bridge: add the beginning of a github importer

1 files changed, 231 insertions, 0 deletions

diff --git a/bridge/github/auth.go b/bridge/github/auth.go
new file mode 100644
index 00000000..b86eeb63
--- /dev/null
+++ b/bridge/github/auth.go
@@ -0,0 +1,231 @@
+package github
+
+import (
+	"bufio"
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"math/rand"
+	"net/http"
+	"os"
+	"strings"
+	"syscall"
+	"time"
+
+	"golang.org/x/crypto/ssh/terminal"
+)
+
+const githubV3Url = "https://api.github.com"
+
+func Configure() (map[string]string, error) {
+	fmt.Println("git-bug will generate an access token in your Github profile.")
+	fmt.Println("TODO: describe token")
+	fmt.Println()
+
+	tokenName, err := promptTokenName()
+	if err != nil {
+		return nil, err
+	}
+
+	fmt.Println()
+
+	username, err := promptUsername()
+	if err != nil {
+		return nil, err
+	}
+
+	fmt.Println()
+
+	password, err := promptPassword()
+	if err != nil {
+		return nil, err
+	}
+
+	fmt.Println()
+
+	// Attempt to authenticate and create a token
+
+	var note string
+	if tokenName == "" {
+		note = "git-bug"
+	} else {
+		note = fmt.Sprintf("git-bug - %s", tokenName)
+	}
+
+	url := fmt.Sprintf("%s/authorizations", githubV3Url)
+	params := struct {
+		Scopes      []string `json:"scopes"`
+		Note        string   `json:"note"`
+		Fingerprint string   `json:"fingerprint"`
+	}{
+		Scopes:      []string{"repo"},
+		Note:        note,
+		Fingerprint: randomFingerprint(),
+	}
+
+	data, err := json.Marshal(params)
+	if err != nil {
+		return nil, err
+	}
+
+	req, err := http.NewRequest("POST", url, bytes.NewBuffer(data))
+	if err != nil {
+		return nil, err
+	}
+	req.SetBasicAuth(username, password)
+	req.Header.Set("Content-Type", "application/json")
+	client := http.Client{}
+
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+
+	defer resp.Body.Close()
+
+	if resp.StatusCode == http.StatusCreated {
+		return decodeBody(resp.Body)
+	}
+
+	// Handle 2FA is needed
+	OTPHeader := resp.Header.Get("X-GitHub-OTP")
+	if resp.StatusCode == http.StatusUnauthorized && OTPHeader != "" {
+		otpCode, err := prompt2FA()
+		if err != nil {
+			return nil, err
+		}
+
+		req.Header.Set("X-GitHub-OTP", otpCode)
+
+		resp2, err := client.Do(req)
+		if err != nil {
+			return nil, err
+		}
+
+		defer resp2.Body.Close()
+
+		if resp2.StatusCode == http.StatusCreated {
+			return decodeBody(resp.Body)
+		}
+	}
+
+	b, _ := ioutil.ReadAll(resp.Body)
+	fmt.Printf("Error %v: %v\n", resp.StatusCode, string(b))
+
+	return nil, nil
+}
+
+func decodeBody(body io.ReadCloser) (map[string]string, error) {
+	data, _ := ioutil.ReadAll(body)
+
+	aux := struct {
+		Token string `json:"token"`
+	}{}
+
+	err := json.Unmarshal(data, &aux)
+	if err != nil {
+		return nil, err
+	}
+
+	return map[string]string{
+		"token": aux.Token,
+	}, nil
+}
+
+func randomFingerprint() string {
+	// Doesn't have to be crypto secure, it's just to avoid token collision
+	rand.Seed(time.Now().UnixNano())
+	var letterRunes = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
+	b := make([]rune, 32)
+	for i := range b {
+		b[i] = letterRunes[rand.Intn(len(letterRunes))]
+	}
+	return string(b)
+}
+
+func promptUsername() (string, error) {
+	for {
+		fmt.Println("Username:")
+
+		line, err := bufio.NewReader(os.Stdin).ReadString('\n')
+		if err != nil {
+			return "", err
+		}
+
+		line = strings.TrimRight(line, "\n")
+
+		ok, err := validateUsername(line)
+		if err != nil {
+			return "", err
+		}
+		if ok {
+			return line, nil
+		}
+
+		fmt.Println("invalid username")
+	}
+}
+
+func promptTokenName() (string, error) {
+	fmt.Println("To help distinguish the token, you can optionally provide a description")
+	fmt.Println("Token name:")
+
+	line, err := bufio.NewReader(os.Stdin).ReadString('\n')
+	if err != nil {
+		return "", err
+	}
+
+	return strings.TrimRight(line, "\n"), nil
+}
+
+func validateUsername(username string) (bool, error) {
+	url := fmt.Sprintf("%s/users/%s", githubV3Url, username)
+
+	resp, err := http.Get(url)
+	if err != nil {
+		return false, err
+	}
+
+	err = resp.Body.Close()
+	if err != nil {
+		return false, err
+	}
+
+	return resp.StatusCode == http.StatusOK, nil
+}
+
+func promptPassword() (string, error) {
+	for {
+		fmt.Println("Password:")
+
+		bytePassword, err := terminal.ReadPassword(int(syscall.Stdin))
+		if err != nil {
+			return "", err
+		}
+
+		if len(bytePassword) > 0 {
+			return string(bytePassword), nil
+		}
+
+		fmt.Println("password is empty")
+	}
+}
+
+func prompt2FA() (string, error) {
+	for {
+		fmt.Println("Two-factor authentication code:")
+
+		byte2fa, err := terminal.ReadPassword(int(syscall.Stdin))
+		if err != nil {
+			return "", err
+		}
+
+		if len(byte2fa) > 0 {
+			return string(byte2fa), nil
+		}
+
+		fmt.Println("code is empty")
+	}
+}