#include "dhcpc.h"
#include <netinet/if_ether.h>
-#include <netpacket/packet.h>
#include <linux/filter.h>
+#include <linux/if_packet.h>
/* "struct client_config_t client_config" is in bb_common_bufsiz1 */
[OPTION_STATIC_ROUTES ] = sizeof("255.255.255.255/32 255.255.255.255 "),
[OPTION_6RD ] = sizeof("32 128 ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 255.255.255.255 "),
[OPTION_STRING ] = 1,
+ [OPTION_STRING_HOST ] = 1,
#if ENABLE_FEATURE_UDHCP_RFC3397
[OPTION_DNS_STRING ] = 1, /* unused */
/* Hmmm, this severely overestimates size if SIP_SERVERS option
return i;
}
+/* Check if a given label represents a valid DNS label
+ * Return pointer to the first character after the label upon success,
+ * NULL otherwise.
+ * See RFC1035, 2.3.1
+ */
+/* We don't need to be particularly anal. For example, allowing _, hyphen
+ * at the end, or leading and trailing dots would be ok, since it
+ * can't be used for attacks. (Leading hyphen can be, if someone uses
+ * cmd "$hostname"
+ * in the script: then hostname may be treated as an option)
+ */
+static const char *valid_domain_label(const char *label)
+{
+ unsigned char ch;
+ unsigned pos = 0;
+
+ for (;;) {
+ ch = *label;
+ if ((ch|0x20) < 'a' || (ch|0x20) > 'z') {
+ if (pos == 0) {
+ /* label must begin with letter */
+ return NULL;
+ }
+ if (ch < '0' || ch > '9') {
+ if (ch == '\0' || ch == '.')
+ return label;
+ /* DNS allows only '-', but we are more permissive */
+ if (ch != '-' && ch != '_')
+ return NULL;
+ }
+ }
+ label++;
+ pos++;
+ //Do we want this?
+ //if (pos > 63) /* NS_MAXLABEL; labels must be 63 chars or less */
+ // return NULL;
+ }
+}
+
+/* Check if a given name represents a valid DNS name */
+/* See RFC1035, 2.3.1 */
+static int good_hostname(const char *name)
+{
+ //const char *start = name;
+
+ for (;;) {
+ name = valid_domain_label(name);
+ if (!name)
+ return 0;
+ if (!name[0])
+ return 1;
+ //Do we want this?
+ //return ((name - start) < 1025); /* NS_MAXDNAME */
+ name++;
+ }
+}
+
/* Create "opt_name=opt_value" string */
static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_optflag *optflag, const char *opt_name)
{
* the case of list of options.
*/
case OPTION_STRING:
+ case OPTION_STRING_HOST:
memcpy(dest, option, len);
dest[len] = '\0';
+ if (type == OPTION_STRING_HOST && !good_hostname(dest))
+ safe_strncpy(dest, "bad", len);
return ret;
case OPTION_STATIC_ROUTES: {
/* Option binary format:
/* +1 element for each option, +2 for subnet option: */
if (packet) {
/* note: do not search for "pad" (0) and "end" (255) options */
+//TODO: change logic to scan packet _once_
for (i = 1; i < 255; i++) {
temp = udhcp_get_option(packet, i);
if (temp) {
static void add_client_options(struct dhcp_packet *packet)
{
- uint8_t c;
int i, end, len;
udhcp_add_simple_option(packet, DHCP_MAX_SIZE, htons(IP_UDP_DHCP_SIZE));
* No bounds checking because it goes towards the head of the packet. */
end = udhcp_end_option(packet->options);
len = 0;
- for (i = 0; (c = dhcp_optflags[i].code) != 0; i++) {
- if (( (dhcp_optflags[i].flags & OPTION_REQ)
- && !client_config.no_default_options
- )
- || (client_config.opt_mask[c >> 3] & (1 << (c & 7)))
- ) {
- packet->options[end + OPT_DATA + len] = c;
+ for (i = 1; i < DHCP_END; i++) {
+ if (client_config.opt_mask[i >> 3] & (1 << (i & 7))) {
+ packet->options[end + OPT_DATA + len] = i;
len++;
}
}
client_config.ifindex);
}
+static int bcast_or_ucast(struct dhcp_packet *packet, uint32_t ciaddr, uint32_t server)
+{
+ if (server)
+ return udhcp_send_kernel_packet(packet,
+ ciaddr, CLIENT_PORT,
+ server, SERVER_PORT);
+ return raw_bcast_from_client_config_ifindex(packet);
+}
+
/* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
/* NOINLINE: limit stack usage in caller */
static NOINLINE int send_discover(uint32_t xid, uint32_t requested)
add_client_options(&packet);
bb_info_msg("Sending renew...");
- if (server)
- return udhcp_send_kernel_packet(&packet,
- ciaddr, CLIENT_PORT,
- server, SERVER_PORT);
- return raw_bcast_from_client_config_ifindex(&packet);
+ return bcast_or_ucast(&packet, ciaddr, server);
}
#if ENABLE_FEATURE_UDHCPC_ARPING
udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
bb_info_msg("Sending release...");
- return udhcp_send_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
+ /* Note: normally we unicast here since "server" is not zero.
+ * However, there _are_ people who run "address-less" DHCP servers,
+ * and reportedly ISC dhcp client and Windows allow that.
+ */
+ return bcast_or_ucast(&packet, ciaddr, server);
}
/* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
int bytes;
struct ip_udp_dhcp_packet packet;
uint16_t check;
+ unsigned char cmsgbuf[CMSG_LEN(sizeof(struct tpacket_auxdata))];
+ struct iovec iov;
+ struct msghdr msg;
+ struct cmsghdr *cmsg;
- bytes = safe_read(fd, &packet, sizeof(packet));
- if (bytes < 0) {
- log1("Packet read error, ignoring");
- /* NB: possible down interface, etc. Caller should pause. */
- return bytes; /* returns -1 */
+ /* used to use just safe_read(fd, &packet, sizeof(packet))
+ * but we need to check for TP_STATUS_CSUMNOTREADY :(
+ */
+ iov.iov_base = &packet;
+ iov.iov_len = sizeof(packet);
+ memset(&msg, 0, sizeof(msg));
+ msg.msg_iov = &iov;
+ msg.msg_iovlen = 1;
+ msg.msg_control = cmsgbuf;
+ msg.msg_controllen = sizeof(cmsgbuf);
+ for (;;) {
+ bytes = recvmsg(fd, &msg, 0);
+ if (bytes < 0) {
+ if (errno == EINTR)
+ continue;
+ log1("Packet read error, ignoring");
+ /* NB: possible down interface, etc. Caller should pause. */
+ return bytes; /* returns -1 */
+ }
+ break;
}
if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
return -2;
}
+ for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
+ if (cmsg->cmsg_level == SOL_PACKET
+ && cmsg->cmsg_type == PACKET_AUXDATA
+ ) {
+ /* some VMs don't checksum UDP and TCP data
+ * they send to the same physical machine,
+ * here we detect this case:
+ */
+ struct tpacket_auxdata *aux = (void *)CMSG_DATA(cmsg);
+ if (aux->tp_status & TP_STATUS_CSUMNOTREADY)
+ goto skip_udp_sum_check;
+ }
+ }
+
/* verify UDP checksum. IP header has to be modified for this */
memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
/* ip.xx fields which are not memset: protocol, check, saddr, daddr */
log1("Packet with bad UDP checksum received, ignoring");
return -2;
}
+ skip_udp_sum_check:
if (packet.data.cookie != htonl(DHCP_MAGIC)) {
bb_info_msg("Packet with bad magic, ignoring");
log1("Opening raw socket on ifindex %d", ifindex); //log2?
fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
- log1("Got raw socket fd %d", fd); //log2?
+ log1("Got raw socket fd"); //log2?
sock.sll_family = AF_PACKET;
sock.sll_protocol = htons(ETH_P_IP);
/* Ignoring error (kernel may lack support for this) */
if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
sizeof(filter_prog)) >= 0)
- log1("Attached filter to raw socket fd %d", fd); // log?
+ log1("Attached filter to raw socket fd"); // log?
+ }
+
+ if (setsockopt(fd, SOL_PACKET, PACKET_AUXDATA,
+ &const_int_1, sizeof(int)) < 0
+ ) {
+ if (errno != ENOPROTOOPT)
+ log1("Can't set PACKET_AUXDATA on raw socket");
}
log1("Created raw socket");
//usage:# define IF_UDHCP_VERBOSE(...)
//usage:#endif
//usage:#define udhcpc_trivial_usage
-//usage: "[-fbnq"IF_UDHCP_VERBOSE("v")"oCRB] [-i IFACE] [-r IP] [-s PROG] [-p PIDFILE]\n"
-//usage: " [-V VENDOR] [-x OPT:VAL]... [-O OPT]..." IF_FEATURE_UDHCP_PORT(" [-P N]")
+//usage: "[-fbq"IF_UDHCP_VERBOSE("v")IF_FEATURE_UDHCPC_ARPING("a")"RB] [-t N] [-T SEC] [-A SEC/-n]\n"
+//usage: " [-i IFACE]"IF_FEATURE_UDHCP_PORT(" [-P PORT]")" [-s PROG] [-p PIDFILE]\n"
+//usage: " [-oC] [-r IP] [-V VENDOR] [-F NAME] [-x OPT:VAL]... [-O OPT]..."
//usage:#define udhcpc_full_usage "\n"
//usage: IF_LONG_OPTS(
//usage: "\n -i,--interface IFACE Interface to use (default eth0)"
-//usage: "\n -p,--pidfile FILE Create pidfile"
+//usage: IF_FEATURE_UDHCP_PORT(
+//usage: "\n -P,--client-port PORT Use PORT (default 68)"
+//usage: )
//usage: "\n -s,--script PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
+//usage: "\n -p,--pidfile FILE Create pidfile"
//usage: "\n -B,--broadcast Request broadcast replies"
-//usage: "\n -t,--retries N Send up to N discover packets"
-//usage: "\n -T,--timeout N Pause between packets (default 3 seconds)"
-//usage: "\n -A,--tryagain N Wait N seconds after failure (default 20)"
+//usage: "\n -t,--retries N Send up to N discover packets (default 3)"
+//usage: "\n -T,--timeout SEC Pause between packets (default 3)"
+//usage: "\n -A,--tryagain SEC Wait if lease is not obtained (default 20)"
+//usage: "\n -n,--now Exit if lease is not obtained"
+//usage: "\n -q,--quit Exit after obtaining lease"
+//usage: "\n -R,--release Release IP on exit"
//usage: "\n -f,--foreground Run in foreground"
//usage: USE_FOR_MMU(
//usage: "\n -b,--background Background if lease is not obtained"
//usage: )
-//usage: "\n -n,--now Exit if lease is not obtained"
-//usage: "\n -q,--quit Exit after obtaining lease"
-//usage: "\n -R,--release Release IP on exit"
//usage: "\n -S,--syslog Log to syslog too"
-//usage: IF_FEATURE_UDHCP_PORT(
-//usage: "\n -P,--client-port N Use port N (default 68)"
-//usage: )
//usage: IF_FEATURE_UDHCPC_ARPING(
//usage: "\n -a,--arping Use arping to validate offered address"
//usage: )
-//usage: "\n -O,--request-option OPT Request option OPT from server (cumulative)"
-//usage: "\n -o,--no-default-options Don't request any options (unless -O is given)"
//usage: "\n -r,--request IP Request this IP address"
+//usage: "\n -o,--no-default-options Don't request any options (unless -O is given)"
+//usage: "\n -O,--request-option OPT Request option OPT from server (cumulative)"
//usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
//usage: "\n Examples of string, numeric, and hex byte opts:"
//usage: "\n -x hostname:bbox - option 12"
//usage: )
//usage: IF_NOT_LONG_OPTS(
//usage: "\n -i IFACE Interface to use (default eth0)"
-//usage: "\n -p FILE Create pidfile"
+//usage: IF_FEATURE_UDHCP_PORT(
+//usage: "\n -P PORT Use PORT (default 68)"
+//usage: )
//usage: "\n -s PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
+//usage: "\n -p FILE Create pidfile"
//usage: "\n -B Request broadcast replies"
-//usage: "\n -t N Send up to N discover packets"
-//usage: "\n -T N Pause between packets (default 3 seconds)"
-//usage: "\n -A N Wait N seconds (default 20) after failure"
+//usage: "\n -t N Send up to N discover packets (default 3)"
+//usage: "\n -T SEC Pause between packets (default 3)"
+//usage: "\n -A SEC Wait if lease is not obtained (default 20)"
+//usage: "\n -n Exit if lease is not obtained"
+//usage: "\n -q Exit after obtaining lease"
+//usage: "\n -R Release IP on exit"
//usage: "\n -f Run in foreground"
//usage: USE_FOR_MMU(
//usage: "\n -b Background if lease is not obtained"
//usage: )
-//usage: "\n -n Exit if lease is not obtained"
-//usage: "\n -q Exit after obtaining lease"
-//usage: "\n -R Release IP on exit"
//usage: "\n -S Log to syslog too"
-//usage: IF_FEATURE_UDHCP_PORT(
-//usage: "\n -P N Use port N (default 68)"
-//usage: )
//usage: IF_FEATURE_UDHCPC_ARPING(
//usage: "\n -a Use arping to validate offered address"
//usage: )
-//usage: "\n -O OPT Request option OPT from server (cumulative)"
-//usage: "\n -o Don't request any options (unless -O is given)"
//usage: "\n -r IP Request this IP address"
+//usage: "\n -o Don't request any options (unless -O is given)"
+//usage: "\n -O OPT Request option OPT from server (cumulative)"
//usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
//usage: "\n Examples of string, numeric, and hex byte opts:"
//usage: "\n -x hostname:bbox - option 12"
SERVER_PORT = CLIENT_PORT - 1;
}
#endif
- if (opt & OPT_o)
- client_config.no_default_options = 1;
while (list_O) {
char *optstr = llist_pop(&list_O);
unsigned n = bb_strtou(optstr, NULL, 0);
}
client_config.opt_mask[n >> 3] |= 1 << (n & 7);
}
+ if (!(opt & OPT_o)) {
+ unsigned i, n;
+ for (i = 0; (n = dhcp_optflags[i].code) != 0; i++) {
+ if (dhcp_optflags[i].flags & OPTION_REQ) {
+ client_config.opt_mask[n >> 3] |= 1 << (n & 7);
+ }
+ }
+ }
while (list_x) {
char *optstr = llist_pop(&list_x);
char *colon = strchr(optstr, ':');
retval = 0;
/* If we already timed out, fall through with retval = 0, else... */
if ((int)tv.tv_sec > 0) {
+ log1("Waiting on select %u seconds", (int)tv.tv_sec);
timestamp_before_wait = (unsigned)monotonic_sec();
- log1("Waiting on select...");
retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
if (retval < 0) {
/* EINTR? A signal was caught, don't panic */
switch (state) {
case INIT_SELECTING:
- if (packet_num < discover_retries) {
+ if (!discover_retries || packet_num < discover_retries) {
if (packet_num == 0)
xid = random_xid();
/* broadcast */
packet_num = 0;
continue;
case REQUESTING:
- if (packet_num < discover_retries) {
+ if (!discover_retries || packet_num < discover_retries) {
/* send broadcast select packet */
send_select(xid, server_addr, requested_ip);
timeout = discover_timeout;
* might work too.
* "Next server" and router are definitely wrong ones to use, though...
*/
+/* We used to ignore pcakets without DHCP_SERVER_ID.
+ * I've got user reports from people who run "address-less" servers.
+ * They either supply DHCP_SERVER_ID of 0.0.0.0 or don't supply it at all.
+ * They say ISC DHCP client supports this case.
+ */
+ server_addr = 0;
temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
if (!temp) {
- bb_error_msg("no server ID, ignoring packet");
- continue;
- /* still selecting - this server looks bad */
+ bb_error_msg("no server ID, using 0.0.0.0");
+ } else {
+ /* it IS unaligned sometimes, don't "optimize" */
+ move_from_unaligned32(server_addr, temp);
}
- /* it IS unaligned sometimes, don't "optimize" */
- move_from_unaligned32(server_addr, temp);
/*xid = packet.xid; - already is */
requested_ip = packet.yiaddr;
#endif
/* enter bound state */
timeout = lease_seconds / 2;
- temp_addr.s_addr = packet.yiaddr;
+ temp_addr.s_addr = packet.yiaddr;
bb_info_msg("Lease of %s obtained, lease time %u",
inet_ntoa(temp_addr), (unsigned)lease_seconds);
requested_ip = packet.yiaddr;