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dhcp.c
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dhcp.c
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/*
* dhcpcd - DHCP client daemon
* Copyright (c) 2006-2012 Roy Marples <roy@marples.name>
* All rights reserved
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include "config.h"
#include "common.h"
#include "dhcp.h"
#define REQUEST (1 << 0)
#define UINT8 (1 << 1)
#define UINT16 (1 << 2)
#define SINT16 (1 << 3)
#define UINT32 (1 << 4)
#define SINT32 (1 << 5)
#define IPV4 (1 << 6)
#define STRING (1 << 7)
#define PAIR (1 << 8)
#define ARRAY (1 << 9)
#define RFC3361 (1 << 10)
#define RFC3397 (1 << 11)
#define RFC3442 (1 << 12)
#define RFC5969 (1 << 13)
#define IPV4R IPV4 | REQUEST
#define DAD "Duplicate address detected"
/* Our aggregate option buffer.
* We ONLY use this when options are split, which for most purposes is
* practically never. See RFC3396 for details. */
static uint8_t *opt_buffer;
struct dhcp_opt {
uint8_t option;
int type;
const char *var;
};
static const struct dhcp_opt const dhcp_opts[] = {
{ 1, IPV4 | REQUEST, "subnet_mask" },
/* RFC 3442 states that the CSR has to come before all other
* routes. For completeness, we also specify static routes,
* then routers. */
{ 121, RFC3442, "classless_static_routes" },
{ 249, RFC3442, "ms_classless_static_routes" },
{ 33, IPV4 | ARRAY | REQUEST, "static_routes" },
{ 3, IPV4 | ARRAY | REQUEST, "routers" },
{ 2, UINT32, "time_offset" },
{ 4, IPV4 | ARRAY, "time_servers" },
{ 5, IPV4 | ARRAY, "ien116_name_servers" },
/* Explicitly include DNS in the list of parameters requested in the DNS request.
* Without this some DHCP servers may skip the DNS entries in the DHCP replies.*/
{ 6, IPV4 | ARRAY | REQUEST, "domain_name_servers" },
{ 7, IPV4 | ARRAY, "log_servers" },
{ 8, IPV4 | ARRAY, "cookie_servers" },
{ 9, IPV4 | ARRAY, "lpr_servers" },
{ 10, IPV4 | ARRAY, "impress_servers" },
{ 11, IPV4 | ARRAY, "resource_location_servers" },
{ 12, STRING, "host_name" },
{ 13, UINT16, "boot_size" },
{ 14, STRING, "merit_dump" },
/* Explicitly include DNS in the list of parameters requested in the DNS request.
* Without this some DHCP servers may skip the DNS entries in the DHCP replies.*/
{ 15, STRING | REQUEST, "domain_name" },
{ 16, IPV4, "swap_server" },
{ 17, STRING, "root_path" },
{ 18, STRING, "extensions_path" },
{ 19, UINT8, "ip_forwarding" },
{ 20, UINT8, "non_local_source_routing" },
{ 21, IPV4 | ARRAY, "policy_filter" },
{ 22, SINT16, "max_dgram_reassembly" },
{ 23, UINT16, "default_ip_ttl" },
{ 24, UINT32, "path_mtu_aging_timeout" },
{ 25, UINT16 | ARRAY, "path_mtu_plateau_table" },
{ 26, UINT16, "interface_mtu" },
{ 27, UINT8, "all_subnets_local" },
{ 28, IPV4 | REQUEST, "broadcast_address" },
{ 29, UINT8, "perform_mask_discovery" },
{ 30, UINT8, "mask_supplier" },
{ 31, UINT8, "router_discovery" },
{ 32, IPV4, "router_solicitation_address" },
{ 34, UINT8, "trailer_encapsulation" },
{ 35, UINT32, "arp_cache_timeout" },
{ 36, UINT16, "ieee802_3_encapsulation" },
{ 37, UINT8, "default_tcp_ttl" },
{ 38, UINT32, "tcp_keepalive_interval" },
{ 39, UINT8, "tcp_keepalive_garbage" },
{ 40, STRING, "nis_domain" },
{ 41, IPV4 | ARRAY, "nis_servers" },
{ 42, IPV4 | ARRAY, "ntp_servers" },
{ 43, STRING, "vendor_encapsulated_options" },
{ 44, IPV4 | ARRAY, "netbios_name_servers" },
{ 45, IPV4, "netbios_dd_server" },
{ 46, UINT8, "netbios_node_type" },
{ 47, STRING, "netbios_scope" },
{ 48, IPV4 | ARRAY, "font_servers" },
{ 49, IPV4 | ARRAY, "x_display_manager" },
{ 50, IPV4, "dhcp_requested_address" },
{ 51, UINT32 | REQUEST, "dhcp_lease_time" },
{ 52, UINT8, "dhcp_option_overload" },
{ 53, UINT8, "dhcp_message_type" },
{ 54, IPV4, "dhcp_server_identifier" },
{ 55, UINT8 | ARRAY, "dhcp_parameter_request_list" },
{ 56, STRING, "dhcp_message" },
{ 57, UINT16, "dhcp_max_message_size" },
{ 58, UINT32 | REQUEST, "dhcp_renewal_time" },
{ 59, UINT32 | REQUEST, "dhcp_rebinding_time" },
{ 64, STRING, "nisplus_domain" },
{ 65, IPV4 | ARRAY, "nisplus_servers" },
{ 66, STRING, "tftp_server_name" },
{ 67, STRING, "bootfile_name" },
{ 68, IPV4 | ARRAY, "mobile_ip_home_agent" },
{ 69, IPV4 | ARRAY, "smtp_server" },
{ 70, IPV4 | ARRAY, "pop_server" },
{ 71, IPV4 | ARRAY, "nntp_server" },
{ 72, IPV4 | ARRAY, "www_server" },
{ 73, IPV4 | ARRAY, "finger_server" },
{ 74, IPV4 | ARRAY, "irc_server" },
{ 75, IPV4 | ARRAY, "streettalk_server" },
{ 76, IPV4 | ARRAY, "streettalk_directory_assistance_server" },
{ 77, STRING, "user_class" },
{ 81, STRING | RFC3397, "fqdn_name" },
{ 85, IPV4 | ARRAY, "nds_servers" },
{ 86, STRING, "nds_tree_name" },
{ 87, STRING, "nds_context" },
{ 88, STRING | RFC3397, "bcms_controller_names" },
{ 89, IPV4 | ARRAY, "bcms_controller_address" },
{ 91, UINT32, "client_last_transaction_time" },
{ 92, IPV4 | ARRAY, "associated_ip" },
{ 98, STRING, "uap_servers" },
{ 112, IPV4 | ARRAY, "netinfo_server_address" },
{ 113, STRING, "netinfo_server_tag" },
{ 114, STRING, "default_url" },
{ 118, IPV4, "subnet_selection" },
{ 119, STRING | RFC3397, "domain_search" },
{ 120, STRING | RFC3361, "sip_server" },
{ 212, RFC5969, "sixrd" },
{ 0, 0, NULL }
};
static const char *if_params[] = {
"interface",
"reason",
"pid",
"ifmetric",
"ifwireless",
"ifflags",
"profile",
"interface_order",
NULL
};
static const char *dhcp_params[] = {
"ip_address",
"subnet_cidr",
"network_number",
"ssid",
"filename",
"server_name",
NULL
};
void
print_options(void)
{
const struct dhcp_opt *opt;
const char **p;
for (p = if_params; *p; p++)
printf(" - %s\n", *p);
for (p = dhcp_params; *p; p++)
printf(" %s\n", *p);
for (opt = dhcp_opts; opt->option; opt++)
if (opt->var)
printf("%03d %s\n", opt->option, opt->var);
}
int make_option_mask(uint8_t *mask, const char *opts, int add)
{
char *token, *o, *p, *t;
const struct dhcp_opt *opt;
int match, n;
o = p = xstrdup(opts);
while ((token = strsep(&p, ", "))) {
if (*token == '\0')
continue;
for (opt = dhcp_opts; opt->option; opt++) {
if (!opt->var)
continue;
match = 0;
if (strcmp(opt->var, token) == 0)
match = 1;
else {
errno = 0;
n = strtol(token, &t, 0);
if (errno == 0 && !*t)
if (opt->option == n)
match = 1;
}
if (match) {
if (add == 2 && !(opt->type & IPV4)) {
free(o);
errno = EINVAL;
return -1;
}
if (add == 1 || add == 2)
add_option_mask(mask,
opt->option);
else
del_option_mask(mask,
opt->option);
break;
}
}
if (!opt->option) {
free(o);
errno = ENOENT;
return -1;
}
}
free(o);
return 0;
}
static int
valid_length(uint8_t option, int dl, int *type)
{
const struct dhcp_opt *opt;
ssize_t sz;
if (dl == 0)
return -1;
for (opt = dhcp_opts; opt->option; opt++) {
if (opt->option != option)
continue;
if (type)
*type = opt->type;
/* The size of RFC3442 and RFC5969 options is checked at a later
* stage in the code */
if (opt->type == 0 ||
opt->type & (STRING | RFC3442 | RFC5969))
return 0;
/* The code does not use SINT16 / SINT32 together with ARRAY.
* It is however far easier to reason about the code if all
* possible array elements are included, and also does not code
* any additional CPU resources. sizeof(uintXX_t) ==
* sizeof(intXX_t) can be assumed. */
sz = 0;
if (opt->type & (UINT32 | SINT32 | IPV4))
sz = sizeof(uint32_t);
else if (opt->type & (UINT16 | SINT16))
sz = sizeof(uint16_t);
else if (opt->type & UINT8)
sz = sizeof(uint8_t);
if (opt->type & ARRAY) {
/* The result of modulo zero is undefined. There are no
* options defined in this file that do not match one of
* the if-clauses above, so the following is not really
* necessary. However, to avoid confusion and unexpected
* behavior if the defined options are ever extended,
* returning false here seems sensible. */
if (!sz) return -1;
return (dl % sz == 0) ? 0 : -1;
}
return (sz == dl) ? 0 : -1;
}
/* unknown option, so let it pass */
return 0;
}
#ifdef DEBUG_MEMORY
static void
free_option_buffer(void)
{
free(opt_buffer);
}
#endif
#define get_option_raw(dhcp, opt) get_option(dhcp, opt, NULL, NULL)
static const uint8_t *
get_option(const struct dhcp_message *dhcp, uint8_t opt, int *len, int *type)
{
const uint8_t *p = dhcp->options;
const uint8_t *e = p + sizeof(dhcp->options);
uint8_t l, ol = 0;
uint8_t o = 0;
uint8_t overl = 0;
uint8_t *bp = NULL;
const uint8_t *op = NULL;
int bl = 0;
/* DHCP Options are in TLV format with T and L each being a single
* byte. In general, here we have p -> T, ol=p+1 -> L, op -> V.
* We must make sure there is enough room to read both T and L.
*/
while (p + 1 < e) {
o = *p++;
if (o == opt) {
if (op) {
if (!opt_buffer) {
opt_buffer = xmalloc(sizeof(*dhcp));
#ifdef DEBUG_MEMORY
atexit(free_option_buffer);
#endif
}
if (!bp)
bp = opt_buffer;
memcpy(bp, op, ol);
bp += ol;
}
ol = (p + *p < e) ? *p : e - (p + 1);
op = p + 1;
bl += ol;
}
switch (o) {
case DHO_PAD:
continue;
case DHO_END:
if (overl & 1) {
/* bit 1 set means parse boot file */
overl &= ~1;
p = dhcp->bootfile;
e = p + sizeof(dhcp->bootfile);
} else if (overl & 2) {
/* bit 2 set means parse server name */
overl &= ~2;
p = dhcp->servername;
e = p + sizeof(dhcp->servername);
} else
goto exit;
break;
case DHO_OPTIONSOVERLOADED:
/* Ensure we only get this option once */
if (!overl)
overl = 0x80 | p[1];
break;
}
l = *p++;
p += l;
}
exit:
if (valid_length(opt, bl, type) == -1) {
errno = EINVAL;
return NULL;
}
if (len)
*len = bl;
if (bp) {
memcpy(bp, op, ol);
return (const uint8_t *)opt_buffer;
}
if (op)
return op;
errno = ENOENT;
return NULL;
}
int
get_option_addr(struct in_addr *a, const struct dhcp_message *dhcp,
uint8_t option)
{
const uint8_t *p = get_option_raw(dhcp, option);
if (!p)
return -1;
memcpy(&a->s_addr, p, sizeof(a->s_addr));
return 0;
}
int
get_option_uint32(uint32_t *i, const struct dhcp_message *dhcp, uint8_t option)
{
const uint8_t *p = get_option_raw(dhcp, option);
uint32_t d;
if (!p)
return -1;
memcpy(&d, p, sizeof(d));
*i = ntohl(d);
return 0;
}
int
get_option_uint16(uint16_t *i, const struct dhcp_message *dhcp, uint8_t option)
{
const uint8_t *p = get_option_raw(dhcp, option);
uint16_t d;
if (!p)
return -1;
memcpy(&d, p, sizeof(d));
*i = ntohs(d);
return 0;
}
int
get_option_uint8(uint8_t *i, const struct dhcp_message *dhcp, uint8_t option)
{
const uint8_t *p = get_option_raw(dhcp, option);
if (!p)
return -1;
if (i)
*i = *(p);
return 0;
}
/* Decode an RFC3397 DNS search order option into a space
* separated string. Returns length of string (including
* terminating zero) or zero on error. out may be NULL
* to just determine output length. */
ssize_t
decode_rfc3397(char *out, ssize_t len, int pl, const uint8_t *p)
{
const uint8_t *r, *q = p;
int count = 0, l, hops;
uint8_t ltype;
while (q - p < pl) {
r = NULL;
hops = 0;
/* We check we are inside our length again incase
* the data is NOT terminated correctly. */
while ((l = *q++) && q - p < pl) {
ltype = l & 0xc0;
if (ltype == 0x80 || ltype == 0x40)
return 0;
else if (ltype == 0xc0) { /* pointer */
l = (l & 0x3f) << 8;
l |= *q++;
/* save source of first jump. */
if (!r)
r = q;
hops++;
if (hops > 255)
return 0;
q = p + l;
if (q - p >= pl)
return 0;
} else {
/* straightforward name segment, add with '.' */
count += l + 1;
if (out) {
if ((ssize_t)l + 1 > len) {
errno = ENOBUFS;
return -1;
}
memcpy(out, q, l);
out += l;
*out++ = '.';
len -= l;
len--;
}
q += l;
}
}
/* change last dot to space */
if (out)
*(out - 1) = ' ';
if (r)
q = r;
}
/* change last space to zero terminator */
if (out)
*(out - 1) = 0;
return count;
}
static ssize_t
decode_rfc3442(char *out, ssize_t len, int pl, const uint8_t *p)
{
const uint8_t *e;
ssize_t b, bytes = 0, ocets;
uint8_t cidr;
struct in_addr addr;
char *o = out;
/* Minimum is 5 -first is CIDR and a router length of 4 */
if (pl < 5) {
errno = EINVAL;
return -1;
}
e = p + pl;
while (p < e) {
cidr = *p++;
if (cidr > 32) {
errno = EINVAL;
return -1;
}
ocets = (cidr + 7) / 8;
if (!out) {
p += 4 + ocets;
bytes += ((4 * 4) * 2) + 4;
continue;
}
if ((((4 * 4) * 2) + 4) > len) {
errno = ENOBUFS;
return -1;
}
if (o != out) {
*o++ = ' ';
len--;
}
/* If we have ocets then we have a destination and netmask */
if (ocets > 0) {
addr.s_addr = 0;
memcpy(&addr.s_addr, p, ocets);
b = snprintf(o, len, "%s/%d", inet_ntoa(addr), cidr);
p += ocets;
} else
b = snprintf(o, len, "0.0.0.0/0");
o += b;
len -= b;
/* Finally, snag the router */
memcpy(&addr.s_addr, p, 4);
p += 4;
b = snprintf(o, len, " %s", inet_ntoa(addr));
o += b;
len -= b;
}
if (out)
return o - out;
return bytes;
}
static struct rt *
decode_rfc3442_rt(int dl, const uint8_t *data)
{
const uint8_t *p = data;
const uint8_t *e;
uint8_t cidr;
size_t ocets;
struct rt *routes = NULL;
struct rt *rt = NULL;
/* Minimum is 5 -first is CIDR and a router length of 4 */
if (dl < 5)
return NULL;
e = p + dl;
while (p < e) {
cidr = *p++;
if (cidr > 32) {
free_routes(routes);
errno = EINVAL;
return NULL;
}
if (rt) {
rt->next = xzalloc(sizeof(*rt));
rt = rt->next;
} else {
routes = rt = xzalloc(sizeof(*routes));
}
rt->next = NULL;
ocets = (cidr + 7) / 8;
/* If we have ocets then we have a destination and netmask */
if (ocets > 0) {
memcpy(&rt->dest.s_addr, p, ocets);
p += ocets;
rt->net.s_addr = htonl(~0U << (32 - cidr));
}
/* Finally, snag the router */
memcpy(&rt->gate.s_addr, p, 4);
p += 4;
}
return routes;
}
static char *
decode_rfc3361(int dl, const uint8_t *data)
{
uint8_t enc;
unsigned int l;
char *sip = NULL;
struct in_addr addr;
char *p;
if (dl < 2) {
errno = EINVAL;
return 0;
}
enc = *data++;
dl--;
switch (enc) {
case 0:
if ((l = decode_rfc3397(NULL, 0, dl, data)) > 0) {
sip = xmalloc(l);
decode_rfc3397(sip, l, dl, data);
}
break;
case 1:
if (dl == 0 || dl % 4 != 0) {
errno = EINVAL;
break;
}
addr.s_addr = INADDR_BROADCAST;
l = ((dl / sizeof(addr.s_addr)) * ((4 * 4) + 1)) + 1;
sip = p = xmalloc(l);
while (dl != 0) {
memcpy(&addr.s_addr, data, sizeof(addr.s_addr));
data += sizeof(addr.s_addr);
p += snprintf(p, l - (p - sip), "%s ", inet_ntoa(addr));
dl -= sizeof(addr.s_addr);
}
*--p = '\0';
break;
default:
errno = EINVAL;
return 0;
}
return sip;
}
/* Decode an RFC5969 6rd order option into a space
* separated string. Returns length of string (including
* terminating zero) or zero on error. */
static ssize_t
decode_rfc5969(char *out, ssize_t len, int pl, const uint8_t *p)
{
uint8_t ipv4masklen, ipv6prefixlen;
uint8_t ipv6prefix[16];
uint8_t br[4];
int i;
ssize_t b, bytes = 0;
if (pl < 22) {
errno = EINVAL;
return 0;
}
ipv4masklen = *p++;
pl--;
ipv6prefixlen = *p++;
pl--;
for (i = 0; i < 16; i++) {
ipv6prefix[i] = *p++;
pl--;
}
if (out) {
b= snprintf(out, len,
"%d %d "
"%02x%02x:%02x%02x:"
"%02x%02x:%02x%02x:"
"%02x%02x:%02x%02x:"
"%02x%02x:%02x%02x",
ipv4masklen, ipv6prefixlen,
ipv6prefix[0], ipv6prefix[1], ipv6prefix[2], ipv6prefix[3],
ipv6prefix[4], ipv6prefix[5], ipv6prefix[6], ipv6prefix[7],
ipv6prefix[8], ipv6prefix[9], ipv6prefix[10],ipv6prefix[11],
ipv6prefix[12],ipv6prefix[13],ipv6prefix[14], ipv6prefix[15]
);
len -= b;
out += b;
bytes += b;
} else {
bytes += 16 * 2 + 8 + 2 + 1 + 2;
}
while (pl >= 4) {
br[0] = *p++;
br[1] = *p++;
br[2] = *p++;
br[3] = *p++;
pl -= 4;
if (out) {
b= snprintf(out, len, " %d.%d.%d.%d",
br[0], br[1], br[2], br[3]);
len -= b;
out += b;
bytes += b;
} else {
bytes += (4 * 4);
}
}
return bytes;
}
char *
get_option_string(const struct dhcp_message *dhcp, uint8_t option)
{
int type = 0;
int len;
const uint8_t *p;
char *s;
p = get_option(dhcp, option, &len, &type);
if (!p || *p == '\0')
return NULL;
if (type & RFC3397) {
type = decode_rfc3397(NULL, 0, len, p);
if (!type) {
errno = EINVAL;
return NULL;
}
s = xmalloc(sizeof(char) * type);
decode_rfc3397(s, type, len, p);
return s;
}
if (type & RFC3361)
return decode_rfc3361(len, p);
s = xmalloc(sizeof(char) * (len + 1));
memcpy(s, p, len);
s[len] = '\0';
return s;
}
/* This calculates the netmask that we should use for static routes.
* This IS different from the calculation used to calculate the netmask
* for an interface address. */
static uint32_t
route_netmask(uint32_t ip_in)
{
/* used to be unsigned long - check if error */
uint32_t p = ntohl(ip_in);
uint32_t t;
if (IN_CLASSA(p))
t = ~IN_CLASSA_NET;
else {
if (IN_CLASSB(p))
t = ~IN_CLASSB_NET;
else {
if (IN_CLASSC(p))
t = ~IN_CLASSC_NET;
else
t = 0;
}
}
while (t & p)
t >>= 1;
return (htonl(~t));
}
/* We need to obey routing options.
* If we have a CSR then we only use that.
* Otherwise we add static routes and then routers. */
struct rt *
get_option_routes(const struct dhcp_message *dhcp,
const char *ifname, unsigned long long *opts)
{
const uint8_t *p;
const uint8_t *e;
struct rt *routes = NULL;
struct rt *route = NULL;
int len;
/* If we have CSR's then we MUST use these only */
p = get_option(dhcp, DHO_CSR, &len, NULL);
/* Check for crappy MS option */
if (!p)
p = get_option(dhcp, DHO_MSCSR, &len, NULL);
if (p) {
routes = decode_rfc3442_rt(len, p);
if (routes) {
if (!(*opts & DHCPCD_CSR_WARNED)) {
syslog(LOG_DEBUG,
"%s: using Classless Static Routes",
ifname);
*opts |= DHCPCD_CSR_WARNED;
}
return routes;
}
}
/* OK, get our static routes first. */
p = get_option(dhcp, DHO_STATICROUTE, &len, NULL);
if (p) {
e = p + len;
while (p < e) {
if (route) {
route->next = xmalloc(sizeof(*route));
route = route->next;
} else
routes = route = xmalloc(sizeof(*routes));
route->next = NULL;
memcpy(&route->dest.s_addr, p, 4);
p += 4;
memcpy(&route->gate.s_addr, p, 4);
p += 4;
route->net.s_addr = route_netmask(route->dest.s_addr);
}
}
/* Now grab our routers */
p = get_option(dhcp, DHO_ROUTER, &len, NULL);
if (p) {
e = p + len;
while (p < e) {
if (route) {
route->next = xzalloc(sizeof(*route));
route = route->next;
} else
routes = route = xzalloc(sizeof(*route));
memcpy(&route->gate.s_addr, p, 4);
p += 4;
}
}
return routes;
}
static size_t
encode_rfc1035(const char *src, uint8_t *dst)
{
uint8_t *p = dst;
uint8_t *lp = p++;
if (*src == '\0')
return 0;
for (; *src; src++) {
if (*src == '\0')
break;
if (*src == '.') {
/* Skip the trailing . */
if (src[1] == '\0')
break;
*lp = p - lp - 1;
if (*lp == '\0')
return p - dst;
lp = p++;
} else
*p++ = (uint8_t)*src;
}
*lp = p - lp - 1;
*p++ = '\0';
return p - dst;
}
#define PUTADDR(_type, _val) \
{ \
*p++ = _type; \
*p++ = 4; \
memcpy(p, &_val.s_addr, 4); \
p += 4; \
}
int
dhcp_message_add_addr(struct dhcp_message *dhcp,
uint8_t type, struct in_addr addr)
{
uint8_t *p;
size_t len;
p = dhcp->options;
while (*p != DHO_END) {
p++;
p += *p + 1;
}
len = p - (uint8_t *)dhcp;
if (len + 6 > sizeof(*dhcp)) {
errno = ENOMEM;
return -1;
}
PUTADDR(type, addr);
*p = DHO_END;
return 0;
}
ssize_t
make_message(struct dhcp_message **message,
const struct interface *iface,
uint8_t type)
{
struct dhcp_message *dhcp;
uint8_t *m, *lp, *p;
uint8_t *n_params = NULL;
time_t up = uptime() - iface->start_uptime;
uint32_t ul;
uint16_t sz;
size_t len;
const char *hp;
const struct dhcp_opt *opt;
const struct if_options *ifo = iface->state->options;
const struct dhcp_lease *lease = &iface->state->lease;
dhcp = xzalloc(sizeof (*dhcp));
m = (uint8_t *)dhcp;
p = dhcp->options;
if ((type == DHCP_INFORM || type == DHCP_RELEASE ||
(type == DHCP_REQUEST &&
iface->net.s_addr == lease->net.s_addr &&
(iface->state->new == NULL ||
iface->state->new->cookie == htonl(MAGIC_COOKIE)))))
{
dhcp->ciaddr = iface->addr.s_addr;
/* In-case we haven't actually configured the address yet */
if (type == DHCP_INFORM && iface->addr.s_addr == 0)
dhcp->ciaddr = lease->addr.s_addr;
}
dhcp->op = DHCP_BOOTREQUEST;
dhcp->hwtype = iface->family;
switch (iface->family) {
case ARPHRD_ETHER:
case ARPHRD_IEEE802:
dhcp->hwlen = iface->hwlen;
memcpy(&dhcp->chaddr, &iface->hwaddr, iface->hwlen);
break;
}
if (ifo->options & DHCPCD_BROADCAST &&
dhcp->ciaddr == 0 &&
type != DHCP_DECLINE &&
type != DHCP_RELEASE)
dhcp->flags = htons(BROADCAST_FLAG);
if (type != DHCP_DECLINE && type != DHCP_RELEASE) {
if (up < 0 || up > (time_t)UINT16_MAX)
dhcp->secs = htons((uint16_t)UINT16_MAX);
else
dhcp->secs = htons(up);
}
dhcp->xid = iface->state->xid;
dhcp->cookie = htonl(MAGIC_COOKIE);
*p++ = DHO_MESSAGETYPE;
*p++ = 1;
*p++ = type;
if (iface->clientid) {
*p++ = DHO_CLIENTID;
memcpy(p, iface->clientid, iface->clientid[0] + 1);
p += iface->clientid[0] + 1;
}
if (lease->addr.s_addr && lease->cookie == htonl(MAGIC_COOKIE)) {
if (type == DHCP_DECLINE ||
(type == DHCP_REQUEST &&
lease->addr.s_addr != iface->addr.s_addr))
{
PUTADDR(DHO_IPADDRESS, lease->addr);
if (lease->server.s_addr)
PUTADDR(DHO_SERVERID, lease->server);
}
if (type == DHCP_RELEASE) {
if (lease->server.s_addr)
PUTADDR(DHO_SERVERID, lease->server);
}
}