Libquic: QUIC, A Multiplexed Stream Transport Over UDP with C++

QUIC, a multiplexed stream transport over UDP

QUIC is an experimental protocol aimed at reducing web latency over that of TCP. On the surface, QUIC is very similar to TCP+TLS+SPDY implemented on UDP. Because TCP is implemented in operating system kernels, and middlebox firmware, making significant changes to TCP is next to impossible. However, since QUIC is built on top of UDP, it suffers from no such limitations.

Key features of QUIC over existing TCP+TLS+SPDY include

Dramatically reduced connection establishment time
Improved congestion control
Multiplexing without head of line blocking
Forward error correction
Connection migration

See Chromium QUIC Page for detailed information.

libquic

This repository is sources and dependencies extracted from Chromium's QUIC Implementation with a few modifications and patches to minimize dependencies needed to build QUIC library.

Notable and only dependency is BoringSSL. The BoringSSL sources is already embedded in this repository and linked with CMake build file. You don't need any kind of dependency installs.

Language Bindings

This library is intended as an essential reference point for other language bindings and possibly for integration with other C/C++ codebase such as HTTP servers like Apache or nginx.

Currently there is only one experimental language binding:

Go binding: goquic

Getting Started

How to build

Building with CMake and Ninja (Recommended):

$ mkdir build/
$ cd build/
$ cmake -GNinja ..
$ ninja

Building with CMake and Make:

$ mkdir build/
$ cd build/
$ cmake ..
$ make -j 4

make -j limits the number of simultaneously executed Recepies. Adapt this number to the capabilities of your build machine.

libquic.a library file will be generated. libssl.a, libcrypto.a will be located in build/boringssl directory.

To do release builds run $ cmake -GNinja -DCMAKE_BUILD_TYPE=Release .. instead of $ cmake -GNinja ...

How to integrate

In order to integrate libquic to your code, your best source of documentation is official Chromium QUIC toy client and server. Golang binding will help too.

Syncing from Upstream

Great effort has been made to make syncing from upstream Chromium sources as effortless as possible. See DEPS file for all the dependencies. See manage.py script for actual syncing.

If you want to apply upstream changes,

Clone & Checkout chromium upstream.
Build QUIC server: cd out/Debug; ninja quic_server
Update "chromium_revision" var at DEPS to your chromium source code revision.
Do ./sync.py <CHROMIUM_GIT_ROOT> All necessary files will be updated to new ones without patches applied.
Temporarily commit here.
Do ./sync.py <CHROMIUM_GIT_ROOT>--patch All the patches will be applied. Some patches will be rejected.
If there is any patch collision, manually apply the rejected patches. Open the *.rej files and carefully apply the rejected hunks manually.
Try build, and you'll find that you may need to add additional modifications to make build successful. There may be added or deleted source files. Update CMakeLists.txt accordingly.
If the build is successful, make a patch by: git diff src/ > patch/basepatch.patch (Make sure you don't include custom/ directory sources to the patch)
Add patch file to DEPS or update existing patch files. Amend previous commit.
Commit DEPS, new patch, and source changes

Author: devsisters
Source Code: https://github.com/devsisters/libquic
License: View license

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Libquic: QUIC, A Multiplexed Stream Transport Over UDP with C++

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C and C++ are the most powerful programming language in the world. Most of the super fast and complex libraries and algorithms are written in C or C++. Most powerful Kernel programs are also written in C. So, there is no way to skip it.

In programming competitions, most programmers prefer to write code in C or C++. Tourist is considered the worlds top programming contestant of all ages who write code in C++.

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I have discussed the steps we need to complete in this blog post before running a C/C++ code in Sublime Text. We will take the inputs from an input file and print outputs to an output file without using freopen file related functions in C/C++.

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Using multiple variables in the print function
Comparing Signed integer with unsigned integer
Putting a semicolon at the end of the loop statement
C preprocessor doesn’t need a semicolon
Size of the string matters
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Character constants are different from string literals
Difference between single(=) and double(==) equal signs.

The below code generates no error since a print function can take any number of inputs but creates a mismatch with the variables. The print function is used to display characters, strings, integers, float, octal, and hexadecimal values onto the output screen. The format specifier is used to display the value of a variable.

%d indicates Integer Format Specifier
%f indicates Float Format Specifier
%c indicates Character Format Specifier
%s indicates String Format Specifier
%u indicates Unsigned Integer Format Specifier
%ld indicates Long Int Format Specifier

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A signed integer is a 32-bit datum that encodes an integer in the range [-2147483648 to 2147483647]. An unsigned integer is a 32-bit datum that encodes a non-negative integer in the range [0 to 4294967295]. The signed integer is represented in twos-complement notation. In the below code the signed integer will be converted to the maximum unsigned integer then compared with the unsigned integer.

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