Binding the same container port to >1 host port is OK

The initial version of the new port code mistakenly restricted
this, so un-restrict it. We still need to maintain the map of
container ports, unfortunately (need to verify if the port in
question is a duplicate, for example).

Fixes containers#7062

Signed-off-by: Matthew Heon <matthew.heon@pm.me>

pkg/specgen/generate/ports.go

@@ -123,19 +123,20 @@ func parsePortMapping(portMappings []specgen.PortMapping) ([]ocicni.PortMapping,
 						postAssignHostPort = true
 					}
 				} else {
-					testCPort := ctrPortMap[cPort]
-					if testCPort != 0 && testCPort != hPort {
-						// This is an attempt to redefine a port
-						return nil, nil, nil, errors.Errorf("conflicting port mappings for container port %d (protocol %s)", cPort, p)
-					}
-					ctrPortMap[cPort] = hPort
-
 					testHPort := hostPortMap[hPort]
 					if testHPort != 0 && testHPort != cPort {
 						return nil, nil, nil, errors.Errorf("conflicting port mappings for host port %d (protocol %s)", hPort, p)
 					}
 					hostPortMap[hPort] = cPort
 
+					// Mapping a container port to multiple
+					// host ports is allowed.
+					// We only store the latest of these in
+					// the container port map - we don't
+					// need to know all of them, just one.
+					testCPort := ctrPortMap[cPort]
+					ctrPortMap[cPort] = hPort
+
 					// If we have an exact duplicate, just continue
 					if testCPort == hPort && testHPort == cPort {
 						continue

test/e2e/run_networking_test.go

@@ -222,6 +222,21 @@ var _ = Describe("Podman run networking", func() {
 		Expect(inspectOut[0].NetworkSettings.Ports["8080/tcp"][0].HostIP).To(Equal(""))
 	})
 
+	It("podman run -p 8080:8080 -p 8081:8080", func() {
+		name := "testctr"
+		session := podmanTest.Podman([]string{"create", "-t", "-p", "8080:8080", "-p", "8081:8080", "--name", name, ALPINE, "/bin/sh"})
+		session.WaitWithDefaultTimeout()
+		inspectOut := podmanTest.InspectContainer(name)
+		Expect(len(inspectOut)).To(Equal(1))
+		Expect(len(inspectOut[0].NetworkSettings.Ports)).To(Equal(2))
+		Expect(len(inspectOut[0].NetworkSettings.Ports["8080/tcp"])).To(Equal(1))
+		Expect(inspectOut[0].NetworkSettings.Ports["8080/tcp"][0].HostPort).To(Equal("8080"))
+		Expect(inspectOut[0].NetworkSettings.Ports["8080/tcp"][0].HostIP).To(Equal(""))
+		Expect(len(inspectOut[0].NetworkSettings.Ports["8081/tcp"])).To(Equal(1))
+		Expect(inspectOut[0].NetworkSettings.Ports["8081/tcp"][0].HostPort).To(Equal("8080"))
+		Expect(inspectOut[0].NetworkSettings.Ports["8081/tcp"][0].HostIP).To(Equal(""))
+	})
+
 	It("podman run network expose host port 80 to container port 8000", func() {
 		SkipIfRootless()
 		session := podmanTest.Podman([]string{"run", "-dt", "-p", "80:8000", ALPINE, "/bin/sh"})