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.
76 jobs for !4465 with 2332-fix-use-after-free-in-tcpdns_send_direct in 4 minutes and 36 seconds (queued for 10 seconds)
detached
Status Job ID Name Coverage
  Autoconf
canceled #1342055
amd64 linux
autoreconf

 
  Precheck
passed #1342057
amd64 linux
clang-format

00:00:18

passed #1342058
amd64 linux
coccinelle

00:03:41

passed #1342059
amd64 linux
danger

00:00:14

passed #1342056
amd64 linux
misc

00:00:16

skipped #1342060
amd64 linux
tarball-create
 
  Build
skipped #1342073
amd64 linux
clang:asan
skipped #1342077
amd64 linux
clang:buster:amd64
skipped #1342080
amd64 libvirt
clang:freebsd11:amd64
skipped #1342081
amd64 libvirt
clang:freebsd12:amd64
skipped #1342082
amd64 libvirt
clang:openbsd:amd64
skipped #1342075
amd64 linux
clang:tsan
skipped #1342061
amd64 linux
gcc:alpine3.12:amd64
skipped #1342072
amd64 linux
gcc:asan
skipped #1342065
amd64 linux
gcc:buster:amd64
skipped #1342062
amd64 linux
gcc:centos7:amd64
skipped #1342063
amd64 linux
gcc:centos8:amd64
skipped #1342071
amd64 linux
gcc:focal:amd64
skipped #1342076
amd64 linux
gcc:mutexatomics
skipped #1342067
amd64 linux
gcc:out-of-tree
skipped #1342066
amd64 linux
gcc:sid:amd64
skipped #1342068
i386 linux
gcc:sid:i386
skipped #1342078
amd64 linux
gcc:softhsm2.4
skipped #1342079
amd64 linux
gcc:softhsm2.6
skipped #1342064
amd64 linux
gcc:stretch:amd64
skipped #1342074
amd64 linux
gcc:tsan
skipped #1342069
amd64 linux
gcc:tumbleweed:amd64
skipped #1342070
amd64 linux
gcc:xenial:amd64
passed #1342083
amd64 windows
msvc:windows:amd64

00:00:43

 
  Unit
skipped #1342095
amd64 linux
unit:clang:asan
skipped #1342099
amd64 linux
unit:clang:buster:amd64
skipped #1342102
amd64 libvirt
unit:clang:freebsd11:amd64
skipped #1342103
amd64 libvirt
unit:clang:freebsd12:amd64
skipped #1342104
amd64 libvirt
unit:clang:openbsd:amd64
skipped #1342097
amd64 linux
unit:clang:tsan
skipped #1342084
amd64 linux
unit:gcc:alpine3.12:amd64
skipped #1342094
amd64 linux
unit:gcc:asan
skipped #1342088
amd64 linux
unit:gcc:buster:amd64
skipped #1342085
amd64 linux
unit:gcc:centos7:amd64
skipped #1342086
amd64 linux
unit:gcc:centos8:amd64
skipped #1342093
amd64 linux
unit:gcc:focal:amd64
skipped #1342098
amd64 linux
unit:gcc:mutexatomics
skipped #1342089
amd64 linux
unit:gcc:sid:amd64
skipped #1342090
i386 linux
unit:gcc:sid:i386
skipped #1342100
amd64 linux
unit:gcc:softhsm2.4
skipped #1342101
amd64 linux
unit:gcc:softhsm2.6
skipped #1342087
amd64 linux
unit:gcc:stretch:amd64
skipped #1342096
amd64 linux
unit:gcc:tsan
skipped #1342091
amd64 linux
unit:gcc:tumbleweed:amd64
skipped #1342092
amd64 linux
unit:gcc:xenial:amd64
 
  System
skipped #1342116
amd64 linux
system:clang:asan
skipped #1342120
amd64 linux
system:clang:buster:amd64
skipped #1342123
amd64 libvirt
system:clang:freebsd11:amd64
skipped #1342124
amd64 libvirt
system:clang:freebsd12:amd64
skipped #1342118
amd64 linux allowed to fail
system:clang:tsan
skipped #1342105
amd64 linux
system:gcc:alpine3.12:amd64
skipped #1342115
amd64 linux
system:gcc:asan
skipped #1342109
amd64 linux
system:gcc:buster:amd64
skipped #1342106
amd64 linux
system:gcc:centos7:amd64
skipped #1342107
amd64 linux
system:gcc:centos8:amd64
skipped #1342114
amd64 linux
system:gcc:focal:amd64
skipped #1342119
amd64 linux
system:gcc:mutexatomics
skipped #1342110
amd64 linux
system:gcc:sid:amd64
skipped #1342111
i386 linux
system:gcc:sid:i386
skipped #1342121
amd64 linux
system:gcc:softhsm2.4
skipped #1342122
amd64 linux
system:gcc:softhsm2.6
skipped #1342108
amd64 linux
system:gcc:stretch:amd64
skipped #1342117
amd64 linux allowed to fail
system:gcc:tsan
skipped #1342112
amd64 linux
system:gcc:tumbleweed:amd64
skipped #1342113
amd64 linux
system:gcc:xenial:amd64
 
  Docs
skipped #1342125
amd64 linux
docs
 
  Postcheck
skipped #1342129
amd64 linux
cppcheck
skipped #1342126
amd64 linux
flake8
skipped #1342130
amd64 linux
gcov
skipped #1342127
amd64 linux
pylint
skipped #1342128
amd64 linux
scan-build