use enum to specify order and indexes of iov struct.

This helps to avoid brainfuck index calculation errors when adding
features.

On my build machine (arch linux x86_64), the stripped binary has exactly
the same size, so this patch should produce the same binary, but
increase code maintainability.

diff --git a/src/dhcpv6.c b/src/dhcpv6.c
index 215f68c86e3c92677959e5120b46777908d4c95c..20343e47538a68d3280c36435bef0d59ff346c82 100644 (file)
--- a/src/dhcpv6.c
+++ b/src/dhcpv6.c
@@ -197,6 +197,23 @@ int init_dhcpv6(const char *ifname, unsigned int options, int sol_timeout)
        return 0;
 }
 
+enum {
+       IOV_HDR=0,
+       IOV_ORO,
+       IOV_ORO_REFRESH,
+       IOV_CL_ID,
+       IOV_SRV_ID,
+       IOV_VENDOR_CLASS_HDR,
+       IOV_VENDOR_CLASS,
+       IOV_USER_CLASS_HDR,
+       IOV_USER_CLASS,
+       IOV_RECONF_ACCEPT,
+       IOV_FQDN,
+       IOV_HDR_IA_NA,
+       IOV_IA_NA,
+       IOV_IA_PD,
+       IOV_TOTAL
+};
 
 void dhcpv6_set_ia_mode(enum odhcp6c_ia_mode na, enum odhcp6c_ia_mode pd)
 {
@@ -401,27 +418,27 @@ static void dhcpv6_send(enum dhcpv6_msg type, uint8_t trid[3], uint32_t ecs)
                htons(DHCPV6_OPT_ORO), htons(oro_len),
        };
 
-       struct iovec iov[] = {
-               {&hdr, sizeof(hdr)},
-               {oro, oro_len},
-               {&oro_refresh, 0},
-               {cl_id, cl_id_len},
-               {srv_id, srv_id_len},
-               {&vendor_class_hdr, vendor_class_len ? sizeof(vendor_class_hdr) : 0},
-               {vendor_class, vendor_class_len},
-               {&user_class_hdr, user_class_len ? sizeof(user_class_hdr) : 0},
-               {user_class, user_class_len},
-               {&reconf_accept, sizeof(reconf_accept)},
-               {&fqdn, fqdn_len},
-               {&hdr_ia_na, sizeof(hdr_ia_na)},
-               {ia_na, ia_na_len},
-               {ia_pd, ia_pd_len},
+       struct iovec iov[IOV_TOTAL] = {
+               [IOV_HDR] = {&hdr, sizeof(hdr)},
+               [IOV_ORO] = {oro, oro_len},
+               [IOV_ORO_REFRESH] = {&oro_refresh, 0},
+               [IOV_CL_ID] = {cl_id, cl_id_len},
+               [IOV_SRV_ID] = {srv_id, srv_id_len},
+               [IOV_VENDOR_CLASS_HDR] = {&vendor_class_hdr, vendor_class_len ? sizeof(vendor_class_hdr) : 0},
+               [IOV_VENDOR_CLASS] = {vendor_class, vendor_class_len},
+               [IOV_USER_CLASS_HDR] = {&user_class_hdr, user_class_len ? sizeof(user_class_hdr) : 0},
+               [IOV_USER_CLASS] = {user_class, user_class_len},
+               [IOV_RECONF_ACCEPT] = {&reconf_accept, sizeof(reconf_accept)},
+               [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},
        };
 
-       size_t cnt = ARRAY_SIZE(iov);
+       size_t cnt = IOV_TOTAL;
        if (type == DHCPV6_MSG_INFO_REQ) {
                cnt = 9;
-               iov[2].iov_len = sizeof(oro_refresh);
+               iov[IOV_ORO_REFRESH].iov_len = sizeof(oro_refresh);
                hdr.oro_len = htons(oro_len + sizeof(oro_refresh));
        } else if (!request_prefix) {
                cnt = 13;
@@ -429,19 +446,19 @@ static void dhcpv6_send(enum dhcpv6_msg type, uint8_t trid[3], uint32_t ecs)
 
        // Disable IAs if not used
        if (type != DHCPV6_MSG_SOLICIT) {
-               iov[9].iov_len = 0;
+               iov[IOV_RECONF_ACCEPT].iov_len = 0;
                if (ia_na_len == 0)
-                       iov[11].iov_len = 0;
+                       iov[IOV_HDR_IA_NA].iov_len = 0;
        }
 
        if (na_mode == IA_MODE_NONE)
-               iov[11].iov_len = 0;
+               iov[IOV_HDR_IA_NA].iov_len = 0;
 
        if (!(client_options & DHCPV6_ACCEPT_RECONFIGURE))
-               iov[9].iov_len = 0;
+               iov[IOV_RECONF_ACCEPT].iov_len = 0;
 
        if (!(client_options & DHCPV6_CLIENT_FQDN))
-               iov[10].iov_len = 0;
+               iov[IOV_FQDN].iov_len = 0;
 
        struct sockaddr_in6 srv = {AF_INET6, htons(DHCPV6_SERVER_PORT),
                0, ALL_DHCPV6_RELAYS, ifindex};