Go net/http

https://pkg.go.dev/net/http
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### Example: HTTP/2 with EnableHTTP2 and StartTLS

Source: https://pkg.go.dev/net/http/httptest

Example of starting an unstarted server with HTTP/2 enabled via EnableHTTP2 and StartTLS, then using the client to make a request. The output is 'Hello, HTTP/2.0'.

```go
package main

import (
	"fmt"
	"io"
	"log"
	"net/http"
	"net/http/httptest"
)

func main() {
	ts := httptest.NewUnstartedServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprintf(w, "Hello, %s", r.Proto)
	}))
	ts.EnableHTTP2 = true
	ts.StartTLS()
	defer ts.Close()

	res, err := ts.Client().Get(ts.URL)
	if err != nil {
		log.Fatal(err)
	}
	greeting, err := io.ReadAll(res.Body)
	res.Body.Close()
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("%s", greeting)

}
```

```text
Output:
Hello, HTTP/2.0
```

--------------------------------

### Example: NewServer with HTTP/1.1

Source: https://pkg.go.dev/net/http/httptest

Complete example of using httptest.NewServer to create a test server, send a GET request, and print the response body. The output is 'Hello, client'.

```go
package main

import (
	"fmt"
	"io"
	"log"
	"net/http"
	"net/http/httptest"
)

func main() {
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprintln(w, "Hello, client")
	}))
	defer ts.Close()

	res, err := http.Get(ts.URL)
	if err != nil {
		log.Fatal(err)
	}
	greeting, err := io.ReadAll(res.Body)
	res.Body.Close()
	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("%s", greeting)
}
```

```text
Output:
Hello, client
```

--------------------------------

### Example: HTTP/2 Server Usage

Source: https://pkg.go.dev/net/http/httptest

Example demonstrating how to create an unstarted test server, enable HTTP/2, start it with TLS, and make a request using the server's client.

```APIDOC
## Example: HTTP/2 Server Usage

### Description
Example demonstrating how to create an unstarted test server, enable HTTP/2, start it with TLS, and make a request using the server's client.

### Code
```go
package main

import (
	"fmt"
	"io"
	"log"
	"net/http"
	"net/http/httptest"
)

func main() {
	ts := httptest.NewUnstartedServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprintf(w, "Hello, %s", r.Proto)
	}))
	ts.EnableHTTP2 = true
	ts.StartTLS()
	defer ts.Close()

	res, err := ts.Client().Get(ts.URL)
	if err != nil {
		log.Fatal(err)
	}
	greeting, err := io.ReadAll(res.Body)
	res.Body.Close()
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("%s", greeting)
}
```

### Output
```
Hello, HTTP/2.0
```
```

--------------------------------

### ListenAndServe example: hello world server

Source: https://pkg.go.dev/net/http

Complete example for the ListenAndServe function. It defines a handler that writes 'Hello, world!' and registers it for the '/hello' pattern, then starts the server on port 8080.

```go
package main

import (
	"io"
	"log"
	"net/http"
)

func main() {
	// Hello world, the web server

	helloHandler := func(w http.ResponseWriter, req *http.Request) {
		io.WriteString(w, "Hello, world!\n")
	}

	http.HandleFunc("/hello", helloHandler)
	log.Fatal(http.ListenAndServe(":8080", nil))
}
```

--------------------------------

### Example: DumpResponse

Source: https://pkg.go.dev/net/http/httputil

Complete example demonstrating DumpResponse. It creates a test server, sends a GET request, and dumps the response with the body. The output is printed as a quoted string.

```go
package main

import (
	"fmt"
	"log"
	"net/http"
	"net/http/httptest"
	"net/http/httputil"
)

func main() {
	const body = "Go is a general-purpose language designed with systems programming in mind."
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Date", "Wed, 19 Jul 1972 19:00:00 GMT")
		fmt.Fprintln(w, body)
	}))
	defer ts.Close()

	resp, err := http.Get(ts.URL)
	if err != nil {
		log.Fatal(err)
	}
	defer resp.Body.Close()

	dump, err := httputil.DumpResponse(resp, true)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("%q", dump)

}
```

```text
Output:
"HTTP/1.1 200 OK\r\nContent-Length: 76\r\nContent-Type: text/plain; charset=utf-8\r\nDate: Wed, 19 Jul 1972 19:00:00 GMT\r\n\r\nGo is a general-purpose language designed with systems programming in mind.\n"
```

--------------------------------

### Output placeholder for Get example

Source: https://pkg.go.dev/net/http

Placeholder for the output of the Get example. The actual output is not shown.

```text
Output:
```

--------------------------------

### Package example: tracing HTTP client request with httptrace

Source: https://pkg.go.dev/net/http/httptrace

This example creates an HTTP GET request, defines a ClientTrace with GotConn and DNSDone hooks, attaches the trace to the request context using WithClientTrace, and performs the request with http.DefaultTransport.RoundTrip. The output is empty as shown.

```Go
package main

import (
	"fmt"
	"log"
	"net/http"
	"net/http/httptrace"
)

func main() {
	req, _ := http.NewRequest("GET", "http://example.com", nil)
	trace := &httptrace.ClientTrace{
		GotConn: func(connInfo httptrace.GotConnInfo) {
			fmt.Printf("Got Conn: %+v\n", connInfo)
		},
		DNSDone: func(dnsInfo httptrace.DNSDoneInfo) {
			fmt.Printf("DNS Info: %+v\n", dnsInfo)
		},
	}
	req = req.WithContext(httptrace.WithClientTrace(req.Context(), trace))
	_, err := http.DefaultTransport.RoundTrip(req)
	if err != nil {
		log.Fatal(err)
	}
}
```

```text
Output:
```

--------------------------------

### Start a server with DefaultServeMux

Source: https://pkg.go.dev/net/http

Shows how to register handlers with http.Handle and http.HandleFunc and start a server with http.ListenAndServe using the default mux.

```go
http.Handle("/foo", fooHandler)

http.HandleFunc("/bar", func(w http.ResponseWriter, r *http.Request) {
	fmt.Fprintf(w, "Hello, %q", html.EscapeString(r.URL.Path))
})

log.Fatal(http.ListenAndServe(":8080", nil))
```

--------------------------------

### Example: Use HTTP/1 and HTTP/2 with Protocols.SetHTTP1 and SetHTTP2

Source: https://pkg.go.dev/net/http

Configures an http.Transport to use either HTTP/1 or HTTP/2 by cloning the default transport, enabling both protocols, and creating an http.Client with that transport. The example makes a GET request to http://www.google.com/robots.txt.

```go
package main

import (
	"log"
	"net/http"
)

func main() {
	t := http.DefaultTransport.(*http.Transport).Clone()

	// Use either HTTP/1 and HTTP/2.
	t.Protocols = new(http.Protocols)
	t.Protocols.SetHTTP1(true)
	t.Protocols.SetHTTP2(true)

	cli := &http.Client{Transport: t}
	res, err := cli.Get("http://www.google.com/robots.txt")
	if err != nil {
		log.Fatal(err)
	}
	res.Body.Close()
}
```

--------------------------------

### Example: Using cookiejar.New with an HTTP client

Source: https://pkg.go.dev/net/http/cookiejar

This example starts a test server that sets and updates a cookie, creates a cookiejar with the publicsuffix list, and uses it with an HTTP client. It prints the cookies after each request. The output shows the cookie value changing from 'Chocolate Chip' to 'Oatmeal Raisin'.

```go
// Start a server to give us cookies.
ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
	if cookie, err := r.Cookie("Flavor"); err != nil {
		http.SetCookie(w, &http.Cookie{Name: "Flavor", Value: "Chocolate Chip"})
	} else {
		cookie.Value = "Oatmeal Raisin"
		http.SetCookie(w, cookie)
	}
}))
defer ts.Close()

u, err := url.Parse(ts.URL)
if err != nil {
	log.Fatal(err)
}

// All users of cookiejar should import "golang.org/x/net/publicsuffix"
jar, err := cookiejar.New(&cookiejar.Options{PublicSuffixList: publicsuffix.List})
if err != nil {
	log.Fatal(err)
}

client := &http.Client{
	Jar: jar,
}

if _, err = client.Get(u.String()); err != nil {
	log.Fatal(err)
}

fmt.Println("After 1st request:")
for _, cookie := range jar.Cookies(u) {
	fmt.Printf("  %s: %s\n", cookie.Name, cookie.Value)
}

if _, err = client.Get(u.String()); err != nil {
	log.Fatal(err)
}

fmt.Println("After 2nd request:")
for _, cookie := range jar.Cookies(u) {
	fmt.Printf("  %s: %s\n", cookie.Name, cookie.Value)
}
```

```go
Output:
After 1st request:
  Flavor: Chocolate Chip
After 2nd request:
  Flavor: Oatmeal Raisin
```

--------------------------------

### func (s *Server) Start()

Source: https://pkg.go.dev/net/http/httptest

Starts the test server on a local loopback network interface. The server should have been created by NewTestServer or NewUnstartedServer.

```APIDOC
## func (s *Server) Start()

### Description
Starts the test server on a local loopback network interface. The server should have been created by NewTestServer or NewUnstartedServer.

### Method
Start

### Signature
func (s *Server) Start()

### Parameters
None

### Return Value
None

### Usage Example
```go
server := httptest.NewUnstartedServer(handler)
server.Start()
```
```

--------------------------------

### func (s *Server) Start()

Source: https://pkg.go.dev/net/http/httptest

Starts the server from an unstarted state. It is an error to call Start on an already started server.

```APIDOC
## func (s *Server) Start()

### Description
Start starts the server from an unstarted state. It is an error to call Start on an already started server.

### Method
N/A (method)

### Endpoint
N/A (method)

### Parameters
None.

### Returns
None.

### Example
```go
server.Start()
```
```

--------------------------------

### ResponseRecorder example with output

Source: https://pkg.go.dev/net/http/httptest

Complete example showing how to use httptest.NewRequest and httptest.NewRecorder to test a handler. The handler writes an HTML string, and the example prints the status code, Content-Type header, and body. The output is shown as displayed.

```go
package main

import (
	"fmt"
	"io"
	"net/http"
	"net/http/httptest"
)

func main() {
	handler := func(w http.ResponseWriter, r *http.Request) {
		io.WriteString(w, "<html><body>Hello World!</body></html>")
	}

	req := httptest.NewRequest("GET", "http://example.com/foo", nil)
	w := httptest.NewRecorder()
	handler(w, req)

	resp := w.Result()
	body, _ := io.ReadAll(resp.Body)

	fmt.Println(resp.StatusCode)
	fmt.Println(resp.Header.Get("Content-Type"))
	fmt.Println(string(body))

}
```

```text
Output:
200
text/html; charset=utf-8
<html><body>Hello World!</body></html>
```

--------------------------------

### HandleFunc example: two handlers

Source: https://pkg.go.dev/net/http

Complete example for the HandleFunc function. It defines two handler functions that write different messages, registers them for the '/' and '/endpoint' patterns, and starts the server on port 8080.

```go
package main

import (
	"io"
	"log"
	"net/http"
)

func main() {
	h1 := func(w http.ResponseWriter, _ *http.Request) {
		io.WriteString(w, "Hello from a HandleFunc #1!\n")
	}
	h2 := func(w http.ResponseWriter, _ *http.Request) {
		io.WriteString(w, "Hello from a HandleFunc #2!\n")
	}

	http.HandleFunc("/", h1)
	http.HandleFunc("/endpoint", h2)

	log.Fatal(http.ListenAndServe(":8080", nil))
}
```

--------------------------------

### Example: Basic Server Usage

Source: https://pkg.go.dev/net/http/httptest

Example demonstrating how to create a test server with httptest.NewServer, make an HTTP request to it, and read the response body.

```APIDOC
## Example: Basic Server Usage

### Description
Example demonstrating how to create a test server with httptest.NewServer, make an HTTP request to it, and read the response body.

### Code
```go
package main

import (
	"fmt"
	"io"
	"log"
	"net/http"
	"net/http/httptest"
)

func main() {
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprintln(w, "Hello, client")
	}))
	defer ts.Close()

	res, err := http.Get(ts.URL)
	if err != nil {
		log.Fatal(err)
	}
	greeting, err := io.ReadAll(res.Body)
	res.Body.Close()
	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("%s", greeting)
}
```

### Output
```
Hello, client
```
```

--------------------------------

### Example: ServeMux.Handle with root and API handlers

Source: https://pkg.go.dev/net/http

Example from the documentation showing how to register an API handler and a root handler using ServeMux.Handle and ServeMux.HandleFunc. The root handler checks the URL path to avoid matching all paths.

```go
package main

import (
	"fmt"
	"net/http"
)

type apiHandler struct{}

func (apiHandler) ServeHTTP(http.ResponseWriter, *http.Request) {}

func main() {
	mux := http.NewServeMux()
	mux.Handle("/api/", apiHandler{})
	mux.HandleFunc("/", func(w http.ResponseWriter, req *http.Request) {
		// The "/" pattern matches everything, so we need to check
		// that we're at the root here.
		if req.URL.Path != "/" {
			http.NotFound(w, req)
			return
		}
		fmt.Fprintf(w, "Welcome to the home page!")
	})
}
```

--------------------------------

### Example: http.Get

Source: https://pkg.go.dev/net/http

Complete example of using http.Get to fetch a URL, read the response body, and check for errors. It prints the body to standard output.

```go
package main

import (
	"fmt"
	"io"
	"log"
	"net/http"
)

func main() {
	res, err := http.Get("http://www.google.com/robots.txt")
	if err != nil {
		log.Fatal(err)
	}
	body, err := io.ReadAll(res.Body)
	res.Body.Close()
	if res.StatusCode > 299 {
		log.Fatalf("Response failed with status code: %d and\nbody: %s\n", res.StatusCode, body)
	}
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("%s", body)
}
```

--------------------------------

### NewTLSServer example

Source: https://pkg.go.dev/net/http/httptest

Example usage of NewTLSServer: creates a TLS test server, uses its client to make a request, and prints the response.

```go
package main

import (
	"fmt"
	"io"
	"log"
	"net/http"
	"net/http/httptest"
)

func main() {
	ts := httptest.NewTLSServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprintln(w, "Hello, client")
	}))
	defer ts.Close()

	client := ts.Client()
	res, err := client.Get(ts.URL)
	if err != nil {
		log.Fatal(err)
	}

	greeting, err := io.ReadAll(res.Body)
	res.Body.Close()
	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("%s", greeting)
}
```

```text
Output:
Hello, client
```

--------------------------------

### ListenAndServeTLS example

Source: https://pkg.go.dev/net/http

Example of using ListenAndServeTLS to serve HTTPS on port 8443. It sets up a handler that returns 'Hello, TLS!' and logs a fatal error if the server fails. The example notes that cert.pem and key.pem can be generated using generate_cert.go in crypto/tls.

```go
package main

import (
	"io"
	"log"
	"net/http"
)

func main() {
	http.HandleFunc("/", func(w http.ResponseWriter, req *http.Request) {
		io.WriteString(w, "Hello, TLS!\n")
	})

	// One can use generate_cert.go in crypto/tls to generate cert.pem and key.pem.
	log.Printf("About to listen on 8443. Go to https://127.0.0.1:8443/")
	err := http.ListenAndServeTLS(":8443", "cert.pem", "key.pem", nil)
	log.Fatal(err)
}
```

--------------------------------

### Example: Serve only HTTP/1 with Protocols.SetHTTP1

Source: https://pkg.go.dev/net/http

Configures an http.Server to serve only HTTP/1 by creating a new Protocols, enabling HTTP1, and calling ListenAndServeTLS. The example uses cert.pem and key.pem files.

```go
package main

import (
	"log"
	"net/http"
)

func main() {
	srv := http.Server{
		Addr: ":8443",
	}

	// Serve only HTTP/1.
	srv.Protocols = new(http.Protocols)
	srv.Protocols.SetHTTP1(true)

	log.Fatal(srv.ListenAndServeTLS("cert.pem", "key.pem"))
}
```

--------------------------------

### Create a custom Server with timeouts

Source: https://pkg.go.dev/net/http

Shows how to create a custom http.Server with Addr, Handler, ReadTimeout, WriteTimeout, and MaxHeaderBytes, and start it with ListenAndServe.

```go
s := &http.Server{
	Addr:           ":8080",
	Handler:        myHandler,
	ReadTimeout:    10 * time.Second,
	WriteTimeout:   10 * time.Second,
	MaxHeaderBytes: 1 << 20,
}
log.Fatal(s.ListenAndServe())
```

--------------------------------

### func (s *Server) StartTLS()

Source: https://pkg.go.dev/net/http/httptest

Starts the server with TLS from an unstarted state. It is an error to call StartTLS on an already started server.

```APIDOC
## func (s *Server) StartTLS()

### Description
StartTLS starts the server with TLS from an unstarted state. It is an error to call StartTLS on an already started server.

### Method
N/A (method)

### Endpoint
N/A (method)

### Parameters
None.

### Returns
None.

### Example
```go
server.StartTLS()
```
```

--------------------------------

### ReverseProxy Example

Source: https://pkg.go.dev/net/http/httputil

Example demonstrating how to use ReverseProxy with the Rewrite field to proxy requests to a backend server.

```APIDOC
## ReverseProxy Example

### Description
Example of using ReverseProxy with the Rewrite field to relay requests to a backend server.

### Code
```go
package main

import (
	"fmt"
	"io"
	"log"
	"net/http"
	"net/http/httptest"
	"net/http/httputil"
	"net/url"
)

func main() {
	backendServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprintln(w, "this call was relayed by the reverse proxy")
	}))
	defer backendServer.Close()

	rpURL, err := url.Parse(backendServer.URL)
	if err != nil {
		log.Fatal(err)
	}
	frontendProxy := httptest.NewServer(&httputil.ReverseProxy{
		Rewrite: func(r *httputil.ProxyRequest) {
			r.SetXForwarded()
			r.SetURL(rpURL)
		},
	})
	defer frontendProxy.Close()

	resp, err := http.Get(frontendProxy.URL)
	if err != nil {
		log.Fatal(err)
	}

	b, err := io.ReadAll(resp.Body)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("%s", b)
}
```

### Output
```
this call was relayed by the reverse proxy
```
```

--------------------------------

### NotFoundHandler example

Source: https://pkg.go.dev/net/http

Example usage of http.NotFoundHandler to return 404 for a specific path while other paths return 200.

```go
package main

import (
	"fmt"
	"log"
	"net/http"
)

func newPeopleHandler() http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprintln(w, "This is the people handler.")
	})
}

func main() {
	mux := http.NewServeMux()

	// Create sample handler to returns 404
	mux.Handle("/resources", http.NotFoundHandler())

	// Create sample handler that returns 200
	mux.Handle("/resources/people/", newPeopleHandler())

	log.Fatal(http.ListenAndServe(":8080", mux))
}
```

--------------------------------

### FileServer example: dot file hiding

Source: https://pkg.go.dev/net/http

Example of a custom http.FileSystem that hides dot files from being served. It wraps the FileSystem and File to filter out files starting with a period and returns a 403 permission error for paths containing dot files.

```go
package main

import (
	"io"
	"io/fs"
	"log"
	"net/http"
	"strings"
)

// containsDotFile reports whether name contains a path element starting with a period.
// The name is assumed to be a delimited by forward slashes, as guaranteed
// by the http.FileSystem interface.
func containsDotFile(name string) bool {
	parts := strings.Split(name, "/")
	for _, part := range parts {
		if strings.HasPrefix(part, ".") {
			return true
		}
	}
	return false
}

// dotFileHidingFile is the http.File use in dotFileHidingFileSystem.
// It is used to wrap the Readdir method of http.File so that we can
// remove files and directories that start with a period from its output.
type dotFileHidingFile struct {
	http.File
}

// Readdir is a wrapper around the Readdir method of the embedded File
// that filters out all files that start with a period in their name.
func (f dotFileHidingFile) Readdir(n int) (fis []fs.FileInfo, err error) {
	files, err := f.File.Readdir(n)
	for _, file := range files { // Filters out the dot files
		if !strings.HasPrefix(file.Name(), ".") {
			fis = append(fis, file)
		}
	}
	if err == nil && n > 0 && len(fis) == 0 {
		err = io.EOF
	}
	return
}

// dotFileHidingFileSystem is an http.FileSystem that hides
// hidden "dot files" from being served.
type dotFileHidingFileSystem struct {
	http.FileSystem
}

// Open is a wrapper around the Open method of the embedded FileSystem
// that serves a 403 permission error when name has a file or directory
// with whose name starts with a period in its path.
func (fsys dotFileHidingFileSystem) Open(name string) (http.File, error) {
	if containsDotFile(name) { // If dot file, return 403 response
		return nil, fs.ErrPermission
	}

	file, err := fsys.FileSystem.Open(name)
	if err != nil {
		return nil, err
	}
	return dotFileHidingFile{file}, nil
}

func main() {
	fsys := dotFileHidingFileSystem{http.Dir(".")}
	http.Handle("/", http.FileServer(fsys))
	log.Fatal(http.ListenAndServe(":8080", nil))
}
```

--------------------------------

### Start HTTP server for pprof

Source: https://pkg.go.dev/net/http/pprof

If the application is not already running an HTTP server, start one on localhost:6060. This code is added to the main function after importing net/http and log.

```go
go func() {
	log.Println(http.ListenAndServe("localhost:6060", nil))
}()
```

--------------------------------

### Server.Start and Server.StartTLS

Source: https://pkg.go.dev/net/http/httptest

Server.Start and Server.StartTLS start the server on a loopback interface with a system-chosen port. Start serves HTTP, while StartTLS serves HTTPS. The server's URL field is set to a base URL containing the server's address.

```APIDOC
## Server.Start and Server.StartTLS

### Description
Server.Start and Server.StartTLS start the server on a loopback interface with a system-chosen port. Start serves HTTP, while StartTLS serves HTTPS. The server's URL field is set to a base URL containing the server's address.

### Methods
- **Server.Start()** - Starts the server serving HTTP.
- **Server.StartTLS()** - Starts the server serving HTTPS.

### Behavior
- The server listens on a system-chosen port on the loopback interface.
- The Server.URL field is set to a base URL containing the server's address.
- When using the loopback network, the http.Client returned by Server.Client is configured to send requests with a hostname of "example.com" or a subdomain of ".example.com" to the server.
- Requests may also be sent to the server's loopback address.

### Example
```go
server := httptest.NewTestServer(t, handler)
server.Start()
client := server.Client()

// This request is sent to the test server.
_, _ = server.Client().Get(server.URL + "/")

// This request (using http.DefaultClient) is also sent to the test server,
// since server.URL contains the server's local IP address.
_, _ = http.Get(server.URL + "/")
```
```

--------------------------------

### Handle example: count handler

Source: https://pkg.go.dev/net/http

Complete example for the Handle function. It defines a countHandler struct with a mutex and an integer, and its ServeHTTP method increments the count and writes it to the response. The main function registers the handler for the '/count' pattern and starts the server on port 8080.

```go
package main

import (
	"fmt"
	"log"
	"net/http"
	"sync"
)

type countHandler struct {
	mu sync.Mutex // guards n
	n  int
}

func (h *countHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	h.mu.Lock()
	defer h.mu.Unlock()
	h.n++
	fmt.Fprintf(w, "count is %d\n", h.n)
}

func main() {
	http.Handle("/count", new(countHandler))
	log.Fatal(http.ListenAndServe(":8080", nil))
}
```

--------------------------------

### FileServer example: simple static webserver

Source: https://pkg.go.dev/net/http

Complete example of a simple static webserver using FileServer with http.Dir. It serves files from /usr/share/doc on port 8080.

```go
package main

import (
	"log"
	"net/http"
)

func main() {
	// Simple static webserver:
	log.Fatal(http.ListenAndServe(":8080", http.FileServer(http.Dir("/usr/share/doc"))))
}
```

--------------------------------

### FileServer example: StripPrefix

Source: https://pkg.go.dev/net/http

Example of using http.StripPrefix to serve a directory on disk under an alternate URL path. It modifies the request URL's path before the FileServer sees it.

```go
package main

import (
	"net/http"
)

func main() {
	// To serve a directory on disk (/tmp) under an alternate URL
	// path (/tmpfiles/), use StripPrefix to modify the request
	// URL's path before the FileServer sees it:
	http.Handle("/tmpfiles/", http.StripPrefix("/tmpfiles/", http.FileServer(http.Dir("/tmp"))))
}
```

--------------------------------

### func NewUnstartedServer(handler http.Handler) *Server

Source: https://pkg.go.dev/net/http/httptest

Returns a new Server but does not start it. The caller must call Start or StartTLS to begin serving.

```APIDOC
## func NewUnstartedServer(handler http.Handler) *Server

### Description
NewUnstartedServer returns a new Server but does not start it. The caller must call Start or StartTLS to begin serving.

### Method
N/A (function)

### Endpoint
N/A (function)

### Parameters
- **handler** (http.Handler) - Required - The HTTP handler to serve.

### Returns
- **\*Server** - The unstarted server.

### Example
```go
server := httptest.NewUnstartedServer(handler)
server.Start()
```
```

--------------------------------

### Create a test server and send a request

Source: https://pkg.go.dev/net/http/httptest

Example usage of httptest.NewTestServer and Server.Client to send a request to the test server.

```go
// Create a test server and send a request to it.
server := httptest.NewTestServer(t, handler)
resp, err := server.Client().Get("http://www.example.com/")
```

--------------------------------

### func (s *Server) StartTLS()

Source: https://pkg.go.dev/net/http/httptest

Starts TLS on a server on a local loopback network interface. The server should have been created by NewTestServer or NewUnstartedServer.

```APIDOC
## func (s *Server) StartTLS()

### Description
Starts TLS on a server on a local loopback network interface. The server should have been created by NewTestServer or NewUnstartedServer.

### Method
StartTLS

### Signature
func (s *Server) StartTLS()

### Parameters
None

### Return Value
None

### Usage Example
```go
server := httptest.NewUnstartedServer(handler)
server.StartTLS()
```
```

--------------------------------

### DumpRequestOut example with output

Source: https://pkg.go.dev/net/http/httputil

Example of using httputil.DumpRequestOut to dump an outgoing client request. The request is a PUT to www.example.org with a body. The output shows the HTTP/1.1 wire format including headers added by the transport.

```go
package main

import (
	"fmt"
	"log"
	"net/http"
	"net/http/httputil"
	"strings"
)

func main() {
	const body = "Go is a general-purpose language designed with systems programming in mind."
	req, err := http.NewRequest("PUT", "http://www.example.org", strings.NewReader(body))
	if err != nil {
		log.Fatal(err)
	}

	dump, err := httputil.DumpRequestOut(req, true)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("%q", dump)

}
```

```text
Output:
"PUT / HTTP/1.1\r\nHost: www.example.org\r\nUser-Agent: Go-http-client/1.1\r\nContent-Length: 75\r\nAccept-Encoding: gzip\r\n\r\nGo is a general-purpose language designed with systems programming in mind."
```

--------------------------------

### Configure a test server before using (httptest.NewTestServer)

Source: https://pkg.go.dev/net/http/httptest

Shows how to set server configuration (MaxHeaderBytes) before the first use. Configuration must not be changed after calling Client, Start, or StartTLS.

```go
// Configure a test server before using.
server := httptest.NewTestServer(t, handler)
server.Config.MaxHeaderBytes = 1024
resp, err := server.Client().Get("http://www.example.com/")
```

--------------------------------

### CrossOriginProtection example

Source: https://pkg.go.dev/net/http

Shows how to use CrossOriginProtection.Handler to block non-safe cross-origin browser requests. The example sets up an HTTP server with a /hello handler and wraps the mux with the protection handler.

```go
package main

import (
	"io"
	"log"
	"net/http"
	"time"
)

func main() {
	mux := http.NewServeMux()

	mux.HandleFunc("/hello", func(w http.ResponseWriter, req *http.Request) {
		io.WriteString(w, "request allowed\n")
	})

	srv := http.Server{
		Addr:         ":8080",
		ReadTimeout:  15 * time.Second,
		WriteTimeout: 15 * time.Second,
		// Use CrossOriginProtection.Handler to block all non-safe cross-origin
		// browser requests to mux.
		Handler: http.NewCrossOriginProtection().Handler(mux),
	}

	log.Fatal(srv.ListenAndServe())
}
```

--------------------------------

### ReverseProxy example with Rewrite

Source: https://pkg.go.dev/net/http/httputil

Complete example of using httputil.ReverseProxy with a Rewrite function to relay requests to a backend server. It sets up a backend httptest server, a frontend proxy, and makes a request, printing the response body. The output is 'this call was relayed by the reverse proxy'.

```go
package main

import (
	"fmt"
	"io"
	"log"
	"net/http"
	"net/http/httptest"
	"net/http/httputil"
	"net/url"
)

func main() {
	backendServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprintln(w, "this call was relayed by the reverse proxy")
	}))
	defer backendServer.Close()

	rpURL, err := url.Parse(backendServer.URL)
	if err != nil {
		log.Fatal(err)
	}
	frontendProxy := httptest.NewServer(&httputil.ReverseProxy{
		Rewrite: func(r *httputil.ProxyRequest) {
			r.SetXForwarded()
			r.SetURL(rpURL)
		},
	})
	defer frontendProxy.Close()

	resp, err := http.Get(frontendProxy.URL)
	if err != nil {
		log.Fatal(err)
	}

	b, err := io.ReadAll(resp.Body)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("%s", b)

}
```

```text
Output:
this call was relayed by the reverse proxy
```

--------------------------------

### Example: Setting HTTP Trailers with ResponseWriter

Source: https://pkg.go.dev/net/http

Shows how to declare and set HTTP trailers in a handler. Trailers must be declared before WriteHeader or Write, and are sent after the response body.

```go
package main

import (
	"io"
	"net/http"
)

func main() {
	mux := http.NewServeMux()
	mux.HandleFunc("/sendstrailers", func(w http.ResponseWriter, req *http.Request) {
		// Before any call to WriteHeader or Write, declare
		// the trailers you will set during the HTTP
		// response. These three headers are actually sent in
		// the trailer.
		w.Header().Set("Trailer", "AtEnd1, AtEnd2")
		w.Header().Add("Trailer", "AtEnd3")

		w.Header().Set("Content-Type", "text/plain; charset=utf-8") // normal header
		w.WriteHeader(http.StatusOK)

		w.Header().Set("AtEnd1", "value 1")
		io.WriteString(w, "This HTTP response has both headers before this text and trailers at the end.\n")
		w.Header().Set("AtEnd2", "value 2")
		w.Header().Set("AtEnd3", "value 3") // These will appear as trailers.
	})
}
```

--------------------------------

### NewUnstartedServer

Source: https://pkg.go.dev/net/http/httptest

Returns a new Server listening on a local network loopback interface. It does not start the server. After changing the server's configuration, the caller should call Server.Start or Server.StartTLS.

```APIDOC
## NewUnstartedServer

### Description
Returns a new Server listening on a local network loopback interface. It does not start the server. After changing the server's configuration, the caller should call Server.Start or Server.StartTLS. The caller should call Server.Close when finished, to shut it down.

### Function Signature
```go
func NewUnstartedServer(handler http.Handler) *Server
```

### Parameters
- **handler** (http.Handler) - Required - The HTTP handler to serve.

### Returns
- **\*Server** - A new unstarted test server.
```

--------------------------------

### DumpRequest example with output

Source: https://pkg.go.dev/net/http/httputil

Example of using httputil.DumpRequest to dump an incoming request in a test server. The server echoes the dump as a quoted string, and the client sends a POST request with a body. The output shows the HTTP/1.1 wire format including headers and body.

```go
package main

import (
	"fmt"
	"io"
	"log"
	"net/http"
	"net/http/httptest"
	"net/http/httputil"
	"strings"
)

func main() {
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		dump, err := httputil.DumpRequest(r, true)
		if err != nil {
			http.Error(w, fmt.Sprint(err), http.StatusInternalServerError)
			return
		}

		fmt.Fprintf(w, "%q", dump)
	}))
	defer ts.Close()

	const body = "Go is a general-purpose language designed with systems programming in mind."
	req, err := http.NewRequest("POST", ts.URL, strings.NewReader(body))
	if err != nil {
		log.Fatal(err)
	}
	req.Host = "www.example.org"
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		log.Fatal(err)
	}
	defer resp.Body.Close()

	b, err := io.ReadAll(resp.Body)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("%s", b)

}
```

```text
Output:
"POST / HTTP/1.1\r\nHost: www.example.org\r\nAccept-Encoding: gzip\r\nContent-Length: 75\r\nUser-Agent: Go-http-client/1.1\r\n\r\nGo is a general-purpose language designed with systems programming in mind."
```

--------------------------------

### Example: copy inbound X-Forwarded-For before SetXForwarded

Source: https://pkg.go.dev/net/http/httputil

Example rewrite function that copies the inbound request's X-Forwarded-For header to the outbound request before calling SetXForwarded, preserving the default ReverseProxy behavior of appending to the inbound header.

```go
rewriteFunc := func(r *httputil.ProxyRequest) {
	r.Out.Header["X-Forwarded-For"] = r.In.Header["X-Forwarded-For"]
	r.SetXForwarded()
}
```

--------------------------------

### Make HTTP requests with Get, Post, and PostForm

Source: https://pkg.go.dev/net/http

Shows how to use http.Get, http.Post, and http.PostForm to make HTTP requests. The caller must close the response body when finished.

```go
resp, err := http.Get("http://example.com/")
...
resp, err := http.Post("http://example.com/upload", "image/jpeg", &buf)
...
resp, err := http.PostForm("http://example.com/form",
	url.Values{"key": {"Value"}, "id": {"123"}})
```

--------------------------------

### Loopback server with Server.Start and Client

Source: https://pkg.go.dev/net/http/httptest

Shows how to start a loopback server with httptest.NewTestServer and Server.Start, then use the returned client and URL to send requests. The client is configured to send requests with hostname 'example.com' or subdomain '.example.com' to the server.

```go
server := httptest.NewTestServer(t, handler)
server.Start()
client := server.Client()

// This request is sent to the test server.
_, _ = server.Client().Get(server.URL + "/")

// This request (using http.DefaultClient) is also sent to the test server,
// since server.URL contains the server's local IP address.
_, _ = http.Get(server.URL + "/")
```

--------------------------------

### Get

Source: https://pkg.go.dev/net/http

Sends an HTTP GET request to the specified URL and returns the response. It is a wrapper around http.DefaultClient.Get.

```APIDOC
## Get

### Description
Sends an HTTP GET request to the specified URL and returns the response. It is a wrapper around http.DefaultClient.Get.

### Method
func Get(url string) (resp *Response, err error)

### Parameters
- **url** (string) - Required - The URL to send the GET request to.

### Returns
- **\*Response** - The HTTP response.
- **error** - An error if the request fails.
```

--------------------------------

### Using http.Dir with FileServer

Source: https://pkg.go.dev/net/http

Shows how to use the operating system's file system implementation with http.Dir. This is a simple way to serve files from a directory.

```go
http.Handle("/", http.FileServer(http.Dir("/tmp")))
```

--------------------------------

### Create a Transport with custom settings

Source: https://pkg.go.dev/net/http

Shows how to create an http.Transport with MaxIdleConns, IdleConnTimeout, and DisableCompression, and use it with a Client. Clients and Transports are safe for concurrent use and should be created once and re-used.

```go
tr := &http.Transport{
	MaxIdleConns:       10,
	IdleConnTimeout:    30 * time.Second,
	DisableCompression: true,
}
client := &http.Client{Transport: tr}
resp, err := client.Get("https://example.com")
```

--------------------------------

### Get function signature

Source: https://pkg.go.dev/net/http

Signature for the net/http.Get function. It issues a GET request to the specified URL and returns a Response and error.

```go
func Get(url string) (resp *Response, err error)
```

--------------------------------

### func Get(url string) (resp *Response, err error)

Source: https://pkg.go.dev/net/http

Get issues a GET to the specified URL. It follows redirects up to a maximum of 10. An error is returned if there were too many redirects or if there was an HTTP protocol error. The caller should close resp.Body when done reading from it.

```APIDOC
## func Get(url string) (resp *Response, err error)

### Description
Get issues a GET to the specified URL. If the response is one of the following redirect codes, Get follows the redirect, up to a maximum of 10 redirects: 301 (Moved Permanently), 302 (Found), 303 (See Other), 307 (Temporary Redirect), 308 (Permanent Redirect). An error is returned if there were too many redirects or if there was an HTTP protocol error. A non-2xx response doesn't cause an error. Any returned error will be of type *url.Error. The url.Error value's Timeout method will report true if the request timed out. When err is nil, resp always contains a non-nil resp.Body. Caller should close resp.Body when done reading from it. Get is a wrapper around DefaultClient.Get.

### Function Signature
func Get(url string) (resp *Response, err error)

### Parameters
- **url** (string) - Required - The URL to send the GET request to.

### Return Values
- **resp** (*Response) - The HTTP response.
- **err** (error) - An error if the request failed.

### Example
```go
package main

import (
	"fmt"
	"io"
	"log"
	"net/http"
)

func main() {
	res, err := http.Get("http://www.google.com/robots.txt")
	if err != nil {
		log.Fatal(err)
	}
	body, err := io.ReadAll(res.Body)
	res.Body.Close()
	if res.StatusCode > 299 {
		log.Fatalf("Response failed with status code: %d and\nbody: %s\n", res.StatusCode, body)
	}
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("%s", body)
}
```
```

--------------------------------

### func (c *Client) Get(url string) (resp *Response, err error)

Source: https://pkg.go.dev/net/http

Sends a GET request to the specified URL.

```APIDOC
## Client.Get

### Description
Sends a GET request to the specified URL.

### Method Signature
func (c *Client) Get(url string) (resp *Response, err error)

### Parameters
- **url** (string) - Required - The URL to request.

### Returns
- **Response** - The response.
- **error** - Any error encountered.
```

--------------------------------

### Create a Client with redirect policy and custom headers

Source: https://pkg.go.dev/net/http

Shows how to create an http.Client with a CheckRedirect function and use it to make requests with custom headers via NewRequest and client.Do.

```go
client := &http.Client{
	CheckRedirect: redirectPolicyFunc,
}

resp, err := client.Get("http://example.com")
// ...

req, err := http.NewRequest("GET", "http://example.com", nil)
// ...
req.Header.Add("If-None-Match", `W/"wyzzy"`)
resp, err := client.Do(req)
// ...
```

--------------------------------

### Redirect codes followed by Get and Head

Source: https://pkg.go.dev/net/http

List of HTTP redirect status codes that Get and Head follow, up to a maximum of 10 redirects.

```text
301 (Moved Permanently)
302 (Found)
303 (See Other)
307 (Temporary Redirect)
308 (Permanent Redirect)
```

--------------------------------

### func (c *Client) Get(url string) (resp *Response, err error)

Source: https://pkg.go.dev/net/http

Get issues a GET to the specified URL. It follows redirects for 301, 302, 303, 307, and 308 status codes after calling Client.CheckRedirect. An error is returned if CheckRedirect fails or if there was an HTTP protocol error, but not for non-2xx responses.

```APIDOC
## func (c *Client) Get(url string) (resp *Response, err error)

### Description
Get issues a GET to the specified URL. If the response is one of the following redirect codes, Get follows the redirect after calling the Client.CheckRedirect function: 301 (Moved Permanently), 302 (Found), 303 (See Other), 307 (Temporary Redirect), 308 (Permanent Redirect). An error is returned if the Client.CheckRedirect function fails or if there was an HTTP protocol error. A non-2xx response doesn't cause an error.

### Method
Get

### Signature
func (c *Client) Get(url string) (resp *Response, err error)

### Parameters
- **url** (string) - Required - The URL to send the GET request to.

### Returns
- **resp** (*Response) - The HTTP response. When err is nil, resp always contains a non-nil resp.Body. Caller should close resp.Body when done reading from it.
- **err** (error) - Any returned error will be of type *url.Error. The url.Error value's Timeout method will report true if the request timed out.

### Behavior
- To make a request with custom headers, use NewRequest and Client.Do.
- To make a request with a specified context.Context, use NewRequestWithContext and Client.Do.
```
Tokens:
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