Code included with this book

The following is a list of the 44 example programs included with this book, by chapter.

Chapter 1 – Introducing Networks and Protocols

This chapter includes the following example programs:

• win_init.c: Example code to initialize Winsock (Windows only)
• win_list.c: Lists all local IP addresses (Windows only)
• unix_list.c: Lists all local IP addresses (Linux and macOS only)

Chapter 2 – Getting to Grips with Socket APIs

This chapter includes the following example programs:

• sock_init.c: Example program to include all necessary headers and initialize
• time_console.c: Prints the current date and time to the console
• time_server.c: Serves a web page giving the current date and time
• time_server_ipv6.c: The same as the preceding code but listens for IPv6 connections
• time_server_dual.c: The same as the preceding code but listens for IPv6/IPv4 dual-stack connections

Chapter 3 – An In-Depth Overview of TCP Connections

This chapter includes the following example programs:

• tcp_client.c: Establishes a TCP connection and sends/receives data from the console.
• tcp_serve_toupper.c: A TCP server servicing multiple connections using select(). Echoes received data back to the client all in uppercase.

• tcp_serve_toupper_fork.c: The same as the preceding code but uses fork() instead of select(). (Linux and macOS only.)
• tcp_serve_chat.c: A TCP server that relays received data to every other connected client.

Chapter 4 – Establishing UDP Connections

This chapter includes the following example programs:

• udp_client.c: Sends/receives UDP data from the console
• udp_recvfrom.c: Uses recvfrom() to receive one UDP datagram
• udp_sendto.c: Uses sendto() to send one UDP datagram
• udp_serve_toupper.c: Listens for UDP data and echoes it back to the sender all in uppercase
• udp_serve_toupper_simple.c: The same as the preceding code but doesn't use select()

Chapter 5 – Hostname Resolution and DNS

This chapter includes the following example programs:

• lookup.c: Uses getaddrinfo() to look up addresses for a given hostname
• dns_query.c: Encodes and sends a UDP DNS query, then listens for and decodes the response

Chapter 6 – Building a Simple Web Client

This chapter includes the following example program:

• web_get.c: A minimal HTTP client to download a web resource from a given URL

Chapter 7 – Building a Simple Web Server

This chapter includes the following example programs:

• web_server.c: A minimal web server capable of serving a static website
• web_server2.c: A minimal web server (no globals)

Chapter 8 – Making Your Program Send Email

This chapter includes the following example program:

• smtp_send.c: A simple program to transmit an email

Chapter 9 – Loading Secure Web Pages with HTTPS and OpenSSL

The examples in this chapter use OpenSSL. Be sure to link to the OpenSSL libraries when compiling (-lssl -lcrypto):

• openssl_version.c: A program to report the installed OpenSSL version
• https_simple.c: A minimal program that requests a web page using HTTPS
• https_get.c: The HTTP client of Chapter 6, Building a Simple Web Client, modified to use HTTPS
• tls_client.c: The TCP client program of Chapter 3, An In-Depth Overview of TCP Connections, modified to use TLS
• tls_get_cert.c: Prints a certificate from a TLS server

Chapter 10 – Implementing a Secure Web Server

The examples in this chapter use OpenSSL. Be sure to link to the OpenSSL libraries when compiling (-lssl -lcrypto):

• tls_time_server.c: The time server of Chapter 2, Getting to Grips with Socket APIs, modified to use HTTPS
• https_server.c: The web server of Chapter 7, Building a Simple Web Server, modified to use HTTPS

Chapter 11 – Establishing SSH Connections with libssh

The examples in this chapter use libssh. Be sure to link to the libssh libraries when compiling (-lssh):

• ssh_version.c: A program to report the libssh version
• ssh_connect.c: A minimal client that establishes an SSH connection
• ssh_auth.c: A client that attempts SSH client authentication using a password
• ssh_command.c: A client that executes a single remote command over SSH
• ssh_download.c: A client that downloads a file over SSH/SCP

Chapter 12 – Network Monitoring and Security

This chapter doesn't include any example programs.

Chapter 13 – Socket Programming Tips and Pitfalls

This chapter includes the following example programs:

• connect_timeout.c: Shows how to time out a connect() call early.
• connect_blocking.c: For comparison with connect_timeout.c.
• server_reuse.c: Demonstrates the use of SO_REUSEADDR.
• server_noreuse.c: For comparison with server_reuse.c.
• server_crash.c: This server purposefully writes to a TCP socket after the client disconnects.
• error_text.c: Shows how to obtain error code descriptions.
• big_send.c: A TCP client that sends lots of data after connecting. Used to show the blocking behavior of send().
• server_ignore.c: A TCP server that accepts connections, then simply ignores them. Used to show the blocking behavior of send().
• setsize.c: Shows the maximum number of sockets select() can handle.

Chapter 14 – Web Programming for the Internet of Things

This chapter doesn't include any example programs.