dhcpv6: offload FQDN construction to init_dhcpv6

Improve performance by doing this only once at init, instead
of every time at dhcpv6_send.

We also add a length check for dn_comp which can return -1.

Signed-off-by: Paul Donald <newtwen+github@gmail.com>
Link: https://github.com/openwrt/odhcp6c/pull/143
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>

diff --git a/src/dhcpv6.c b/src/dhcpv6.c
index f3e0be1e6abb5c309dc945b0d06e78e6f120af06..1f210047eacb11825a7e107a6fc7217b89651be3 100644 (file)
--- a/src/dhcpv6.c
+++ b/src/dhcpv6.c
@@ -583,6 +583,30 @@ int init_dhcpv6(const char *ifname)
        if (fd_set_nonblocking(sock) < 0)
                goto failure;
 
+       // Build our FQDN
+       size_t fqdn_len;
+       odhcp6c_get_state(STATE_OUR_FQDN, &fqdn_len);
+       if(fqdn_len == 0) {
+               char fqdn_buf[256];
+               gethostname(fqdn_buf, sizeof(fqdn_buf));
+               struct {
+                       uint16_t type;
+                       uint16_t len;
+                       uint8_t flags;
+                       uint8_t data[256];
+               } fqdn = {0};
+               int dn_result = dn_comp(fqdn_buf, fqdn.data,
+                               sizeof(fqdn.data), NULL, NULL);
+               fqdn_len = 0;
+               if (dn_result > 0) {
+                       fqdn.type = htons(DHCPV6_OPT_FQDN);
+                       fqdn.len = htons(1 + dn_result);
+                       fqdn.flags = 0;
+                       fqdn_len = DHCPV6_OPT_HDR_SIZE + 1 + dn_result;
+               }
+               odhcp6c_add_state(STATE_OUR_FQDN, &fqdn, fqdn_len);
+       }
+
        // Create client DUID
        size_t client_id_len;
        odhcp6c_get_state(STATE_CLIENT_ID, &client_id_len);
@@ -707,19 +731,8 @@ int dhcpv6_get_ia_mode(void)
 static void dhcpv6_send(enum dhcpv6_msg req_msg_type, uint8_t trid[3], uint32_t ecs)
 {
        // Build FQDN
-       char fqdn_buf[256];
-       gethostname(fqdn_buf, sizeof(fqdn_buf));
-       struct {
-               uint16_t type;
-               uint16_t len;
-               uint8_t flags;
-               uint8_t data[256];
-       } fqdn;
-       size_t fqdn_len = 5 + dn_comp(fqdn_buf, fqdn.data,
-                       sizeof(fqdn.data), NULL, NULL);
-       fqdn.type = htons(DHCPV6_OPT_FQDN);
-       fqdn.len = htons(fqdn_len - DHCPV6_OPT_HDR_SIZE);
-       fqdn.flags = 0;
+       size_t fqdn_len;
+       void *fqdn = odhcp6c_get_state(STATE_OUR_FQDN, &fqdn_len);
 
        // Build Client ID
        size_t cl_id_len;
@@ -934,7 +947,7 @@ static void dhcpv6_send(enum dhcpv6_msg req_msg_type, uint8_t trid[3], uint32_t
                [IOV_SRV_ID] = {srv_id, srv_id_len},
                [IOV_OPTS] = { opts, opts_len },
                [IOV_RECONF_ACCEPT] = {&reconf_accept, sizeof(reconf_accept)},
-               [IOV_FQDN] = {&fqdn, fqdn_len},
+               [IOV_FQDN] = {fqdn, fqdn_len},
                [IOV_HDR_IA_NA] = {&hdr_ia_na, sizeof(hdr_ia_na)},
                [IOV_IA_NA] = {ia_na, ia_na_len},
                [IOV_IA_PD] = {ia_pd, ia_pd_len},

diff --git a/src/odhcp6c.h b/src/odhcp6c.h
index c57f88517ee4e68ca1b0a1b8f4ca9a3b223b12a5..84054398e568cde307de7f89684da4c36c6e6323 100644 (file)
--- a/src/odhcp6c.h
+++ b/src/odhcp6c.h
@@ -415,6 +415,7 @@ struct dhcpv6_stats {
 enum odhcp6c_state {
        STATE_CLIENT_ID,
        STATE_SERVER_ID,
+       STATE_OUR_FQDN,
        STATE_SERVER_CAND,
        STATE_SERVER_ADDR,
        STATE_ORO,