Getting Started with C: Build a Tiny HTTP Server (Chinese‑Annotated Version)

Overview

TinyHttp is a minimal web server written in 1999 by J. David Blackstone for a class assignment. It supports static page browsing and CGI execution. This fork adds Chinese annotations to httpd.c and simpleclient.c, and introduces two helper functions— request_write and response_read —to simulate HTTP GET requests.

Repository

https://github.com/gofish2020/Tinyhttp

Environment Setup

Install a C development and debugging toolchain (e.g., gcc, make). Reference: https://zhuanlan.zhihu.com/p/571934657?utm_id=0

Verify Perl installation: which perl Expected output like /usr/bin/perl.

Install the Perl‑CGI module via CPAN:

perl -MCPAN -e shell
cpan[1]> install CGI.pm
perl -MCGI -e 'print "CGI.pm version $CGI::VERSION
";'

Expected output: CGI.pm version 4.48.

Common Pitfalls

In check.cgi and color.cgi the shebang line #!/usr/bin/perl -Tw must match the actual Perl path on the system.

Make the CGI scripts executable:

chmod a+x check.cgi
chmod a+x color.cgi

Code Flow

Program entry at main. startup binds the IP address and port, then starts listening.

Each incoming connection spawns a thread; the callback accept_request processes the HTTP request. get_line reads a line from the socket using \r\n as delimiter and parses the request line to identify the target file.

If the target is a directory, serve_file serves the static file.

If the target is a CGI script, execute_cgi runs the script.

Key Functions

get_line reads until the \r\n sequence, reflecting the HTTP packet format.

Example request line:

GET /user?id=1&country=china HTTP/1.1

execute_cgi creates a pipe, forks, and redirects STDIN/STDOUT to run the CGI program.

Demo Procedure

Compile the source: make Start the server: ./httpd Open a browser and navigate to http://127.0.0.1:4000.

Enter a color value (e.g., red) and submit; the CGI script returns the response.