariaDB SQL client so you can run SQL code: apt install mariadb-client -y Connect to the database, or more precisely, to the MaxScale database proxy: mariadb -h 192.168.0.15 --port 4000 -u user -p As you can see, it’s as if MaxScale was a single database. Create the following table: MariaDB SQL CREATE TABLE demo.message(content TEXT); We want to insert rows that contain the unique server ID of the MariaDB instance that actually performs the insert operation. Here’s how: MariaDB SQL INSERT INTO demo.message VALUES \
    (CONCAT("Write from server ", @@server_id)), \
    (CONCAT("Write from server ", @@server_id)), \
    (CONCAT("Write from server ", @@server_id)); Now let’s see which MariaDB server performed the write and read operations: MariaDB SQL SELECT *, CONCAT("Read from server ", @@server_id) FROM demo.message; Run the previous query several times. You should get a result like this: In my cluster, all the writes were performed by server ID which is the primary node. Reads were executed by server IDs and which are the replica nodes. You can confirm the ID values by running the following on the primary and replica nodes: 367 908 308 docker exec -it mariadb-primary mariadb -u root -p \
    --execute="SELECT @@server_id"
 
docker exec -it mariadb-replica mariadb -u root -p \
    --execute="SELECT @@server_id" What’s Next? We focused on basic read/write splitting in this tutorial, but MaxScale can do much more than this. For example, enforce to your backend database topology, perform , perform load balancing, import and export data from and into , and even convert NoSQL/MongoDB API commands to SQL. MaxScale also includes a and for operations. Check the to learn more about MaxScale. security automated failover connection-based Kafka REST API web-based GUI documentation Also Published Here

How to do Database Read/Write Splitting With Your Browser

In Ruby read and write JSON file to hash can be achieved using File Handling. Example to parse JSON file into a hash and write data into our JSON file is illustrated with this tutorial. Before getting started, lets talk about what is a JSON file. In an overview, JSON (JavaScript Object Notation) is a lightweight data-interchange format. It is easy for humans to read and write. It is easy for machines to parse and generate. It is based on a subset of the . JSON is a text format that is completely language independent but uses conventions that are familiar to programmers of the C-family of languages, including C, C++, C#, Java, JavaScript, Perl, Python, and many others. These properties make JSON an ideal data-interchange language. JavaScript Programming Language Standard ECMA-262 3rd Edition - December 1999 If you want to know more about JSON you might want to read . Introduction to JSON Installation. If you don't have already installed JSON gem on your computer you can install it running the following command. gem install json You can check if everything is installed correctly if it is, you are going to have something like this: => true require 'json' Reading the file. In order to read the file, we have to execute the following command, giving the file that we would like to read. file = File.read( ) './file-name-to-be-read.json' Parsing the file into hash. Then we will have to parse the data from the file using file handle created with name ‘file’ and store it into 'data_hash' variable. data_hash = .parse(file) JSON Step - 1 In this case we are going to use the following JSON file to get the data, save into a hash, make modifications and save the changes into the same JSON file. { : , : , :
    { : , : , : }
} "author" "Isaac Asimov" "url" "https://isaacbooks.com" "books" "1" "Fantastic Voyage" "2" "The Robots of Dawn" "3" "Pebble In The Sky" Step - 2 In order to get the file into a proper hash to start working in it, we have to read the file and save into a variable, then we have to parse that variable. file = File.read( )
data_hash = .parse(file) require 'json' './sample-data.json' JSON Step - 3 Next we are going to make some changes into the hash we already have saved into 'data_hash' variable. data_hash[ ][ ] = data_hash[ ][ ] = 'books' '1' 'I, Robot' 'books' '2' 'The Caves of Steel' Step - 4 In order to write the changes into the JSON file, we have to run the write command into the file that is on the root folder or any other location you want. File.write( , .dump(data_hash)) './sample-data.json' JSON After this, we are going to have the following result in our JSON file. { => , => , =>{ => , => , => }} "author" "Isaac Asimov" "url" "https://isaacbooks.com" "books" "1" "I, Robot" "2" "The Caves of Steel" "3" "Pebble In The Sky" Conclusion With this feature, we can easily access and save important data from our program or application following the JSON standard. This is a quick guide to make the JSON file work in your application / program easily and quickly. I hope this tutorial is useful to you. If you liked please share it. I am on | | GitHub Twitter LinkedIn Reference JSON Module in Ruby. Introducing to JSON.

Ruby: How to read/write JSON File

Ruby: Cómo leer/escribir un archivo JSON

It’s a good time to be a job seeker. With low unemployment rates and more than 10 million available positions, applicants have the upper hand over employers. They also have another advantage: technology. Plenty of tech tools have sprung up to make life easier for job candidates. And if you’re eager to begin a new career path, you should know what they are. That way, you can masterfully navigate your way into the perfect role. Below are some of the top tech resources that will help you improve your competitive edge while on the job hunt. 1. AI-fueled resume builders For many years, human resources professionals and recruiters have relied on AI-powered software to analyze applications. The software made it simpler to pick candidates likely to have the skill sets for a particular job. The only problem was that applicants couldn’t always tell if their resume submissions were likely to pass the algorithms. Until now, that is. Today, like Teal are allowing job seekers to refine their information like never before. Like other programs, Teal offers users the chance to write, upload, and store resumes. However, the platform folds in an important dose of AI. Anyone can evaluate a resume against an existing job position and discover how to make the resume more appropriate, but AI tools will help tell you if your resume is being ignored. resume-building software programs If you’re tired of wondering if your resume is getting overlooked by bots, try bolstering its heft with an AI solution. It may be the missing puzzle piece to snagging lucrative interviews and getting seen. 2. One-sided video interview recordings You submit a resume hoping to hear a response. What you receive is an email asking you to videotape yourself answering a handful of questions. This is one of the latest ways to screen applicants and it’s also your moment to shine. A smart way to do that is by applying some technical savvy to the experience. For example, consider investing in the most basic podcasting setup out there. Buzzsprout estimates you can get for around $150. That’s not a lot, especially if the items help you land a better job with an attractive salary to match. Once you have your equipment, use it to record studio-grade videos. They’ll sound crisper, look better, and differentiate you from the people who just recorded on their iPhones. decent recording equipment and accessories 3. Video conferencing sites By now, nearly everyone’s been part of a Zoom or Teams meeting. But you might not have engaged with an interviewer via a live video. Odds are, the longer your job search goes on, the greater your odds of a Zoom interview will be. Eighty-two percent of organizations say they’re to meet and evaluate top talent. using videoconferencing Interviewing through a video feed has its upsides and drawbacks, though. The upsides are obvious: You can interview for any job from anywhere. A dedicated Internet connection is all you need. With that being said, you shouldn’t just toss on a nice outfit, do your hair, and feel camera-ready. Interviews on Zoom require practice. Remember: You won’t be able to read body language over the computer. Additionally, you may have multiple people interviewing you from a variety of locations. Be sure to wait your turn and not talk too quickly. Otherwise, you may end up cutting people off mid-sentence. Oh, and be sure you’re in a quiet environment. Nothing spoils a Zoom interview like the neighbor’s lawn mower or a noisy coffee shop atmosphere. 4. ChatGPT You shouldn’t depend on an AI solution like ChatGPT to do all your work for you when you’re looking for work. Nevertheless, ChatGPT and similar tech such as Google Bard can serve in an assistive capacity. Every time you get an interview, sign in to your ChatGPT account. Ask the system to come up with potential interview questions for particular jobs, industries, subjects, etc. It won’t take long for the system to reward you with tons of replies. Look through them, decide which are most relevant, and put them into a bullet-point list. With your list in front of you, go into pre-interview rehearsal mode. Answer the questions aloud. You might feel strange, but you’ll be less likely to go blank when you’re in an in-person or online interview. Best of all, the experience will allow you to feel more confident and less anxious. Ready to grab the attention of employers and wow them with your abilities? Rather than leaving anything to fate, lean on the best job search tech tools on the market and land the position of your dreams. This story was distributed by ReadWrite under HackerNoon’s Brand As An Author Program. Learn more about the program . here

4 Tech Tools Changing The Way You Apply For Jobs

4 herramientas tecnológicas que cambiarán la forma en que solicita empleos

4 outils techniques qui changent la façon dont vous postulez à des emplois

नौकरियों के लिए आवेदन करने के तरीके को बदलने वाले 4 तकनीकी उपकरण

求人への応募方法を変える 4 つのテクノロジー ツール

4 ferramentas tecnológicas que mudam a maneira como você se candidata a empregos

4 công cụ công nghệ thay đổi cách bạn nộp đơn xin việc

4 种改变您申请工作方式的技术工具

Mission-critical applications require . The goal of high availability is to provide users with consistent access to services or resources, minimizing the chances of interruption. is a specific mechanism used to achieve high availability. It involves automatically detecting the failure of a system component (like a server, network, or database) and immediately switching operations to a standby component without human intervention. This increases resiliency. high availability Automatic failover MariaDB MaxScale is a database proxy that includes features for high availability. In this article, I'll show you how you can try it out with an application implemented in Java and Svelte. online store simulator Architecture The following diagram shows the architecture of the demo application: A web application developed with JavaScript and the Svelte framework makes HTTP requests to a Java backend. The backend answers with that the frontend uses to update the user interface on the browser. server-sent events The backend is implemented with and connects to a database cluster using (reactive). The backend logic is, in short, a simulation of reads and writes to an online store database. The simulation is parameterized, and the user can adjust: Spring Boot MariaDB R2DBC How many reads to the database per minute. Product visits per minute: How many writes to the database per minute. Orders per minute: Write amplification. Products per order: How many seconds until a request to the database is considered failed. Timeout in milliseconds: The database cluster is front-ended by a called MaxScale. This proxy makes the cluster look like a single logical database to the Java backend. MaxScale also performs read/write splitting (sending writes to the primary MariaDB server and reads to replicas), as well as load-balancing of reads among replica servers using a configurable algorithm. Data is automatically replicated from the primary to the replica database servers. database proxy Building the Docker images from source I have prepared custom Docker images for every component in the simulator. You can either build the images from the source (optional) or use the already built and published images from Docker Hub. If you decide to build the images yourself, you can find the source code on GitHub: Custom images for easy deployment of replicated MariaDB topologies with MaxScale. These images are suitable only for demo applications. Use the for production deployments. : MariaDB deployments DO NOT USE THESE IN PRODUCTION! official MariaDB Docker images The backend application that connects to the database cluster. : Backend application The frontend application that makes simulation configuration requests to the backend and receives events to show the simulation result. : Frontend application Each repository has Dockerfiles that you can use to build your own Docker images. For example, to build the backend application image, run: docker build --tag alejandrodu/online-store-simulator-java-backend . Running the simulation All the services can be started using the following Docker Compose file ( ): docker-compose.yml version: "3.9"
services:
  server-1:
    container_name: server-1
    image: alejandrodu/mariadb
    ports:
      - "3306:3306"
    environment:
      - MARIADB_CREATE_DATABASE=demo
      - MARIADB_CREATE_USER=user:Password123!
      - MARIADB_CREATE_REPLICATION_USER=replication_user:ReplicationPassword123!
      - MARIADB_CREATE_MAXSCALE_USER=maxscale_user:MaxScalePassword123!

  server-2:
    container_name: server-2
    image: alejandrodu/mariadb
    ports:
      - "3307:3306"
    environment:
      - MARIADB_REPLICATE_FROM=replication_user:ReplicationPassword123!@server-1:3306

  server-3:
    container_name: server-3
    image: alejandrodu/mariadb
    ports:
      - "3308:3306"
    environment:
      - MARIADB_REPLICATE_FROM=replication_user:ReplicationPassword123!@server-1:3306

  maxscale:
    container_name: maxscale
    image: alejandrodu/mariadb-maxscale
    command: --admin_host 0.0.0.0 --admin_secure_gui false
    ports:
      - "4000:4000"
      - "8989:8989"
      - "27017:27017"
    environment:
      - MAXSCALE_USER=maxscale_user:MaxScalePassword123!
      - MARIADB_HOST_1=server-1 3306
      - MARIADB_HOST_2=server-2 3306
      - MARIADB_HOST_3=server-3 3306
    healthcheck:
      test: ["CMD", "maxctrl", "list", "servers"]
      interval: 5s
      timeout: 10s
      retries: 5

  java-backend:
    container_name: java-backend
    image: alejandrodu/online-store-simulator-java-backend
    ports:
      - "8080:8080"
    environment:
    - spring.r2dbc.url=r2dbc:mariadb://maxscale:4000/demo
    - spring.r2dbc.username=user
    - spring.r2dbc.password=Password123!
    - spring.liquibase.url=jdbc:mariadb://maxscale:4000/demo
    - spring.liquibase.user=user
    - spring.liquibase.password=Password123!
    depends_on:
      maxscale:
        condition: service_healthy

  svelte-frontend:
    container_name: svelte-fronted
    image: alejandrodu/online-store-simulator-svelte-frontend
    ports:
      - "5173:80"
    environment:
      - BACKEND_URL=http://java-backend:8080 Move to the directory in which the Docker Compose file is, and start the services in detached mode as follows: docker compose up -d Configuring MaxScale Before you start the simulation, configure MaxScale for transaction replay. Also, timeouts should be adjusted to make the simulation more interesting. Navigate to and log into the UI using: http://localhost:8989/ Username: admin Password: mariadb You'll see a dashboard with the MariaDB cluster state. There's a primary server ( ), and two replicas ( and ). Replication is already configured from (primary) to and (replicas). All servers should be up and running. server-1 server-2 server-3 server-1 server-2 server-3 Click on and then on the icon to enable parameter editing. Set the following parameters: mdb_monitor pencil ( ): This enables automatic failover. When a MariaDB server is down, MaxScale selects a replica server and reconfigures it as the new primary so that writes can continue to happen. auto_failover true ( ): This enables the automatic rejoin of recovered servers. When a failed server is up again, MaxScale detects it and configures it as an available replica server. auto_rejoin true ( ): Sets the number of monitor (a component in MaxScale that checks server status) iterations required for a server to be down in order to activate the failover process. We set a value of to make sure the failover starts immediately after failure. failcount 1 1 ( ): Connection timeout for monitor connections. We set a low value (one second) to quickly activate failover for this demo. backend_connect_timeout 1000 ( ): Read timeout for monitor connections. backend_read_timeout 1000 ( ): Write timeout for monitor connections. backend_write_timeout 1000 ( ): Primary failure timeout. master_failure_timeout 1000 ( ): How often the servers are monitored. monitor_interval 1000 ⚠️ These values are appropriate for this demo but very likely not the best for production environments! WARNING: Once the parameters are set, click on and . Done Editing Confirm You also need to enable transaction replay, which automatically re-executes failed in-flight transactions on servers that went down just after a SQL statement was routed. This is a useful feature for software developers since it prevents the need for coding failure cases and transaction retry. On the main menu, click on and then on any of the links in the list of servers. Edit the parameters as follows: Dashboard query_router_service ( ): Activates automatic retry of failed transactions. transaction_replay true ( ): Same as the previous when a deadlock occurs. transaction_replay_retry_on_deadlock true ( ): Same as the previous when a checksum mismatch occurs. transaction_replay_retry_on_mismatch true Once the parameters are set, click on and . Done Editing Confirm Starting the simulation With everything configured, you can start the simulation. Navigate to and configure the following parameters (names are, I hope, self-explanatory): http://localhost:5173/ Product visits per minute: 6000 Orders per minute: 60 Timeout in milliseconds: 8000 But before you start the simulation, you need to create the products for the online store. Click on | . Leave the default values and click on . You should see the UI updating as products are created in the database. Data Create products... Create Now, you can finally click on and see the simulation in action. Start Simulating a server failure At this point, the primary server is handling writes (orders). What happens if you stop that server? In the command line run: docker stop server-1 Depending on multiple factors, you might get some "disappointed visitors" or even a few "missed opportunities" in the simulator. Or maybe you don't get any at all! Product visits (reads) and orders (writes) continue to happen, thanks to MaxScale. Without automatic failover, you have to reconfigure everything manually, which results in more offline time, many disappointed visitors, and missed opportunities! Start the failed server: docker start server-1 Go to the MaxScale ( ) and check that is now a functioning replica. Dashboard http://localhost:8989/ server-1 You can perform a manual to make the primary server again. Click on and then mouse hover over the section. Click on the icon and select . Click and check again in the that the new primary server is . switchover server-1 mdb_monitor MASTER pencil server-1 Swap Dashboard server-1 Conclusion Automatic failover is only one of the components in highly available systems. You can use a database proxy like MaxScale to set up automatic failover, as well as other components such as load-balancing, query routing, transaction retry, topology isolation, and more. Check out the documentation at . https://mariadb.com/kb/en/maxscale/ Also published . here

Achieving High Availability with MariaDB MaxScale

Using Python to Read, Write, and Manipulate JSON Files JSON (JavaScript Object Notation) is a popular data interchange format that is easy for humans to read and write. JSON often comes into play when interacting with web APIs or HTTP requests within the field of programming. provides built-in support for working with JSON files through the module. In this article, we will discuss how to use Python to read, write, and manipulate JSON files. Python json Reading JSON Files To read a JSON file in Python, you can follow these steps: Import the module. json Open the JSON file using Python's function with the mode set to . open() r Use the function to load the contents of the file as a Python dictionary. json.load() Here is an example code snippet that demonstrates how to read a JSON file: import json

# Open the JSON file
with open('data.json') as f:
    data = json.load(f)

# Print the data (it will be stored as a Python dictionary)
print(data) Writing JSON Files To write data to a JSON file in Python, you can use the module as well. Here are the steps to write data to a JSON file: json Define the data that you want to write as a Python dictionary. Open a new file using Python's function. open() Use the function to write the dictionary data to the file in JSON format. json.dump() Here is an example code snippet that demonstrates how to write data to a JSON file: import json

# Define the data as a Python dictionary
data = {
    'name': 'Bob',
    'age': '25',
    'city': 'Los Angeles'
}

# Write data to a JSON file
with open('output.json', 'w') as f:
    json.dump(data, f) You can read the file, modify the data dictionary by adding a new key-value pair, and then save it as another JSON file. Here's an example code snippet to achieve that: output.json # Read the data from the written file and print it
with open('output.json') as f:
    output_data = json.load(f)
    print(output_data)

# Modify the data by adding a new key-value pair
output_data['job'] = 'Engineer'

# Write the modified data to a new JSON file
with open('modified_output.json', 'w') as f:
    json.dump(output_data, f)
    
# Read the modified data from the newly written file and print it
with open('modified_output.json') as f:
    modified_data = json.load(f)
    print('Modified data:', modified_data) In this code snippet: We first read the data from the file. output.json We then modify the dictionary by adding a new key-value pair. output_data The modified data is then written to a new JSON file named . modified_output.json Finally, we read the modified data from and print it. modified_output.json Conclusion In conclusion, Python's module makes it simple to work with JSON files. You can read, write, and manipulate JSON data using Python's built-in functions, making it a powerful tool for handling JSON data in your Python projects. json Thank you for taking the time to explore data-related insights with me. I appreciate your engagement. If you find this information helpful, I invite you to follow me or connect with me on or (@Luca_DataTeam). You can also catch glimpses of my personal life on , Happy exploring!👋 LinkedIn X Instagram

How to read and write JSON files in Python

My team recently discovered , the widely popular graphics library – (with a high NVD severity ). These vulnerabilities cause a denial-of-service and remote code execution. X11’s latest versions contain fixes for these vulnerabilities. two security vulnerabilities in X.Org libX11 CVE-2023-43786 and CVE-2023-43787 CVSS 7.8 The team constantly monitors open-source projects to find new vulnerabilities and malicious packages and shares them with the wider community to help improve their overall security posture. This 2-part blog series provides details of the inner workings of the vulnerable Xpm file format and deep-dives into exploiting these vulnerabilities. What is libX11? Xorg X11, often referred to as X Window System, is an graphical server protocol that enables the creation and management of graphical user interfaces in Unix-like operating systems. It provides a framework for running graphical applications, managing Windows, and handling user input in a networked environment. open-source The libx11 package offers the essential shared libraries that client applications require to render and present data on your desktop. What is libXpm? libXpm provides functions to read, write, and display images in the (XPM) format. X Pixmap XPM primarily aims to generate icon pixmaps with support for transparent pixels. It is based on the XBM syntax, and it can be either a plain text file in the XPM2 format or utilize a C programming language syntax, making it suitable for inclusion within a C program file. XPM image format – versions Predecessor – XBM Before XPM (X PixMap) came to be in 1989, there was the XBM format (X BitMap). A plain-text binary image format, used for storing icon and cursor bitmaps that were used in the X GUI. XBM files are structured as C source files. This is their main distinction from most image formats around today. That way, they can be incorporated into applications directly. However, due to this and the fact no compression can be employed (1 character to 1-byte mapping), they are also far larger than their raw pixel data. X BitMap (XBM) data comprises a sequence of static unsigned char arrays that store the raw monochrome pixel information. For example, the following C code is the XBM file for in the image: hello #define hello_width 35
#define hello_height 25
static char hello_bits[] = {
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10, 
  0x00, 0x88, 0x00, 0x00, 0x10, 0x00, 0x88, 0x00, 0x00, 0x10, 0x00, 0x88, 
  0x00, 0x00, 0xD0, 0xE1, 0x88, 0x78, 0x00, 0x30, 0x13, 0x89, 0xC4, 0x00, 
  0x10, 0x12, 0x89, 0x84, 0x00, 0x10, 0xF2, 0x89, 0x84, 0x00, 0x10, 0x12, 
  0x88, 0x84, 0x00, 0x10, 0x12, 0x88, 0x44, 0x00, 0x10, 0xE2, 0x89, 0x38, 
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
  0x00, 0x00, 0x00, 0x00, 0x00
}; Instead of the usual image file-format headers, XBM files have statements. The first pair of values defines the pixel dimensions of the bitmap, indicating its height and width. #define X BitMap (XBM) image data is structured as a continuous sequence of pixel values, which are stored within a static array. Given that each pixel is symbolized by a single bit (with 0 indicating white and 1 representing black), each byte in the array encompasses the data for eight individual pixels. Notably, the first byte’s least significant bit serves as the anchor for the upper-left pixel within the bitmap. XPM1 Meet XPM version 1. First released in 1989, it shares a lot of similarities with the XBM format outlined above. While XBM was monochrome, XPM1 introduced colors to the images. It uses additional macros and variables for colors and replaces bytes with characters for pixel data. For example, here is the same black-and-white picture in the XPM1 format: hello /* XPM */
static char *_hello[] = {
/* columns rows colors chars-per-pixel */
"35 25 2 1 ",
"  c white",
"b c black",
/* pixels */
"                                   ",
"                                   ",
"                                   ",
"                                   ",
"                                   ",
"                                   ",
"                                   ",
"    b              b   b           ",
"    b              b   b           ",
"    b              b   b           ",
"    b bbb    bbb   b   b   bbbb    ",
"    bb  bb  b   b  b   b  b   bb   ",
"    b    b  b   b  b   b  b    b   ",
"    b    b  bbbbb  b   b  b    b   ",
"    b    b  b      b   b  b    b   ",
"    b    b  b      b   b  b   b    ",
"    b    b   bbbb  b   b   bbb     ",
"                                   ",
"                                   ",
"                                   ",
"                                   ",
"                                   ",
"                                   ",
"                                   ",
"                                   "
}; here denotes the number of colors in the image, and denotes the number of characters per pixel. XFACE_ncolors XFACE_chars_per_pixel Each will be replaced by the white color “#ffffff”, and each will be replaced by the black color “#000000”. a b XPM2 A year later, in 1990, the second version of the format was set to improve things. It simplified things and removed all C code from the image format. The simplified structure: ! XPM2
<Header>
<Colors>
<Pixels> The header line denotes the image dimensions similar to XPM1’s #define statements. The colors section defines the character values. A new type concept was introduced: – is for color pixel c – is for monochrome m – is for grayscale g – is for symbolic s The symbolic feature is used to assign colors by context, and to create variable names for them for easier reading. Example of an XPM2 image, with the same as shown in the previous examples: hello ! XPM2
35 25 2 1
a c #000000
b c #ffffff
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaabaaaaaaaaaaaaaabaaabaaaaaaaaaaa
aaaabaaaaaaaaaaaaaabaaabaaaaaaaaaaa
aaaabaaaaaaaaaaaaaabaaabaaaaaaaaaaa
aaaababbbaaaabbbaaabaaabaaabbbbaaaa
aaaabbaabbaabaaabaabaaabaabaaabbaaa
aaaabaaaabaabaaabaabaaabaabaaaabaaa
aaaabaaaabaabbbbbaabaaabaabaaaabaaa
aaaabaaaabaabaaaaaabaaabaabaaaabaaa
aaaabaaaabaabaaaaaabaaabaabaaabaaaa
aaaabaaaabaaabbbbaabaaabaaabbbaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa Apart from hexadecimal color codes, the colors can also be specified using any of the X11 color names (e.g. ), with indicating transparency. red None XPM3 This is the current version of the XPM format. The version, released in 1991, brought back the C code, but instead of using a pure C code style, the values inside are essentially the same as in the XPM2 format. Example: /* XPM */
static char *_hello[] = {
/* columns rows colors chars-per-pixel */
"35 25 2 1 ",
"  c white",
"b c black",
/* pixels */
"                                   ",
"                                   ",
"                                   ",
"                                   ",
"                                   ",
"                                   ",
"                                   ",
"    b              b   b           ",
"    b              b   b           ",
"    b              b   b           ",
"    b bbb    bbb   b   b   bbbb    ",
"    bb  bb  b   b  b   b  b   bb   ",
"    b    b  b   b  b   b  b    b   ",
"    b    b  bbbbb  b   b  b    b   ",
"    b    b  b      b   b  b    b   ",
"    b    b  b      b   b  b   b    ",
"    b    b   bbbb  b   b   bbb     ",
"                                   ",
"                                   ",
"                                   ",
"                                   ",
"                                   ",
"                                   ",
"                                   ",
"                                   "
}; As discussed, the XPM format can also represent more sophisticated images, like the JFrog logo: DoS vulnerability – CVE-2023-43786 The CVE-2023-43786 vulnerability is essentially an endless loop resulting from an incorrect recursion stop condition calculation. Fix commit: https://gitlab.freedesktop.org/xorg/lib/libx11/-/commit/204c3393c4c90a29ed6bef64e43849536e863a86 is a function in libX11 that lets you place images onto an X Drawable, usually an X Window. With this function, one can transfer pixel information from an XImage structure to a designated drawable, like a window or a pixmap, and position it as needed. XPutImage xpmCreatePixmapFromImage The libXpm function calls for this function: xpmCreatePixmapFromImage XPutImage void
xpmCreatePixmapFromImage(
    Display	*display,
    Drawable	 d,
    XImage	*ximage,
    Pixmap	*pixmap_return)
{
    GC gc;
    XGCValues values;

    *pixmap_return = XCreatePixmap(display, d, ximage->width,
				   ximage->height, ximage->depth);
    /* set fg and bg in case we have an XYBitmap */
    values.foreground = 1;
    values.background = 0;
    gc = XCreateGC(display, *pixmap_return,
		   GCForeground | GCBackground, &values);

    XPutImage(display, *pixmap_return, gc, ximage, 0, 0, 0, 0,
	      ximage->width, ximage->height);

    XFreeGC(display, gc);
} In this function, is the source image pixel data to be displayed and is copied to the object (in this case ). ximage X Drawable pixmap_return XPutImage Here is the libX11 function: XPutImage int
XPutImage (
register Display *dpy,
Drawable d,
GC gc,
register XImage *image,
int req_xoffset,
int req_yoffset,
int x,
int y,
unsigned int req_width,
unsigned int req_height){
.....
PutSubImage(dpy, d, gc, &img, 0, 0, x, y,
(unsigned int) width, (unsigned int) height,
dest_bits_per_pixel, dest_scanline_pad);
UnlockDisplay(dpy);
SyncHandle();
Xfree(img.data);
return 0;
}
} LockDisplay(dpy);
FlushGC(dpy, gc);

PutSubImage(dpy, d, gc, image, req_xoffset, req_yoffset, x, y,
	(unsigned int) width, (unsigned int) height,
	dest_bits_per_pixel, dest_scanline_pad);.........
} It calls to the function: PutSubImage static void
PutSubImage (
    register Display *dpy,
    Drawable d,
    GC gc,
    register XImage *image,
    int req_xoffset,
    int req_yoffset,
    int x, int y,
    unsigned int req_width,
    unsigned int req_height,
    int dest_bits_per_pixel,
    int dest_scanline_pad)
{
    int left_pad, BytesPerRow, Available;

    if ((req_width == 0) || (req_height == 0))
	return;

    Available = ((65536 < dpy->max_request_size) ? (65536 << 2)
                        : (dpy->max_request_size << 2)) - SIZEOF(xPutImageReq);
    if ((image->bits_per_pixel == 1) || (image->format != ZPixmap)) {               [1]
        left_pad = (image->xoffset + req_xoffset) & (dpy->bitmap_unit - 1);
        BytesPerRow = (ROUNDUP((long)req_width + left_pad,
                                dpy->bitmap_pad) >> 3) * image->depth;
    } else {                                                                        [2]
        left_pad = 0;
        BytesPerRow = ROUNDUP((long)req_width * dest_bits_per_pixel,                [3]
                                dest_scanline_pad) >> 3;
    }

    if ((BytesPerRow * req_height) <= Available) {                                  [4]
        PutImageRequest(dpy, d, gc, image, req_xoffset, req_yoffset, x, y,
                        req_width, req_height,
                        dest_bits_per_pixel, dest_scanline_pad);
    } else if (req_height > 1) {
        int SubImageHeight = Available / BytesPerRow;

        if (SubImageHeight == 0)
            SubImageHeight = 1;

        PutSubImage(dpy, d, gc, image, req_xoffset, req_yoffset, x, y,
                    req_width, (unsigned int) SubImageHeight,
                    dest_bits_per_pixel, dest_scanline_pad);

        PutSubImage(dpy, d, gc, image, req_xoffset,
                    req_yoffset + SubImageHeight, x, y + SubImageHeight,
                    req_width, req_height - SubImageHeight,
                    dest_bits_per_pixel, dest_scanline_pad);
    } else {                                                                        [5]
        int SubImageWidth = (((Available << 3) / dest_scanline_pad)                 [6]
                                * dest_scanline_pad) - left_pad;

        PutSubImage(dpy, d, gc, image, req_xoffset, req_yoffset, x, y,
                    (unsigned int) SubImageWidth, 1,
                    dest_bits_per_pixel, dest_scanline_pad);

        PutSubImage(dpy, d, gc, image, req_xoffset + SubImageWidth,
                    req_yoffset, x + SubImageWidth, y,
                    req_width - SubImageWidth, 1,
                    dest_bits_per_pixel, dest_scanline_pad);
    }
} Technical Vulnerability Details Let’s take the following example image: Available [the requested size] = (65,536 * 4) - 28 = 262,116
bits_per_pixel = 32
width = 90,000 pixels
height = 1 pixel Since the image is 32, the conditional statement at [1] will not pass, leading us to enter the alternative code block defined in [2]. bits_per_pixel It then calculates the on [3] then divides it by 8. In our example: BytesPerRow  = 90000 * 32 / 8 = 360,000 BytesPerRow In the example, the check on [4] would not pass, as 360000 is not less than the requested size 262116, and is not able to fit a single line of the requested width into a single request – this initiates the on [5]. else This determines the number of pixels that can be included in a single request. It then initiates a recursive call to the function to pass just that subset, followed by a subsequent recursive call to manage the remaining portion of the line. If needed, this remaining part may also be divided further through additional recursive calls. PutSubImage However, the calculation on [6] fails to take into account the bits per pixel, and the recursive call makes requests sending 2096928 pixels instead of 2096928 bits – which is larger than can be fit in a single request. This leads to , consistently resulting in a number too large to fit and trying again the process to retry with the same values. This recursion persists until the call stack is exhausted. an endless loop of attempting to split the line of pixels The changed the calculation on [6] and took into account the . In the example, it would result in a recursive call requesting to send just 65529 pixels, resulting in a BytesPerRow of 262116 that perfectly fits inside the available space, thus allowing the recursion to make forward progress and finish in just 2 calls. bug fix bits_per_pixel Example proof-of-concept image to trigger the bug: https://github.com/jfrog/jfrog-CVE-2023-43786-libX11_DoS/blob/main/cve-2023-43786.xpm How the bug can be triggered An example of an app that calls the vulnerable libXpm library function is the CLI utility , which is used to display Xpm images on the screen. sxpm It calls the vulnerable Xpm function, which then calls the vulnerable libX11 functions then . xpmCreatePixmapFromImage XPutImage PutSubImage Also published here. Read the second part of this article here: Uncovering and Exploiting a 35-Year-Old Vulnerability, *nix libX11: Part 2

READWRITE

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READWRITE

readwrite.com

11-50 employees

Since 2003

COMPANY RANKING

READWRITE

EVERGREEN INDEX #8330

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