dhcpv6: set static defines for DHCPv6 option header size

so the number 4 isn't so mysterious at first glance.

Signed-off-by: Paul Donald <newtwen+github@gmail.com>
Link: https://github.com/openwrt/odhcpd/pull/363
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>

diff --git a/src/dhcpv6-ia.c b/src/dhcpv6-ia.c
index d1881ee5cd6848254702cccaf9b68e926a1d02bd..4747151e8d060af7b54218ee88f48d1324ced869 100644 (file)
--- a/src/dhcpv6-ia.c
+++ b/src/dhcpv6-ia.c
@@ -587,14 +587,14 @@ static size_t build_ia(uint8_t *buf, size_t buflen, uint16_t status,
                        uint16_t val;
                } o_status = {
                        .type = htons(DHCPV6_OPT_STATUS),
-                       .len = htons(sizeof(o_status) - 4),
+                       .len = htons(sizeof(o_status) - DHCPV6_OPT_HDR_SIZE),
                        .val = htons(status),
                };
 
                memcpy(buf + ia_len, &o_status, sizeof(o_status));
                ia_len += sizeof(o_status);
 
-               o_ia.len = htons(ia_len - 4);
+               o_ia.len = htons(ia_len - DHCPV6_OPT_HDR_SIZE);
                memcpy(buf, &o_ia, sizeof(o_ia));
 
                return ia_len;
@@ -668,7 +668,7 @@ static size_t build_ia(uint8_t *buf, size_t buflen, uint16_t status,
                        if (a->flags & OAF_DHCPV6_PD) {
                                struct dhcpv6_ia_prefix o_ia_p = {
                                        .type = htons(DHCPV6_OPT_IA_PREFIX),
-                                       .len = htons(sizeof(o_ia_p) - 4),
+                                       .len = htons(sizeof(o_ia_p) - DHCPV6_OPT_HDR_SIZE),
                                        .preferred_lt = htonl(prefix_preferred_lt),
                                        .valid_lt = htonl(prefix_valid_lt),
                                        .prefix_len = a->length,
@@ -691,7 +691,7 @@ static size_t build_ia(uint8_t *buf, size_t buflen, uint16_t status,
                        if (a->flags & OAF_DHCPV6_NA) {
                                struct dhcpv6_ia_addr o_ia_a = {
                                        .type = htons(DHCPV6_OPT_IA_ADDR),
-                                       .len = htons(sizeof(o_ia_a) - 4),
+                                       .len = htons(sizeof(o_ia_a) - DHCPV6_OPT_HDR_SIZE),
                                        .addr = in6_from_prefix_and_iid(&addrs[i], a->assigned_host_id),
                                        .preferred_lt = htonl(prefix_preferred_lt),
                                        .valid_lt = htonl(prefix_valid_lt)
@@ -736,16 +736,16 @@ static size_t build_ia(uint8_t *buf, size_t buflen, uint16_t status,
        }
 
        if (!request) {
-               uint8_t *odata, *end = ((uint8_t*)ia) + htons(ia->len) + 4;
+               uint8_t *odata, *end = ((uint8_t*)ia) + htons(ia->len) + DHCPV6_OPT_HDR_SIZE;
                uint16_t otype, olen;
 
                dhcpv6_for_each_option((uint8_t*)&ia[1], end, otype, olen, odata) {
-                       struct dhcpv6_ia_prefix *ia_p = (struct dhcpv6_ia_prefix *)&odata[-4];
-                       struct dhcpv6_ia_addr *ia_a = (struct dhcpv6_ia_addr *)&odata[-4];
+                       struct dhcpv6_ia_prefix *ia_p = (struct dhcpv6_ia_prefix *)&odata[-DHCPV6_OPT_HDR_SIZE];
+                       struct dhcpv6_ia_addr *ia_a = (struct dhcpv6_ia_addr *)&odata[-DHCPV6_OPT_HDR_SIZE];
                        bool found = false;
 
-                       if ((otype != DHCPV6_OPT_IA_PREFIX || olen < sizeof(*ia_p) - 4) &&
-                                       (otype != DHCPV6_OPT_IA_ADDR || olen < sizeof(*ia_a) - 4))
+                       if ((otype != DHCPV6_OPT_IA_PREFIX || olen < sizeof(*ia_p) - DHCPV6_OPT_HDR_SIZE) &&
+                                       (otype != DHCPV6_OPT_IA_ADDR || olen < sizeof(*ia_a) - DHCPV6_OPT_HDR_SIZE))
                                continue;
 
                        if (a) {
@@ -785,7 +785,7 @@ static size_t build_ia(uint8_t *buf, size_t buflen, uint16_t status,
                                if (otype == DHCPV6_OPT_IA_PREFIX) {
                                        struct dhcpv6_ia_prefix o_ia_p = {
                                                .type = htons(DHCPV6_OPT_IA_PREFIX),
-                                               .len = htons(sizeof(o_ia_p) - 4),
+                                               .len = htons(sizeof(o_ia_p) - DHCPV6_OPT_HDR_SIZE),
                                                .preferred_lt = 0,
                                                .valid_lt = 0,
                                                .prefix_len = ia_p->prefix_len,
@@ -800,7 +800,7 @@ static size_t build_ia(uint8_t *buf, size_t buflen, uint16_t status,
                                } else {
                                        struct dhcpv6_ia_addr o_ia_a = {
                                                .type = htons(DHCPV6_OPT_IA_ADDR),
-                                               .len = htons(sizeof(o_ia_a) - 4),
+                                               .len = htons(sizeof(o_ia_a) - DHCPV6_OPT_HDR_SIZE),
                                                .addr = ia_a->addr,
                                                .preferred_lt = 0,
                                                .valid_lt = 0,
@@ -816,7 +816,7 @@ static size_t build_ia(uint8_t *buf, size_t buflen, uint16_t status,
                }
        }
 
-       o_ia.len = htons(ia_len - 4);
+       o_ia.len = htons(ia_len - DHCPV6_OPT_HDR_SIZE);
        memcpy(buf, &o_ia, sizeof(o_ia));
        return ia_len;
 }
@@ -906,16 +906,16 @@ static bool dhcpv6_ia_on_link(const struct dhcpv6_ia_hdr *ia, struct dhcpv6_leas
        struct odhcpd_ipaddr *addrs = iface->addr6;
        size_t addrlen = iface->addr6_len;
        time_t now = odhcpd_time();
-       uint8_t *odata, *end = ((uint8_t*)ia) + htons(ia->len) + 4;
+       uint8_t *odata, *end = ((uint8_t*)ia) + htons(ia->len) + DHCPV6_OPT_HDR_SIZE;
        uint16_t otype, olen;
        bool onlink = true;
 
        dhcpv6_for_each_option((uint8_t*)&ia[1], end, otype, olen, odata) {
-               struct dhcpv6_ia_prefix *p = (struct dhcpv6_ia_prefix *)&odata[-4];
-               struct dhcpv6_ia_addr *n = (struct dhcpv6_ia_addr *)&odata[-4];
+               struct dhcpv6_ia_prefix *p = (struct dhcpv6_ia_prefix *)&odata[-DHCPV6_OPT_HDR_SIZE];
+               struct dhcpv6_ia_addr *n = (struct dhcpv6_ia_addr *)&odata[-DHCPV6_OPT_HDR_SIZE];
 
-               if ((otype != DHCPV6_OPT_IA_PREFIX || olen < sizeof(*p) - 4) &&
-                               (otype != DHCPV6_OPT_IA_ADDR || olen < sizeof(*n) - 4))
+               if ((otype != DHCPV6_OPT_IA_PREFIX || olen < sizeof(*p) - DHCPV6_OPT_HDR_SIZE) &&
+                               (otype != DHCPV6_OPT_IA_ADDR || olen < sizeof(*n) - DHCPV6_OPT_HDR_SIZE))
                        continue;
 
                onlink = false;
@@ -992,7 +992,7 @@ ssize_t dhcpv6_ia_handle_IAs(uint8_t *buf, size_t buflen, struct interface *ifac
                if (!is_pd && !is_na)
                        continue;
 
-               struct dhcpv6_ia_hdr *ia = (struct dhcpv6_ia_hdr*)&odata[-4];
+               struct dhcpv6_ia_hdr *ia = (struct dhcpv6_ia_hdr*)&odata[-DHCPV6_OPT_HDR_SIZE];
                size_t ia_response_len = 0;
                uint8_t reqlen = (is_pd) ? 62 : 128;
                uint32_t reqhint = 0;
@@ -1010,10 +1010,10 @@ ssize_t dhcpv6_ia_handle_IAs(uint8_t *buf, size_t buflen, struct interface *ifac
                        uint8_t *sdata;
                        uint16_t stype, slen;
                        dhcpv6_for_each_sub_option(&ia[1], odata + olen, stype, slen, sdata) {
-                               if (stype != DHCPV6_OPT_IA_PREFIX || slen < sizeof(struct dhcpv6_ia_prefix) - 4)
+                               if (stype != DHCPV6_OPT_IA_PREFIX || slen < sizeof(struct dhcpv6_ia_prefix) - DHCPV6_OPT_HDR_SIZE)
                                        continue;
 
-                               struct dhcpv6_ia_prefix *p = (struct dhcpv6_ia_prefix*)&sdata[-4];
+                               struct dhcpv6_ia_prefix *p = (struct dhcpv6_ia_prefix*)&sdata[-DHCPV6_OPT_HDR_SIZE];
                                if (p->prefix_len) {
                                        reqlen = p->prefix_len;
                                        reqhint = ntohl(p->addr.s6_addr32[1]);
@@ -1053,7 +1053,7 @@ ssize_t dhcpv6_ia_handle_IAs(uint8_t *buf, size_t buflen, struct interface *ifac
                        uint8_t *sdata;
                        uint16_t stype, slen;
                        dhcpv6_for_each_sub_option(&ia[1], odata + olen, stype, slen, sdata) {
-                               if (stype != DHCPV6_OPT_IA_ADDR || slen < sizeof(struct dhcpv6_ia_addr) - 4)
+                               if (stype != DHCPV6_OPT_IA_ADDR || slen < sizeof(struct dhcpv6_ia_addr) - DHCPV6_OPT_HDR_SIZE)
                                        continue;
 
                                ia_addr_present = true;
@@ -1211,7 +1211,7 @@ proceed:
                                if (hdr->msg_type == DHCPV6_MSG_REQUEST) {
                                        struct dhcpv6_auth_reconfigure auth = {
                                                htons(DHCPV6_OPT_AUTH),
-                                               htons(sizeof(auth) - 4),
+                                               htons(sizeof(auth) - DHCPV6_OPT_HDR_SIZE),
                                                3, 1, 0,
                                                {htonl(time(NULL)), htonl(++serial)},
                                                1,

diff --git a/src/dhcpv6.c b/src/dhcpv6.c
index 9d32e6b053a760bf78fafb0f19a7a0da8efbc054..a211b259a5c6f225acb233d4136bd2fe9c32edcd 100644 (file)
--- a/src/dhcpv6.c
+++ b/src/dhcpv6.c
@@ -400,7 +400,7 @@ static void handle_client_request(void *addr, void *data, size_t len,
                uint16_t type;
                uint16_t len;
                uint32_t value;
-       } maxrt = {htons(DHCPV6_OPT_SOL_MAX_RT), htons(sizeof(maxrt) - 4),
+       } maxrt = {htons(DHCPV6_OPT_SOL_MAX_RT), htons(sizeof(maxrt) - DHCPV6_OPT_HDR_SIZE),
                        htonl(60)};
 
        struct _o_packed {
@@ -412,7 +412,7 @@ static void handle_client_request(void *addr, void *data, size_t len,
                uint16_t type;
                uint16_t len;
                uint16_t value;
-       } stat = {htons(DHCPV6_OPT_STATUS), htons(sizeof(stat) - 4),
+       } stat = {htons(DHCPV6_OPT_STATUS), htons(sizeof(stat) - DHCPV6_OPT_HDR_SIZE),
                        htons(DHCPV6_STATUS_USEMULTICAST)};
 
        struct _o_packed {

diff --git a/src/odhcpd.h b/src/odhcpd.h
index f005909b91975a23f9443a48971173441cc262bc..9298d62a3266517d1790cf7e6ca64fa3188afb22 100644 (file)
--- a/src/odhcpd.h
+++ b/src/odhcpd.h
@@ -194,6 +194,8 @@ enum odhcpd_assignment_flags {
        OAF_DHCPV6_PD           = (1 << 1),
 };
 
+#define DHCPV6_OPT_HDR_SIZE 4
+
 /* 2-byte type + 128-byte DUID, RFC8415, §11.1 */
 #define DUID_MAX_LEN 130
 /* In theory, 2 (type only), or 7 (DUID-EN + 1-byte data), but be reasonable */