Add github oauth provider.

1 files changed, 95 insertions, 0 deletions

diff --git a/server/auth/github/github.go b/server/auth/github/github.go
new file mode 100644
index 0000000..da12531
--- /dev/null
+++ b/server/auth/github/github.go
@@ -0,0 +1,95 @@
+package github
+
+import (
+	"net/http"
+
+	"github.com/nsheridan/cashier/server/auth"
+	"github.com/nsheridan/cashier/server/config"
+
+	githubapi "github.com/google/go-github/github"
+	"golang.org/x/oauth2"
+	"golang.org/x/oauth2/github"
+)
+
+const (
+	// revokeURL = "https://accounts.google.com/o/oauth2/revoke?token=%s"
+	name = "github"
+)
+
+// Config is an implementation of `auth.Provider` for authenticating using a
+// Github account.
+type Config struct {
+	config       *oauth2.Config
+	organization string
+}
+
+// New creates a new Github provider from a configuration.
+func New(c *config.Auth) auth.Provider {
+	return &Config{
+		config: &oauth2.Config{
+			ClientID:     c.OauthClientID,
+			ClientSecret: c.OauthClientSecret,
+			RedirectURL:  c.OauthCallbackURL,
+			Endpoint:     github.Endpoint,
+			Scopes: []string{
+				string(githubapi.ScopeUser),
+				string(githubapi.ScopeReadOrg),
+			},
+		},
+		organization: c.ProviderOpts["organization"],
+	}
+}
+
+// A new oauth2 http client.
+func (c *Config) newClient(token *oauth2.Token) *http.Client {
+	return c.config.Client(oauth2.NoContext, token)
+}
+
+// Name returns the name of the provider.
+func (c *Config) Name() string {
+	return name
+}
+
+// Valid validates the oauth token.
+func (c *Config) Valid(token *oauth2.Token) bool {
+	if !token.Valid() {
+		return false
+	}
+	if c.organization == "" {
+		return true
+	}
+	client := githubapi.NewClient(c.newClient(token))
+	member, _, err := client.Organizations.IsMember(c.organization, c.Username(token))
+	if err != nil {
+		return false
+	}
+	return member
+}
+
+// Revoke disables the access token.
+func (c *Config) Revoke(token *oauth2.Token) error {
+	return nil
+}
+
+// StartSession retrieves an authentication endpoint from Github.
+func (c *Config) StartSession(state string) *auth.Session {
+	return &auth.Session{
+		AuthURL: c.config.AuthCodeURL(state),
+		State:   state,
+	}
+}
+
+// Exchange authorizes the session and returns an access token.
+func (c *Config) Exchange(code string) (*oauth2.Token, error) {
+	return c.config.Exchange(oauth2.NoContext, code)
+}
+
+// Username retrieves the username portion of the user's email address.
+func (c *Config) Username(token *oauth2.Token) string {
+	client := githubapi.NewClient(c.newClient(token))
+	u, _, err := client.Users.Get("")
+	if err != nil {
+		return ""
+	}
+	return *u.Login
+}