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Introduce node IDs.

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This introduces a new type of identifier for nodes, which complements
node names: node IDs. Node IDs are defined as the first 6 bytes of the
SHA-256 hash of the node name. They will be used in future code in lieu
of node names as unique node identifiers in contexts where space is at
a premium (such as VPN packets).

The semantics of node IDs is that they are supposed to be unique in a
tinc graph; i.e. two different nodes that are part of the same graph
should not have the same ID, otherwise things could break. This
solution provides this guarantee based on realistic probabilities:
indeed, according to the birthday problem, with a 48-bit hash, the
probability of at least one collision is 1e-13 with 10 nodes, 1e-11
with 100 nodes, 1e-9 with 1000 nodes and 1e-7 with 10000 nodes. Things
only start getting hairy with more than 1 million nodes, as the
probability gets over 0.2%.
This commit is contained in:
Etienne Dechamps 2014-09-21 18:17:02 +01:00
parent ac77e3c1eb
commit 55a78da4e0
5 changed files with 48 additions and 9 deletions
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6
src/info.c
View file

@ -50,6 +50,7 @@ static int info_node(int fd, const char *item) {
char line[4096];
char node[4096];
char id[4096];
char from[4096];
char to[4096];
char subnet[4096];
@ -68,12 +69,12 @@ static int info_node(int fd, const char *item) {
long int last_state_change;
while(recvline(fd, line, sizeof line)) {
int n = sscanf(line, "%d %d %s %s port %s %d %d %d %d %x %"PRIx32" %s %s %d %hd %hd %hd %ld", &code, &req, node, host, port, &cipher, &digest, &maclength, &compression, &options, &status_union.raw, nexthop, via, &distance, &pmtu, &minmtu, &maxmtu, &last_state_change);
int n = sscanf(line, "%d %d %s %s %s port %s %d %d %d %d %x %"PRIx32" %s %s %d %hd %hd %hd %ld", &code, &req, node, id, host, port, &cipher, &digest, &maclength, &compression, &options, &status_union.raw, nexthop, via, &distance, &pmtu, &minmtu, &maxmtu, &last_state_change);
if(n == 2)
break;
if(n != 18) {
if(n != 19) {
fprintf(stderr, "Unable to parse node dump from tincd.\n");
return 1;
}
@ -95,6 +96,7 @@ static int info_node(int fd, const char *item) {
}
printf("Node: %s\n", item);
printf("Node ID: %s\n", id);
printf("Address: %s port %s\n", host, port);
char timestr[32] = "never";

4
src/net.h
View file

@ -52,6 +52,10 @@ typedef struct ipv6_t {
uint16_t x[8];
} ipv6_t;
typedef struct node_id_t {
uint8_t x[6];
} node_id_t;
typedef short length_t;
#define AF_UNKNOWN 255

36
src/node.c
View file

@ -30,7 +30,10 @@
#include "utils.h"
#include "xalloc.h"
static digest_t *sha256;
splay_tree_t *node_tree;
static splay_tree_t *node_id_tree;
static hash_t *node_udp_cache;
node_t *myself;
@ -39,14 +42,24 @@ static int node_compare(const node_t *a, const node_t *b) {
return strcmp(a->name, b->name);
}
static int node_id_compare(const node_t *a, const node_t *b) {
return memcmp(&a->id, &b->id, sizeof(node_id_t));
}
void init_nodes(void) {
sha256 = digest_open_by_name("sha256", sizeof(node_id_t));
node_tree = splay_alloc_tree((splay_compare_t) node_compare, (splay_action_t) free_node);
node_id_tree = splay_alloc_tree((splay_compare_t) node_id_compare, NULL);
node_udp_cache = hash_alloc(0x100, sizeof(sockaddr_t));
}
void exit_nodes(void) {
hash_free(node_udp_cache);
splay_delete_tree(node_id_tree);
splay_delete_tree(node_tree);
digest_close(sha256);
}
node_t *new_node(void) {
@ -93,7 +106,10 @@ void free_node(node_t *n) {
}
void node_add(node_t *n) {
digest_create(sha256, n->name, strlen(n->name), &n->id);
splay_insert(node_tree, n);
splay_insert(node_id_tree, n);
}
void node_del(node_t *n) {
@ -103,6 +119,7 @@ void node_del(node_t *n) {
for splay_each(edge_t, e, n->edge_tree)
edge_del(e);
splay_delete(node_id_tree, n);
splay_delete(node_tree, n);
}
@ -114,6 +131,14 @@ node_t *lookup_node(char *name) {
return splay_search(node_tree, &n);
}
node_t *lookup_node_id(const node_id_t *id) {
node_t n = {NULL};
n.id = *id;
return splay_search(node_id_tree, &n);
}
node_t *lookup_node_udp(const sockaddr_t *sa) {
return hash_search(node_udp_cache, sa);
}
@ -150,12 +175,17 @@ void update_node_udp(node_t *n, const sockaddr_t *sa) {
}
bool dump_nodes(connection_t *c) {
for splay_each(node_t, n, node_tree)
send_request(c, "%d %d %s %s %d %d %d %d %x %x %s %s %d %hd %hd %hd %ld", CONTROL, REQ_DUMP_NODES,
n->name, n->hostname ?: "unknown port unknown", cipher_get_nid(n->outcipher),
for splay_each(node_t, n, node_tree) {
char id[2 * sizeof n->id + 1];
for (size_t c = 0; c < sizeof n->id; ++c)
sprintf(id + 2 * c, "%02hhx", n->id.x[c]);
id[sizeof id - 1] = 0;
send_request(c, "%d %d %s %s %s %d %d %d %d %x %x %s %s %d %hd %hd %hd %ld", CONTROL, REQ_DUMP_NODES,
n->name, id, n->hostname ?: "unknown port unknown", cipher_get_nid(n->outcipher),
digest_get_nid(n->outdigest), (int)digest_length(n->outdigest), n->outcompression,
n->options, bitfield_to_int(&n->status, sizeof n->status), n->nexthop ? n->nexthop->name : "-",
n->via ? n->via->name ?: "-" : "-", n->distance, n->mtu, n->minmtu, n->maxmtu, (long)n->last_state_change);
}
return send_request(c, "%d %d", CONTROL, REQ_DUMP_NODES);
}

2
src/node.h
View file

@ -43,6 +43,7 @@ typedef struct node_status_t {
typedef struct node_t {
char *name; /* name of this node */
node_id_t id; /* unique node ID (name hash) */
uint32_t options; /* options turned on for this node */
int sock; /* Socket to use for outgoing UDP packets */
@ -111,6 +112,7 @@ extern void free_node(node_t *);
extern void node_add(node_t *);
extern void node_del(node_t *);
extern node_t *lookup_node(char *);
extern node_t *lookup_node_id(const node_id_t *);
extern node_t *lookup_node_udp(const sockaddr_t *);
extern bool dump_nodes(struct connection_t *);
extern bool dump_traffic(struct connection_t *);

9
src/tincctl.c
View file

@ -1002,6 +1002,7 @@ static int cmd_dump(int argc, char *argv[]) {
break;
char node[4096];
char id[4096];
char from[4096];
char to[4096];
char subnet[4096];
@ -1019,8 +1020,8 @@ static int cmd_dump(int argc, char *argv[]) {
switch(req) {
case REQ_DUMP_NODES: {
int n = sscanf(line, "%*d %*d %s %s port %s %d %d %d %d %x %x %s %s %d %hd %hd %hd %ld", node, host, port, &cipher, &digest, &maclength, &compression, &options, &status_int, nexthop, via, &distance, &pmtu, &minmtu, &maxmtu, &last_state_change);
if(n != 16) {
int n = sscanf(line, "%*d %*d %s %s %s port %s %d %d %d %d %x %x %s %s %d %hd %hd %hd %ld", node, id, host, port, &cipher, &digest, &maclength, &compression, &options, &status_int, nexthop, via, &distance, &pmtu, &minmtu, &maxmtu, &last_state_change);
if(n != 17) {
fprintf(stderr, "Unable to parse node dump from tincd: %s\n", line);
return 1;
}
@ -1043,8 +1044,8 @@ static int cmd_dump(int argc, char *argv[]) {
} else {
if(only_reachable && !status.reachable)
continue;
printf("%s at %s port %s cipher %d digest %d maclength %d compression %d options %x status %04x nexthop %s via %s distance %d pmtu %hd (min %hd max %hd)\n",
node, host, port, cipher, digest, maclength, compression, options, status_int, nexthop, via, distance, pmtu, minmtu, maxmtu);
printf("%s id %s at %s port %s cipher %d digest %d maclength %d compression %d options %x status %04x nexthop %s via %s distance %d pmtu %hd (min %hd max %hd)\n",
node, id, host, port, cipher, digest, maclength, compression, options, status_int, nexthop, via, distance, pmtu, minmtu, maxmtu);
}
} break;