Retry: always use interface, if set, for retry DB key. Bug 1678

Even constant values must be used, as multiple transports with
different values may be in play and should be kept distinct.

4 files changed, 14 insertions, 15 deletions

diff --git a/src/src/functions.h b/src/src/functions.h
index 4af0017c1..fcfe74675 100644
--- a/src/src/functions.h
+++ b/src/src/functions.h
@@ -377,7 +377,7 @@ extern int     smtp_sock_connect(host_item *, int, int, uschar *,
 extern int     smtp_feof(void);
 extern int     smtp_ferror(void);
 extern uschar *smtp_get_connection_info(void);
-extern BOOL    smtp_get_interface(uschar *, int, address_item *, BOOL *,
+extern BOOL    smtp_get_interface(uschar *, int, address_item *,
                  uschar **, uschar *);
 extern BOOL    smtp_get_port(uschar *, address_item *, int *, uschar *);
 extern int     smtp_getc(void);
diff --git a/src/src/smtp_out.c b/src/src/smtp_out.c
index 88dde8301..d32ef89b5 100644
--- a/src/src/smtp_out.c
+++ b/src/src/smtp_out.c
@@ -26,7 +26,6 @@ Arguments:
                which case the function does nothing
   host_af    AF_INET or AF_INET6 for the outgoing IP address
   addr       the mail address being handled (for setting errors)
-  changed    if not NULL, set TRUE if expansion actually changed istring
   interface  point this to the interface
   msg        to add to any error message
 
@@ -36,7 +35,7 @@ Returns:     TRUE on success, FALSE on failure, with error message
 
 BOOL
 smtp_get_interface(uschar *istring, int host_af, address_item *addr,
-  BOOL *changed, uschar **interface, uschar *msg)
+  uschar **interface, uschar *msg)
 {
 const uschar * expint;
 uschar *iface;
@@ -54,8 +53,6 @@ if (expint == NULL)
   return FALSE;
   }
 
-if (changed != NULL) *changed = expint != istring;
-
 while (isspace(*expint)) expint++;
 if (*expint == 0) return TRUE;
 
diff --git a/src/src/transports/smtp.c b/src/src/transports/smtp.c
index ac40460f1..f129cce9b 100644
--- a/src/src/transports/smtp.c
+++ b/src/src/transports/smtp.c
@@ -3259,7 +3259,6 @@ for (cutoff_retry = 0; expired &&
     BOOL serialized = FALSE;
     BOOL host_is_expired = FALSE;
     BOOL message_defer = FALSE;
-    BOOL ifchanges = FALSE;
     BOOL some_deferred = FALSE;
     address_item *first_addr = NULL;
     uschar *interface = NULL;
@@ -3435,15 +3434,18 @@ for (cutoff_retry = 0; expired &&
     if (Ustrcmp(pistring, ":25") == 0) pistring = US"";
 
     /* Select IPv4 or IPv6, and choose an outgoing interface. If the interface
-    string changes upon expansion, we must add it to the key that is used for
-    retries, because connections to the same host from a different interface
-    should be treated separately. */
+    string is set, even if constant (as different transports can have different
+    constant settings), we must add it to the key that is used for retries,
+    because connections to the same host from a different interface should be
+    treated separately. */
 
     host_af = (Ustrchr(host->address, ':') == NULL)? AF_INET : AF_INET6;
-    if (!smtp_get_interface(ob->interface, host_af, addrlist, &ifchanges,
-         &interface, tid))
-      return FALSE;
-    if (ifchanges) pistring = string_sprintf("%s/%s", pistring, interface);
+    if ((rs = ob->interface) && *rs)
+      {
+      if (!smtp_get_interface(rs, host_af, addrlist, &interface, tid))
+	return FALSE;
+      pistring = string_sprintf("%s/%s", pistring, interface);
+      }
 
     /* The first time round the outer loop, check the status of the host by
     inspecting the retry data. The second time round, we are interested only
diff --git a/src/src/verify.c b/src/src/verify.c
index dc9c58224..cb88f28a9 100644
--- a/src/src/verify.c
+++ b/src/src/verify.c
@@ -444,7 +444,7 @@ can do it there for the non-rcpt-verify case.  For this we keep an addresscount.
 
 	  host_af = (Ustrchr(host->address, ':') == NULL)? AF_INET:AF_INET6;
 
-	  if (!smtp_get_interface(tf->interface, host_af, addr, NULL, &interface,
+	  if (!smtp_get_interface(tf->interface, host_af, addr, &interface,
 		  US"callout") ||
 	      !smtp_get_port(tf->port, addr, &port, US"callout"))
 	    log_write(0, LOG_MAIN|LOG_PANIC, "<%s>: %s", addr->address,
@@ -579,7 +579,7 @@ can do it there for the non-rcpt-verify case.  For this we keep an addresscount.
     deliver_domain = addr->domain;
     transport_name = addr->transport->name;
 
-    if (  !smtp_get_interface(tf->interface, host_af, addr, NULL, &interface,
+    if (  !smtp_get_interface(tf->interface, host_af, addr, &interface,
             US"callout")
        || !smtp_get_port(tf->port, addr, &port, US"callout")
        )