NAME

getprotoent(), getprotoent_r(), getprotobynumber(), getprotobynumber_r(), getprotobyname(), getprotobyname_r(), setprotoent(), setprotoent_r(), endprotoent(), endprotoent_r() − get protocol entry
 

SYNOPSIS

#include <netdb.h>

struct protoent *getprotoent(void);

int getprotoent_r(struct protoent *result,
                  struct protoent_data *buffer);

struct protoent *getprotobyname(const char *name);

int getprotobyname_r(const char *name,
                     struct protoent *result,
                     struct protoent_data *buffer);

struct protoent *getprotobynumber(int proto);

int getprotobynumber_r(int proto,
                       struct protoent *result,
                       struct protoent_data *buffer);

int setprotoent(int stayopen);

int setprotoent_r(int stayopen, struct protoent_data *buffer);

int endprotoent(void);

int endprotoent_r(struct protoent_data *buffer);

_XOPEN_SOURCE_EXTENDED only
void setprotoent(int stayopen);
void endprotoent(void);

DESCRIPTION

The getprotoent(), getprotobyname(), and getprotobynumber() functions each return a pointer to a structure of type protoent containing the broken-out fields of a line in the network protocol data base, /etc/protocols. 

The members of this structure are:

p_name The official name of the protocol. 

p_aliases A null-terminated list of alternate names for the protocol. 

p_proto The protocol number. 

Functions behave as follows:

getprotoent() Reads the next line of the file, opening the file if necessary. 

setprotoent() Opens and rewinds the file.  If the stayopen flag is non-zero, the protocol data base is not closed after each call to getprotoent() (either directly or indirectly through one of the other getproto* calls). 

endprotoent() Closes the file. 

getprotobyname()

getprotobynumber() Each sequentially searches from the beginning of the file until a matching protocol name (among either the official names or the aliases) or protocol number is found, or until EOF is encountered. 

If the system is running the Network Information Service (NIS) services, getprotobyname() and getprotobynumber() get the protocol information from the NIS server (see ypserv(1M) and ypfiles(4)).

Reentrant Interfaces

getprotoent_r(), getprotobyname_r(), and getprotobynumber_r() expect to be passed the address of a struct protoent and will store the result at the supplied location.  An additional parameter, a pointer to a struct protoent_data, must also be supplied.  This structure is used to store data, to which fields in the struct protoent will point, as well as state information such as open file descriptors.  The struct protoent_data is defined in the file <netdb.h>. 

setprotoent_r() and endprotoent_r() are to be used only in conjunction with getprotoent_r() and take the same pointer to a struct protoent_data as a parameter.  If the Network Information Service is being used, setprotoent_r() initializes an internal database key.  If the /etc/protocols file is being used, setprotoent_r() opens or rewinds the file.  endprotoent_r() should always be called to ensure that files are closed and internally allocated data structures are released. 

The stayopen parameter to setprotoent_r() currently has no effect.  However, setprotoent() can still be used to keep the /etc/protocols file open when making calls to getprotobyname_r() and getprotobynumber_r(). 

The proto_fp field in the struct protoent_data must be initialized to NULL before it is passed to either getprotoent_r() or setprotoent_r() for the first time.  Thereafter it should not be modified in any way.  This is the only protoent_data field that should ever be explicitly accessed. 

Name Service Switch-Based Operation

The library routines, getprotobyname(), getprotobynumber(), getprotoent(), and their reentrant counterparts, internally call the name service switch to access the "protocols" database lookup policy configured in the /etc/nsswitch.conf file (see switch(4)).  The lookup policy defines the order and the criteria of the supported name services used to resolve protocol names and numbers. 

RETURN VALUE

getprotoent(), getprotobyname(), and getprotobynumber() return a null pointer (0) on EOF or when they are unable to open /etc/protocols. 

For the reentrant (_r) versions of these routines, -1 will be returned if the operation is unsuccessful or, in the case of getprotoent_r(), if the end of the protocols list has been reached.  0 is returned otherwise. 

EXAMPLES

The following code excerpt counts the number of protocols entries:

int count = 0;
struct protoent protobuf;
struct protoent_data pdbuf;

pdbuf.proto_fp = NULL;
(void) setprotoent_r(0, &pdbuf);
while (getprotoent_r(&protobuf, &pdbuf) != -1)
     count++;
(void) endprotoent_r(&pdbuf);

WARNINGS

In the non-reentrant versions of these routines, all information is contained in a static area so it must be copied if it is to be saved. 

getprotoent(), getprotobynumber(), getprotobyname(), setprotoent(), and endprotoent() are unsafe in multi-thread applications.  getprotoent_r(), getprotobynumber_r(), getprotobyname_r(), setprotoent_r(), and endprotoent_r() are MT-Safe and should be used instead. 

AUTHOR

getprotoent() was developed by the University of California, Berkeley. 

FILES

/etc/protocols

SEE ALSO

ypserv(1M), protocols(4), ypfiles(4). 

STANDARDS CONFORMANCE

getprotoent(): XPG4

Hewlett-Packard Company  —  HP-UX Release 10.20:  July 1996