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|
package main
import (
"errors"
"fmt"
"net/http"
"github.com/go-ldap/ldap/v3"
)
/* Check credentials against LDAP */
type LdapPreAuth struct {
WithConfig *Config
OnWrongPassword ErrorHandler
OnFailure ErrorHandler
OnCreds CredsHandler
}
func (l LdapPreAuth) WithCreds(username, password string) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
var e *LdapWrongPasswordError
access_key, secret_key, err := LdapGetS3(l.WithConfig, username, password)
if err == nil {
l.OnCreds.WithCreds(access_key, secret_key).ServeHTTP(w, r)
} else if errors.As(err, &e) {
l.OnWrongPassword.WithError(err).ServeHTTP(w, r)
} else {
l.OnFailure.WithError(e).ServeHTTP(w, r)
}
})
}
/**
* Private logic
*/
type ldapConnector struct {
conn *ldap.Conn
config *Config
userDn string
}
type LdapError struct {
Username string
Err error
}
func (e *LdapError) Error() string { return "ldap error for "+e.Username+": "+e.Err.Error() }
type LdapWrongPasswordError struct { LdapError }
func LdapGetS3(c *Config, username, password string) (access_key, secret_key string, werr error) {
// 1. Connect to the server
conn, err := ldapConnect(c)
if err != nil {
werr = &LdapError { username, err }
return
}
defer conn.Close()
// 2. Authenticate with provided credentials
// @FIXME we should better check the error, it could also be due to an LDAP error
err = conn.auth(username, password)
if err != nil {
werr = &LdapWrongPasswordError { LdapError { username, err } }
return
}
// 3. Fetch user's profile
profile, err := conn.profile()
if err != nil {
werr = &LdapError { username, err }
return
}
// 4. Basic checks upon users' attributes
access_key = profile.GetAttributeValue("garage_s3_access_key")
secret_key = profile.GetAttributeValue("garage_s3_secret_key")
if access_key == "" || secret_key == "" {
err = errors.New(fmt.Sprintf("Either access key or secret key is missing in LDAP for %s", conn.userDn))
werr = &LdapError { username, err }
return
}
// 5. Send fetched credentials to the next middleware
return
}
func ldapConnect(c *Config) (ldapConnector, error) {
ldapSock, err := ldap.Dial("tcp", c.LdapServer)
if err != nil {
return ldapConnector{}, err
}
return ldapConnector{
conn: ldapSock,
config: c,
}, nil
}
func (l *ldapConnector) auth(username, password string) error {
l.userDn = fmt.Sprintf("%s=%s,%s", l.config.UserNameAttr, username, l.config.UserBaseDN)
return l.conn.Bind(l.userDn, password)
}
func (l *ldapConnector) profile() (*ldap.Entry, error) {
searchRequest := ldap.NewSearchRequest(
l.userDn,
ldap.ScopeBaseObject,
ldap.NeverDerefAliases,
0,
0,
false,
"(objectClass=*)",
[]string{"garage_s3_access_key", "garage_s3_secret_key"},
nil)
sr, err := l.conn.Search(searchRequest)
if err != nil {
return nil, err
}
if len(sr.Entries) != 1 {
return nil, errors.New(fmt.Sprintf("Wrong number of LDAP entries, expected 1, got %d", len(sr.Entries)))
}
return sr.Entries[0], nil
}
func (l *ldapConnector) Close() {
if l.conn != nil {
l.conn.Close()
l.conn = nil
}
}
|
