Rewrite DHCP options parsing to conform to RFC 3396: options concatenation is
now fully supported.
This commit is contained in:
Nicholas J. Kain
parent
d7103c887d
commit
13f5ab56e2
@ -219,18 +219,18 @@ static size_t send_client_ip(char *out, size_t olen, struct dhcpmsg *packet)
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static size_t send_cmd(char *out, size_t olen, struct dhcpmsg *packet,
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uint8_t code)
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{
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char buf[256];
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uint8_t *optdata, *olddata;
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char buf[2048];
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uint8_t optdata[MAX_DOPT_SIZE], olddata[MAX_DOPT_SIZE];
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ssize_t optlen, oldlen;
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if (!packet)
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return 0;
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memset(buf, '\0', sizeof buf);
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optdata = get_option_data(packet, code, &optlen);
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optlen = get_dhcp_opt(packet, code, optdata, sizeof optdata);
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if (!optlen)
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return 0;
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olddata = get_option_data(&cfg_packet, code, &oldlen);
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oldlen = get_dhcp_opt(&cfg_packet, code, olddata, sizeof olddata);
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if (oldlen == optlen && !memcmp(optdata, olddata, optlen))
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return 0;
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if (ifchd_cmd(buf, sizeof buf, optdata, optlen, code) == -1)
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159
ndhc/options.c
159
ndhc/options.c
@ -34,84 +34,83 @@
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#include "log.h"
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#include "ifch_proto.h"
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// Worker function for get_option_data(). Optlen will be set to the length
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// of the option data.
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static uint8_t *do_get_option_data(uint8_t *buf, ssize_t buflen, int code,
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char *overload, ssize_t *optlen)
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static int do_overload_value(uint8_t *buf, ssize_t blen, int overload)
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{
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// option bytes: [code][len]([data1][data2]..[dataLEN])
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*overload = 0;
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while (buflen > 0) {
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// Advance over padding.
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if (buf[0] == DCODE_PADDING) {
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buflen--;
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buf++;
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ssize_t i = 0;
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while (i < blen) {
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if (buf[i] == DCODE_PADDING) {
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++i;
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continue;
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}
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// We hit the end.
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if (buf[0] == DCODE_END) {
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*optlen = 0;
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return NULL;
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if (buf[i] == DCODE_END)
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break;
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if (i >= blen - 2)
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break;
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if (buf[i] == DCODE_OVERLOAD) {
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if (buf[i+1] == 1) {
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overload |= buf[i+2];
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i += 3;
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continue;
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}
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}
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buflen -= buf[1] + 2;
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if (buflen < 0) {
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log_warning("Bad option data: length would exceed options field size.");
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*optlen = 0;
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return NULL;
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}
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if (buf[0] == code) {
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*optlen = buf[1];
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return buf + 2;
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}
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if (buf[0] == DCODE_OVERLOAD) {
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if (buf[1] == 1)
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*overload |= buf[2];
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// fall through
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}
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buf += buf[1] + 2;
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i += buf[i+1] + 2;
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}
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// End of options field was unmarked: no option data
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*optlen = 0;
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return NULL;
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return overload;
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}
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// XXX: Never concatenates options. If this is added, refer to RFC3396.
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// Get an option with bounds checking (warning, result is not aligned)
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// optlen will be equal to the length of the option data.
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uint8_t *get_option_data(struct dhcpmsg *packet, int code, ssize_t *optlen)
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static int overload_value(struct dhcpmsg *packet)
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{
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uint8_t *option, *buf;
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ssize_t buflen;
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char overload, parsed_ff = 0;
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buf = packet->options;
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buflen = sizeof packet->options;
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option = do_get_option_data(buf, buflen, code, &overload, optlen);
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if (option)
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return option;
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if (overload & 1) {
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parsed_ff = 1;
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option = do_get_option_data(packet->file, sizeof packet->file,
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code, &overload, optlen);
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if (option)
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return option;
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int ol = do_overload_value(packet->options, sizeof packet->options, 0);
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if (ol & 1 && ol & 2)
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return ol;
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if (ol & 1) {
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ol |= do_overload_value(packet->file, sizeof packet->file, ol);
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return ol;
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}
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if (overload & 2) {
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option = do_get_option_data(packet->sname, sizeof packet->sname,
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code, &overload, optlen);
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if (option)
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return option;
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if (!parsed_ff && overload & 1)
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option = do_get_option_data(packet->file, sizeof packet->file,
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code, &overload, optlen);
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if (ol & 2) {
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ol |= do_overload_value(packet->sname, sizeof packet->sname, ol);
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return ol;
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}
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return option;
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return ol; // ol == 0
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}
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static ssize_t do_get_dhcp_opt(uint8_t *sbuf, ssize_t slen, uint8_t code,
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uint8_t *dbuf, ssize_t dlen, ssize_t didx)
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{
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ssize_t i = 0;
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while (i < slen) {
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if (sbuf[i] == DCODE_PADDING) {
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++i;
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continue;
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}
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if (sbuf[i] == DCODE_END)
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break;
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if (i >= slen - 2)
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break;
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if (sbuf[i] == code) {
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if (dlen - didx < sbuf[i+1])
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return didx;
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memcpy(dbuf+didx, sbuf+i+2, sbuf[i+1]);
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didx += sbuf[i+1];
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}
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i += sbuf[i+1] + 2;
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}
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return didx;
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}
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ssize_t get_dhcp_opt(struct dhcpmsg *packet, uint8_t code, uint8_t *dbuf,
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ssize_t dlen)
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{
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int ol = overload_value(packet);
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ssize_t didx = do_get_dhcp_opt(packet->options, sizeof packet->options,
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code, dbuf, dlen, 0);
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if (ol & 1)
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didx += do_get_dhcp_opt(packet->file, sizeof packet->file, code,
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dbuf, dlen, didx);
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if (ol & 2)
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didx += do_get_dhcp_opt(packet->sname, sizeof packet->sname, code,
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dbuf, dlen, didx);
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return didx;
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}
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// return the position of the 'end' option
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@ -297,9 +296,10 @@ uint32_t get_option_router(struct dhcpmsg *packet)
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{
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ssize_t ol;
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uint32_t ret = 0;
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uint8_t *od = get_option_data(packet, DCODE_ROUTER, &ol);
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uint8_t buf[MAX_DOPT_SIZE];
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ol = get_dhcp_opt(packet, DCODE_ROUTER, buf, sizeof buf);
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if (ol == sizeof ret)
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memcpy(&ret, od, sizeof ret);
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memcpy(&ret, buf, sizeof ret);
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return ret;
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}
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@ -307,22 +307,23 @@ uint8_t get_option_msgtype(struct dhcpmsg *packet)
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{
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ssize_t ol;
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uint8_t ret = 0;
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uint8_t *t = get_option_data(packet, DCODE_MSGTYPE, &ol);
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if (t)
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ret = *t;
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uint8_t buf[MAX_DOPT_SIZE];
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ol = get_dhcp_opt(packet, DCODE_MSGTYPE, buf, sizeof buf);
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if (ol == sizeof ret)
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ret = buf[0];
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return ret;
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}
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uint32_t get_option_serverid(struct dhcpmsg *packet, int *found)
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{
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ssize_t ol;
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uint8_t *t;
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uint32_t ret = 0;
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uint8_t buf[MAX_DOPT_SIZE];
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*found = 0;
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t = get_option_data(packet, DCODE_SERVER_ID, &ol);
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ol = get_dhcp_opt(packet, DCODE_SERVER_ID, buf, sizeof buf);
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if (ol == sizeof ret) {
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*found = 1;
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memcpy(&ret, t, sizeof ret);
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memcpy(&ret, buf, sizeof ret);
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}
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return ret;
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}
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@ -330,11 +331,11 @@ uint32_t get_option_serverid(struct dhcpmsg *packet, int *found)
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uint32_t get_option_leasetime(struct dhcpmsg *packet)
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{
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ssize_t ol;
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uint8_t *t;
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uint32_t ret = 0;
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t = get_option_data(packet, DCODE_LEASET, &ol);
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uint8_t buf[MAX_DOPT_SIZE];
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ol = get_dhcp_opt(packet, DCODE_LEASET, buf, sizeof buf);
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if (ol == sizeof ret) {
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memcpy(&ret, t, sizeof ret);
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memcpy(&ret, buf, sizeof ret);
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ret = ntohl(ret);
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}
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return ret;
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@ -54,7 +54,10 @@
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#define DCODE_CLIENT_ID 0x3d
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#define DCODE_END 0xff
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uint8_t *get_option_data(struct dhcpmsg *packet, int code, ssize_t *optlen);
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#define MAX_DOPT_SIZE 500
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ssize_t get_dhcp_opt(struct dhcpmsg *packet, uint8_t code, uint8_t *dbuf,
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ssize_t dlen);
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ssize_t get_end_option_idx(struct dhcpmsg *packet);
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size_t add_option_request_list(struct dhcpmsg *packet);
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