dhcpv6: split clientid to a separate struct

Change handle_client_request() so that the serverid and clientid are in
separate structs. This makes it easy to support a variable-length server DUID
in the future.

Note that some of the variables (like "dest") have a bit misleading names now,
but that is something that I plan to address later, this patch was
intentionally kept as simple as possible.

Signed-off-by: David Härdeman <[email protected]>
Link: https://github.com/openwrt/odhcpd/pull/274
Signed-off-by: Álvaro Fernández Rojas <[email protected]>

diff --git a/src/dhcpv6.c b/src/dhcpv6.c
index ef84687446d2c9e03531c9d8f1ab055dd6f8f026..72e1855b3c02df22da2e8ad76ba8a5128df59c22 100644 (file)
--- a/src/dhcpv6.c
+++ b/src/dhcpv6.c
@@ -166,6 +166,7 @@ out:
 enum {
        IOV_NESTED = 0,
        IOV_DEST,
+       IOV_CLIENTID,
        IOV_MAXRT,
 #define IOV_STAT IOV_MAXRT
        IOV_RAPID_COMMIT,
@@ -364,27 +365,33 @@ static void handle_client_request(void *addr, void *data, size_t len,
        debug("Got a DHCPv6-request on %s", iface->name);
 
        /* Construct reply message */
-       struct __attribute__((packed)) {
+       struct _packed {
                uint8_t msg_type;
                uint8_t tr_id[3];
                uint16_t serverid_type;
                uint16_t serverid_length;
-               uint16_t duid_type;
-               uint16_t hardware_type;
-               uint8_t mac[6];
-               uint16_t clientid_type;
-               uint16_t clientid_length;
-               uint8_t clientid_buf[130];
+               uint8_t serverid_buf[DUID_MAX_LEN];
        } dest = {
                .msg_type = DHCPV6_MSG_REPLY,
                .serverid_type = htons(DHCPV6_OPT_SERVERID),
-               .serverid_length = htons(10),
-               .duid_type = htons(3),
-               .hardware_type = htons(1),
-               .clientid_type = htons(DHCPV6_OPT_CLIENTID),
-               .clientid_buf = {0}
+               .serverid_length = 0,
+               .serverid_buf = { 0 },
+       };
+
+       uint8_t duid_ll_hdr[] = { 0x00, 0x03, 0x00, 0x01 };
+       memcpy(dest.serverid_buf, duid_ll_hdr, sizeof(duid_ll_hdr));
+       odhcpd_get_mac(iface, &dest.serverid_buf[sizeof(duid_ll_hdr)]);
+       dest.serverid_length = htons(sizeof(duid_ll_hdr) + ETH_ALEN);
+
+       struct _packed {
+               uint16_t type;
+               uint16_t len;
+               uint8_t buf[DUID_MAX_LEN];
+       } clientid = {
+               .type = htons(DHCPV6_OPT_CLIENTID),
+               .len = 0,
+               .buf = { 0 },
        };
-       odhcpd_get_mac(iface, dest.mac);
 
        struct __attribute__((packed)) {
                uint16_t type;
@@ -623,7 +630,8 @@ static void handle_client_request(void *addr, void *data, size_t len,
        uint8_t pdbuf[512];
        struct iovec iov[IOV_TOTAL] = {
                [IOV_NESTED] = {NULL, 0},
-               [IOV_DEST] = {&dest, (uint8_t*)&dest.clientid_type - (uint8_t*)&dest},
+               [IOV_DEST] = {&dest, offsetof(typeof(dest), serverid_buf) + ntohs(dest.serverid_length) },
+               [IOV_CLIENTID] = {&clientid, 0},
                [IOV_MAXRT] = {&maxrt, sizeof(maxrt)},
                [IOV_RAPID_COMMIT] = {&rapid_commit, 0},
                [IOV_DNS] = {&dns, (dns_cnt) ? sizeof(dns) : 0},
@@ -659,13 +667,13 @@ static void handle_client_request(void *addr, void *data, size_t len,
 
        /* Go through options and find what we need */
        dhcpv6_for_each_option(opts, opts_end, otype, olen, odata) {
-               if (otype == DHCPV6_OPT_CLIENTID && olen <= 130) {
-                       dest.clientid_length = htons(olen);
-                       memcpy(dest.clientid_buf, odata, olen);
-                       iov[IOV_DEST].iov_len += 4 + olen;
+               if (otype == DHCPV6_OPT_CLIENTID && olen <= DUID_MAX_LEN) {
+                       clientid.len = htons(olen);
+                       memcpy(clientid.buf, odata, olen);
+                       iov[IOV_CLIENTID].iov_len = offsetof(typeof(clientid), buf) + olen;
                } else if (otype == DHCPV6_OPT_SERVERID) {
                        if (olen != ntohs(dest.serverid_length) ||
-                                       memcmp(odata, &dest.duid_type, olen))
+                           memcmp(odata, &dest.serverid_buf, olen))
                                return; /* Not for us */
                } else if (iface->filter_class && otype == DHCPV6_OPT_USER_CLASS) {
                        uint8_t *c = odata, *cend = &odata[olen];