Mail: support SASL EXTERNAL (RFC 4422).

This is needed to allow TLS client certificate auth to work. With
ssl_verify_client configured, the auth daemon can choose to allow the
connection to proceed based on the certificate data.

This has been tested with Thunderbird for IMAP only. I've not yet found a
client that will do client certificate auth for POP3 or SMTP, and the method is
not really documented anywhere that I can find. That said, its simple enough
that the way I've done is probably right.

1 files changed, 10 insertions, 3 deletions

diff --git a/src/mail/ngx_mail.h b/src/mail/ngx_mail.h
index c30af35c9..600250820 100644
--- a/src/mail/ngx_mail.h
+++ b/src/mail/ngx_mail.h
@@ -132,7 +132,8 @@ typedef enum {
     ngx_pop3_auth_login_username,
     ngx_pop3_auth_login_password,
     ngx_pop3_auth_plain,
-    ngx_pop3_auth_cram_md5
+    ngx_pop3_auth_cram_md5,
+    ngx_pop3_auth_external
 } ngx_pop3_state_e;
 
 
@@ -142,6 +143,7 @@ typedef enum {
     ngx_imap_auth_login_password,
     ngx_imap_auth_plain,
     ngx_imap_auth_cram_md5,
+    ngx_imap_auth_external,
     ngx_imap_login,
     ngx_imap_user,
     ngx_imap_passwd
@@ -154,6 +156,7 @@ typedef enum {
     ngx_smtp_auth_login_password,
     ngx_smtp_auth_plain,
     ngx_smtp_auth_cram_md5,
+    ngx_smtp_auth_external,
     ngx_smtp_helo,
     ngx_smtp_helo_xclient,
     ngx_smtp_helo_from,
@@ -285,14 +288,16 @@ typedef struct {
 #define NGX_MAIL_AUTH_LOGIN_USERNAME    2
 #define NGX_MAIL_AUTH_APOP              3
 #define NGX_MAIL_AUTH_CRAM_MD5          4
-#define NGX_MAIL_AUTH_NONE              5
+#define NGX_MAIL_AUTH_EXTERNAL          5
+#define NGX_MAIL_AUTH_NONE              6
 
 
 #define NGX_MAIL_AUTH_PLAIN_ENABLED     0x0002
 #define NGX_MAIL_AUTH_LOGIN_ENABLED     0x0004
 #define NGX_MAIL_AUTH_APOP_ENABLED      0x0008
 #define NGX_MAIL_AUTH_CRAM_MD5_ENABLED  0x0010
-#define NGX_MAIL_AUTH_NONE_ENABLED      0x0020
+#define NGX_MAIL_AUTH_EXTERNAL_ENABLED  0x0020
+#define NGX_MAIL_AUTH_NONE_ENABLED      0x0040
 
 
 #define NGX_MAIL_PARSE_INVALID_COMMAND  20
@@ -377,6 +382,8 @@ ngx_int_t ngx_mail_auth_login_password(ngx_mail_session_t *s,
 ngx_int_t ngx_mail_auth_cram_md5_salt(ngx_mail_session_t *s,
     ngx_connection_t *c, char *prefix, size_t len);
 ngx_int_t ngx_mail_auth_cram_md5(ngx_mail_session_t *s, ngx_connection_t *c);
+ngx_int_t ngx_mail_auth_external(ngx_mail_session_t *s, ngx_connection_t *c,
+    ngx_uint_t n);
 ngx_int_t ngx_mail_auth_parse(ngx_mail_session_t *s, ngx_connection_t *c);
 
 void ngx_mail_send(ngx_event_t *wev);