In this chapter, we worked through implementing an HTTP server in C from scratch. That's no small feat! Although the text-based nature of HTTP makes parsing HTTP requests simple, we needed to spend a lot of effort to ensure that multiple clients could be served simultaneously. We accomplished this by buffering received data for each client separately. Each client's state information was organized into a linked list.
Another difficulty was ensuring the safe handling of received data and detecting errors. We learned that a programmer must be very careful when handling network data to avoid creating security risks. We also saw that even very subtle issues, such as Windows's special filenames, can potentially create dangerous security holes for networked server applications.
In the next chapter, Chapter 8, Making Your Program Send Email, we move on from HTTP and consider the primary protocol associated with email—Simple Mail Transfer Protocol (SMTP).