Try to improve readability in kernel_socket.

kernel_socket.c

@@ -389,11 +389,12 @@ kernel_route(int operation, const unsigned char *dest, unsigned short plen,
              const unsigned char *newgate, int newifindex,
              unsigned int newmetric)
 {
-    unsigned char msg[512];
-    struct rt_msghdr *rtm;
-    struct sockaddr_in6 *sin6;
-    struct sockaddr_in *sin;
-    int rc, len, ipv4;
+    struct {
+      struct rt_msghdr m_rtm;
+      char m_space[512];
+    } msg;
+    char *data = msg.m_space;
+    int rc, ipv4;
 
     char local6[1][1][16] = IN6ADDR_LOOPBACK_INIT;
     char local4[1][1][16] =
@@ -443,103 +444,90 @@ kernel_route(int operation, const unsigned char *dest, unsigned short plen,
     if(kernel_socket < 0) kernel_setup_socket(1);
 
     memset(&msg, 0, sizeof(msg));
-    rtm = (struct rt_msghdr *)msg;
-    rtm->rtm_version = RTM_VERSION;
+    msg.m_rtm.rtm_version = RTM_VERSION;
     switch(operation) {
     case ROUTE_FLUSH:
-        rtm->rtm_type = RTM_DELETE; break;
+        msg.m_rtm.rtm_type = RTM_DELETE; break;
     case ROUTE_ADD:
-        rtm->rtm_type = RTM_ADD; break;
-    case ROUTE_MODIFY: 
-        rtm->rtm_type = RTM_CHANGE; break;
-    default: 
+        msg.m_rtm.rtm_type = RTM_ADD; break;
+    case ROUTE_MODIFY:
+        msg.m_rtm.rtm_type = RTM_CHANGE; break;
+    default:
         return -1;
     };
-    rtm->rtm_index = ifindex;
-    rtm->rtm_flags = RTF_UP | RTF_PROTO2;
-    if(plen == 128) rtm->rtm_flags |= RTF_HOST;
-    /*     if(memcmp(nexthop->id, dest, 16) == 0) { */
-    /*         rtm -> rtm_flags |= RTF_LLINFO; */
-    /*         rtm -> rtm_flags |= RTF_CLONING; */
-    /*     } else { */
-    rtm->rtm_flags |= RTF_GATEWAY;
-    /*     } */
+    msg.m_rtm.rtm_index = ifindex;
+    msg.m_rtm.rtm_flags = RTF_UP | RTF_PROTO2;
+    if(plen == 128) msg.m_rtm.rtm_flags |= RTF_HOST;
+    msg.m_rtm.rtm_flags |= RTF_GATEWAY;
     if(metric == KERNEL_INFINITY) {
-        rtm->rtm_flags |= RTF_BLACKHOLE;
+        msg.m_rtm.rtm_flags |= RTF_BLACKHOLE;
         if(ifindex_lo < 0) {
             ifindex_lo = if_nametoindex("lo0");
             if(ifindex_lo <= 0)
                 return -1;
         }
-        rtm->rtm_index = ifindex_lo;      
-    }
-    rtm->rtm_seq = ++seq;
-    rtm->rtm_addrs = RTA_DST | RTA_GATEWAY;
-    if(!(operation == ROUTE_MODIFY && plen == 128)) {
-        rtm->rtm_addrs |= RTA_NETMASK;
+        msg.m_rtm.rtm_index = ifindex_lo;
     }
+    msg.m_rtm.rtm_seq = ++seq;
+    msg.m_rtm.rtm_addrs = RTA_DST | RTA_GATEWAY;
+    if(plen != 128) msg.m_rtm.rtm_addrs |= RTA_NETMASK;
+
+#define PUSHADDR(src) \
+    do { struct sockaddr_in *sin = (struct sockaddr_in*) data; \
+         sin->sin_len = sizeof(struct sockaddr_in);  \
+         sin->sin_family = AF_INET; \
+         memcpy(&sin->sin_addr, (src) + 12, 4); \
+         data = data + ROUNDUP(sin->sin_len); \
+    } while (0)
 
-#define push_sockaddr_in(ptr, offset) \
-    do { (ptr) = (struct sockaddr_in *)((char *)(ptr) + (offset)); \
-         (ptr)->sin_len = sizeof(struct sockaddr_in); \
-         (ptr)->sin_family = AF_INET; } while (0)
-
-#define get_sin_addr(dst,src) \
-    do { memcpy((dst), (src) + 12, 4); } while (0)
-
-#define push_sockaddr_in6(ptr, offset) \
-    do { (ptr) = (struct sockaddr_in6 *)((char *)(ptr) + (offset)); \
-         (ptr)->sin6_len = sizeof(struct sockaddr_in6); \
-         (ptr)->sin6_family = AF_INET6; } while (0)
-
-#define get_sin6_addr(dst,src) \
-    do { memcpy((dst), (src), 16); } while (0)
+#define PUSHADDR6(src) \
+    do { struct sockaddr_in6 *sin6 = (struct sockaddr_in6*) data; \
+         sin6->sin6_len = sizeof(struct sockaddr_in6); \
+         sin6->sin6_family = AF_INET6; \
+         memcpy(&sin6->sin6_addr, (src), 16); \
+         if(IN6_IS_ADDR_LINKLOCAL (&sin6->sin6_addr)) \
+            SET_IN6_LINKLOCAL_IFINDEX (sin6->sin6_addr, ifindex); \
+         data = data + ROUNDUP(sin6->sin6_len); \
+    } while (0)
 
     /* KAME ipv6 stack does not support IPv4 mapped IPv6, so we have to
      * duplicate the codepath */
     if(ipv4) {
-        sin = (struct sockaddr_in *)msg;
-        /* destination */
-        push_sockaddr_in(sin, sizeof(*rtm));
-        get_sin_addr(&(sin->sin_addr), dest);
-        /* gateway */
-        push_sockaddr_in(sin, ROUNDUP(sin->sin_len));
-        if (metric == KERNEL_INFINITY)
-            get_sin_addr(&(sin->sin_addr),**local4);
-        else
-            get_sin_addr(&(sin->sin_addr),gate);
-        /* netmask */
-        if((rtm->rtm_addrs | RTA_NETMASK) != 0) {
+
+        PUSHADDR(dest);
+        if (metric == KERNEL_INFINITY) {
+            PUSHADDR(**local4);
+        } else {
+            PUSHADDR(gate);
+        }
+        if((msg.m_rtm.rtm_addrs & RTA_NETMASK) != 0) {
             struct in6_addr tmp_sin6_addr;
-            push_sockaddr_in(sin, ROUNDUP(sin->sin_len));
             plen2mask(plen, &tmp_sin6_addr);
-            get_sin_addr(&(sin->sin_addr), (char *)&tmp_sin6_addr);
+            PUSHADDR((char *)&tmp_sin6_addr);
         }
-        len = (char *)sin + ROUNDUP(sin->sin_len) - (char *)msg;
+
     } else {
-        sin6 = (struct sockaddr_in6 *)msg;
-        /* destination */
-        push_sockaddr_in6(sin6, sizeof(*rtm));
-        get_sin6_addr(&(sin6->sin6_addr), dest);
-        /* gateway */
-        push_sockaddr_in6(sin6, ROUNDUP(sin6->sin6_len));
-        if (metric == KERNEL_INFINITY)
-            get_sin6_addr(&(sin6->sin6_addr),**local6);
-        else
-            get_sin6_addr(&(sin6->sin6_addr),gate);
-        if(IN6_IS_ADDR_LINKLOCAL (&sin6->sin6_addr))
-            SET_IN6_LINKLOCAL_IFINDEX (sin6->sin6_addr, ifindex);
-        /* netmask */
-        if((rtm->rtm_addrs | RTA_NETMASK) != 0) {
-            push_sockaddr_in6(sin6, ROUNDUP(sin6->sin6_len));
-            plen2mask(plen, &sin6->sin6_addr);
+
+        PUSHADDR6(dest);
+        if (metric == KERNEL_INFINITY) {
+            PUSHADDR6(**local6);
+        } else {
+            PUSHADDR6(gate);
         }
-        len = (char *)sin6 + ROUNDUP(sin6->sin6_len) - (char *)msg;
+        if((msg.m_rtm.rtm_addrs & RTA_NETMASK) != 0) {
+            struct in6_addr tmp_sin6_addr;
+            plen2mask(plen, &tmp_sin6_addr);
+            PUSHADDR6((char*)&tmp_sin6_addr);
+        }
+
     }
-    rtm->rtm_msglen = len;
 
-    rc = write(kernel_socket, msg, rtm->rtm_msglen);
-    if (rc < rtm->rtm_msglen)
+#undef PUSHADDR
+#undef PUSHADDR6
+
+    msg.m_rtm.rtm_msglen = data - (char *)&msg;
+    rc = write(kernel_socket, (char*)&msg, msg.m_rtm.rtm_msglen);
+    if (rc < msg.m_rtm.rtm_msglen)
         return -1;
 
     return 1;