dhcpv4: add support for RFC4361-style clientid

This adds support for DHCPv6-style client identifiers to the dhcpv4 codebase,
as per RFC4361. It also ensures RFC6842-compliance by including the client
identifier (no matter which kind it is) in replies.

Signed-off-by: David Härdeman <[email protected]>
Link: https://github.com/openwrt/odhcpd/pull/299
Signed-off-by: Álvaro Fernández Rojas <[email protected]>

diff --git a/src/dhcpv4.c b/src/dhcpv4.c
index b64b1c3a1a1e9a95cbff188c30da3e823292baec..73bb66ce654498b7c2b7bd26d3e7e4f64c700276 100644 (file)
--- a/src/dhcpv4.c
+++ b/src/dhcpv4.c
@@ -348,14 +348,16 @@ void dhcpv4_free_lease(struct dhcpv4_lease *lease)
 }
 
 static struct dhcpv4_lease *
-dhcpv4_alloc_lease(struct interface *iface, const uint8_t *hwaddr, size_t hwaddr_len)
+dhcpv4_alloc_lease(struct interface *iface, const uint8_t *hwaddr,
+                  size_t hwaddr_len, const uint8_t *duid, size_t duid_len,
+                  uint32_t iaid)
 {
        struct dhcpv4_lease *lease;
 
        if (!iface || !hwaddr || hwaddr_len == 0 || hwaddr_len > sizeof(lease->hwaddr))
                return NULL;
 
-       lease = calloc(1, sizeof(*lease));
+       lease = calloc(1, sizeof(*lease) + duid_len);
        if (!lease)
                return NULL;
 
@@ -363,6 +365,11 @@ dhcpv4_alloc_lease(struct interface *iface, const uint8_t *hwaddr, size_t hwaddr
 
        lease->hwaddr_len = hwaddr_len;
        memcpy(lease->hwaddr, hwaddr, hwaddr_len);
+       if (duid_len > 0) {
+               lease->duid_len = duid_len;
+               memcpy(lease->duid, duid, duid_len);
+               lease->iaid = iaid;
+       }
        lease->iface = iface;
 
        return lease;
@@ -476,16 +483,56 @@ static struct dhcpv4_lease *find_lease_by_hwaddr(struct interface *iface, const
        return NULL;
 }
 
+static struct dhcpv4_lease *
+find_lease_by_duid_iaid(struct interface *iface, const uint8_t *duid,
+                       size_t duid_len, uint32_t iaid)
+{
+       struct dhcpv4_lease *lease;
+
+       list_for_each_entry(lease, &iface->dhcpv4_leases, head) {
+               if (lease->duid_len != duid_len || lease->iaid != iaid)
+                       continue;
+               if (!memcmp(lease->duid, duid, duid_len))
+                       return lease;
+       }
+
+       return NULL;
+}
+
 static struct dhcpv4_lease *
 dhcpv4_lease(struct interface *iface, enum dhcpv4_msg req_msg, const uint8_t *req_mac,
-            const uint32_t req_addr, uint32_t *req_leasetime, const char *req_hostname,
-            const size_t req_hostname_len, const bool req_accept_fr, bool *reply_incl_fr,
+            const uint8_t *clid, size_t clid_len, const uint32_t req_addr,
+            uint32_t *req_leasetime, const char *req_hostname, const size_t
+            req_hostname_len, const bool req_accept_fr, bool *reply_incl_fr,
             uint32_t *fr_serverid)
 {
-       struct dhcpv4_lease *lease = find_lease_by_hwaddr(iface, req_mac);
-       struct lease_cfg *lease_cfg = config_find_lease_cfg_by_mac(req_mac);
+       struct dhcpv4_lease *lease = NULL;
+       struct lease_cfg *lease_cfg = NULL;
+       const uint8_t *duid = NULL;
+       size_t duid_len = 0;
+       uint32_t iaid = 0;
        time_t now = odhcpd_time();
 
+       // RFC4361, §6.1, §6.3 - MUST use clid if provided, MAY use chaddr
+       if (clid && clid_len > (1 + sizeof(iaid) + DUID_MIN_LEN) &&
+           clid[0] == DHCPV4_CLIENTID_TYPE_DUID_IAID &&
+           clid_len <= (1 + sizeof(iaid) + DUID_MAX_LEN)) {
+               memcpy(&iaid, &clid[1], sizeof(uint32_t));
+               iaid = ntohl(iaid);
+
+               duid = &clid[1 + sizeof(iaid)];
+               duid_len = clid_len - (1 + sizeof(iaid));
+
+               lease = find_lease_by_duid_iaid(iface, duid, duid_len, iaid);
+               lease_cfg = config_find_lease_cfg_by_duid_and_iaid(duid, duid_len, iaid);
+       }
+
+       if (!lease)
+               lease = find_lease_by_hwaddr(iface, req_mac);
+
+       if (!lease_cfg)
+               lease_cfg = config_find_lease_cfg_by_mac(req_mac);
+
        /*
         * If we found a static lease cfg, but no old assignment for this
         * hwaddr, we need to clear out any old assignments given to other
@@ -527,8 +574,9 @@ dhcpv4_lease(struct interface *iface, enum dhcpv4_msg req_msg, const uint8_t *re
                if (!(lease->flags & OAF_STATIC) || lease->lease_cfg->ipaddr != lease->addr) {
                        memset(lease->hwaddr, 0, sizeof(lease->hwaddr));
                        lease->valid_until = now + 3600; /* Block address for 1h */
-               } else
+               } else {
                        lease->valid_until = now - 1;
+               }
                break;
 
        case DHCPV4_MSG_DISCOVER:
@@ -554,7 +602,7 @@ dhcpv4_lease(struct interface *iface, enum dhcpv4_msg req_msg, const uint8_t *re
 
                if (!lease) {
                        /* Create new binding */
-                       lease = dhcpv4_alloc_lease(iface, req_mac, ETH_ALEN);
+                       lease = dhcpv4_alloc_lease(iface, req_mac, ETH_ALEN, duid, duid_len, iaid);
                        if (!lease) {
                                warn("Failed to allocate memory for DHCPv4 lease on interface %s", iface->ifname);
                                return NULL;
@@ -701,6 +749,8 @@ enum {
        IOV_HEADER = 0,
        IOV_MESSAGE,
        IOV_SERVERID,
+       IOV_CLIENTID,
+       IOV_CLIENTID_DATA,
        IOV_NETMASK,
        IOV_ROUTER,
        IOV_ROUTER_ADDR,
@@ -740,6 +790,8 @@ void dhcpv4_handle_msg(void *src_addr, void *data, size_t len,
        uint32_t req_leasetime = 0;
        char *req_hostname = NULL;
        size_t req_hostname_len = 0;
+       uint8_t *req_clientid = NULL;
+       size_t req_clientid_len = 0;
        bool req_accept_fr = false;
 
        /* Reply variables */
@@ -770,6 +822,9 @@ void dhcpv4_handle_msg(void *src_addr, void *data, size_t len,
                .len = sizeof(struct in_addr),
                .data = iface->dhcpv4_local.s_addr,
        };
+       struct dhcpv4_option reply_clientid = {
+               .code = DHCPV4_OPT_CLIENTID,
+       };
        struct dhcpv4_option_u32 reply_netmask = {
                .code = DHCPV4_OPT_NETMASK,
                .len = sizeof(uint32_t),
@@ -835,6 +890,8 @@ void dhcpv4_handle_msg(void *src_addr, void *data, size_t len,
                [IOV_HEADER]            = { &reply, sizeof(reply) },
                [IOV_MESSAGE]           = { &reply_msg, sizeof(reply_msg) },
                [IOV_SERVERID]          = { &reply_serverid, sizeof(reply_serverid) },
+               [IOV_CLIENTID]          = { &reply_clientid, 0 },
+               [IOV_CLIENTID_DATA]     = { NULL, 0 },
                [IOV_NETMASK]           = { &reply_netmask, 0 },
                [IOV_ROUTER]            = { &reply_router, 0 },
                [IOV_ROUTER_ADDR]       = { NULL, 0 },
@@ -871,6 +928,7 @@ void dhcpv4_handle_msg(void *src_addr, void *data, size_t len,
                DHCPV4_OPT_LEASETIME,
                DHCPV4_OPT_RENEW,
                DHCPV4_OPT_REBIND,
+               DHCPV4_OPT_CLIENTID, // Must be in reply if present in req, RFC6842, §3
                DHCPV4_OPT_AUTHENTICATION,
                DHCPV4_OPT_SEARCH_DOMAIN,
                DHCPV4_OPT_FORCERENEW_NONCE_CAPABLE,
@@ -927,6 +985,12 @@ void dhcpv4_handle_msg(void *src_addr, void *data, size_t len,
                                req_opts_len = opt->len;
                        }
                        break;
+               case DHCPV4_OPT_CLIENTID:
+                       if (opt->len >= 2) {
+                               req_clientid = opt->data;
+                               req_clientid_len = opt->len;
+                       }
+                       break;
                case DHCPV4_OPT_LEASETIME:
                        if (opt->len == 4) {
                                memcpy(&req_leasetime, opt->data, 4);
@@ -953,16 +1017,18 @@ void dhcpv4_handle_msg(void *src_addr, void *data, size_t len,
        case DHCPV4_MSG_DECLINE:
                _fallthrough;
        case DHCPV4_MSG_RELEASE:
-               dhcpv4_lease(iface, req_msg, req->chaddr, req_addr,
-                            &req_leasetime, req_hostname, req_hostname_len,
-                            req_accept_fr, &reply_incl_fr, &fr_serverid);
+               dhcpv4_lease(iface, req_msg, req->chaddr, req_clientid,
+                            req_clientid_len, req_addr, &req_leasetime,
+                            req_hostname, req_hostname_len, req_accept_fr,
+                            &reply_incl_fr, &fr_serverid);
                return;
        case DHCPV4_MSG_DISCOVER:
                _fallthrough;
        case DHCPV4_MSG_REQUEST:
-               lease = dhcpv4_lease(iface, req_msg, req->chaddr, req_addr,
-                                    &req_leasetime, req_hostname, req_hostname_len,
-                                    req_accept_fr, &reply_incl_fr, &fr_serverid);
+               lease = dhcpv4_lease(iface, req_msg, req->chaddr, req_clientid,
+                                    req_clientid_len, req_addr, &req_leasetime,
+                                    req_hostname, req_hostname_len, req_accept_fr,
+                                    &reply_incl_fr, &fr_serverid);
                break;
        default:
                return;
@@ -1103,6 +1169,15 @@ void dhcpv4_handle_msg(void *src_addr, void *data, size_t len,
                        iov[IOV_REBIND].iov_len = sizeof(reply_rebind);
                        break;
 
+               case DHCPV4_OPT_CLIENTID:
+                       if (!req_clientid)
+                               break;
+                       reply_clientid.len = req_clientid_len;
+                       iov[IOV_CLIENTID].iov_len = sizeof(reply_clientid);
+                       iov[IOV_CLIENTID_DATA].iov_base = req_clientid;
+                       iov[IOV_CLIENTID_DATA].iov_len = req_clientid_len;
+                       break;
+
                case DHCPV4_OPT_AUTHENTICATION:
                        if (!lease || !reply_incl_fr || req_msg != DHCPV4_MSG_REQUEST)
                                break;

diff --git a/src/dhcpv4.h b/src/dhcpv4.h
index c3a9bcda5ecc2febbfaf0961837b72d9d8f0fbf6..9b28059255f143f995203dad6039657b3ba2db65 100644 (file)
--- a/src/dhcpv4.h
+++ b/src/dhcpv4.h
@@ -25,6 +25,9 @@
 #define DHCPV4_FR_MIN_DELAY    500
 #define DHCPV4_FR_MAX_FUZZ     500
 
+// RFC4361, §6.1
+#define DHCPV4_CLIENTID_TYPE_DUID_IAID 255
+
 enum dhcpv4_op {
        DHCPV4_OP_BOOTREQUEST = 1,
        DHCPV4_OP_BOOTREPLY = 2,
@@ -70,6 +73,7 @@ enum dhcpv4_opt {
        DHCPV4_OPT_REQOPTS = 55,
        DHCPV4_OPT_RENEW = 58,
        DHCPV4_OPT_REBIND = 59,
+       DHCPV4_OPT_CLIENTID = 61,
        DHCPV4_OPT_USER_CLASS = 77,
        DHCPV4_OPT_AUTHENTICATION = 90,
        DHCPV4_OPT_SEARCH_DOMAIN = 119,

diff --git a/src/odhcpd.h b/src/odhcpd.h
index 6449ae1e6d6bdfd229a4c36b6675b3c047c9c87a..23f82d8dfe14473128e176dacee5fc562c1fb87f 100644 (file)
--- a/src/odhcpd.h
+++ b/src/odhcpd.h
@@ -249,6 +249,11 @@ struct dhcpv4_lease {
        unsigned fr_cnt;                        // FR messages sent
        uint8_t key[16];                        // FR nonce
        struct odhcpd_ref_ip *fr_ip;            // FR message old serverid/IP
+
+       // RFC4361
+       uint32_t iaid;
+       uint8_t duid_len;
+       uint8_t duid[];
 };
 
 struct dhcpv6_lease {