├── .gitignore
├── README.md
├── go.mod
├── main.go
└── public
    ├── index.html
    └── welcome.html


/.gitignore:
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1 | tmp*
2 | go-oauth-example
3 | .vscode


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/README.md:
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 1 | ## Go OAuth Example
 2 | 
 3 | Read the blog post [here](https://www.sohamkamani.com/golang/oauth)
 4 | 
 5 | This is an example node application that implements Githubs OAuth2 API.
 6 | 
 7 | In order to run the application:
 8 | 
 9 | 1. Register your new application on Github : https://github.com/settings/applications/new. In the "callback URL" field, enter "http://localhost:8080/oauth/redirect". Once you register, you will get a client ID and client secret.
10 | 2. Replace the values of the `clientID` and `clientSecret` variables in the [main.go](/main.go) file and also the [index.html](https://github.com/sohamkamani/go-oauth-example/blob/master/public/index.html#L14) file 
11 | 4. Start the server by executing `go run main.go`
12 | 5. Navigate to http://localhost:8080 on your browser.
13 | 


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/go.mod:
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1 | module github.com/sohamkamani/go-oauth-example
2 | 
3 | go 1.16
4 | 


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/main.go:
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 1 | package main
 2 | 
 3 | import (
 4 | 	"encoding/json"
 5 | 	"fmt"
 6 | 	"net/http"
 7 | 	"os"
 8 | )
 9 | 
10 | const clientID = "<your client id>"
11 | const clientSecret = "<your client secret>"
12 | 
13 | func main() {
14 | 	fs := http.FileServer(http.Dir("public"))
15 | 	http.Handle("/", fs)
16 | 
17 | 	// We will be using `httpClient` to make external HTTP requests later in our code
18 | 	httpClient := http.Client{}
19 | 
20 | 	// Create a new redirect route route
21 | 	http.HandleFunc("/oauth/redirect", func(w http.ResponseWriter, r *http.Request) {
22 | 		// First, we need to get the value of the `code` query param
23 | 		err := r.ParseForm()
24 | 		if err != nil {
25 | 			fmt.Fprintf(os.Stdout, "could not parse query: %v", err)
26 | 			w.WriteHeader(http.StatusBadRequest)
27 | 			return
28 | 		}
29 | 		code := r.FormValue("code")
30 | 
31 | 		// Next, lets for the HTTP request to call the github oauth enpoint
32 | 		// to get our access token
33 | 		reqURL := fmt.Sprintf("https://github.com/login/oauth/access_token?client_id=%s&client_secret=%s&code=%s", clientID, clientSecret, code)
34 | 		req, err := http.NewRequest(http.MethodPost, reqURL, nil)
35 | 		if err != nil {
36 | 			fmt.Fprintf(os.Stdout, "could not create HTTP request: %v", err)
37 | 			w.WriteHeader(http.StatusBadRequest)
38 | 			return
39 | 		}
40 | 		// We set this header since we want the response
41 | 		// as JSON
42 | 		req.Header.Set("accept", "application/json")
43 | 
44 | 		// Send out the HTTP request
45 | 		res, err := httpClient.Do(req)
46 | 		if err != nil {
47 | 			fmt.Fprintf(os.Stdout, "could not send HTTP request: %v", err)
48 | 			w.WriteHeader(http.StatusInternalServerError)
49 | 			return
50 | 		}
51 | 		defer res.Body.Close()
52 | 
53 | 		// Parse the request body into the `OAuthAccessResponse` struct
54 | 		var t OAuthAccessResponse
55 | 		if err := json.NewDecoder(res.Body).Decode(&t); err != nil {
56 | 			fmt.Fprintf(os.Stdout, "could not parse JSON response: %v", err)
57 | 			w.WriteHeader(http.StatusBadRequest)
58 | 			return
59 | 		}
60 | 
61 | 		// Finally, send a response to redirect the user to the "welcome" page
62 | 		// with the access token
63 | 		w.Header().Set("Location", "/welcome.html?access_token="+t.AccessToken)
64 | 		w.WriteHeader(http.StatusFound)
65 | 	})
66 | 
67 | 	http.ListenAndServe(":8080", nil)
68 | }
69 | 
70 | type OAuthAccessResponse struct {
71 | 	AccessToken string `json:"access_token"`
72 | }
73 | 


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/public/index.html:
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 1 | <!DOCTYPE html>
 2 | <html>
 3 | 
 4 | <head>
 5 |         <meta charset="utf-8" />
 6 |         <meta http-equiv="X-UA-Compatible" content="IE=edge">
 7 |         <title>Go OAuth2 Example</title>
 8 |         <meta name="viewport" content="width=device-width, initial-scale=1">
 9 |         <!-- <link rel="stylesheet" type="text/css" media="screen" href="main.css" /> -->
10 |         <!-- <script src="main.js"></script> -->
11 | </head>
12 | 
13 | <body>
14 |         <a href="https://github.com/login/oauth/authorize?client_id=b9305af8a8b0ff6e76e9&redirect_uri=http://localhost:8080/oauth/redirect">Login with github</a>
15 | </body>
16 | 
17 | </html>


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/public/welcome.html:
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 1 | <!DOCTYPE html>
 2 | <html lang="en">
 3 | 
 4 | <head>
 5 | 	<meta charset="UTF-8">
 6 | 	<meta name="viewport" content="width=device-width, initial-scale=1.0">
 7 | 	<meta http-equiv="X-UA-Compatible" content="ie=edge">
 8 | 	<title>Hello</title>
 9 | </head>
10 | 
11 | <body>
12 | 
13 | </body>
14 | <script>
15 | 	// We can get the token from the "access_token" query
16 | 	// param, available in the browsers "location" global
17 | 	const query = window.location.search.substring(1)
18 | 	const token = query.split('access_token=')[1]
19 | 
20 | 	// Call the user info API using the fetch browser library
21 | 	fetch('https://api.github.com/user', {
22 | 			headers: {
23 | 				// Include the token in the Authorization header
24 | 				Authorization: 'token ' + token
25 | 			}
26 | 		})
27 | 		// Parse the response as JSON
28 | 		.then(res => res.json())
29 | 		.then(res => {
30 | 			// Once we get the response (which has many fields)
31 | 			// Documented here: https://developer.github.com/v3/users/#get-the-authenticated-user
32 | 			// Write "Welcome <user name>" to the documents body
33 | 			const nameNode = document.createTextNode(`Welcome, ${res.name}`)
34 | 			document.body.appendChild(nameNode)
35 | 		})
36 | </script>
37 | 
38 | </html>


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