/* vi: set sw=4 ts=4: */ /* * Copyright (C) 2000-2006 Erik Andersen <andersen@uclibc.org> * * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball. */ #include <errno.h> #include <unistd.h> #include <sys/types.h> #include <fcntl.h> #include <stdlib.h> #include <string.h> #include <netdb.h> #include <not-cancel.h> #define HOSTID "/etc/hostid" #ifdef __USE_BSD int sethostid(long int new_id) { int fd; int ret; if (geteuid() || getuid()) return __set_errno(EPERM); fd = open_not_cancel(HOSTID, O_CREAT|O_WRONLY, 0644); if (fd < 0) return fd; ret = write_not_cancel(fd, &new_id, sizeof(new_id)) == sizeof(new_id) ? 0 : -1; close_not_cancel_no_status (fd); return ret; } #endif #define _addr(a) (((struct sockaddr_in*)a->ai_addr)->sin_addr.s_addr) long int gethostid(void) { char host[HOST_NAME_MAX + 1]; int fd, id = 0; /* If hostid was already set then we can return that value. * It is not an error if we cannot read this file. It is not even an * error if we cannot read all the bytes, we just carry on trying... */ fd = open_not_cancel_2(HOSTID, O_RDONLY); if (fd >= 0) { int i = read_not_cancel(fd, &id, sizeof(id)); close_not_cancel_no_status(fd); if (i > 0) return id; } /* Try some methods of returning a unique 32 bit id. Clearly IP * numbers, if on the internet, will have a unique address. If they * are not on the internet then we can return 0 which means they should * really set this number via a sethostid() call. If their hostname * returns the loopback number (i.e. if they have put their hostname * in the /etc/hosts file with 127.0.0.1) then all such hosts will * have a non-unique hostid, but it doesn't matter anyway and * gethostid() will return a non zero number without the need for * setting one anyway. * Mitch */ if (gethostname(host, HOST_NAME_MAX) >= 0 && *host) { struct addrinfo hints, *results, *addr; memset(&hints, 0, sizeof(struct addrinfo)); if (!getaddrinfo(host, NULL, &hints, &results)) { for (addr = results; addr; addr = results->ai_next) { /* Just so it doesn't look exactly like the IP addr */ id = _addr(addr) << 16 | _addr(addr) >> 16; break; } freeaddrinfo(results); } } return id; }