Don't use stack allocated buffer for uv_write()

On FreeBSD, the stack is destroyed more aggressively than on Linux and
that revealed a bug where we were allocating the 16-bit len for the
TCPDNS message on the stack and the buffer got garbled before the
uv_write() sendback was executed.  Now, the len is part of the uvreq, so
we can safely pass it to the uv_write() as the req gets destroyed after
the sendcb is executed.

(cherry picked from commit 94afea932567bf1eb6ee5b80a1c7b2d4071980bd)

diff --git a/lib/isc/netmgr/netmgr-int.h b/lib/isc/netmgr/netmgr-int.h
index 7a19af56d17d8eb2da824d02aaf5d489796fafd8..9591475522710fbfb385877b8189d70bf69e387c 100644 (file)
--- a/lib/isc/netmgr/netmgr-int.h
+++ b/lib/isc/netmgr/netmgr-int.h
@@ -287,6 +287,7 @@ struct isc__nm_uvreq {
        int magic;
        isc_nmsocket_t *sock;
        isc_nmhandle_t *handle;
+       char tcplen[2];       /* The TCP DNS message length */
        uv_buf_t uvbuf;       /* translated isc_region_t, to be
                               * sent or received */
        isc_sockaddr_t local; /* local address */

diff --git a/lib/isc/netmgr/tcpdns.c b/lib/isc/netmgr/tcpdns.c
index 0b976ecdc5ccc6e04019b450a4dde590538e9529..9d55f9412d294bd636da39a1b752c4211f8e4155 100644 (file)
--- a/lib/isc/netmgr/tcpdns.c
+++ b/lib/isc/netmgr/tcpdns.c
@@ -1238,6 +1238,7 @@ isc__nm_tcpdns_send(isc_nmhandle_t *handle, isc_region_t *region,
        REQUIRE(sock->type == isc_nm_tcpdnssocket);
 
        uvreq = isc__nm_uvreq_get(sock->mgr, sock);
+       *(uint16_t *)uvreq->tcplen = htons(region->length);
        uvreq->uvbuf.base = (char *)region->base;
        uvreq->uvbuf.len = region->length;
 
@@ -1300,8 +1301,7 @@ tcpdns_send_direct(isc_nmsocket_t *sock, isc__nm_uvreq_t *req) {
        REQUIRE(sock->type == isc_nm_tcpdnssocket);
 
        int r;
-       uint16_t len = htons(req->uvbuf.len);
-       uv_buf_t bufs[2] = { { .base = (char *)&len, .len = 2 },
+       uv_buf_t bufs[2] = { { .base = req->tcplen, .len = 2 },
                             { .base = req->uvbuf.base,
                               .len = req->uvbuf.len } };