diff options
Diffstat (limited to 'tdeio/misc/kpac/kpac_dhcp_helper.c')
| -rw-r--r-- | tdeio/misc/kpac/kpac_dhcp_helper.c | 229 |
1 files changed, 229 insertions, 0 deletions
diff --git a/tdeio/misc/kpac/kpac_dhcp_helper.c b/tdeio/misc/kpac/kpac_dhcp_helper.c new file mode 100644 index 000000000..906e89dfa --- /dev/null +++ b/tdeio/misc/kpac/kpac_dhcp_helper.c @@ -0,0 +1,229 @@ +/* This file is part of the KDE Libraries + Copyright (c) 2001 Malte Starostik <malte@kde.org> + + This library is free software; you can redistribute it and/or + modify it under the terms of the GNU Library General Public + License version 2 as published by the Free Software Foundation. + + This library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Library General Public License for more details. + + You should have received a copy of the GNU Library General Public License + along with this library; see the file COPYING.LIB. If not, write to + the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, + Boston, MA 02110-1301, USA. +*/ + + +#include <config.h> +#include <sys/types.h> +#include <grp.h> + +#include <unistd.h> +#include <stdlib.h> +#include <stdio.h> +#include <string.h> +#include <sys/time.h> +#include <sys/socket.h> +#include <time.h> +#include <netdb.h> +#include <netinet/in.h> + +#include "dhcp.h" + +#ifndef INADDR_NONE /* some OSes don't define this */ +#define INADDR_NONE -1 +#endif + +int set_gid(gid_t); +int set_uid(uid_t); +int get_port(const char *); +int init_socket(void); +uint32_t send_request(int); +void get_reply(int, uint32_t); + +int set_gid(gid_t gid) +{ +#ifdef HAVE_SHORTSETGROUPS + short x[2]; + x[0] = gid; + x[1] = 73; /* catch errors */ + if (setgroups(1, x) == -1) + return -1; +#else + if (setgroups(1, &gid) == -1) + return -1; +#endif + return setgid(gid); /* _should_ be redundant, but on some systems it isn't */ +} + +int set_uid(uid_t uid) +{ + return setuid(uid); +} + +/* All functions below do an exit(1) on the slightest error */ + +/* Returns the UDP port number for the given service name */ +int get_port(const char *service) +{ + struct servent *serv = getservbyname(service, "udp"); + if (serv == NULL) + exit(1); + + return serv->s_port; +} + +/* Opens the UDP socket, binds to the bootpc port and drops root privileges */ +int init_socket() +{ + struct sockaddr_in addr; + struct protoent *proto; + int sock; + int bcast = 1; + + memset(&addr, 0, sizeof(addr)); + addr.sin_family = AF_INET; + addr.sin_addr.s_addr = INADDR_ANY; + addr.sin_port = get_port("bootpc"); + + if ((proto = getprotobyname("udp")) == NULL || + (sock = socket(AF_INET, SOCK_DGRAM, proto->p_proto)) == -1) + exit(1); + + if (setsockopt(sock, SOL_SOCKET, SO_BROADCAST, &bcast, sizeof(bcast)) == -1 || + setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &bcast, sizeof(bcast)) == -1 || + bind(sock, (struct sockaddr *)&addr, sizeof(addr)) == -1) + exit(1); + + if (set_gid(getgid()) != 0 || /* we don't need it anymore */ + set_uid(getuid()) != 0) + exit(1); + return sock; +} + +/* Fills the DHCPINFORM request packet, returns the transaction id */ +uint32_t send_request(int sock) +{ + char hostname[256]; + struct hostent *hent; + struct sockaddr_in addr; + struct dhcp_msg request; + uint8_t *offs = request.options; + + hostname[0] = '\0'; + hostname[255] = '\0'; + if (gethostname(hostname, 255) == -1 || + strlen(hostname) == 0 || + (hent = gethostbyname(hostname)) == NULL) + exit(1); + + memset(&addr, 0, sizeof(addr)); + addr.sin_family = AF_INET; + addr.sin_addr.s_addr = INADDR_NONE; + addr.sin_port = get_port("bootps"); + + memset(&request, 0, sizeof(request)); + request.op = DHCP_BOOTREQUEST; + srand(time(NULL)); + request.xid = rand(); + request.ciaddr = *(uint32_t*)*hent->h_addr_list; + + *offs++ = DHCP_MAGIC1; + *offs++ = DHCP_MAGIC2; + *offs++ = DHCP_MAGIC3; + *offs++ = DHCP_MAGIC4; + + *offs++ = DHCP_OPT_MSGTYPE; + *offs++ = 1; /* length */ + *offs++ = DHCP_INFORM; + + *offs++ = DHCP_OPT_PARAMREQ; + *offs++ = 1; /* length */ + *offs++ = DHCP_OPT_WPAD; + + *offs++ = DHCP_OPT_END; + + if (sendto(sock, &request, sizeof(request), 0, + (struct sockaddr *)&addr, sizeof(addr)) != sizeof(request)) + exit(1); + + return request.xid; +} + +/* Reads the reply from the socket, checks it and outputs the URL to STDOUT */ +void get_reply(int sock, uint32_t xid) +{ + struct dhcp_msg reply; + int len; + char wpad[DHCP_OPT_LEN + 1]; + uint8_t wpad_len; + uint8_t *offs = reply.options; + uint8_t *end; + + if ((len = recvfrom(sock, &reply, sizeof(reply), 0, NULL, NULL)) <= 0) + exit(1); + + end = (uint8_t *)&reply + len; + if (end < offs + 4 || + end > &reply.options[DHCP_OPT_LEN] || + reply.op != DHCP_BOOTREPLY || + reply.xid != xid || + *offs++ != DHCP_MAGIC1 || + *offs++ != DHCP_MAGIC2 || + *offs++ != DHCP_MAGIC3 || + *offs++ != DHCP_MAGIC4) + exit(1); + + for ( ; offs < end - 1; offs += *offs+1) + { + switch (*offs++) + { + case DHCP_OPT_END: + exit(1); + case DHCP_OPT_MSGTYPE: + if (*offs != 1 || (offs >= end - 1) || *(offs + 1) != DHCP_ACK) + exit(1); + break; + case DHCP_OPT_WPAD: + memset(wpad, 0, sizeof(wpad)); + wpad_len = *offs++; + if (offs >= end) + exit(1); + if (wpad_len > end - offs) + wpad_len = end - offs; + strncpy(wpad, (char *)offs, wpad_len); + wpad[wpad_len] = 0; + printf("%s\n", wpad); + close(sock); + exit(0); + } + } + exit(1); +} + +int main() +{ + fd_set rfds; + struct timeval tv; + int sock; + uint32_t xid; + + sock = init_socket(); + xid = send_request(sock); + + FD_ZERO(&rfds); + FD_SET(sock, &rfds); + tv.tv_sec = 5; + tv.tv_usec = 0; + if (select(sock + 1, &rfds, NULL, NULL, &tv) == 1 && FD_ISSET(sock, &rfds)) + get_reply(sock, xid); + + close(sock); + exit(1); +} + +/* vim: ts=4 sw=4 noet + */ |