1netdir(3NSL)         Networking Services Library Functions        netdir(3NSL)
2
3
4

NAME

6       netdir,    netdir_getbyname,    netdir_getbyaddr,   netdir_free,   net‐
7       dir_options, taddr2uaddr, uaddr2taddr,  netdir_perror,  netdir_sperror,
8       netdir_mergeaddr - generic transport name-to-address translation
9

SYNOPSIS

11       cc [ flag... ] file... -lnsl [ library...]
12       #include <netdir.h>
13
14       int netdir_getbyname(struct netconfig  *config,
15            struct nd_hostserv *service, struct nd_addrlist **addrs);
16
17
18       int netdir_getbyaddr(struct netconfig  *config,
19            struct nd_hostservlist **service, struct netbuf  *netaddr);
20
21
22       void netdir_free(void *ptr, int struct_type);
23
24
25       int netdir_options(struct netconfig  *config, int option, int fildes,
26            char *point_to_args);
27
28
29       char *taddr2uaddr(struct netconfig *config, struct netbuf *addr);
30
31
32       struct netbuf *uaddr2taddr(struct netconfig *config, char *uaddr);
33
34
35       void netdir_perror(char *s);
36
37
38       char *netdir_sperror(void);
39
40

DESCRIPTION

42       The  netdir  functions  provide a generic interface for name-to-address
43       mapping that will work with all  transport  protocols.  This  interface
44       provides  a  generic  way  for  programs  to convert transport specific
45       addresses into common structures and back again. The  netconfig  struc‐
46       ture,  described on the netconfig(4) manual page, identifies the trans‐
47       port.
48
49
50       The netdir_getbyname() function maps the machine name and service  name
51       in  the  nd_hostserv structure to a collection of addresses of the type
52       understood by the transport identified in the netconfig structure. This
53       function returns all addresses that are valid for that transport in the
54       nd_addrlist structure. The nd_hostserv structure contains the following
55       members:
56
57         char *h_host;      /* host name */
58         char *h_serv;      /* service name */
59
60
61
62       The nd_addrlist structure contains the following members:
63
64         int  n_cnt;       /* number of addresses */
65         struct netbuf *n_addrs;
66
67
68
69       The  netdir_getbyname()  function accepts some special-case host names.
70       The host names are defined in <netdir.h>. The  currently  defined  host
71       names are:
72
73       HOST_SELF            Represents  the  address  to  which local programs
74                            will bind their endpoints. HOST_SELF differs  from
75                            the  host  name provided by gethostname(3C), which
76                            represents the address to  which  remote  programs
77                            will bind their endpoints.
78
79
80       HOST_ANY             Represents  any  host accessible by this transport
81                            provider. HOST_ANY allows applications to  specify
82                            a required service without specifying a particular
83                            host name.
84
85
86       HOST_SELF_CONNECT    Represents the host address that can  be  used  to
87                            connect to the local host.
88
89
90       HOST_BROADCAST       Represents the address for all hosts accessible by
91                            this transport provider. Network requests to  this
92                            address are received by all machines.
93
94
95
96       All fields of the nd_hostserv structure must be initialized.
97
98
99       To find the address of a given host and service on all available trans‐
100       ports, call the netdir_getbyname() function with each struct  netconfig
101       structure returned by getnetconfig(3NSL).
102
103
104       The  netdir_getbyaddr()  function  maps addresses to service names. The
105       function returns service, a list of host and service pairs  that  yield
106       these  addresses.  If  more  than one tuple of host and service name is
107       returned, the first tuple  contains  the  preferred  host  and  service
108       names:
109
110         struct nd_hostservlist {
111            int  *h_cnt;                  /* number of hostservs found */
112            struct hostserv *h_hostservs;
113         }
114
115
116
117       The netdir_free() structure is used to free the structures allocated by
118       the name to address translation functions. The ptr parameter points  to
119       the  structure  that has to be freed. The parameter struct_type identi‐
120       fies the structure:
121
122         struct netbuf            ND_ADDR
123         struct nd_addrlist       ND_ADDRLIST
124         struct hostserv          ND_HOSTSERV
125         struct nd_hostservlist   ND_HOSTSERVLIST
126
127
128
129       The free() function is used to free the universal address  returned  by
130       the taddr2uaddr() function.
131
132
133       The netdir_options() function is used to do all transport-specific set‐
134       ups and option management. fildes is the  associated  file  descriptor.
135       option,  fildes, and pointer_to_args are passed to the netdir_options()
136       function for the transport specified in config. Currently  four  values
137       are defined for option:
138         ND_SET_BROADCAST
139         ND_SET_RESERVEDPORT
140         ND_CHECK_RESERVEDPORT
141         ND_MERGEADDR
142
143
144       The  taddr2uaddr()  and  uaddr2taddr()  functions  support  translation
145       between universal addresses and TLI  type  netbufs.  The  taddr2uaddr()
146       function  takes a struct netbuf data structure and returns a pointer to
147       a string that contains the universal address. It returns  NULL  if  the
148       conversion  is  not  possible.  This  is  not a fatal condition as some
149       transports do not support a universal address form.
150
151
152       The uaddr2taddr() function is the reverse of  the  taddr2uaddr()  func‐
153       tion. It returns the struct netbuf data structure for the given univer‐
154       sal address.
155
156
157       If a transport provider does  not  support  an  option,  netdir_options
158       returns -1 and the error message can be printed through netdir_perror()
159       or netdir_sperror().
160
161
162       The specific actions of each option follow.
163
164       ND_SET_BROADCAST         Sets the transport provider up to allow broad‐
165                                cast  if  the  transport  supports  broadcast.
166                                fildes is a file descriptor  into  the  trans‐
167                                port,  that  is,  the  result  of  a t_open of
168                                /dev/udp. pointer_to_args is not used. If this
169                                completes,  broadcast  operations  can be per‐
170                                formed on file descriptor fildes.
171
172
173       ND_SET_RESERVEDPORT      Allows the application to bind to  a  reserved
174                                port  if that concept exists for the transport
175                                provider. fildes is an unbound file descriptor
176                                into  the  transport.  If  pointer_to_args  is
177                                NULL, fildes is bound to a reserved  port.  If
178                                pointer_to_args  is  a  pointer  to  a  netbuf
179                                structure, an attempt is made to bind  to  any
180                                reserved port on the specified address.
181
182
183       ND_CHECK_RESERVEDPORT    Used to verify that the address corresponds to
184                                a reserved port if that concept exists for the
185                                transport   provider.   fildes  is  not  used.
186                                pointer_to_args  is  a  pointer  to  a  netbuf
187                                structure  that  contains  the  address.  This
188                                option returns 0 only if the address specified
189                                in pointer_to_args is reserved.
190
191
192       ND_MERGEADDR             Used  to  take  a  ``local address'' such as a
193                                0.0.0.0  TCP  address  and  return  a   ``real
194                                address''  to  which  client machines can con‐
195                                nect. fildes is not used. pointer_to_args is a
196                                pointer  to a struct nd_mergearg which has the
197                                following members:
198
199                                  char s_uaddr;    /* server's universal address */
200                                  char c_uaddr;    /* client's universal address */
201                                  char m_uaddr;    /* the result */
202
203                                If s_uaddr is an address such as 0.0.0.0.1.12,
204                                and  the  call is successful m_uaddr is set to
205                                an address  such  as  192.11.109.89.1.12.  For
206                                most   transports,  m_uaddr  is  identical  to
207                                s_uaddr.
208
209

RETURN VALUES

211       The netdir_perror() function prints an error message in standard output
212       that  states  the cause of a name-to-address mapping failure. The error
213       message is preceded by the string given as an argument.
214
215
216       The netdir_sperror() function returns a string with  an  error  message
217       that states the cause of a name-to-address mapping failure.
218
219
220       The  netdir_sperror() function returns a pointer to a buffer which con‐
221       tains the error message string. The buffer is overwritten on each call.
222       In  multithreaded  applications, thise buffer is implemented as thread-
223       specific data.
224
225
226       The netdir_getbyaddr() function returns 0 on  success  and  a  non-zero
227       value on failure.
228

ATTRIBUTES

230       See attributes(5) for descriptions of the following attributes:
231
232
233
234
235       ┌─────────────────────────────┬─────────────────────────────┐
236       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
237       ├─────────────────────────────┼─────────────────────────────┤
238       │MT-Level                     │Safe                         │
239       └─────────────────────────────┴─────────────────────────────┘
240

SEE ALSO

242       gethostname(3C),  getnetconfig(3NSL),  getnetpath(3NSL),  netconfig(4),
243       attributes(5)
244
245
246
247SunOS 5.11                        28 Jan 2005                     netdir(3NSL)
Impressum