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| -rw-r--r-- | share/man/man4/ip.4 | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/share/man/man4/ip.4 b/share/man/man4/ip.4 index 7130014..93bf0de 100644 --- a/share/man/man4/ip.4 +++ b/share/man/man4/ip.4 @@ -164,6 +164,22 @@ control message from can be used directly as a control message for .Xr sendmsg 2 . .Pp +If the +.Dv IP_RECVIF +option is enabled on a +.Dv SOCK_DGRAM +socket, the +.Xr recvmsg 2 +call returns a struct sockaddr_dl corresponding to the interface on which the +packet was received. The msg_control field in the msghdr structure points +to a buffer that contains a cmsghdr structure followed by the +struct sockaddr_dl. The cmsghdr fields have the following values: +.Bd -literal +cmsg_len = sizeof(struct sockaddr_dl) +cmsg_level = IPPROTO_IP +cmsg_type = IP_RECVIF +.Ed +.Pp .Dv IP_PORTRANGE may be used to set the port range used for selecting a local port number on a socket with an unspecified (zero) port number. |
