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9914d8b86

Martin Lewis
Martin Lewis
2020-08-13
SUCCESS Duration: 150s

Subject

udhcpc: add support for long options

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Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

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Commit Diff GitHub →

networking/udhcp/dhcpc.c +103 -35networking/udhcp/dhcpc.h +1 -0
networking/udhcp/dhcpc.c+103 -35
@@ -115,6 +115,13 @@ enum {
/*** Script execution code ***/
+struct dhcp_optitem {
+ unsigned len;
+ uint8_t code;
+ uint8_t malloced;
+ uint8_t *data;
+ char *env;
+};
/* get a rough idea of how long an option will be (rounding up...) */
static const uint8_t len_of_option_as_string[] ALIGN1 = {
@@ -186,15 +193,15 @@ static int good_hostname(const char *name)
#endif
/* Create "opt_name=opt_value" string */
-static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_optflag *optflag, const char *opt_name)
+static NOINLINE char *xmalloc_optname_optval(const struct dhcp_optitem *opt_item, const struct dhcp_optflag *optflag, const char *opt_name)
{
unsigned upper_length;
int len, type, optlen;
char *dest, *ret;
+ uint8_t *option;
- /* option points to OPT_DATA, need to go back to get OPT_LEN */
- len = option[-OPT_DATA + OPT_LEN];
-
+ option = opt_item->data;
+ len = opt_item->len;
type = optflag->flags & OPTION_TYPE_MASK;
optlen = dhcp_option_lengths[type];
upper_length = len_of_option_as_string[type]
@@ -386,11 +393,70 @@ static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_
return ret;
}
-static void putenvp(llist_t **envp, char *new_opt)
+static void optitem_unset_env_and_free(void *item)
{
- putenv(new_opt);
+ struct dhcp_optitem *opt_item = item;
+ bb_unsetenv_and_free(opt_item->env);
+ if (opt_item->malloced)
+ free(opt_item->data);
+ free(opt_item);
+}
+
+/* Used by static options (interface, siaddr, etc) */
+static void putenvp(char *new_opt)
+{
+ struct dhcp_optitem *opt_item;
+
+ opt_item = xzalloc(sizeof(*opt_item));
+ /* opt_item->code = 0, so it won't appear in concat_option's lookup */
+ /* opt_item->malloced = 0 */
+ /* opt_item->data = NULL */
+ opt_item->env = new_opt;
+ llist_add_to(&client_data.envp, opt_item);
log2(" %s", new_opt);
- llist_add_to(envp, new_opt);
+ putenv(new_opt);
+}
+
+/* Support RFC3396 Long Encoded Options */
+static struct dhcp_optitem *concat_option(uint8_t *data, uint8_t len, uint8_t code)
+{
+ llist_t *item;
+ struct dhcp_optitem *opt_item;
+
+ /* Check if an option with the code already exists.
+ * A possible optimization is to create a bitmap of all existing options in the packet,
+ * and iterate over the option list only if they exist.
+ * This will result in bigger code, and because dhcp packets don't have too many options it
+ * shouldn't have a big impact on performance.
+ */
+ for (item = client_data.envp; item != NULL; item = item->link) {
+ opt_item = (struct dhcp_optitem *)item->data;
+ if (opt_item->code == code) {
+ /* This option was seen already, concatenate */
+ uint8_t *new_data;
+
+ new_data = xmalloc(len + opt_item->len);
+ memcpy(
+ mempcpy(new_data, opt_item->data, opt_item->len),
+ data, len
+ );
+ opt_item->len += len;
+ if (opt_item->malloced)
+ free(opt_item->data);
+ opt_item->malloced = 1;
+ opt_item->data = new_data;
+ return opt_item;
+ }
+ }
+
+ /* This is a new option, add a new dhcp_optitem to the list */
+ opt_item = xzalloc(sizeof(*opt_item));
+ opt_item->code = code;
+ /* opt_item->malloced = 0 */
+ opt_item->data = data;
+ opt_item->len = len;
+ llist_add_to(&client_data.envp, opt_item);
+ return opt_item;
}
static const char* get_optname(uint8_t code, const struct dhcp_optflag **dh)
@@ -403,7 +469,7 @@ static const char* get_optname(uint8_t code, const struct dhcp_optflag **dh)
* and they'll count as unknown options.
*/
for (*dh = dhcp_optflags; (*dh)->code && (*dh)->code < code; (*dh)++)
- continue;
+ continue;
if ((*dh)->code == code)
return nth_string(dhcp_option_strings, (*dh - dhcp_optflags));
@@ -412,50 +478,54 @@ static const char* get_optname(uint8_t code, const struct dhcp_optflag **dh)
}
/* put all the parameters into the environment */
-static llist_t *fill_envp(struct dhcp_packet *packet)
+static void fill_envp(struct dhcp_packet *packet)
{
uint8_t *optptr;
struct dhcp_scan_state scan_state;
char *new_opt;
- llist_t *envp = NULL;
- putenvp(&envp, xasprintf("interface=%s", client_data.interface));
+ putenvp(xasprintf("interface=%s", client_data.interface));
if (!packet)
- return envp;
+ return;
init_scan_state(packet, &scan_state);
/* Iterate over the packet options.
* Handle each option based on whether it's an unknown / known option.
- * There may be (although unlikely) duplicate options. For now, only the last
- * appearing option will be stored in the environment, and all duplicates
- * are freed properly.
- * Long options may be implemented in the future (see RFC 3396) if needed.
+ * Long options are supported in compliance with RFC 3396.
*/
while ((optptr = udhcp_scan_options(packet, &scan_state)) != NULL) {
const struct dhcp_optflag *dh;
const char *opt_name;
+ struct dhcp_optitem *opt_item;
uint8_t code = optptr[OPT_CODE];
uint8_t len = optptr[OPT_LEN];
uint8_t *data = optptr + OPT_DATA;
+ opt_item = concat_option(data, len, code);
opt_name = get_optname(code, &dh);
if (opt_name) {
- new_opt = xmalloc_optname_optval(data, dh, opt_name);
- if (code == DHCP_SUBNET && len == 4) {
+ new_opt = xmalloc_optname_optval(opt_item, dh, opt_name);
+ if (opt_item->code == DHCP_SUBNET && opt_item->len == 4) {
+ /* Generate extra envvar for DHCP_SUBNET, $mask */
uint32_t subnet;
- putenvp(&envp, new_opt);
- move_from_unaligned32(subnet, data);
- new_opt = xasprintf("mask=%u", mton(subnet));
+ move_from_unaligned32(subnet, opt_item->data);
+ putenvp(xasprintf("mask=%u", mton(subnet)));
}
} else {
unsigned ofs;
- new_opt = xmalloc(sizeof("optNNN=") + 1 + len*2);
- ofs = sprintf(new_opt, "opt%u=", code);
- bin2hex(new_opt + ofs, (char *)data, len)[0] = '\0';
+ new_opt = xmalloc(sizeof("optNNN=") + 1 + opt_item->len*2);
+ ofs = sprintf(new_opt, "opt%u=", opt_item->code);
+ bin2hex(new_opt + ofs, (char *)opt_item->data, opt_item->len)[0] = '\0';
}
- putenvp(&envp, new_opt);
+ log2(" %s", new_opt);
+ putenv(new_opt);
+ /* putenv will replace the existing environment variable in case of a duplicate.
+ * Free the previous occurrence (NULL if it's the first one).
+ */
+ free(opt_item->env);
+ opt_item->env = new_opt;
}
/* Export BOOTP fields. Fields we don't (yet?) export:
@@ -473,41 +543,38 @@ static llist_t *fill_envp(struct dhcp_packet *packet)
/* Most important one: yiaddr as $ip */
new_opt = xmalloc(sizeof("ip=255.255.255.255"));
sprint_nip(new_opt, "ip=", (uint8_t *) &packet->yiaddr);
- putenvp(&envp, new_opt);
+ putenvp(new_opt);
if (packet->siaddr_nip) {
/* IP address of next server to use in bootstrap */
new_opt = xmalloc(sizeof("siaddr=255.255.255.255"));
sprint_nip(new_opt, "siaddr=", (uint8_t *) &packet->siaddr_nip);
- putenvp(&envp, new_opt);
+ putenvp(new_opt);
}
if (packet->gateway_nip) {
/* IP address of DHCP relay agent */
new_opt = xmalloc(sizeof("giaddr=255.255.255.255"));
sprint_nip(new_opt, "giaddr=", (uint8_t *) &packet->gateway_nip);
- putenvp(&envp, new_opt);
+ putenvp(new_opt);
}
if (!(scan_state.overload & FILE_FIELD) && packet->file[0]) {
/* watch out for invalid packets */
new_opt = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
- putenvp(&envp, new_opt);
+ putenvp(new_opt);
}
if (!(scan_state.overload & SNAME_FIELD) && packet->sname[0]) {
/* watch out for invalid packets */
new_opt = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
- putenvp(&envp, new_opt);
+ putenvp(new_opt);
}
-
- return envp;
}
/* Call a script with a par file and env vars */
static void udhcp_run_script(struct dhcp_packet *packet, const char *name)
{
- llist_t *envp;
char *argv[3];
- envp = fill_envp(packet);
+ fill_envp(packet);
/* call script */
log1("executing %s %s", client_data.script, name);
@@ -517,7 +584,8 @@ static void udhcp_run_script(struct dhcp_packet *packet, const char *name)
spawn_and_wait(argv);
/* Free all allocated environment variables */
- llist_free(envp, (void (*)(void *))bb_unsetenv_and_free);
+ llist_free(client_data.envp, optitem_unset_env_and_free);
+ client_data.envp = NULL;
}
networking/udhcp/dhcpc.h+1 -0
@@ -21,6 +21,7 @@ struct client_data_t {
uint8_t *vendorclass; /* Optional vendor class-id to use */
uint8_t *hostname; /* Optional hostname to use */
uint8_t *fqdn; /* Optional fully qualified domain name to use */
+ llist_t *envp; /* list of DHCP options used for env vars */
unsigned first_secs;
unsigned last_secs;