Explicitly support DHCP + add tests+ update libslirp to v4.6.1

.github/workflows/main.yaml

@@ -5,7 +5,7 @@ jobs:
     runs-on: ubuntu-20.04
     strategy:
       matrix:
-        libslirp_commit: [master, v4.6.0, v4.5.0, v4.1.0]
+        libslirp_commit: [master, v4.6.1, v4.5.0, v4.1.0]
     steps:
     - uses: actions/checkout@v2
     - run: docker build -t slirp4netns-tests --build-arg LIBSLIRP_COMMIT -f Dockerfile.tests .
@@ -47,7 +47,7 @@ jobs:
       run: sh ./run-vagrant-tests
       env:
         LIBSECCOMP_COMMIT: v2.5.0
-        LIBSLIRP_COMMIT: v4.6.0
+        LIBSLIRP_COMMIT: v4.6.1
   artifact:
     runs-on: ubuntu-20.04
     steps:

Dockerfile.artifact

@@ -1,4 +1,4 @@
-ARG LIBSLIRP_COMMIT=v4.6.0
+ARG LIBSLIRP_COMMIT=v4.6.1
 ARG DEBIAN_VERSION=10
 
 FROM --platform=$TARGETPLATFORM debian:${DEBIAN_VERSION} AS build

Dockerfile.buildtests

@@ -1,4 +1,4 @@
-ARG LIBSLIRP_COMMIT=v4.6.0
+ARG LIBSLIRP_COMMIT=v4.6.1
 
 # Alpine
 FROM alpine:3 AS buildtest-alpine3-static

Dockerfile.tests

@@ -1,4 +1,4 @@
-ARG LIBSLIRP_COMMIT=v4.6.0
+ARG LIBSLIRP_COMMIT=v4.6.1
 
 FROM ubuntu:20.04 AS build
 ENV DEBIAN_FRONTEND=noninteractive
@@ -16,6 +16,6 @@ RUN ./autogen.sh && ./configure && make -j $(nproc)
 
 FROM build AS test
 USER 0
-RUN apt update && apt install -y git libtool iproute2 clang clang-format clang-tidy iputils-ping iperf3 ncat jq
+RUN apt update && apt install -y git libtool iproute2 clang clang-format clang-tidy iputils-ping iperf3 ncat jq udhcpc
 USER 1000:1000
 CMD ["make", "ci"]

Makefile.am

@@ -5,7 +5,7 @@ AM_CFLAGS = @GLIB_CFLAGS@ @SLIRP_CFLAGS@ @LIBCAP_CFLAGS@ @LIBSECCOMP_CFLAGS@
 noinst_LIBRARIES = libparson.a
 
 AM_TESTS_ENVIRONMENT = PATH="$(abs_top_builddir):$(PATH)"
-TESTS = tests/test-slirp4netns.sh tests/test-slirp4netns-configure.sh tests/test-slirp4netns-exit-fd.sh tests/test-slirp4netns-ready-fd.sh tests/test-slirp4netns-api-socket.sh tests/test-slirp4netns-disable-host-loopback.sh tests/test-slirp4netns-cidr.sh tests/test-slirp4netns-outbound-addr.sh tests/test-slirp4netns-disable-dns.sh tests/test-slirp4netns-seccomp.sh tests/test-slirp4netns-macaddress.sh
+TESTS = tests/test-slirp4netns.sh tests/test-slirp4netns-configure.sh tests/test-slirp4netns-exit-fd.sh tests/test-slirp4netns-ready-fd.sh tests/test-slirp4netns-api-socket.sh tests/test-slirp4netns-disable-host-loopback.sh tests/test-slirp4netns-cidr.sh tests/test-slirp4netns-outbound-addr.sh tests/test-slirp4netns-disable-dns.sh tests/test-slirp4netns-seccomp.sh tests/test-slirp4netns-macaddress.sh tests/test-slirp4netns-dhcp.sh
 
 EXTRA_DIST = \
 	slirp4netns.1.md \

Vagrantfile

@@ -23,6 +23,8 @@ Vagrant.configure("2") do |config|
         glib2-devel libcap-devel \
         git-core libtool iproute iputils iperf3 nmap jq
 
+      # TODO: install udhcpc (required by test-slirp4netns-dhcp.sh)
+
       cd /src
       chown vagrant .
 

main.c

@@ -266,6 +266,13 @@ static int parent(int sock, int ready_fd, int exit_fd, const char *api_socket,
                   struct slirp4netns_config *cfg, pid_t target_pid)
 {
     int rc, tapfd;
+    struct in_addr vdhcp_end = {
+#define NB_BOOTP_CLIENTS 16
+        /* NB_BOOTP_CLIENTS is hard-coded to 16 in libslirp:
+           https://gitlab.freedesktop.org/slirp/libslirp/-/issues/49 */
+        .s_addr = htonl(ntohl(cfg->vdhcp_start.s_addr) + NB_BOOTP_CLIENTS - 1),
+#undef NB_BOOTP_CLIENTS
+    };
     if ((tapfd = recvfd(sock)) < 0) {
         return tapfd;
     }
@@ -277,6 +284,8 @@ static int parent(int sock, int ready_fd, int exit_fd, const char *api_socket,
     printf("* Netmask:         %s\n", inet_ntoa(cfg->vnetmask));
     printf("* Gateway:         %s\n", inet_ntoa(cfg->vhost));
     printf("* DNS:             %s\n", inet_ntoa(cfg->vnameserver));
+    printf("* DHCP begin:      %s\n", inet_ntoa(cfg->vdhcp_start));
+    printf("* DHCP end:        %s\n", inet_ntoa(vdhcp_end));
     printf("* Recommended IP:  %s\n", inet_ntoa(cfg->recommended_vguest));
     if (api_socket != NULL) {
         printf("* API Socket:      %s\n", api_socket);

slirp4netns.1

@@ -1,5 +1,5 @@
 .nh
-.TH SLIRP4NETNS 1 "November 2020" "Rootless Containers" "User Commands"
+.TH SLIRP4NETNS 1 "June 2021" "Rootless Containers" "User Commands"
 
 .SH NAME
 .PP
@@ -31,6 +31,10 @@ Gateway/Host:      10.0.2.2    (network address + 2)
 .IP \(bu 2
 DNS:               10.0.2.3    (network address + 3)
 .IP \(bu 2
+DHCP begin:        10.0.2.15   (network address + 15)
+.IP \(bu 2
+DHCP end:          10.0.2.30   (network address + 30)
+.IP \(bu 2
 IPv6 CIDR:         fd00::/64
 .IP \(bu 2
 IPv6 Gateway/Host: fd00::2

slirp4netns.1.md

@@ -1,4 +1,4 @@
-SLIRP4NETNS 1 "November 2020" "Rootless Containers" "User Commands"
+SLIRP4NETNS 1 "June 2021" "Rootless Containers" "User Commands"
 ==================================================
 
 # NAME
@@ -21,6 +21,8 @@ Default configuration:
 * CIDR:              10.0.2.0/24
 * Gateway/Host:      10.0.2.2    (network address + 2)
 * DNS:               10.0.2.3    (network address + 3)
+* DHCP begin:        10.0.2.15   (network address + 15)
+* DHCP end:          10.0.2.30   (network address + 30)
 * IPv6 CIDR:         fd00::/64
 * IPv6 Gateway/Host: fd00::2
 * IPv6 DNS:          fd00::3

tests/common.sh

@@ -1,5 +1,8 @@
 #!/bin/bash
 
+# See https://www.gnu.org/software/automake/manual/html_node/Scripts_002dbased-Testsuites.html#Testsuite-progress-on-console
+TEST_EXIT_CODE_SKIP=77
+
 function nsenter_flags {
   pid=$1
   flags="--target=${pid}"

tests/test-slirp4netns-dhcp.sh

@@ -0,0 +1,35 @@
+#!/bin/bash
+
+# This test should pass with libslirp < 4.6.0 and libslirp >= 4.6.1,
+# but should fail with libslirp == 4.6.0 .
+# https://gitlab.freedesktop.org/slirp/libslirp/-/issues/48
+
+set -xeuo pipefail
+
+. $(dirname $0)/common.sh
+
+if ! command -v udhcpc 2>&1; then
+	echo "udhcpc is missing, skipping the test"
+	exit "$TEST_EXIT_CODE_SKIP"
+fi
+
+unshare -r -n sleep infinity &
+child=$!
+
+wait_for_network_namespace $child
+
+slirp4netns $child tap0 &
+slirp_pid=$!
+
+udhcpc_log=$(mktemp /tmp/slirp4netns-test-udhcpc.XXXXXXXXXX)
+
+function cleanup {
+	kill -9 $child $slirp_pid
+	rm -f $udhcpc_log
+}
+trap cleanup EXIT
+
+nsenter $(nsenter_flags $child) ip link set lo up
+nsenter $(nsenter_flags $child) ip link set tap0 up
+nsenter $(nsenter_flags $child) timeout 10s udhcpc -q -i tap0 -s /bin/true 2>&1 | tee $udhcpc_log
+grep 10.0.2.15 $udhcpc_log