/* passivesock.c - passivesock */
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdlib.h>
#include <string.h>
#include <netdb.h>
#include <errno.h>
extern int errno;
int errexit(const char *format, ...);
unsigned short portbase = 0; /* port base, for non-root servers */
/*------------------------------------------------------------------------
* passivesock - allocate & bind a server socket using TCP or UDP
*------------------------------------------------------------------------
*/
int
passivesock(const char *service, const char *transport, int qlen)
/*
* Arguments:
* service - service associated with the desired port
* transport - transport protocol to use ("tcp" or "udp")
* qlen - maximum server request queue length
*/
{
struct servent *pse; /* pointer to service information entry */
struct protoent *ppe; /* pointer to protocol information entry*/
struct sockaddr_in sin; /* an Internet endpoint address */
int s, type; /* socket descriptor and socket type */
memset(&sin, 0, sizeof(sin));
sin.sin_family = AF_INET;
sin.sin_addr.s_addr = INADDR_ANY;
/* Map service name to port number */
if ( pse = getservbyname(service, transport) )
sin.sin_port = htons(ntohs((unsigned short)pse->s_port)
+ portbase);
else if ((sin.sin_port=htons((unsigned short)atoi(service))) == 0)
errexit("can't get \"%s\" service entry\n", service);
/* Map protocol name to protocol number */
if ( (ppe = getprotobyname(transport)) == 0)
errexit("can't get \"%s\" protocol entry\n", transport);
/* Use protocol to choose a socket type */
if (strcmp(transport, "udp") == 0)
type = SOCK_DGRAM;
else
type = SOCK_STREAM;
/* Allocate a socket */
s = socket(PF_INET, type, ppe->p_proto);
if (s < 0)
errexit("can't create socket: %s\n", strerror(errno));
/* Bind the socket */
if (bind(s, (struct sockaddr *)&sin, sizeof(sin)) < 0)
errexit("can't bind to %s port: %s\n", service,
strerror(errno));
if (type == SOCK_STREAM && listen(s, qlen) < 0)
errexit("can't listen on %s port: %s\n", service,
strerror(errno));
return s;
}
