What is getservbyname?
Description: The getservbyname() function gets the entry for the given name and protocol from the network services database, /etc/services. This function returns a pointer of type servent, which contains the broken-out fields of a line in the network services database.
Why is Getservbyname system call used in TCP IP programming?
The caller provides a service name, such as “smtp” or “http” and a protocol such as “tcp” or “udp.” The function returns a pointer to a servent structure representing the requested protocol, or NULL representing either an error or service not found. …
What is the return type of Getservbyname ()?
The getservbyname socket function returns the port number for a specified Internet service name and protocol.
What does the getservbyname function return in Windows Sockets?
The getservbyname function returns a pointer to the servent structure containing the name (s) and service number that match the string in the name parameter. All strings are null -terminated. The pointer that is returned points to the servent structure allocated by the Windows Sockets library.
What does getservbyname ( ) do in Python?
The function getservbyname () takes a network service name and an underlying protocol name and returns the port number on which the service is defined by /etc/services. By network service we mean an application protocol like http or ftp. The underlying protocol means is the transport layer protocol like tcp or udp.
When does the getservbyname function return a pointer?
If this pointer is NULL , the getservbyname function returns the first service entry where name matches the s_name member of the servent structure or the s_aliases member of the servent structure. Otherwise, getservbyname matches both the name and the proto. If no error occurs, getservbyname returns a pointer to the servent structure.
What does a null pointer in getservbyname mean?
If getservbyname succeeds, it returns a pointer to the servent structure. A null pointer indicates an error or an end-of-file. The value that getservbyname returns points to a static structure within the library. You must copy the information from this structure before you make further getservbyname , getservbyport , or getservent calls.
