Use completely static-sized buffers

(cherry picked from commit 49f90025a07be39d1236504d46db3ce73f1578ee)
(cherry picked from commit 4007a9d02060764c208289ee781a428ce3027e99)

diff --git a/lib/isc/unix/socket.c b/lib/isc/unix/socket.c
index 1375b6534163e74d56142285c9d8096073ef3572..32fbd812954a1c255edc3c4ef3a8772a7f7ece48 100644 (file)
--- a/lib/isc/unix/socket.c
+++ b/lib/isc/unix/socket.c
@@ -318,6 +318,35 @@ typedef isc_event_t intev_t;
 #define RCVBUFSIZE (32*1024)
 #endif /* TUNE_LARGE */
 
+/*%
+ * Instead of calculating the cmsgbuf lengths every time we take
+ * a rule of thumb approach - sizes are taken from x86_64 linux,
+ * multiplied by 2, everything should fit. Those sizes are not
+ * large enough to cause any concern.
+ */
+#if defined(USE_CMSG) && defined(ISC_PLATFORM_HAVEIN6PKTINFO)
+#define CMSG_SP_IN6PKT 40
+#else
+#define CMSG_SP_IN6PKT 0
+#endif
+
+#if defined(USE_CMSG) && defined(SO_TIMESTAMP)
+#define CMSG_SP_TIMESTAMP 32
+#else
+#define CMSG_SP_TIMESTAMP 0
+#endif
+
+#if defined(USE_CMSG) && (defined(IPV6_TCLASS) || defined(IP_TOS))
+#define CMSG_SP_TCTOS 24
+#else
+#define CMSG_SP_TCTOS 0
+#endif
+
+#define CMSG_SP_INT 24
+
+#define RECVCMSGBUFLEN (2*(CMSG_SP_IN6PKT + CMSG_SP_TIMESTAMP + CMSG_SP_TCTOS)+1)
+#define SENDCMSGBUFLEN (2*(CMSG_SP_IN6PKT + CMSG_SP_INT + CMSG_SP_TCTOS)+1)
+
 /*%
  * The number of times a send operation is repeated if the result is EINTR.
  */
@@ -374,9 +403,6 @@ struct isc__socket {
        unsigned char           overflow; /* used for MSG_TRUNC fake */
 #endif
 
-       ISC_SOCKADDR_LEN_T      recvcmsgbuflen;
-       ISC_SOCKADDR_LEN_T      sendcmsgbuflen;
-
        void                    *fdwatcharg;
        isc_sockfdwatch_t       fdwatchcb;
        int                     fdwatchflags;
@@ -1453,10 +1479,6 @@ build_msghdr_send(isc__socket_t *sock, char* cmsgbuf, isc_socketevent_t *dev,
 
        memset(msg, 0, sizeof(*msg));
 
-       if (sock->sendcmsgbuflen != 0U) {
-               memset(cmsgbuf, 0, sock->sendcmsgbuflen);
-       }
-
        if (!sock->connected) {
                msg->msg_name = (void *)&dev->address.type.sa;
                msg->msg_namelen = dev->address.length;
@@ -1535,7 +1557,7 @@ build_msghdr_send(isc__socket_t *sock, char* cmsgbuf, isc_socketevent_t *dev,
 
                msg->msg_control = (void *)cmsgbuf;
                msg->msg_controllen = cmsg_space(sizeof(struct in6_pktinfo));
-               INSIST(msg->msg_controllen <= sock->sendcmsgbuflen);
+               INSIST(msg->msg_controllen <= SENDCMSGBUFLEN);
 
                cmsgp = (struct cmsghdr *)cmsgbuf;
                cmsgp->cmsg_level = IPPROTO_IPV6;
@@ -1554,8 +1576,10 @@ build_msghdr_send(isc__socket_t *sock, char* cmsgbuf, isc_socketevent_t *dev,
 
                cmsgp = (struct cmsghdr *)(cmsgbuf +
                                           msg->msg_controllen);
+
+               msg->msg_control = (void *)cmsgbuf;
                msg->msg_controllen += cmsg_space(sizeof(use_min_mtu));
-               INSIST(msg->msg_controllen <= sock->sendcmsgbuflen);
+               INSIST(msg->msg_controllen <= SENDCMSGBUFLEN);
 
                cmsgp->cmsg_level = IPPROTO_IPV6;
                cmsgp->cmsg_type = IPV6_USE_MIN_MTU;
@@ -1585,7 +1609,7 @@ build_msghdr_send(isc__socket_t *sock, char* cmsgbuf, isc_socketevent_t *dev,
                                                   msg->msg_controllen);
                        msg->msg_control = (void *)cmsgbuf;
                        msg->msg_controllen += cmsg_space(sizeof(dscp));
-                       INSIST(msg->msg_controllen <= sock->sendcmsgbuflen);
+                       INSIST(msg->msg_controllen <= SENDCMSGBUFLEN);
 
                        cmsgp->cmsg_level = IPPROTO_IP;
                        cmsgp->cmsg_type = IP_TOS;
@@ -1616,7 +1640,7 @@ build_msghdr_send(isc__socket_t *sock, char* cmsgbuf, isc_socketevent_t *dev,
                                                   msg->msg_controllen);
                        msg->msg_control = (void *)cmsgbuf;
                        msg->msg_controllen += cmsg_space(sizeof(dscp));
-                       INSIST(msg->msg_controllen <= sock->sendcmsgbuflen);
+                       INSIST(msg->msg_controllen <= SENDCMSGBUFLEN);
 
                        cmsgp->cmsg_level = IPPROTO_IPV6;
                        cmsgp->cmsg_type = IPV6_TCLASS;
@@ -1641,10 +1665,10 @@ build_msghdr_send(isc__socket_t *sock, char* cmsgbuf, isc_socketevent_t *dev,
                }
 #endif
                if (msg->msg_controllen != 0 &&
-                   msg->msg_controllen < sock->sendcmsgbuflen)
+                   msg->msg_controllen < SENDCMSGBUFLEN)
                {
                        memset(cmsgbuf + msg->msg_controllen, 0,
-                              sock->sendcmsgbuflen - msg->msg_controllen);
+                              SENDCMSGBUFLEN - msg->msg_controllen);
                }
        }
 #endif
@@ -1770,7 +1794,7 @@ build_msghdr_recv(isc__socket_t *sock, char *cmsgbuf, isc_socketevent_t *dev,
 #ifdef ISC_NET_BSD44MSGHDR
 #if defined(USE_CMSG)
        msg->msg_control = cmsgbuf;
-       msg->msg_controllen = sock->recvcmsgbuflen;
+       msg->msg_controllen = RECVCMSGBUFLEN;
 #else
        msg->msg_control = NULL;
        msg->msg_controllen = 0;
@@ -1873,7 +1897,7 @@ doio_recv(isc__socket_t *sock, isc_socketevent_t *dev) {
        isc_buffer_t *buffer;
        int recv_errno;
        char strbuf[ISC_STRERRORSIZE];
-       char cmsgbuf[sock->recvcmsgbuflen];
+       char cmsgbuf[RECVCMSGBUFLEN] = {0};
 
        build_msghdr_recv(sock, cmsgbuf, dev, &msghdr, iov, &read_count);
 
@@ -2069,7 +2093,7 @@ doio_send(isc__socket_t *sock, isc_socketevent_t *dev) {
        int attempts = 0;
        int send_errno;
        char strbuf[ISC_STRERRORSIZE];
-       char cmsgbuf[sock->sendcmsgbuflen];
+       char cmsgbuf[SENDCMSGBUFLEN] = {0};
 
        build_msghdr_send(sock, cmsgbuf, dev, &msghdr, iov, &write_count);
 
@@ -2289,7 +2313,6 @@ allocate_socket(isc__socketmgr_t *manager, isc_sockettype_t type,
 {
        isc__socket_t *sock;
        isc_result_t result;
-       ISC_SOCKADDR_LEN_T cmsgbuflen;
 
        sock = isc_mem_get(manager->mctx, sizeof(*sock));
 
@@ -2310,36 +2333,6 @@ allocate_socket(isc__socketmgr_t *manager, isc_sockettype_t type,
 
        ISC_LINK_INIT(sock, link);
 
-       /*
-        * Set up cmsg buffer lengths.
-        */
-       cmsgbuflen = 0;
-#if defined(USE_CMSG) && defined(ISC_PLATFORM_HAVEIN6PKTINFO)
-       cmsgbuflen += cmsg_space(sizeof(struct in6_pktinfo));
-#endif
-#if defined(USE_CMSG) && defined(SO_TIMESTAMP)
-       cmsgbuflen += cmsg_space(sizeof(struct timeval));
-#endif
-#if defined(USE_CMSG) && (defined(IPV6_TCLASS) || defined(IP_TOS))
-       cmsgbuflen += cmsg_space(sizeof(int));
-#endif
-       sock->recvcmsgbuflen = cmsgbuflen;
-
-       cmsgbuflen = 0;
-#if defined(USE_CMSG) && defined(ISC_PLATFORM_HAVEIN6PKTINFO)
-       cmsgbuflen += cmsg_space(sizeof(struct in6_pktinfo));
-#if defined(IPV6_USE_MIN_MTU)
-       /*
-        * Provide space for working around FreeBSD's broken IPV6_USE_MIN_MTU
-        * support.
-        */
-       cmsgbuflen += cmsg_space(sizeof(int));
-#endif
-#endif
-#if defined(USE_CMSG) && (defined(IP_TOS) || defined(IPV6_TCLASS))
-       cmsgbuflen += cmsg_space(sizeof(int));
-#endif
-       sock->sendcmsgbuflen = cmsgbuflen;
 
        memset(sock->name, 0, sizeof(sock->name));
        sock->tag = NULL;
@@ -2784,15 +2777,6 @@ opensocket(isc__socketmgr_t *manager, isc__socket_t *sock,
 #endif /* SO_TIMESTAMP */
 
 #if defined(ISC_PLATFORM_HAVEIPV6)
-               if (sock->pf == AF_INET6 && sock->recvcmsgbuflen == 0U) {
-                       /*
-                        * Warn explicitly because this anomaly can be hidden
-                        * in usual operation (and unexpectedly appear later).
-                        */
-                       UNEXPECTED_ERROR(__FILE__, __LINE__,
-                                        "No buffer available to receive "
-                                        "IPv6 destination");
-               }
 #ifdef ISC_PLATFORM_HAVEIN6PKTINFO
 #ifdef IPV6_RECVPKTINFO
                /* RFC 3542 */