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package github
import (
"context"
"errors"
"net/http"
"time"
"github.com/nsheridan/cashier/server/auth"
"github.com/nsheridan/cashier/server/config"
"github.com/nsheridan/cashier/server/metrics"
githubapi "github.com/google/go-github/github"
"golang.org/x/oauth2"
"golang.org/x/oauth2/github"
)
const (
name = "github"
)
// Config is an implementation of `auth.Provider` for authenticating using a
// Github account.
type Config struct {
config *oauth2.Config
organization string
whitelist map[string]bool
}
var _ auth.Provider = (*Config)(nil)
// New creates a new Github provider from a configuration.
func New(c *config.Auth) (*Config, error) {
uw := make(map[string]bool)
for _, u := range c.UsersWhitelist {
uw[u] = true
}
if c.ProviderOpts["organization"] == "" && len(uw) == 0 {
return nil, errors.New("either GitHub organization or users whitelist must be specified")
}
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"],
whitelist: uw,
}, nil
}
// 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 len(c.whitelist) > 0 && !c.whitelist[c.Username(token)] {
return false
}
if !token.Valid() {
return false
}
if c.organization == "" {
// There's no organization and the token is valid. Can only reach here
// if there's a user whitelist set and the user is in the whitelist.
metrics.M.AuthValid.WithLabelValues("github").Inc()
return true
}
client := githubapi.NewClient(c.newClient(token))
member, _, err := client.Organizations.IsMember(context.TODO(), c.organization, c.Username(token))
if err != nil {
return false
}
if member {
metrics.M.AuthValid.WithLabelValues("github").Inc()
}
return member
}
// Revoke is a no-op revoke method. GitHub doesn't seem to allow token
// revocation - tokens are indefinite and there are no refresh options etc.
// Returns nil to satisfy the Provider interface.
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),
}
}
// Exchange authorizes the session and returns an access token.
func (c *Config) Exchange(code string) (*oauth2.Token, error) {
t, err := c.config.Exchange(oauth2.NoContext, code)
if err != nil {
return nil, err
}
// Github tokens don't have an expiry. Set one so that the session expires
// after a period.
if t.Expiry.Unix() <= 0 {
t.Expiry = time.Now().Add(1 * time.Hour)
}
metrics.M.AuthExchange.WithLabelValues("github").Inc()
return t, nil
}
// 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(context.TODO(), "")
if err != nil {
return ""
}
return *u.Login
}
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