Uptrenda on Mar 29, Oh boy, this one brings me back. I can't tell you how many times I read this guide back in the day. Beej was the bomb when it came to network programming. Failing that, there's the classic Unix Network Programming Vol 1 and 2 which gives a good outline of what to expect.

Author:Gojas Yozshukasa
Language:English (Spanish)
Published (Last):21 December 2019
PDF File Size:13.57 Mb
ePub File Size:5.75 Mb
Price:Free* [*Free Regsitration Required]

Socket programming got you down? Is this stuff just a little too difficult to figure out from the man pages? Well, guess what! This document has been written as a tutorial, not a complete reference.

It is probably at its best when read by individuals who are just starting out with socket programming and are looking for a foothold. It is certainly not the complete and total guide to sockets programming, by any means. It should, however, build on just about any platform that uses gcc.

When compiling for Solaris or SunOS, you need to specify some extra command-line switches for linking in the proper libraries. If you still get errors, you could try further adding a -lxnet to the end of that command line. Another place that you might find problems is in the call to setsockopt.

The prototype differs from that on my Linux box, so instead of:. But I should really be fair and tell you that Windows has a huge install base and is obviously a perfectly fine operating system. They say absence makes the heart grow fonder, and in this case, I believe it to be true.

But people like what they like, and you Windows folk will be pleased to know that this information is generally applicable to you guys, with a few minor changes, if any. One cool thing you can do is install Cygwin 3 , which is a collection of Unix tools for Windows. Another thing that you should consider is the Windows Subsystem for Linux 4. This basically allows you to install a Linux VM-ish thing on Windows That will also definitely get you situated.

But some of you might want to do things the Pure Windows Way. All you need to include is:. You also have to make a call to WSAStartup before doing anything else with the sockets library. The code to do that looks something like this:. You also have to tell your compiler to link in the Winsock library, usually called wsock See your online help for details.

Once you do that, the rest of the examples in this tutorial should generally apply, with a few exceptions. Also, select only works with socket descriptors, not file descriptors like 0 for stdin.

There is also a socket class that you can use, CSocket. Check your compilers help pages for more information. Finally, I hear that Windows has no fork system call which is, unfortunately, used in some of my examples.

I can only talk about so much, you know! As a rule, the more complex the question, the less likely I am to respond. You are more than welcome to mirror this site, whether publicly or privately. If you publicly mirror the site and want me to link to it from the main page, drop me a line at beej beej. If you want to translate the guide into another language, write me at beej beej. Feel free to add your name and contact info to the translation.

Please note the license restrictions in the Copyright, Distribution, and Legal section, below. If you want me to host the translation, just ask.

With specific exceptions for source code and translations, below, this work is licensed under the Creative Commons Attribution- Noncommercial- No Derivative Works 3. To view a copy of this license, visit. The same license restrictions apply to the translation as to the original guide. The translation may also include the name and contact information for the translator. The C source code presented in this document is hereby granted to the public domain, and is completely free of any license restriction.

Unless otherwise mutually agreed by the parties in writing, the author offers the work as-is and makes no representations or warranties of any kind concerning the work, express, implied, statutory or otherwise, including, without limitation, warranties of title, merchantibility, fitness for a particular purpose, noninfringement, or the absence of latent or other defects, accuracy, or the presence of absence of errors, whether or not discoverable.

Except to the extent required by applicable law, in no event will the author be liable to you on any legal theory for any special, incidental, consequential, punitive or exemplary damages arising out of the use of the work, even if the author has been advised of the possibility of such damages. Thanks to everyone who has helped in the past and future with me getting this guide written. And finally a big thank-you to the literally thousands of you who have written in with suggestions for improvements and words of encouragement.

I dedicate this guide to some of my biggest heroes and inpirators in the world of computers: Donald Knuth, Bruce Schneier, W. A file descriptor is simply an integer associated with an open file. Everything in Unix is a file! It returns the socket descriptor, and you communicate through it using the specialized send and recv man send , man recv socket calls. What next? How about this: there are all kinds of sockets. This document deals only with the first: Internet Sockets. There are two types of Internet sockets?

Well, no. All right, already. What are the two types? See connect , below. Stream sockets are reliable two-way connected communication streams. They will also be error-free. What uses stream sockets? Well, you may have heard of the telnet application, yes? It uses stream sockets. All the characters you type need to arrive in the same order you type them, right? Also, web browsers use the HTTP protocol which uses stream sockets to get pages. This should work well for all the needs of the guide.

How do stream sockets achieve this high level of data transmission quality? TCP makes sure your data arrives sequentially and error-free.

IP deals primarily with Internet routing and is not generally responsible for data integrity. What about Datagram sockets? Why are they called connectionless? What is the deal, here, anyway? Why are they unreliable? Well, here are some facts: if you send a datagram, it may arrive. It may arrive out of order. If it arrives, the data within the packet will be error-free. Why are they connectionless?

You just build a packet, slap an IP header on it with destination information, and send it out. No connection needed. Sample applications: tftp trivial file transfer protocol, a little brother to FTP , dhcpcd a DHCP client , multiplayer games, streaming audio, video conferencing, etc. What kind of dark magic is this? Well, my human friend, tftp and similar programs have their own protocol on top of UDP.

For unreliable applications like games, audio, or video, you just ignore the dropped packets, or perhaps try to cleverly compensate for them. Quake players will know the manifestation this effect by the technical term: accursed lag.

Why would you use an unreliable underlying protocol? Two reasons: speed and speed. Practically, you can probably skip this section. This is very very important. This Network Model describes a system of network functionality that has many advantages over other models. For instance, you can write sockets programs that are exactly the same without caring how the data is physically transmitted serial, thin Ethernet, AUI, whatever because programs on lower levels deal with it for you.

The actual network hardware and topology is transparent to the socket programmer. Remember this for network class exams:. The Physical Layer is the hardware serial, Ethernet, etc. Now, this model is so general you could probably use it as an automobile repair guide if you really wanted to. A layered model more consistent with Unix might be:. At this point in time, you can probably see how these layers correspond to the encapsulation of the original data. See how much work there is in building a simple packet?

Just kidding. All you have to do for stream sockets is send the data out.


Beej's Guide to Network Programming








Related Articles