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32 .\" From: @(#)inet.3 8.1 (Berkeley) 6/4/93
48 .Nd Internet address manipulation routines
57 .Fn inet_aton "const char *cp" "struct in_addr *pin"
59 .Fn inet_addr "const char *cp"
61 .Fn inet_network "const char *cp"
63 .Fn inet_ntoa "struct in_addr in"
67 .Fa "const void * restrict src"
68 .Fa "char * restrict dst"
72 .Fn inet_pton "int af" "const char * restrict src" "void * restrict dst"
74 .Fn inet_makeaddr "in_addr_t net" "in_addr_t lna"
76 .Fn inet_lnaof "struct in_addr in"
78 .Fn inet_netof "struct in_addr in"
85 interpret character strings representing
86 numbers expressed in the Internet standard
92 function converts a presentation format address (that is, printable form
93 as held in a character string) to network format (usually a
95 or some other internal binary representation, in network byte order).
96 It returns 1 if the address was valid for the specified address family, or
97 0 if the address was not parseable in the specified address family, or -1
98 if some system error occurred (in which case
101 This function is presently valid for
108 routine interprets the specified character string as an Internet address,
109 placing the address into the structure provided.
110 It returns 1 if the string was successfully interpreted,
111 or 0 if the string is invalid.
116 functions return numbers suitable for use
117 as Internet addresses and Internet network
118 numbers, respectively.
127 or some other binary form, in network byte order) to presentation format
128 (suitable for external display purposes).
131 argument specifies the size, in bytes, of the buffer
133 It returns NULL if a system error occurs (in which case,
135 will have been set), or it returns a pointer to the destination string.
136 This function is presently valid for
143 takes an Internet address and returns an
145 string representing the address in
150 takes an Internet network number and a local
151 network address and constructs an Internet address
157 break apart Internet host addresses, returning
158 the network number and local network address part,
161 All Internet addresses are returned in network
162 order (bytes ordered from left to right).
163 All network numbers and local address parts are
164 returned as machine byte order integer values.
165 .Sh INTERNET ADDRESSES
166 Values specified using the
169 of the following forms:
170 .Bd -literal -offset indent
177 When four parts are specified, each is interpreted
178 as a byte of data and assigned, from left to right,
179 to the four bytes of an Internet address.
181 that when an Internet address is viewed as a 32-bit
182 integer quantity on the
184 the bytes referred to
190 ordered from right to left.
192 When a three part address is specified, the last
193 part is interpreted as a 16-bit quantity and placed
194 in the right-most two bytes of the network address.
195 This makes the three part address format convenient
196 for specifying Class B network addresses as
197 .Dq Li 128.net.host .
199 When a two part address is supplied, the last part
200 is interpreted as a 24-bit quantity and placed in
201 the right most three bytes of the network address.
202 This makes the two part address format convenient
203 for specifying Class A network addresses as
206 When only one part is given, the value is stored
207 directly in the network address without any byte
210 All numbers supplied as
215 may be decimal, octal, or hexadecimal, as specified
216 in the C language (i.e., a leading 0x or 0X implies
217 hexadecimal; otherwise, a leading 0 implies octal;
218 otherwise, the number is interpreted as decimal).
224 functions are semi-deprecated in favor of the
227 However, since those functions are not yet widely implemented,
228 portable programs cannot rely on their presence and will continue
231 functions for some time.
239 for malformed requests.
247 was not large enough to store the presentation form of the address.
248 .It Bq Er EAFNOSUPPORT
259 .Xr gethostbyname 3 ,
268 .%T "IP Version 6 Addressing Architecture"
279 does not accept 1-, 2-, or 3-part dotted addresses; all four parts
280 must be specified and are interpreted only as decimal values.
281 This is a narrower input set than that accepted by
285 functions appeared in
290 (0xffffffff) is a valid broadcast address, but
292 cannot return that value without indicating failure.
295 function does not share this problem.
296 The problem of host byte ordering versus network byte ordering is
298 The string returned by
300 resides in a static memory area.
302 Inet_addr should return a