getprotobyname()--Get Protocol Information for Protocol Name

  #include <netdb.h>

 struct protoent *getprotobyname(char *protocol_name)

  #define _XOPEN_SOURCE 520
  #include <netdb.h>

 struct protoent *getprotobyname(const char *protocol_name)

The getprotobyname() function is used to retrieve information about a protocol. The information is retrieved from the protocol database file.

There are two versions of the API, as shown above. The base IBM^® i API uses BSD 4.3 structures and syntax. The other uses syntax and structures compatible with the UNIX 98 programming interface specifications. You can select the UNIX 98 compatible interface with the _XOPEN_SOURCE macro.

Parameters

protocol_name

(Input) The pointer to the character string that contains the name of the protocol for which information is to be retrieved.

Authorities

No authorization is required.

Return Value

getprotobyname() returns a pointer. Possible values are:

• NULL (unsuccessful)
  
  
• p (successful), where p is a pointer to struct protoent

The structure struct protoent is defined in <netdb.h>.

      struct protoent {
        char            *p_name;
        char            **p_aliases;
        int             p_proto;
      };

p_name points to the character string that contains the name of the protocol. p_aliases is a pointer to a NULL-terminated array of alternate names for the protocol. p_proto is the protocol number.

Usage Notes

1. System i^® Navigator or the following CL commands can be used to access the protocol database file:
   
   
   • WRKPCLTBLE (Work with Protocol Table Entries)
     
     
   • ADDPCLTBLE (Add Protocol Table Entry)
     
     
   • RMVPCLTBLE (Remove Protocol Table Entry)
   
   
   
2. The pointer returned by getprotobyname() points to static storage that is overwritten on subsequent calls to the getprotobyname(), getprotobynumber(), or getprotoent() functions.
   
   
3. When the protocol information is obtained from the protocol database file, the file is opened and the protocol information is retrieved (if it exists) from the file. The file is then closed only if a setprotoent() with a nonzero parameter value was not previously done.
   
   
4. A coded character set identifier (CCSID) of 65535 for the job requests that no database translation be performed. For translation to occur for the protocol name specified by the protocol_name parameter, and for the protocol names returned in the protoent structure, the job CCSID must be something other than 65535.
   
   
5. Do not use the getprotobyname() function in a multithreaded environment. See the multithread alternative getprotobyname_r() function.
   
   
6. When you develop in C-based languages and an application is compiled with the _XOPEN_SOURCE macro defined to the value 520 or greater, the getprotobyname() API is mapped to qso_getprotobyname98().

Related Information

• _XOPEN_SOURCE--Using _XOPEN_SOURCE for the UNIX 98 compatible interface
  
  
• getprotobynumber()--Get Protocol Information for Protocol Number
  
  
• getprotoent()--Get Next Entry from Protocol Database
  
  
• setprotoent()--Open Protocol Database
  
  
• endprotoent()--Close Protocol Database

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