udhcpc: fix a TODO in fill_envp using option scanner
fill_envp now iterates over the packet only once instead of a few hundred times using the new option scanner. function old new delta udhcp_scan_options - 189 +189 putenvp - 46 +46 init_scan_state - 22 +22 udhcp_get_option 227 104 -123 udhcp_run_script 835 601 -234 ------------------------------------------------------------------------------ (add/remove: 3/0 grow/shrink: 0/2 up/down: 257/-357) Total: -100 bytes Signed-off-by: Martin Lewis <martin.lewis.x84@gmail.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Martin Lewis
Denys Vlasenko
parent
acdc8eed89
commit
1f86ecb729
@ -386,59 +386,78 @@ static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_
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return ret;
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}
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/* put all the parameters into the environment */
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static char **fill_envp(struct dhcp_packet *packet)
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static void putenvp(llist_t **envp, char *new_opt)
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{
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int envc;
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int i;
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char **envp, **curr;
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const char *opt_name;
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uint8_t *temp;
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uint8_t overload = 0;
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putenv(new_opt);
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log2(" %s", new_opt);
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llist_add_to(envp, new_opt);
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}
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#define BITMAP unsigned
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#define BBITS (sizeof(BITMAP) * 8)
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#define BMASK(i) (1 << (i & (sizeof(BITMAP) * 8 - 1)))
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#define FOUND_OPTS(i) (found_opts[(unsigned)i / BBITS])
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BITMAP found_opts[256 / BBITS];
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memset(found_opts, 0, sizeof(found_opts));
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/* We need 7 elements for:
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* "interface=IFACE"
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* "ip=N.N.N.N" from packet->yiaddr
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* "giaddr=IP" from packet->gateway_nip (unless 0)
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* "siaddr=IP" from packet->siaddr_nip (unless 0)
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* "boot_file=FILE" from packet->file (unless overloaded)
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* "sname=SERVER_HOSTNAME" from packet->sname (unless overloaded)
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* terminating NULL
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static const char* get_optname(uint8_t code, const struct dhcp_optflag **dh)
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{
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/* Find the option:
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* dhcp_optflags is sorted so we stop searching when dh->code >= code, which is faster
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* than iterating over the entire array.
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* Options which don't have a match in dhcp_option_strings[], e.g DHCP_REQUESTED_IP,
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* are located after the sorted array, so these entries will never be reached
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* and they'll count as unknown options.
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*/
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envc = 7;
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/* +1 element for each option, +2 for subnet option: */
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if (packet) {
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/* note: do not search for "pad" (0) and "end" (255) options */
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//TODO: change logic to scan packet _once_
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for (i = 1; i < 255; i++) {
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temp = udhcp_get_option(packet, i);
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if (temp) {
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if (i == DHCP_OPTION_OVERLOAD)
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overload |= *temp;
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else if (i == DHCP_SUBNET)
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envc++; /* for $mask */
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envc++;
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/*if (i != DHCP_MESSAGE_TYPE)*/
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FOUND_OPTS(i) |= BMASK(i);
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}
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}
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}
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curr = envp = xzalloc(sizeof(envp[0]) * envc);
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for (*dh = dhcp_optflags; (*dh)->code && (*dh)->code < code; (*dh)++)
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continue;
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*curr = xasprintf("interface=%s", client_data.interface);
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putenv(*curr++);
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if ((*dh)->code == code)
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return nth_string(dhcp_option_strings, (*dh - dhcp_optflags));
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return NULL;
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}
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/* put all the parameters into the environment */
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static llist_t *fill_envp(struct dhcp_packet *packet)
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{
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uint8_t *optptr;
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struct dhcp_scan_state scan_state;
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char *new_opt;
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llist_t *envp = NULL;
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putenvp(&envp, xasprintf("interface=%s", client_data.interface));
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if (!packet)
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return envp;
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init_scan_state(packet, &scan_state);
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/* Iterate over the packet options.
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* Handle each option based on whether it's an unknown / known option.
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* There may be (although unlikely) duplicate options. For now, only the last
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* appearing option will be stored in the environment, and all duplicates
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* are freed properly.
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* Long options may be implemented in the future (see RFC 3396) if needed.
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*/
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while ((optptr = udhcp_scan_options(packet, &scan_state)) != NULL) {
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const struct dhcp_optflag *dh;
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const char *opt_name;
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uint8_t code = optptr[OPT_CODE];
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uint8_t len = optptr[OPT_LEN];
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uint8_t *data = optptr + OPT_DATA;
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opt_name = get_optname(code, &dh);
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if (opt_name) {
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new_opt = xmalloc_optname_optval(data, dh, opt_name);
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if (code == DHCP_SUBNET && len == 4) {
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uint32_t subnet;
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putenvp(&envp, new_opt);
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move_from_unaligned32(subnet, data);
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new_opt = xasprintf("mask=%u", mton(subnet));
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}
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} else {
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unsigned ofs;
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new_opt = xmalloc(sizeof("optNNN=") + 1 + len*2);
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ofs = sprintf(new_opt, "opt%u=", code);
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bin2hex(new_opt + ofs, (char *)data, len)[0] = '\0';
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}
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putenvp(&envp, new_opt);
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}
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/* Export BOOTP fields. Fields we don't (yet?) export:
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* uint8_t op; // always BOOTREPLY
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* uint8_t htype; // hardware address type. 1 = 10mb ethernet
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@ -452,77 +471,31 @@ static char **fill_envp(struct dhcp_packet *packet)
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* uint8_t chaddr[16]; // link-layer client hardware address (MAC)
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*/
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/* Most important one: yiaddr as $ip */
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*curr = xmalloc(sizeof("ip=255.255.255.255"));
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sprint_nip(*curr, "ip=", (uint8_t *) &packet->yiaddr);
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putenv(*curr++);
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new_opt = xmalloc(sizeof("ip=255.255.255.255"));
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sprint_nip(new_opt, "ip=", (uint8_t *) &packet->yiaddr);
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putenvp(&envp, new_opt);
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if (packet->siaddr_nip) {
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/* IP address of next server to use in bootstrap */
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*curr = xmalloc(sizeof("siaddr=255.255.255.255"));
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sprint_nip(*curr, "siaddr=", (uint8_t *) &packet->siaddr_nip);
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putenv(*curr++);
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new_opt = xmalloc(sizeof("siaddr=255.255.255.255"));
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sprint_nip(new_opt, "siaddr=", (uint8_t *) &packet->siaddr_nip);
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putenvp(&envp, new_opt);
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}
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if (packet->gateway_nip) {
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/* IP address of DHCP relay agent */
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*curr = xmalloc(sizeof("giaddr=255.255.255.255"));
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sprint_nip(*curr, "giaddr=", (uint8_t *) &packet->gateway_nip);
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putenv(*curr++);
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new_opt = xmalloc(sizeof("giaddr=255.255.255.255"));
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sprint_nip(new_opt, "giaddr=", (uint8_t *) &packet->gateway_nip);
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putenvp(&envp, new_opt);
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}
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if (!(overload & FILE_FIELD) && packet->file[0]) {
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if (!(scan_state.overload & FILE_FIELD) && packet->file[0]) {
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/* watch out for invalid packets */
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*curr = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
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putenv(*curr++);
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new_opt = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
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putenvp(&envp, new_opt);
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}
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if (!(overload & SNAME_FIELD) && packet->sname[0]) {
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if (!(scan_state.overload & SNAME_FIELD) && packet->sname[0]) {
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/* watch out for invalid packets */
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*curr = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
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putenv(*curr++);
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}
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/* Export known DHCP options */
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opt_name = dhcp_option_strings;
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i = 0;
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while (*opt_name) {
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uint8_t code = dhcp_optflags[i].code;
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BITMAP *found_ptr = &FOUND_OPTS(code);
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BITMAP found_mask = BMASK(code);
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if (!(*found_ptr & found_mask))
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goto next;
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*found_ptr &= ~found_mask; /* leave only unknown options */
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temp = udhcp_get_option(packet, code);
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*curr = xmalloc_optname_optval(temp, &dhcp_optflags[i], opt_name);
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putenv(*curr++);
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if (code == DHCP_SUBNET && temp[-OPT_DATA + OPT_LEN] == 4) {
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/* Subnet option: make things like "$ip/$mask" possible */
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uint32_t subnet;
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move_from_unaligned32(subnet, temp);
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*curr = xasprintf("mask=%u", mton(subnet));
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putenv(*curr++);
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}
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next:
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opt_name += strlen(opt_name) + 1;
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i++;
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}
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/* Export unknown options */
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for (i = 0; i < 256;) {
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BITMAP bitmap = FOUND_OPTS(i);
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if (!bitmap) {
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i += BBITS;
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continue;
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}
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if (bitmap & BMASK(i)) {
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unsigned len, ofs;
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temp = udhcp_get_option(packet, i);
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/* udhcp_get_option returns ptr to data portion,
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* need to go back to get len
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*/
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len = temp[-OPT_DATA + OPT_LEN];
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*curr = xmalloc(sizeof("optNNN=") + 1 + len*2);
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ofs = sprintf(*curr, "opt%u=", i);
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*bin2hex(*curr + ofs, (void*) temp, len) = '\0';
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putenv(*curr++);
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}
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i++;
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new_opt = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
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putenvp(&envp, new_opt);
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}
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return envp;
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@ -531,7 +504,7 @@ static char **fill_envp(struct dhcp_packet *packet)
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/* Call a script with a par file and env vars */
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static void udhcp_run_script(struct dhcp_packet *packet, const char *name)
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{
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char **envp, **curr;
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llist_t *envp;
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char *argv[3];
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envp = fill_envp(packet);
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@ -543,11 +516,8 @@ static void udhcp_run_script(struct dhcp_packet *packet, const char *name)
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argv[2] = NULL;
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spawn_and_wait(argv);
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for (curr = envp; *curr; curr++) {
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log2(" %s", *curr);
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bb_unsetenv_and_free(*curr);
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}
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free(envp);
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/* Free all allocated environment variables */
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llist_free(envp, (void (*)(void *))bb_unsetenv_and_free);
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}
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