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authorLennart Poettering <lennart@poettering.net>2016-05-23 19:24:21 +0200
committerLennart Poettering <lennart@poettering.net>2016-05-26 15:34:43 +0200
commit96a7979f3d77d1e629dcfe5ee018d18c281771a1 (patch)
tree29b1b6e1623d03d7cb8b858eecf88eeafbbeed16 /src/libsystemd-network
parent38958cd66e87037c75109408bf4093be21811eba (diff)
ipv4acd: rework how we pick ipv4ll addresses
Let's make the seed actually work as stable seed, and use siphash24 to generate the series of addresses, instead of the opaque libc random_r(). This not only makes the seed truly work as stable, portable seed, but also makes the code quite a bit shorter, and removes a couple of memory allocations.
Diffstat (limited to 'src/libsystemd-network')
-rw-r--r--src/libsystemd-network/sd-ipv4ll.c131
1 files changed, 61 insertions, 70 deletions
diff --git a/src/libsystemd-network/sd-ipv4ll.c b/src/libsystemd-network/sd-ipv4ll.c
index 0e6a9df9e5..4fcb06a308 100644
--- a/src/libsystemd-network/sd-ipv4ll.c
+++ b/src/libsystemd-network/sd-ipv4ll.c
@@ -28,6 +28,7 @@
#include "sd-ipv4ll.h"
#include "alloc-util.h"
+#include "ether-addr-util.h"
#include "in-addr-util.h"
#include "list.h"
#include "random-util.h"
@@ -35,8 +36,8 @@
#include "sparse-endian.h"
#include "util.h"
-#define IPV4LL_NETWORK 0xA9FE0000UL
-#define IPV4LL_NETMASK 0xFFFF0000UL
+#define IPV4LL_NETWORK UINT32_C(0xA9FE0000)
+#define IPV4LL_NETMASK UINT32_C(0xFFFF0000)
#define IPV4LL_DONT_DESTROY(ll) \
_cleanup_(sd_ipv4ll_unrefp) _unused_ sd_ipv4ll *_dont_destroy_##ll = sd_ipv4ll_ref(ll)
@@ -45,16 +46,25 @@ struct sd_ipv4ll {
unsigned n_ref;
sd_ipv4acd *acd;
+
be32_t address; /* the address pushed to ACD */
- struct random_data *random_data;
- char *random_data_state;
+ struct ether_addr mac;
+
+ struct {
+ le64_t value;
+ le64_t generation;
+ } seed;
+ bool seed_set;
/* External */
be32_t claimed_address;
+
sd_ipv4ll_callback_t callback;
void* userdata;
};
+static void ipv4ll_on_acd(sd_ipv4acd *ll, int event, void *userdata);
+
sd_ipv4ll *sd_ipv4ll_ref(sd_ipv4ll *ll) {
if (!ll)
return NULL;
@@ -76,16 +86,11 @@ sd_ipv4ll *sd_ipv4ll_unref(sd_ipv4ll *ll) {
return NULL;
sd_ipv4acd_unref(ll->acd);
-
- free(ll->random_data);
- free(ll->random_data_state);
free(ll);
return NULL;
}
-static void ipv4ll_on_acd(sd_ipv4acd *ll, int event, void *userdata);
-
int sd_ipv4ll_new(sd_ipv4ll **ret) {
_cleanup_(sd_ipv4ll_unrefp) sd_ipv4ll *ll = NULL;
int r;
@@ -113,43 +118,32 @@ int sd_ipv4ll_new(sd_ipv4ll **ret) {
}
int sd_ipv4ll_stop(sd_ipv4ll *ll) {
- int r;
-
assert_return(ll, -EINVAL);
- r = sd_ipv4acd_stop(ll->acd);
- if (r < 0)
- return r;
-
- return 0;
+ return sd_ipv4acd_stop(ll->acd);
}
int sd_ipv4ll_set_ifindex(sd_ipv4ll *ll, int ifindex) {
assert_return(ll, -EINVAL);
assert_return(ifindex > 0, -EINVAL);
+ assert_return(sd_ipv4ll_is_running(ll) == 0, -EBUSY);
return sd_ipv4acd_set_ifindex(ll->acd, ifindex);
}
-#define HASH_KEY SD_ID128_MAKE(df,04,22,98,3f,ad,14,52,f9,87,2e,d1,9c,70,e2,f2)
-
int sd_ipv4ll_set_mac(sd_ipv4ll *ll, const struct ether_addr *addr) {
int r;
assert_return(ll, -EINVAL);
+ assert_return(addr, -EINVAL);
+ assert_return(sd_ipv4ll_is_running(ll) == 0, -EBUSY);
- if (!ll->random_data) {
- uint64_t seed;
-
- /* If no random data is set, generate some from the MAC */
- seed = siphash24(&addr->ether_addr_octet, ETH_ALEN, HASH_KEY.bytes);
-
- r = sd_ipv4ll_set_address_seed(ll, htole64(seed));
- if (r < 0)
- return r;
- }
+ r = sd_ipv4acd_set_mac(ll->acd, addr);
+ if (r < 0)
+ return r;
- return sd_ipv4acd_set_mac(ll->acd, addr);
+ ll->mac = *addr;
+ return 0;
}
int sd_ipv4ll_detach_event(sd_ipv4ll *ll) {
@@ -186,31 +180,11 @@ int sd_ipv4ll_get_address(sd_ipv4ll *ll, struct in_addr *address) {
}
int sd_ipv4ll_set_address_seed(sd_ipv4ll *ll, uint64_t seed) {
- _cleanup_free_ struct random_data *random_data = NULL;
- _cleanup_free_ char *random_data_state = NULL;
- int r;
-
assert_return(ll, -EINVAL);
+ assert_return(sd_ipv4ll_is_running(ll) == 0, -EBUSY);
- random_data = new0(struct random_data, 1);
- if (!random_data)
- return -ENOMEM;
-
- random_data_state = new0(char, 128);
- if (!random_data_state)
- return -ENOMEM;
-
- r = initstate_r((unsigned) seed, random_data_state, 128, random_data);
- if (r < 0)
- return r;
-
- free(ll->random_data);
- ll->random_data = random_data;
- random_data = NULL;
-
- free(ll->random_data_state);
- ll->random_data_state = random_data_state;
- random_data_state = NULL;
+ ll->seed.value = htole64(seed);
+ ll->seed_set = true;
return 0;
}
@@ -254,48 +228,64 @@ int sd_ipv4ll_set_address(sd_ipv4ll *ll, const struct in_addr *address) {
return 0;
}
+#define PICK_HASH_KEY SD_ID128_MAKE(15,ac,82,a6,d6,3f,49,78,98,77,5d,0c,69,02,94,0b)
+
static int ipv4ll_pick_address(sd_ipv4ll *ll) {
- struct in_addr in_addr;
be32_t addr;
- int r;
- int32_t random;
assert(ll);
- assert(ll->random_data);
do {
- r = random_r(ll->random_data, &random);
- if (r < 0)
- return r;
- addr = htobe32((random & 0x0000FFFF) | IPV4LL_NETWORK);
- } while (addr == ll->address ||
- (ntohl(addr) & 0x0000FF00) == 0x0000 ||
- (ntohl(addr) & 0x0000FF00) == 0xFF00);
+ uint64_t h;
- in_addr.s_addr = addr;
+ h = siphash24(&ll->seed, sizeof(ll->seed), PICK_HASH_KEY.bytes);
- r = sd_ipv4ll_set_address(ll, &in_addr);
- if (r < 0)
- return r;
+ /* Increase the generation counter by one */
+ ll->seed.generation = htole64(le64toh(ll->seed.generation) + 1);
- return 0;
+ addr = htobe32((h & UINT32_C(0x0000FFFF)) | IPV4LL_NETWORK);
+ } while (addr == ll->address ||
+ (be32toh(addr) & 0x0000FF00) == 0x0000 ||
+ (be32toh(addr) & 0x0000FF00) == 0xFF00);
+
+ return sd_ipv4ll_set_address(ll, &(struct in_addr) { addr });
}
+#define MAC_HASH_KEY SD_ID128_MAKE(df,04,22,98,3f,ad,14,52,f9,87,2e,d1,9c,70,e2,f2)
+
int sd_ipv4ll_start(sd_ipv4ll *ll) {
int r;
+ bool picked_address = false;
assert_return(ll, -EINVAL);
- assert_return(ll->random_data, -EINVAL);
+ assert_return(!ether_addr_is_null(&ll->mac), -EINVAL);
+ assert_return(sd_ipv4ll_is_running(ll) == 0, -EBUSY);
+
+ /* If no random seed is set, generate some from the MAC address */
+ if (!ll->seed_set)
+ ll->seed.value = htole64(siphash24(ll->mac.ether_addr_octet, ETH_ALEN, MAC_HASH_KEY.bytes));
+
+ /* Restart the generation counter. */
+ ll->seed.generation = 0;
if (ll->address == 0) {
r = ipv4ll_pick_address(ll);
if (r < 0)
return r;
+
+ picked_address = true;
}
r = sd_ipv4acd_start(ll->acd);
- if (r < 0)
+ if (r < 0) {
+
+ /* We couldn't start? If so, let's forget the picked address again, the user might make a change and
+ * retry, and we want the new data to take effect when picking an address. */
+ if (picked_address)
+ ll->address = 0;
+
return r;
+ }
return 0;
}
@@ -345,6 +335,7 @@ void ipv4ll_on_acd(sd_ipv4acd *acd, int event, void *userdata) {
}
break;
+
default:
assert_not_reached("Invalid IPv4ACD event.");
}