path: root/Documentation/networking
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authorGerrit Renker <gerrit@erg.abdn.ac.uk>2010-02-07 20:20:28 (GMT)
committerDavid S. Miller <davem@davemloft.net>2010-02-12 19:47:00 (GMT)
commit69a6a0b38a139ccceef32222108caca8a9b0b795 (patch)
tree04e24f2b012c14f33f5bc3d6f96f84056cf1fbbe /Documentation/networking
parent7455a76f170f794498d26081a5f15b797ef1a2aa (diff)
dccp: allow probing of CCID-array length
This fixes a problem in the DCCP getsockopt() API: currently there is no way for a user to a priori know the number of built-in CCIDs, other than trying DCCP_SOCKOPT_AVAILABLE_CCIDS in a loop, incrementing the option length until EINVAL is no longer returned. This patch truncates the array to the user-provided length. No copy is made when the length is <= 0. Due to the length restriction in do_dccp_getsockopt() to sizeof(int), the minimum array length remains 4, which is a reasonable default (only 3 CCIDs, CCID-2..4, are currently defined). Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'Documentation/networking')
1 files changed, 4 insertions, 2 deletions
diff --git a/Documentation/networking/dccp.txt b/Documentation/networking/dccp.txt
index b132e4a3..a62fdf7 100644
--- a/Documentation/networking/dccp.txt
+++ b/Documentation/networking/dccp.txt
@@ -58,8 +58,10 @@ DCCP_SOCKOPT_GET_CUR_MPS is read-only and retrieves the current maximum packet
size (application payload size) in bytes, see RFC 4340, section 14.
DCCP_SOCKOPT_AVAILABLE_CCIDS is also read-only and returns the list of CCIDs
-supported by the endpoint (see include/linux/dccp.h for symbolic constants).
-The caller needs to provide a sufficiently large (> 2) array of type uint8_t.
+supported by the endpoint. The option value is an array of type uint8_t whose
+size is passed as option length. The minimum array size is 4 elements, the
+value returned in the optlen argument always reflects the true number of
+built-in CCIDs.
DCCP_SOCKOPT_CCID is write-only and sets both the TX and RX CCIDs at the same
time, combining the operation of the next two socket options. This option is

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