system tests: new random_free_port helper

Picks a pseudorandom open port within a range. Refactor existing
instances of such code.

Signed-off-by: Ed Santiago <santiago@redhat.com>

test/system/150-login.bats

@@ -22,12 +22,7 @@ fi
 
 # Randomly-assigned port in the 5xxx range
 if [ -z "${PODMAN_LOGIN_REGISTRY_PORT}" ]; then
-    for port in $(shuf -i 5000-5999);do
-        if ! { exec 3<> /dev/tcp/127.0.0.1/$port; } &>/dev/null; then
-            export PODMAN_LOGIN_REGISTRY_PORT=$port
-            break
-        fi
-    done
+    export PODMAN_LOGIN_REGISTRY_PORT=$(random_free_port)
 fi
 
 # Override any user-set path to an auth file

test/system/200-pod.bats

@@ -76,11 +76,7 @@ function teardown() {
     fi
 
     # Randomly-assigned port in the 5xxx range
-    for port in $(shuf -i 5000-5999);do
-        if ! { exec 3<> /dev/tcp/127.0.0.1/$port; } &>/dev/null; then
-            break
-        fi
-    done
+    port=$(random_free_port)
 
     # Listener. This will exit as soon as it receives a message.
     run_podman run -d --pod $podname $IMAGE nc -l -p $port
@@ -183,16 +179,8 @@ function random_ip() {
     pod_id_file=${PODMAN_TMPDIR}/pod-id-file
 
     # Randomly-assigned ports in the 5xxx and 6xxx range
-    for port_in in $(shuf -i 5000-5999);do
-        if ! { exec 3<> /dev/tcp/127.0.0.1/$port_in; } &>/dev/null; then
-            break
-        fi
-    done
-    for port_out in $(shuf -i 6000-6999);do
-        if ! { exec 3<> /dev/tcp/127.0.0.1/$port_out; } &>/dev/null; then
-            break
-        fi
-    done
+    port_in=$(random_free_port 5000-5999)
+    port_out=$(random_free_port 6000-6999)
 
     # Create a pod with all the desired options
     # FIXME: --ip=$ip fails:

test/system/271-tcp-cors-server.bats

@@ -14,7 +14,7 @@ SOCKET_FILE="$UNIT_DIR/$SERVICE_NAME.socket"
 
 @test "podman system service - tcp CORS" {
     skip_if_remote "system service tests are meaningless over remote"
-    PORT=$(( ((RANDOM<<15)|RANDOM) % 63001 + 2000 ))
+    PORT=$(random_free_port 63000-64999)
     run_podman system service --cors="*" tcp:$SERVICE_TCP_HOST:$PORT -t 20 &
     podman_pid="$!"
     sleep 5s
@@ -26,7 +26,7 @@ SOCKET_FILE="$UNIT_DIR/$SERVICE_NAME.socket"
 
 @test "podman system service - tcp without CORS" {
     skip_if_remote "system service tests are meaningless over remote"
-    PORT=$(( ((RANDOM<<15)|RANDOM) % 63001 + 2000 ))
+    PORT=$(random_free_port 63000-64999)
     run_podman system service tcp:$SERVICE_TCP_HOST:$PORT -t 20 &
     podman_pid="$!"
     sleep 5s

test/system/500-networking.bats

@@ -23,7 +23,7 @@ load helpers
     random_1=$(random_string 30)
     random_2=$(random_string 30)
 
-    HOST_PORT=8080
+    HOST_PORT=$(random_free_port)
     SERVER=http://127.0.0.1:$HOST_PORT
 
     # Create a test file with random content
@@ -114,11 +114,8 @@ load helpers
 
 # Issue #5466 - port-forwarding doesn't work with this option and -d
 @test "podman networking: port with --userns=keep-id" {
-    # FIXME: randomize port, and create second random host port
-    myport=54321
-
     for cidr in "" "$(random_rfc1918_subnet).0/24"; do
-        myport=$(( myport + 1 ))
+        myport=$(random_free_port 52000-52999)
         if [[ -z $cidr ]]; then
             # regex to match that we are in 10.X subnet
             match="10\..*"
@@ -188,6 +185,7 @@ load helpers
 
 # "network create" now works rootless, with the help of a special container
 @test "podman network create" {
+    # Deliberately use a fixed port, not random_open_port, because of #10806
     myport=54322
 
     local mynetname=testnet-$(random_string 10)
@@ -244,7 +242,7 @@ load helpers
     skip_if_remote "podman network reload does not have remote support"
 
     random_1=$(random_string 30)
-    HOST_PORT=12345
+    HOST_PORT=$(random_free_port)
     SERVER=http://127.0.0.1:$HOST_PORT
 
     # Create a test file with random content
@@ -396,7 +394,7 @@ load helpers
 # Test for https://github.com/containers/podman/issues/10052
 @test "podman network connect/disconnect with port forwarding" {
     random_1=$(random_string 30)
-    HOST_PORT=12345
+    HOST_PORT=$(random_free_port)
     SERVER=http://127.0.0.1:$HOST_PORT
 
     # Create a test file with random content

test/system/helpers.bash

@@ -278,6 +278,23 @@ function wait_for_ready {
     wait_for_output 'READY' "$@"
 }
 
+######################
+#  random_free_port  #  Pick an available port within a specified range
+######################
+function random_free_port() {
+    local range=${1:-5000-5999}
+
+    local port
+    for port in $(shuf -i ${range}); do
+        if ! { exec {unused_fd}<> /dev/tcp/127.0.0.1/$port; } &>/dev/null; then
+            echo $port
+            return
+        fi
+    done
+
+    die "Could not find open port in range $range"
+}
+
 ###################
 #  wait_for_port  #  Returns once port is available on host
 ###################
@@ -288,7 +305,7 @@ function wait_for_port() {
 
     # Wait
     while [ $_timeout -gt 0 ]; do
-        { exec 5<> /dev/tcp/$host/$port; } &>/dev/null && return
+        { exec {unused_fd}<> /dev/tcp/$host/$port; } &>/dev/null && return
         sleep 1
         _timeout=$(( $_timeout - 1 ))
     done

test/system/helpers.t

@@ -213,8 +213,16 @@ declare -a lines=(
 )
 check_same_dev "zero-line output"
 
-
 # END   remove_same_dev_warning
 ###############################################################################
+# BEGIN random_free_port
+
+# Assumes that 16700 is open
+found=$(random_free_port 16700-16700)
+
+check_result "$found" "16700" "random_free_port"
+
+# END   random_free_port
+###############################################################################
 
 exit $rc