INET(3) 1990 INET(3) NNAAMMEE inet_aton, inet_addr, inet_network, inet_ntoa, inet_makeaddr, inet_lnaof, inet_netof - Internet address manipulation routines SSYYNNOOPPSSIISS ##iinncclluuddee <<ssyyss//ssoocckkeett..hh>> ##iinncclluuddee <<nneettiinneett//iinn..hh>> ##iinncclluuddee <<aarrppaa//iinneett..hh>> iinntt iinneett__aattoonn((ccpp,, ppiinn)) cchhaarr **ccpp;; ssttrruucctt iinn__aaddddrr **ppiinn;; uunnssiiggnneedd lloonngg iinneett__aaddddrr((ccpp)) cchhaarr **ccpp;; uunnssiiggnneedd lloonngg iinneett__nneettwwoorrkk((ccpp)) cchhaarr **ccpp;; cchhaarr **iinneett__nnttooaa((iinn)) ssttrruucctt iinn__aaddddrr iinn;; ssttrruucctt iinn__aaddddrr iinneett__mmaakkeeaaddddrr((nneett,, llnnaa)) iinntt nneett,, llnnaa;; uunnssiiggnneedd lloonngg iinneett__llnnaaooff((iinn)) ssttrruucctt iinn__aaddddrr iinn;; uunnssiiggnneedd lloonngg iinneett__nneettooff((iinn)) ssttrruucctt iinn__aaddddrr iinn;; DDEESSCCRRIIPPTTIIOONN The routines _i_n_e_t__a_t_o_n, _i_n_e_t__a_d_d_r and _i_n_e_t__n_e_t_w_o_r_k interpret character strings representing numbers expressed in the Internet standard "." notation. The _i_n_e_t__a_t_o_n routine interprets the specified character string as an Internet address, placing the address into the structure provided. It returns 1 if the string was successfully interpreted, or 0 if the string is invalid. The _i_n_e_t__a_d_d_r and _i_n_e_t__n_e_t_w_o_r_k functions return numbers suitable for use as Internet addresses and Internet network numbers, respectively. The routine _i_n_e_t__n_t_o_a takes an Internet address and returns an ASCII string representing the address in "." notation. The routine _i_n_e_t__m_a_k_e_a_d_d_r takes an Internet network number and a local network address and constructs an Internet address from it. The routines _i_n_e_t__n_e_t_o_f and _i_n_e_t__l_n_a_o_f break apart Internet host addresses, returning the network number and local network address part, respectively. All Internet addresses are returned in network order (bytes ordered from left to right). All network numbers and local Printed 7/27/90 June 1 INET(3) 1990 INET(3) address parts are returned as machine format integer values. IINNTTEERRNNEETT AADDDDRREESSSSEESS Values specified using the "." notation take one of the fol- lowing forms: 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 net- work addresses as "128.net.host". When a two part address is supplied, the last part is inter- preted 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 "." notation may be decimal, octal, or hexadecimal, as specified in the C language (i.e., a leading 0x or 0X implies hexadecimal; oth- erwise, a leading 0 implies octal; otherwise, the number is interpreted as decimal). SSEEEE AALLSSOO gethostbyname(3), getnetent(3), hosts(5), networks(5), DDIIAAGGNNOOSSTTIICCSS The constant IINNAADDDDRR__NNOONNEE is returned by _i_n_e_t__a_d_d_r and _i_n_e_t__n_e_t_w_o_r_k for malformed requests. BBUUGGSS The value INADDR_NONE (0xffffffff) is a valid broadcast address, but _i_n_e_t__a_d_d_r cannot return that value without indicating failure. The newer _i_n_e_t__a_t_o_n function does not share this problem. The problem of host byte ordering versus network byte ordering is confusing. The string returned by _i_n_e_t__n_t_o_a resides in a static memory area. Inet_addr should return a struct in_addr. Printed 7/27/90 June 2