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32 .\" From: @(#)inet.3 8.1 (Berkeley) 6/4/93
33 .\" $FreeBSD: src/lib/libc/net/inet.3,v 1.8.2.8 2001/12/01 21:15:38 cjc Exp $
34 .\" $DragonFly: src/lib/libc/net/inet.3,v 1.2 2003/06/17 06:26:44 dillon Exp $
49 .Nd Internet address manipulation routines
58 .Fn inet_aton "const char *cp" "struct in_addr *pin"
60 .Fn inet_addr "const char *cp"
62 .Fn inet_network "const char *cp"
64 .Fn inet_ntoa "struct in_addr in"
66 .Fn inet_ntop "int af" "const void *src" "char *dst" "size_t size"
68 .Fn inet_pton "int af" "const char *src" "void *dst"
70 .Fn inet_makeaddr "in_addr_t net" "in_addr_t lna"
72 .Fn inet_lnaof "struct in_addr in"
74 .Fn inet_netof "struct in_addr in"
81 interpret character strings representing
82 numbers expressed in the Internet standard
88 function converts a presentation format address (that is, printable form
89 as held in a character string) to network format (usually a
91 or some other internal binary representation, in network byte order).
92 It returns 1 if the address was valid for the specified address family, or
93 0 if the address wasn't parseable in the specified address family, or -1
94 if some system error occurred (in which case
97 This function is presently valid for
104 routine interprets the specified character string as an Internet address,
105 placing the address into the structure provided.
106 It returns 1 if the string was successfully interpreted,
107 or 0 if the string is invalid.
112 functions return numbers suitable for use
113 as Internet addresses and Internet network
114 numbers, respectively.
118 converts an address from network format (usually a
120 or some other binary form, in network byte order) to presentation format
121 (suitable for external display purposes).
122 It returns NULL if a system error occurs (in which case,
124 will have been set), or it returns a pointer to the destination string.
125 This function is presently valid for
132 takes an Internet address and returns an
134 string representing the address in
136 notation. The routine
138 takes an Internet network number and a local
139 network address and constructs an Internet address
140 from it. The routines
144 break apart Internet host addresses, returning
145 the network number and local network address part,
148 All Internet addresses are returned in network
149 order (bytes ordered from left to right).
150 All network numbers and local address parts are
151 returned as machine byte order integer values.
152 .Sh INTERNET ADDRESSES
153 Values specified using the
156 of the following forms:
157 .Bd -literal -offset indent
164 When four parts are specified, each is interpreted
165 as a byte of data and assigned, from left to right,
166 to the four bytes of an Internet address. Note
167 that when an Internet address is viewed as a 32-bit
168 integer quantity on the
170 the bytes referred to
176 ordered from right to left.
178 When a three part address is specified, the last
179 part is interpreted as a 16-bit quantity and placed
180 in the right-most two bytes of the network address.
181 This makes the three part address format convenient
182 for specifying Class B network addresses as
183 .Dq Li 128.net.host .
185 When a two part address is supplied, the last part
186 is interpreted as a 24-bit quantity and placed in
187 the right most three bytes of the network address.
188 This makes the two part address format convenient
189 for specifying Class A network addresses as
192 When only one part is given, the value is stored
193 directly in the network address without any byte
196 All numbers supplied as
201 may be decimal, octal, or hexadecimal, as specified
202 in the C language (i.e., a leading 0x or 0X implies
203 hexadecimal; otherwise, a leading 0 implies octal;
204 otherwise, the number is interpreted as decimal).
210 functions are semi-deprecated in favor of the
212 family. However, since those functions are not yet widely implemented,
213 portable programs cannot rely on their presence and will continue
216 functions for some time.
224 for malformed requests.
228 .Xr gethostbyname 3 ,
237 .%T "IP Version 6 Addressing Architecture"
248 does not accept 1-, 2-, or 3-part dotted addresses; all four parts
249 must be specified and are interpreted only as decimal values.
250 This is a narrower input set than that accepted by
254 functions appeared in
259 (0xffffffff) is a valid broadcast address, but
261 cannot return that value without indicating failure.
264 function does not share this problem.
265 The problem of host byte ordering versus network byte ordering is
267 The string returned by
269 resides in a static memory area.
271 Inet_addr should return a