ipcpd: Add DHT as directory in normal IPCP

This implements a Distributed Hash Table (DHT) based on the Kademlia
protocol, with default parameters set as used in the BitTorrent
Mainline DHT. This initial implementation is almost feature complete,
except for some things to be done after a testing period: caching and
stale peer bumping, and setting the expiration timeout via the IRM
tool.

1 files changed, 84 insertions, 83 deletions

diff --git a/src/ipcpd/normal/dir.c b/src/ipcpd/normal/dir.c
index 5ea8a300..697c02da 100644
--- a/src/ipcpd/normal/dir.c
+++ b/src/ipcpd/normal/dir.c
@@ -20,129 +20,130 @@
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
+#define OUROBOROS_PREFIX "directory"
+
 #include <ouroboros/config.h>
+#include <ouroboros/endian.h>
 #include <ouroboros/errno.h>
+#include <ouroboros/logs.h>
 #include <ouroboros/rib.h>
+#include <ouroboros/utils.h>
 
 #include "dir.h"
+#include "dht.h"
 #include "ipcp.h"
 #include "ribconfig.h"
 
 #include <stdlib.h>
 #include <string.h>
 #include <assert.h>
+#include <inttypes.h>
 
-static char dir_path[RIB_MAX_PATH_LEN + 1];
+#define KAD_B (hash_len(ipcpi.dir_hash_algo) * CHAR_BIT)
+#define ENROL_RETR 6
+#define ENROL_INTV 1
 
-static void dir_path_reset(void) {
-        dir_path[strlen(DIR_PATH)]= '\0';
-        assert(strcmp(DIR_PATH, dir_path) == 0);
-}
+struct dht * dht;
 
-int dir_init(void)
+static uint64_t find_peer_addr(void)
 {
-        /* FIXME: set ribmgr dissemination here */
-        if (rib_add(RIB_ROOT, DIR_NAME))
-                return -1;
+        ssize_t  i;
+        char ** members;
+        ssize_t n_members;
+        size_t  reset;
+        char    path[RIB_MAX_PATH_LEN + 1];
 
-        strcpy(dir_path, DIR_PATH);
+        strcpy(path, MEMBERS_PATH);
 
-        return 0;
-}
+        reset = strlen(path);
 
-int dir_fini(void)
-{
-        /* FIXME: remove ribmgr dissemination here*/
+        n_members = rib_children(path, &members);
+        if (n_members == 1) {
+                freepp(ssize_t, members, n_members);
+                return 0;
+        }
+
+        for (i = 0; i < n_members; ++i) {
+                uint64_t addr;
+                rib_path_append(path, members[i]);
+                if (rib_read(path, &addr, sizeof(addr)) != sizeof(addr)) {
+                        log_err("Failed to read address from RIB.");
+                        freepp(ssize_t, members, n_members);
+                        return ipcpi.dt_addr;
+                }
+
+                if (addr != ipcpi.dt_addr) {
+                        freepp(ssize_t, members, n_members);
+                        return addr;
+                }
+
+                path[reset] = '\0';
+        }
 
-        dir_path_reset();
-        rib_del(dir_path);
+        freepp(ssize_t, members, n_members);
 
         return 0;
 }
 
-int dir_reg(const uint8_t * hash)
+int dir_init()
 {
-        char hashstr[ipcp_dir_hash_strlen() + 1];
-        int ret;
-
-        assert(hash);
-
-        dir_path_reset();
+        uint64_t addr;
 
-        ipcp_hash_str(hashstr, hash);
-
-        ret = rib_add(dir_path, hashstr);
-        if (ret == -ENOMEM)
-                 return -ENOMEM;
-
-        rib_path_append(dir_path, hashstr);
+        dht = dht_create(ipcpi.dt_addr);
+        if (dht == NULL)
+                return -ENOMEM;
 
-        ret = rib_add(dir_path, ipcpi.name);
-        if (ret == -EPERM)
+        addr = find_peer_addr();
+        if (addr == ipcpi.dt_addr) {
+                log_err("Failed to get peer address.");
+                dht_destroy(dht);
                 return -EPERM;
-        if (ret == -ENOMEM) {
-                if (rib_children(dir_path, NULL) == 0)
-                        rib_del(dir_path);
-                return -ENOMEM;
         }
 
-        return 0;
-}
-
-int dir_unreg(const uint8_t * hash)
-{
-        char hashstr[ipcp_dir_hash_strlen() + 1];
-        size_t len;
-
-        assert(hash);
-
-        dir_path_reset();
+        if (addr != 0) {
+                size_t retr = 0;
+                log_dbg("Enrolling directory with peer %" PRIu64 ".", addr);
+                /* NOTE: we could try other members if dht_enroll times out. */
+                while (dht_enroll(dht, addr)) {
+                        if (retr++ == ENROL_RETR) {
+                                dht_destroy(dht);
+                                return -EPERM;
+                        }
 
-        ipcp_hash_str(hashstr, hash);
+                        log_dbg("Directory enrollment failed, retrying...");
+                        sleep(ENROL_INTV);
+                }
 
-        rib_path_append(dir_path, hashstr);
-
-        if (!rib_has(dir_path))
                 return 0;
+        }
 
-        len = strlen(dir_path);
-
-        rib_path_append(dir_path, ipcpi.name);
-
-        rib_del(dir_path);
-
-        dir_path[len] = '\0';
+        log_dbg("Bootstrapping DHT.");
 
-        if (rib_children(dir_path, NULL) == 0)
-                rib_del(dir_path);
+        /* TODO: get parameters for bootstrap from IRM tool. */
+        if (dht_bootstrap(dht, KAD_B, 86400)) {
+                dht_destroy(dht);
+                return -ENOMEM;
+        }
 
         return 0;
 }
 
-int dir_query(const uint8_t * hash)
+void dir_fini(void)
 {
-        char hashstr[ipcp_dir_hash_strlen() + 1];
-        size_t len;
-
-        dir_path_reset();
-
-        ipcp_hash_str(hashstr, hash);
-
-        rib_path_append(dir_path, hashstr);
-
-        if (!rib_has(dir_path))
-                return -1;
-
-        /* FIXME: assert after local IPCP is deprecated */
-        len = strlen(dir_path);
+        dht_destroy(dht);
+}
 
-        rib_path_append(dir_path, ipcpi.name);
+int dir_reg(const uint8_t * hash)
+{
+        return dht_reg(dht, hash);
+}
 
-        if (rib_has(dir_path)) {
-                dir_path[len] = '\0';
-                if (rib_children(dir_path, NULL) == 1)
-                        return -1;
-        }
+int dir_unreg(const uint8_t * hash)
+{
+        return dht_unreg(dht, hash);
+}
 
-        return 0;
+uint64_t dir_query(const uint8_t * hash)
+{
+        return dht_query(dht, hash);
 }