#include <netdb.h> #include <stdint.h> #include <stdlib.h> #include <unistd.h> #include <netinet/in.h> #include <sys/types.h> #include <stdio.h> static void pserv(const struct servent *svp) { char **pp; printf("name=%s, port=%d, proto=%s, aliases=", svp->s_name, ntohs((uint16_t)svp->s_port), svp->s_proto); for (pp = svp->s_aliases; *pp; pp++) printf("%s ", *pp); printf("\n"); } static void usage(void) { (void)fprintf(stderr, "Usage: %s\n" "\t%s -p <port> [-P <proto>]\n" "\t%s -n <name> [-P <proto>]\n", getprogname(), getprogname(), getprogname()); exit(1); } int main(int argc, char *argv[]) { struct servent *svp; const char *port = NULL, *proto = NULL, *name = NULL; int c; while ((c = getopt(argc, argv, "p:n:P:")) != -1) { switch (c) { case 'n': name = optarg; break; case 'p': port = optarg; break; case 'P': proto = optarg; break; default: usage(); } } if (port && name) usage(); if (port) { if ((svp = getservbyport(htons(atoi(port)), proto)) != NULL) pserv(svp); return 0; } if (name) { if ((svp = getservbyname(name, proto)) != NULL) pserv(svp); return 0; } setservent(0); while ((svp = getservent()) != NULL) pserv(svp); endservent(); return 0; }