Table of Contents
Acknowledgments xvii
Introduction xix
Who This Book Is For xx
Installing Go xx
Recommended Development Environments xxi
What's in This Book xxi
Part I Network Architecture 1
1 An Overview of Networked Systems 3
Choosing a Network Topology 3
Bandwidth vs. Latency 6
The Open Systems Interconnection Reference Model 7
The Hierarchal Layers of the OSI Reference Model 8
Sending Traffic by Using Data Encapsulation 10
The TCP/IP Model 12
The Application Layer 13
The Transport Layer 14
The Internet Layer 14
The Link Layer 15
What You've Learned 15
2 Resource Location and Traffic Routing 17
The Internet Protocol 18
IPv4 Addressing 18
Network and Host IDs 19
Subdividing IPv4 Addresses into Subnets 20
Ports and Socket Addresses 23
Network Address Translation 24
Unicasting, Multicasting, and Broadcasting 25
Resolving the MAC Address to a Physical Network Connection 26
IPv6 Addressing 26
Writing IPv6 Addresses 26
IPv6 Address Categories 28
Advantages of IPv6 over IPv4 30
The Internet Control Message Protocol 31
Internet Traffic Routing 32
Routing Protocols 33
The Border Gateway Protocol 34
Name and Address Resolution 34
Domain Name Resource Records 35
Multicast DNS 40
Privacy and Security Considerations of DNS Queries 40
What You've Learned 41
Part II Socket-Level Programming 43
3 Reliable Tcp Data Streams 45
What Makes TCP Reliable? 46
Working with TCP Sessions 46
Establishing a Session with the TCP Handshake 47
Acknowledging Receipt of Packets by Using Their Sequence Numbers 47
Receive Buffers and Window Sizes 48
Gracefully Terminating TCP Sessions 50
Handling Less Graceful Terminations 51
Establishing a TCP Connection by Using Go's Standard Library 51
Binding, Listening for, and Accepting Connections 51
Establishing a Connection with a Server 53
Implementing Deadlines 62
What You've Learned 71
4 Sending Tcp Data 73
Using the net. Conn Interface 74
Sending and Receiving Data 74
Reading Data into a Fixed Buffer 74
Delimited Reading by Using a Scanner 76
Dynamically Allocating the Buffer Size 79
Handling Errors While Reading and Writing Data 86
Creating Robust Network Applications by Using the io Package 87
Proxying Data Between Connections 87
Monitoring a Network Connection 93
Pinging a Host in ICMP-Filtered Environments 96
Exploring Go's TCPConn Object 98
Controlling Keepalive Messages 99
Handling Pending Data on Close 99
Overriding Default Receive and Send Buffers 100
Solving Common Go TCP Network Problems 101
Zero Window Errors 101
Sockets Stuck in the CLOSE_WAIT State 102
What You've Learned 102
5 Unreliable UDP Communication 105
Using UDP: Simple and Unreliable 106
Sending and Receiving UDP Data 107
Using a UDP Echo Server 107
Receiving Data from the Echo Server 109
Every UDP Connection Is a Listener 110
Using net. Conn in UDP 113
Avoiding Fragmentation 115
What You've Learned 117
6 Ensuring UDP Reliability 119
Reliable File Transfers Using TFTP 119
TFTP Types 120
Read Requests 121
Data Packets 124
Acknowledgments 128
Handling Errors 129
The TFTP Server 131
Writing the Server Code 131
Handling Read Requests 132
Starting the Server 135
Downloading Files over UDP 135
What You've Learned 139
7 Unix Domain Sockets 141
What Are Unix Domain Sockets? 142
Binding to Unix Domain Socket Files 143
Changing a Socket File's Ownership and Permissions 143
Understanding Unix Domain Socket Types 144
Writing a Service That Authenticates Clients 154
Requesting Peer Credentials 154
Writing the Service 156
Testing the Service with Netcat 159
What You've Learned 160
Part III Application-Level Programming 163
8 Writing Http Clients 165
Understanding the Basics of HTTP 166
Uniform Resource Locators 166
Client Resource Requests 167
Server Responses 170
From Request to Rendered Page 172
Retrieving Web Resources in Go 173
Using Go's Default HTTP Client 173
Closing the Response Body 174
Implementing Time-outs and Cancellations 176
Disabling Persistent TCP Connections 178
Posting Data over HTTP 179
Posting JSON to a Web Server 179
Posting a Multipart Form with Attached files 181
What You've Learned 184
9 Building HTTP Services 187
The Anatomy of a Go HTTP Server 188
Clients Don't Respect Your Time 191
Adding TLS Support 192
Handlers 193
Test Your Handlers with httptest 195
How You Write the Response Matters 196
Any Type Can Be a Handler 198
Injecting Dependencies into Handlers 200
Middleware 202
Timing Out Slow Clients 203
Protecting Sensitive Files 204
Multiplexers 207
HTTP/2 Server Pushes 209
Pushing Resources to the Client 210
Don't Be Too Pushy 214
What You've Learned 215
10 Caddy: A Contemporary Web Server 217
What Is Caddy? 218
Let's Encrypt Integration 218
How Does Caddy Fit into the Equation? 219
Retrieving Caddy 219
Downloading Caddy 219
Building Caddy from Source Code 220
Running and Configuring Caddy 220
Modifying Caddy's Configuration in Real Time 222
Storing the Configuration in a Fife 224
Extending Caddy with Modules and Adapters 224
Writing a Configuration Adapter 225
Writing a Restrict Prefix Middleware Module 226
Injecting Your Module into Caddy 231
Reverse-Proxying Requests to a Backend Web Service 232
Creating a Simple Backend Web Service 232
Setting Up Caddy's Configuration 234
Adding a Reverse-Proxy to Your Service 235
Serving Static Files 236
Checking Your Work 236
Adding Automatic HTTPS 237
What You've Learned 238
11 Securing Communications With TLS 241
Closer Look at Transport Layer Security 242
Forward Secrecy 243
In Certificate Authorities We Trust 243
How to Compromise TLS 244
Protecting Data in Transit 245
Client-side TLS 245
TLS over TCP 247
Server-side TLS 249
Certificate Pinning 252
Mutual TLS Authentication 255
Generating Certificates for Authentication 256
Implementing Mutual TLS 259
What You've Learned 265
Part IV Service Architecture 267
12 Data Serialization 269
Serializing Objects 270
JSON 276
Gob 278
Protocol Buffers 280
Transmitting Serialized Objects 284
Connecting Services with gRPC 284
Creating a TLS-Enabled gRPC Server 286
Creating a gRPC Client to Test the Server 289
What You've Learned 294
13 Logging and Metrics 295
Event Logging 296
The log Package 297
Leveled Log Entries 300
Structured Logging 301
Scaling Up with Wide Event Logging 312
Log Rotation with Lumberjack 315
Instrumenting Your Code 316
Setup 317
Counters 317
Gauges 318
Histograms and Summaries 319
Instrumenting a Basic HTTP Server 320
What You've Learned 326
14 Moving To the Cloud 329
Laying Some Groundwork 330
AWS Lambda 333
Installing the AWS Command Line interface 333
Configuring the CLI 333
11 Creating a Role 335
Defining an AWS Lambda Function 336
Compiling, Packaging, and Deploying Your Function 339
Testing Your AWS Lambda Function 340
Google Cloud Functions 341
Installing the Google Cloud Software Development Kit 341
Initializing the Google Cloud SDK 341
Enable Billing and Cloud Functions 342
Defining a Cloud Function 342
Deploying Your Cloud Function 344
Testing Your Google Cloud Function 345
Azure Functions 346
Installing the Azure Command Line Interface 346
Configuring the Azure CLI 347
Installing Azure Functions Core Tools 347
Creating a Custom Handler 348
Defining a Custom Handler 349
Locally Testing the Custom Handler 350
Deploying the Custom Handler 351
Testing the Custom Handler 353
What You've Learned 353
Index 355
