[DCCP]: Allow default/fallback service code.

This has been discussed on dccp@vger and removes the necessity for applications
to supply service codes in each and every case.

If an application does not want to provide a service code, that's fine, it will
be given 0. Otherwise, service codes can be set via socket options as before.

This patch has been tested using various client/server configurations
(including listening on multiple service codes).

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>

4 files changed, 7 insertions, 21 deletions

diff --git a/Documentation/networking/dccp.txt b/Documentation/networking/dccp.txt
index c45daabd3bfe..74563b38ffd9 100644
--- a/Documentation/networking/dccp.txt
+++ b/Documentation/networking/dccp.txt
@@ -1,7 +1,6 @@
 DCCP protocol
 ============
 
-Last updated: 10 November 2005
 
 Contents
 ========
@@ -42,8 +41,11 @@ Socket options
 DCCP_SOCKOPT_PACKET_SIZE is used for CCID3 to set default packet size for
 calculations.
 
-DCCP_SOCKOPT_SERVICE sets the service. This is compulsory as per the
-specification. If you don't set it you will get EPROTO.
+DCCP_SOCKOPT_SERVICE sets the service. The specification mandates use of
+service codes (RFC 4340, sec. 8.1.2); if this socket option is not set,
+the socket will fall back to 0 (which means that no meaningful service code
+is present). Connecting sockets set at most one service option; for
+listening sockets, multiple service codes can be specified.
 
 Notes
 =====
diff --git a/include/linux/dccp.h b/include/linux/dccp.h
index 2d7671c92c0b..29f9291e45c0 100644
--- a/include/linux/dccp.h
+++ b/include/linux/dccp.h
@@ -404,6 +404,7 @@ struct dccp_service_list {
 };
 
 #define DCCP_SERVICE_INVALID_VALUE htonl((__u32)-1)
+#define DCCP_SERVICE_CODE_IS_ABSENT              0
 
 static inline int dccp_list_has_service(const struct dccp_service_list *sl,
                                         const __be32 service)
@@ -484,11 +485,6 @@ static inline struct dccp_minisock *dccp_msk(const struct sock *sk)
         return (struct dccp_minisock *)&dccp_sk(sk)->dccps_minisock;
 }
 
-static inline int dccp_service_not_initialized(const struct sock *sk)
-{
-        return dccp_sk(sk)->dccps_service == DCCP_SERVICE_INVALID_VALUE;
-}
-
 static inline const char *dccp_role(const struct sock *sk)
 {
         switch (dccp_sk(sk)->dccps_role) {
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index 9a1a76a7dc41..66be29b6f508 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -56,9 +56,6 @@ int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 
         dp->dccps_role = DCCP_ROLE_CLIENT;
 
-        if (dccp_service_not_initialized(sk))
-                return -EPROTO;
-
         if (addr_len < sizeof(struct sockaddr_in))
                 return -EINVAL;
 
diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index 962df0ea31aa..72cbdcfc2c65 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -217,7 +217,7 @@ int dccp_init_sock(struct sock *sk, const __u8 ctl_sock_initialized)
         icsk->icsk_sync_mss     = dccp_sync_mss;
         dp->dccps_mss_cache     = 536;
         dp->dccps_role          = DCCP_ROLE_UNDEFINED;
-        dp->dccps_service       = DCCP_SERVICE_INVALID_VALUE;
+        dp->dccps_service       = DCCP_SERVICE_CODE_IS_ABSENT;
         dp->dccps_l_ack_ratio   = dp->dccps_r_ack_ratio = 1;
 
         return 0;
@@ -267,12 +267,6 @@ static inline int dccp_listen_start(struct sock *sk)
         struct dccp_sock *dp = dccp_sk(sk);
 
         dp->dccps_role = DCCP_ROLE_LISTEN;
-        /*
-         * Apps need to use setsockopt(DCCP_SOCKOPT_SERVICE)
-         * before calling listen()
-         */
-        if (dccp_service_not_initialized(sk))
-                return -EPROTO;
         return inet_csk_listen_start(sk, TCP_SYNQ_HSIZE);
 }
 
@@ -540,9 +534,6 @@ static int dccp_getsockopt_service(struct sock *sk, int len,
         int err = -ENOENT, slen = 0, total_len = sizeof(u32);
 
         lock_sock(sk);
-        if (dccp_service_not_initialized(sk))
-                goto out;
-
         if ((sl = dp->dccps_service_list) != NULL) {
                 slen = sl->dccpsl_nr * sizeof(u32);
                 total_len += slen;