diff options
Diffstat (limited to 'lib/libc')
| -rw-r--r-- | lib/libc/net/gethostbyname.3 | 47 |
1 files changed, 46 insertions, 1 deletions
diff --git a/lib/libc/net/gethostbyname.3 b/lib/libc/net/gethostbyname.3 index 3c20288..6ce7690 100644 --- a/lib/libc/net/gethostbyname.3 +++ b/lib/libc/net/gethostbyname.3 @@ -76,7 +76,34 @@ functions each return a pointer to an object with the following structure describing an internet host referenced by name or by address, respectively. -This structure contains either the information obtained from the name server, +.Pp +The +.Fa name +parameter passed to +.Fn gethostbyname +or +.Fn gethostbyname2 +should point to a NUL-terminated hostname. +The +.Fa addr +parameter passed to +.Fn gethostbyaddr +should point to an address which is +.Fa len +bytes long, +in binary form +(i.e. not an IP address in human readable ASCII form). +The +.Fa type +parameter specifies the address family +(e.g. +.Dv AF_INET , +.Dv AF_INET6 , +etc) +of this address. +.Pp +The structure returned contains either the information obtained from the name +server, .Xr named 8 , broken-out fields from a line in .Pa /etc/hosts , @@ -188,6 +215,23 @@ parameter. .It Pa /etc/nsswitch.conf .It Pa /etc/resolv.conf .El +.Sh EXAMPLES +Print out the hostname associated with a specific IP address: +.Pp +.Bd -literal + const char *ipstr = "127.0.0.1"; + struct in_addr ip; + struct hostent *hp; + + if (!inet_aton(ipstr, &ip)) + errx(1, "can't parse IP address %s", ipstr); + + if ((hp = gethostbyaddr((const char *)&ip, + sizeof ip, AF_INET)) == NULL) + errx(1, "no name associated with %s", ipstr); + + printf("name associated with %s is %s\en", ipstr, hp->h_name); +.Ed -literal .Sh DIAGNOSTICS Error return status from .Fn gethostbyname , @@ -233,6 +277,7 @@ will result in an answer; for example, a mail-forwarder may be registered for this domain. .El .Sh SEE ALSO +.Xr inet_aton 3 , .Xr resolver 3 , .Xr hosts 5 , .Xr hostname 7 , |
