DSCP support, tentative

6 files changed, 143 insertions, 4 deletions

diff --git a/src/src/functions.h b/src/src/functions.h
index 5616db2de..dd9549b18 100644
--- a/src/src/functions.h
+++ b/src/src/functions.h
@@ -109,6 +109,7 @@ extern int     dns_lookup(dns_answer *, uschar *, int, uschar **);
 extern int     dns_special_lookup(dns_answer *, uschar *, int, uschar **);
 extern dns_record *dns_next_rr(dns_answer *, dns_scan *, int);
 extern uschar *dns_text_type(int);
+extern BOOL    dscp_lookup(const uschar *, int, int *, int *, int *);
 
 extern void    enq_end(uschar *);
 extern BOOL    enq_start(uschar *);
@@ -290,7 +291,7 @@ extern int     sieve_interpret(uschar *, int, uschar *, uschar *, uschar *,
 extern void    sigalrm_handler(int);
 extern BOOL    smtp_buffered(void);
 extern void    smtp_closedown(uschar *);
-extern int     smtp_connect(host_item *, int, int, uschar *, int, BOOL);
+extern int     smtp_connect(host_item *, int, int, uschar *, int, BOOL, const uschar *);
 extern int     smtp_feof(void);
 extern int     smtp_ferror(void);
 extern uschar *smtp_get_connection_info(void);
diff --git a/src/src/ip.c b/src/src/ip.c
index 8dbc2b3e0..66a750dfd 100644
--- a/src/src/ip.c
+++ b/src/src/ip.c
@@ -359,4 +359,114 @@ return -1;
 }
 
 
+
+
+/*************************************************
+*       Lookup DSCP settings for a socket        *
+*************************************************/
+
+struct dscp_name_tableentry {
+  const uschar *name;
+  int value;
+};
+/* Keep both of these tables sorted! */
+static struct dscp_name_tableentry dscp_table[] = {
+#ifdef IPTOS_DSCP_AF11
+    { "af11", IPTOS_DSCP_AF11 },
+    { "af12", IPTOS_DSCP_AF12 },
+    { "af13", IPTOS_DSCP_AF13 },
+    { "af21", IPTOS_DSCP_AF21 },
+    { "af22", IPTOS_DSCP_AF22 },
+    { "af23", IPTOS_DSCP_AF23 },
+    { "af31", IPTOS_DSCP_AF31 },
+    { "af32", IPTOS_DSCP_AF32 },
+    { "af33", IPTOS_DSCP_AF33 },
+    { "af41", IPTOS_DSCP_AF41 },
+    { "af42", IPTOS_DSCP_AF42 },
+    { "af43", IPTOS_DSCP_AF43 },
+    { "ef", IPTOS_DSCP_EF },
+#endif
+#ifdef IPTOS_LOWCOST
+    { "lowcost", IPTOS_LOWCOST },
+#endif
+    { "lowdelay", IPTOS_LOWDELAY },
+#ifdef IPTOS_MINCOST
+    { "mincost", IPTOS_MINCOST },
+#endif
+    { "reliability", IPTOS_RELIABILITY },
+    { "throughput", IPTOS_THROUGHPUT }
+};
+static int dscp_table_size =
+  sizeof(dscp_table) / sizeof(struct dscp_name_tableentry);
+
+/* DSCP values change by protocol family, and so do the options used for
+setsockopt(); this utility does all the lookups.
+
+Arguments:
+  dscp_name   a string, so far unvalidated
+  af          address_family in use
+  level       setsockopt level to use
+  optname     setsockopt name to use
+  dscp_value  value for dscp_name
+
+Returns: TRUE if okay to setsockopt(), else FALSE
+*/
+
+BOOL
+dscp_lookup(const uschar *dscp_name, int af,
+    int *level, int *optname, int *dscp_value)
+{
+uschar *dscp_lookup;
+int first, last;
+
+if (af == AF_INET)
+  {
+  *level = IPPROTO_IP;
+  *optname = IP_TOS;
+  }
+else if (af == AF_INET6)
+  {
+  *level = IPPROTO_IPV6;
+  *optname = IPV6_TCLASS;
+  }
+else
+  {
+  DEBUG(D_transport)
+    debug_printf("Unhandled address family %d in dscp_lookup()\n", af);
+  return FALSE;
+  }
+if (!dscp_name)
+  {
+  DEBUG(D_transport)
+    debug_printf("[empty DSCP]\n");
+  return FALSE;
+  }
+dscp_lookup = expand_string(US dscp_name);
+if (dscp_lookup == NULL || *dscp_lookup == '\0')
+  return FALSE;
+
+first = 0;
+last = dscp_table_size;
+while (last > first)
+  {
+  int middle = (first + last)/2;
+  int c = Ustrcmp(dscp_lookup, dscp_table[middle].name);
+  if (c == 0)
+    {
+    *dscp_value = dscp_table[middle].value;
+    return TRUE;
+    }
+  else if (c > 0)
+    {
+    first = middle + 1;
+    }
+  else
+    {
+    last = middle;
+    }
+  }
+return FALSE;
+}
+
+
 /* End of ip.c */
diff --git a/src/src/smtp_out.c b/src/src/smtp_out.c
index d6cfbba7d..7b58b4a74 100644
--- a/src/src/smtp_out.c
+++ b/src/src/smtp_out.c
@@ -164,16 +164,20 @@ Arguments:
   interface   outgoing interface address or NULL
   timeout     timeout value or 0
   keepalive   TRUE to use keepalive
+  dscp        DSCP value to assign to socket
 
 Returns:      connected socket number, or -1 with errno set
 */
 
 int
 smtp_connect(host_item *host, int host_af, int port, uschar *interface,
-  int timeout, BOOL keepalive)
+  int timeout, BOOL keepalive, const uschar *dscp)
 {
 int on = 1;
 int save_errno = 0;
+int dscp_value;
+int dscp_level;
+int dscp_option;
 int sock;
 
 if (host->port != PORT_NONE)
@@ -202,6 +206,25 @@ if ((sock = ip_socket(SOCK_STREAM, host_af)) < 0) return -1;
 
 setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, (uschar *)(&on), sizeof(on));
 
+/* Set DSCP value, if we can. For now, if we fail to set the value, we don't
+bomb out, just log it and continue in default traffic class. */
+
+if (dscp && dscp_lookup(dscp, host_af, &dscp_level, &dscp_option, &dscp_value))
+  {
+  HDEBUG(D_transport|D_acl|D_v)
+    debug_printf("DSCP \"%s\"=%d ", dscp, dscp_value);
+  if (setsockopt(sock, dscp_level, dscp_option, &dscp_value, sizeof(dscp_value)) < 0)
+    HDEBUG(D_transport|D_acl|D_v)
+      debug_printf("failed to set DSCP: %s ", strerror(errno));
+  /* If the kernel supports IPv4 and IPv6 on an IPv6 socket, we need to set the
+  option for both; ignore failures here */
+  if (host_af == AF_INET6 &&
+      dscp_lookup(dscp, AF_INET, &dscp_level, &dscp_option, &dscp_value))
+    {
+    (void) setsockopt(sock, dscp_level, dscp_option, &dscp_value, sizeof(dscp_value));
+    }
+  }
+
 /* Bind to a specific interface if requested. Caller must ensure the interface
 is the same type (IPv4 or IPv6) as the outgoing address. */
 
diff --git a/src/src/transports/smtp.c b/src/src/transports/smtp.c
index b3856f553..5322cc58d 100644
--- a/src/src/transports/smtp.c
+++ b/src/src/transports/smtp.c
@@ -55,6 +55,8 @@ optionlist smtp_transport_options[] = {
       (void *)offsetof(smtp_transport_options_block, dns_qualify_single) },
   { "dns_search_parents",   opt_bool,
       (void *)offsetof(smtp_transport_options_block, dns_search_parents) },
+  { "dscp",                 opt_stringptr,
+      (void *)offsetof(smtp_transport_options_block, dscp) },
   { "fallback_hosts",       opt_stringptr,
       (void *)offsetof(smtp_transport_options_block, fallback_hosts) },
   { "final_timeout",        opt_time,
@@ -162,6 +164,7 @@ smtp_transport_options_block smtp_transport_option_defaults = {
   NULL,                /* interface */
   NULL,                /* port */
   US"smtp",            /* protocol */
+  NULL,                /* DSCP */
   NULL,                /* serialize_hosts */
   NULL,                /* hosts_try_auth */
   NULL,                /* hosts_require_auth */
@@ -945,7 +948,7 @@ if (continue_hostname == NULL)
   {
   inblock.sock = outblock.sock =
     smtp_connect(host, host_af, port, interface, ob->connect_timeout,
-      ob->keepalive);   /* This puts port into host->port */
+      ob->keepalive, ob->dscp);   /* This puts port into host->port */
 
   if (inblock.sock < 0)
     {
diff --git a/src/src/transports/smtp.h b/src/src/transports/smtp.h
index 17b75cf3b..067681118 100644
--- a/src/src/transports/smtp.h
+++ b/src/src/transports/smtp.h
@@ -17,6 +17,7 @@ typedef struct {
   uschar *interface;
   uschar *port;
   uschar *protocol;
+  uschar *dscp;
   uschar *serialize_hosts;
   uschar *hosts_try_auth;
   uschar *hosts_require_auth;
diff --git a/src/src/verify.c b/src/src/verify.c
index 475f52d92..fed6ae37d 100644
--- a/src/src/verify.c
+++ b/src/src/verify.c
@@ -473,7 +473,8 @@ for (host = host_list; host != NULL && !done; host = host->next)
   set the error for the last one. Use the callout_connect timeout. */
 
   inblock.sock = outblock.sock =
-    smtp_connect(host, host_af, port, interface, callout_connect, TRUE);
+    smtp_connect(host, host_af, port, interface, callout_connect, TRUE, NULL);
+  /* reconsider DSCP here */
   if (inblock.sock < 0)
     {
     addr->message = string_sprintf("could not connect to %s [%s]: %s",