gethostbyname(3xnet)

1endhostent(3XNET)X/Open Networking Services Library Functionsendhostent(3XNET)
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NAME

6       endhostent, gethostbyaddr, gethostbyname, gethostent, sethostent - net‐
7       work host database functions
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SYNOPSIS

10       cc [ flag ... ] file ... -lxnet [ library ... ]
11       #include <netdb.h>
12       extern int h_errno;
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14       void endhostent(void)
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17       struct hostent *gethostbyaddr(const void *addr, socklen_t len, int type);
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20       struct hostent *gethostbyname(const char *name);
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23       struct hostent *gethostent(void)
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26       void sethostent(int stayopen);
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DESCRIPTION

30       The gethostent(), gethostbyaddr(), and gethostbyname()  functions  each
31       return  a  pointer to a hostent structure, the members of which contain
32       the fields of an entry in the network host database.
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35       The gethostent() function reads the next entry of the database, opening
36       a connection to the database if necessary.
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39       The  gethostbyaddr()  function searches the database and finds an entry
40       which matches the address family specified by  the  type  argument  and
41       which  matches  the address pointed to by the addr argument,  opening a
42       connection to the database  if  necessary.   The  addr  argument  is  a
43       pointer  to the binary-format (that is, not null-terminated) address in
44       network byte order, whose length is specified by the len argument.  The
45       datatype  of the address depends on the address family.  For an address
46       of  type  AF_INET,  this  is   an   in_addr   structure,   defined   in
47       <netinet/in.h>.  For  an address of type AF_INET6, there is an in6_addr
48       structure defined in <netinet/in.h>.
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51       The gethostbyname() function searches the database and finds  an  entry
52       which  matches  the host name specified by the name argument, opening a
53       connection to the database if necessary. If  name is  an  alias  for  a
54       valid  host  name, the function returns information about the host name
55       to which the alias refers, and  name is included in the list of aliases
56       returned.
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59       The  sethostent() function opens a connection to the network host data‐
60       base, and sets the position of the next entry to the first  entry.   If
61       the  stayopen argument is non-zero, the connection to the host database
62       will not be closed after each call to gethostent() (either directly, or
63       indirectly through one of the other gethost*() functions).
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66       The endhostent() function closes the connection to the database.
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USAGE

69       The  gethostent(),  gethostbyaddr(),  and gethostbyname() functions may
70       return pointers to static data, which may be overwritten by  subsequent
71       calls to any of these functions.
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74       These functions are generally used with the Internet address family.
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RETURN VALUES

77       On  successful completion, gethostbyaddr(), gethostbyname() and gethos‐
78       tent() return a pointer to a hostent structure if the  requested  entry
79       was found, and a null pointer if the end of the database was reached or
80       the requested entry was  not  found.   Otherwise,  a  null  pointer  is
81       returned.
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84       On  unsuccessful  completion, gethostbyaddr() and gethostbyname() func‐
85       tions set h_errno to indicate the error.
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ERRORS

88       No errors are defined for endhostent(), gethostent() and sethostent().
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91       The gethostbyaddr() and gethostbyname() functions will fail in the fol‐
92       lowing  cases,  setting  h_errno  to the value shown in the list below.
93       Any changes to errno are unspecified.
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95       HOST_NOT_FOUND    No such host is known.
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98       NO_DATA           The server recognised the request and the name but no
99                         address  is available. Another type of request to the
100                         name server for the domain might return an answer.
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103       NO_RECOVERY       An unexpected server failure occurred which  can  not
104                         be recovered.
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107       TRY_AGAIN         A  temporary  and  possibly transient error occurred,
108                         such as a failure of a server to respond.
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ATTRIBUTES

112       See attributes(5) for descriptions of the following attributes:
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117       ┌─────────────────────────────┬─────────────────────────────┐
118       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
119       ├─────────────────────────────┼─────────────────────────────┤
120       │Interface Stability          │Standard                     │
121       ├─────────────────────────────┼─────────────────────────────┤
122       │MT-Level                     │MT-Safe                      │
123       └─────────────────────────────┴─────────────────────────────┘
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