Get a network host entry by name
#include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #include <netdb.h> struct hostent *gethostbyname_r( const char * name, struct hostent * result, char * buffer, int bufflen, int * h_errnop );
- The name of the Internet host whose entry you want to find.
- A pointer to a struct hostent where the function can store the host entry.
- A pointer to a buffer that the function can use during the operation to store host database entries; buffer should be large enough to hold all of the data associated with the host entry. A 2K buffer is usually more than enough; a 256-byte buffer is safe in most cases.
- The length of the area pointed to by buffer.
- A pointer to a location where the function can store an herrno value if an error occurs.
Use the -l socket option to qcc to link against this library.
The gethostbyname_r() function is a thread-safe version of gethostbyname() . This function gets the network host entry for the host specified by name, and stores the entry in the struct hostent pointed to by result.
A pointer to result, or NULL if an error occurs.
If an error occurs, the int pointed to by h_errnop is set to:
- The supplied buffer isn't large enough to store the result.
- Authoritative answer: Unknown host.
- No address associated with name; look for an MX record.
- Valid name, but no data record of the requested type. The name is known to the name server, but has no IP address associated with it—this isn't a temporary error. Another type of request to the name server using this domain name will result in an answer (e.g. a mail-forwarder may be registered for this domain).
- Unknown server error. An unexpected server failure was encountered. This is a nonrecoverable network error.
- Nonauthoritative answer: Host name lookup failure. This is usually a temporary error and means that the local server didn't receive a response from an authoritative server. A retry at some later time may succeed.
- Local host database file.
For information about these files, see the Utilities Reference.
Last modified: 2013-12-23