INET(3N) COMMAND REFERENCE INET(3N) NAME inet, inet_addr, inet_network, inet_ntoa, inet_makeaddr, inet_lnaof, inet_netof - internet address manipulation routines SYNOPSIS #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> ulong inetaddr(cp) char *cp; ulong inetnetwork(cp) char *cp; char *inetntoa(in) struct inaddr in; struct inaddr inetmakeaddr(net, lna) int net, lna; int inetlnaof(in) struct inaddr in; int inetnetof(in) struct inaddr in; DESCRIPTION The routines inetaddr and inetnetwork each interpret character strings representing numbers expressed in the Internet standard dot (.) notation, returning numbers suitable for use as Internet addresses and Internet network numbers, respectively. The routine inetntoa takes an Internet address and returns an ASCII string representing the address in dot (.) notation. The routine inetmakeaddr takes an Internet network number and a local network address and constructs an Internet address from it. The routines inetnetof and inetlnaof break apart Internet host addresses, returning the network number and local network address part, respectively. All Internet address are returned in network order (bytes ordered from left to right). All network numbers and local address parts are returned as machine format integer values. Internet Addresses Values specified using the dot (.) notation take one of the following forms: Printed 3/13/89 1
INET(3N) COMMAND REFERENCE INET(3N) a.b.c.d a.b.c a.b a When four parts are specified, each is interpreted as a byte of data and assigned, from left to right, to the four bytes of an Internet address. Note that when an Internet address is viewed as a 32-bit integer quantity on the VAX, the bytes referred to above appear as d.c.b.a. That is, VAX bytes are ordered from right to left. When a three part address is specified, the last part is interpreted as a 16-bit quantity and placed in the right most two bytes of the network address. This makes the three part address format convenient for specifying Class B network addresses as 128.net.host. When a two part address is supplied, the last part is interpreted as a 24-bit quantity and placed in the right most three bytes of the network address. This makes the two part address format convenient for specifying Class A network addresses as net.host. When only one part is given, the value is stored directly in the network address without any byte rearrangement. All numbers supplied as parts in a dot (.) notation may be decimal, octal, or hexadecimal, as specified in the C language (for example, a leading 0x or 0X implies hexadecimal; otherwise, a leading 0 implies octal; otherwise, the number is interpreted as decimal). DIAGNOSTICS The value -1 is returned by inetaddr and inetnetwork for malformed requests. CAVEATS The string returned by inetntoa resides in a static memory area so it must be copied if it is to be saved. SEE ALSO gethostent(3n), getnetent(3n), hosts(5n), and networks(5n). Printed 3/13/89 2
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