1DDP(7) Linux Programmer's Manual DDP(7)
2
6 ddp - Linux AppleTalk protocol implementation
7
9 #include <sys/socket.h>
10 #include <netatalk/at.h>
11 ddp_socket = socket(PF_APPLETALK, SOCK_DGRAM, 0);
13 raw_socket = socket(PF_APPLETALK, SOCK_RAW, protocol);
14
16 Linux implements the Appletalk protocols described in Inside Appletalk.
17 Only the DDP layer and AARP are present in the kernel. They are
18 designed to be used via the netatalk protocol libraries. This page doc‐
19 uments the interface for those who wish or need to use the DDP layer
20 directly.
21 The communication between Appletalk and the user program works using a
23 BSD-compatible socket interface. For more information on sockets, see
24 socket(7).
25 An AppleTalk socket is created by calling the socket(2) function with a
27 PF_APPLETALK socket family argument. Valid socket types are SOCK_DGRAM
28 to open a ddp socket or SOCK_RAW to open a raw socket. protocol is the
29 Appletalk protocol to be received or sent. For SOCK_RAW you must spec‐
30 ify ATPROTO_DDP.
31 Raw sockets may be only opened by a process with effective user ID 0 or
33 when the process has the CAP_NET_RAW capability.
34
36 An Appletalk socket address is defined as a combination of a network
37 number, a node number, and a port number.
38 struct at_addr {
40 u_short s_net;
41 u_char s_node;
42 };
43 struct sockaddr_atalk {
45 sa_family_t sat_family; /* address family */
46 u_char sat_port; /* port */
47 struct at_addr sat_addr; /* net/node */
48 };
49 sat_family is always set to AF_APPLETALK. sat_port contains the port.
51 The port numbers below 129 are known as reserved ports. Only processes
52 with the effective user ID 0 or the CAP_NET_BIND_SERVICE capability may
53 bind(2) to these sockets. sat_addr is the host address. The net mem‐
54 ber of struct at_addr contains the host network in network byte order.
55 The value of AT_ANYNET is a wildcard and also implies “this network.”
56 The node member of struct at_addr contains the host node number. The
57 value of AT_ANYNODE is a wildcard and also implies “this node.” The
58 value of ATADDR_BCAST is a link local broadcast address.
59
61 No protocol-specific socket options are supported.
62
64 IP supports a sysctl interface to configure some global AppleTalk
65 parameters. The sysctls can be accessed by reading or writing the
66 /proc/sys/net/atalk/* files or with the sysctl(2) interface.
67 aarp-expiry-time
69 The time interval (in seconds) before an AARP cache entry
70 expires.
71 aarp-resolve-time
73 The time interval (in seconds) before an AARP cache entry is
74 resolved.
75 aarp-retransmit-limit
77 The number of retransmissions of an AARP query before the node
78 is declared dead.
79 aarp-tick-time
81 The timer rate (in seconds) for the timer driving AARP.
82 The default values match the specification and should never need to be
84 changed.
85
88 All ioctls described in socket(7) apply to ddp.
89
92 Be very careful with the SO_BROADCAST option - it is not privileged in
93 Linux. It is easy to overload the network with careless sending to
94 broadcast addresses.
95
97 Appletalk is supported by Linux 2.0 or higher. The sysctl interface is
98 new in Linux 2.2.
99
101 ENOTCONN
102 The operation is only defined on a connected socket, but the
103 socket wasn't connected.
104 EINVAL Invalid argument passed.
106 EMSGSIZE
108 Datagram is bigger than the DDP MTU.
109 EACCES The user tried to execute an operation without the necessary
111 permissions. These include sending to a broadcast address with‐
112 out having the broadcast flag set, and trying to bind to a
113 reserved port without effective user ID 0 or CAP_NET_BIND_SER‐
114 VICE.
115 EADDRINUSE
117 Tried to bind to an address already in use.
118 ENOMEM and ENOBUFS
120 Not enough memory available.
121 ENOPROTOOPT and EOPNOTSUPP
123 Invalid socket option passed.
124 EPERM User doesn't have permission to set high priority, make a con‐
126 figuration change, or send signals to the requested process or
127 group,
128 EADDRNOTAVAIL
130 A non-existent interface was requested or the requested source
131 address was not local.
132 EAGAIN Operation on a nonblocking socket would block.
134 ESOCKTNOSUPPORT
136 The socket was unconfigured, or an unknown socket type was
137 requested.
138 EISCONN
140 connect(2) was called on an already connected socket.
141 EALREADY
143 A connection operation on a non-blocking socket is already in
144 progress.
145 ECONNABORTED
147 A connection was closed during an accept(2).
148 EPIPE The connection was unexpectedly closed or shut down by the other
150 end.
151 ENOENT SIOCGSTAMP was called on a socket where no packet arrived.
153 EHOSTUNREACH
155 No routing table entry matches the destination address.
156 ENODEV Network device not available or not capable of sending IP.
158 ENOPKG A kernel subsystem was not configured.
160
162 The basic AppleTalk socket interface is compatible with netatalk on
163 BSD-derived systems. Many BSD systems fail to check SO_BROADCAST when
164 sending broadcast frames; this can lead to compatibility problems.
165 The raw socket mode is unique to Linux and exists to support the alter‐
167 native CAP package and AppleTalk monitoring tools more easily.
168
170 There are too many inconsistent error values.
171 The ioctls used to configure routing tables, devices, AARP tables and
173 other devices are not yet described.
174
176 recvmsg(2), sendmsg(2), capabilities(7), socket(7)
177Linux Man Page 1999-05-01 DDP(7)