Rework port parsing to support --expose and -P

As part of this, make a major change to the type we use to
represent port mappings in SpecGen (from using existing OCICNI
structs to using our own custom one). This struct has the
advantage of supporting ranges, massively reducing traffic over
the wire for Podman commands using them (for example, the
`podman run -p 5000-6000` command will now send only one struct
instead of 1000). This struct also allows us to easily validate
which ports are in use, and which are not, which is necessary for
--expose.

Once we have parsed the ports from the new struct, we can produce
an accurate map including all currently requested ports, and use
that to determine what ports need to be exposed (some requested
exposed ports may already be included in a mapping from --publish
and will be ignored) and what open ports on the host we can map
them to.

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

2 files changed, 194 insertions, 31 deletions

diff --git a/cmd/podman/common/specgen.go b/cmd/podman/common/specgen.go
index 33cba30cd..7467c184a 100644
--- a/cmd/podman/common/specgen.go
+++ b/cmd/podman/common/specgen.go
@@ -192,7 +192,6 @@ func getMemoryLimits(s *specgen.SpecGenerator, c *ContainerCLIOpts, args []strin
 func FillOutSpecGen(s *specgen.SpecGenerator, c *ContainerCLIOpts, args []string) error {
 	var (
 		err error
-		// namespaces map[string]string
 	)
 
 	// validate flags as needed
@@ -234,9 +233,15 @@ func FillOutSpecGen(s *specgen.SpecGenerator, c *ContainerCLIOpts, args []string
 	// We are not handling the Expose flag yet.
 	// s.PortsExpose = c.Expose
 	s.PortMappings = c.Net.PublishPorts
-	s.PublishImagePorts = c.PublishAll
+	s.PublishExposedPorts = c.PublishAll
 	s.Pod = c.Pod
 
+	expose, err := createExpose(c.Expose)
+	if err != nil {
+		return err
+	}
+	s.Expose = expose
+
 	for k, v := range map[string]*specgen.Namespace{
 		c.IPC:       &s.IpcNS,
 		c.PID:       &s.PidNS,
diff --git a/cmd/podman/common/util.go b/cmd/podman/common/util.go
index 47bbe12fa..a3626b4e4 100644
--- a/cmd/podman/common/util.go
+++ b/cmd/podman/common/util.go
@@ -1,43 +1,201 @@
 package common
 
 import (
+	"net"
 	"strconv"
+	"strings"
 
-	"github.com/cri-o/ocicni/pkg/ocicni"
-	"github.com/docker/go-connections/nat"
+	"github.com/containers/libpod/pkg/specgen"
 	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
 )
 
-// createPortBindings iterates ports mappings and exposed ports into a format CNI understands
-func createPortBindings(ports []string) ([]ocicni.PortMapping, error) {
-	// TODO wants someone to rewrite this code in the future
-	var portBindings []ocicni.PortMapping
-	// The conversion from []string to natBindings is temporary while mheon reworks the port
-	// deduplication code.  Eventually that step will not be required.
-	_, natBindings, err := nat.ParsePortSpecs(ports)
-	if err != nil {
-		return nil, err
-	}
-	for containerPb, hostPb := range natBindings {
-		var pm ocicni.PortMapping
-		pm.ContainerPort = int32(containerPb.Int())
-		for _, i := range hostPb {
-			var hostPort int
-			var err error
-			pm.HostIP = i.HostIP
-			if i.HostPort == "" {
-				hostPort = containerPb.Int()
+// createExpose parses user-provided exposed port definitions and converts them
+// into SpecGen format.
+// TODO: The SpecGen format should really handle ranges more sanely - we could
+// be massively inflating what is sent over the wire with a large range.
+func createExpose(expose []string) (map[uint16]string, error) {
+	toReturn := make(map[uint16]string)
+
+	for _, e := range expose {
+		// Check for protocol
+		proto := "tcp"
+		splitProto := strings.Split(e, "/")
+		if len(splitProto) > 2 {
+			return nil, errors.Errorf("invalid expose format - protocol can only be specified once")
+		} else if len(splitProto) == 2 {
+			proto = splitProto[1]
+		}
+
+		// Check for a range
+		start, len, err := parseAndValidateRange(splitProto[0])
+		if err != nil {
+			return nil, err
+		}
+
+		var index uint16
+		for index = 0; index < len; index++ {
+			portNum := start + index
+			protocols, ok := toReturn[portNum]
+			if !ok {
+				toReturn[portNum] = proto
 			} else {
-				hostPort, err = strconv.Atoi(i.HostPort)
-				if err != nil {
-					return nil, errors.Wrapf(err, "unable to convert host port to integer")
-				}
+				newProto := strings.Join(append(strings.Split(protocols, ","), strings.Split(proto, ",")...), ",")
+				toReturn[portNum] = newProto
 			}
+		}
+	}
+
+	return toReturn, nil
+}
+
+// createPortBindings iterates ports mappings into SpecGen format.
+func createPortBindings(ports []string) ([]specgen.PortMapping, error) {
+	// --publish is formatted as follows:
+	// [[hostip:]hostport[-endPort]:]containerport[-endPort][/protocol]
+	toReturn := make([]specgen.PortMapping, 0, len(ports))
+
+	for _, p := range ports {
+		var (
+			ctrPort                 string
+			proto, hostIP, hostPort *string
+		)
+
+		splitProto := strings.Split(p, "/")
+		switch len(splitProto) {
+		case 1:
+			// No protocol was provided
+		case 2:
+			proto = &(splitProto[1])
+		default:
+			return nil, errors.Errorf("invalid port format - protocol can only be specified once")
+		}
 
-			pm.HostPort = int32(hostPort)
-			pm.Protocol = containerPb.Proto()
-			portBindings = append(portBindings, pm)
+		splitPort := strings.Split(splitProto[0], ":")
+		switch len(splitPort) {
+		case 1:
+			ctrPort = splitPort[0]
+		case 2:
+			hostPort = &(splitPort[0])
+			ctrPort = splitPort[1]
+		case 3:
+			hostIP = &(splitPort[0])
+			hostPort = &(splitPort[1])
+			ctrPort = splitPort[2]
+		default:
+			return nil, errors.Errorf("invalid port format - format is [[hostIP:]hostPort:]containerPort")
+		}
+
+		newPort, err := parseSplitPort(hostIP, hostPort, ctrPort, proto)
+		if err != nil {
+			return nil, err
+		}
+
+		toReturn = append(toReturn, newPort)
+	}
+
+	return toReturn, nil
+}
+
+// parseSplitPort parses individual components of the --publish flag to produce
+// a single port mapping in SpecGen format.
+func parseSplitPort(hostIP, hostPort *string, ctrPort string, protocol *string) (specgen.PortMapping, error) {
+	newPort := specgen.PortMapping{}
+	if ctrPort == "" {
+		return newPort, errors.Errorf("must provide a non-empty container port to publish")
+	}
+	ctrStart, ctrLen, err := parseAndValidateRange(ctrPort)
+	if err != nil {
+		return newPort, errors.Wrapf(err, "error parsing container port")
+	}
+	newPort.ContainerPort = ctrStart
+	newPort.Range = ctrLen
+
+	if protocol != nil {
+		if *protocol == "" {
+			return newPort, errors.Errorf("must provide a non-empty protocol to publish")
+		}
+		newPort.Protocol = *protocol
+	}
+	if hostIP != nil {
+		if *hostIP == "" {
+			return newPort, errors.Errorf("must provide a non-empty container host IP to publish")
 		}
+		testIP := net.ParseIP(*hostIP)
+		if testIP == nil {
+			return newPort, errors.Errorf("cannot parse %q as an IP address", *hostIP)
+		}
+		newPort.HostIP = testIP.String()
+	}
+	if hostPort != nil {
+		if *hostPort == "" {
+			return newPort, errors.Errorf("must provide a non-empty container host port to publish")
+		}
+		hostStart, hostLen, err := parseAndValidateRange(*hostPort)
+		if err != nil {
+			return newPort, errors.Wrapf(err, "error parsing host port")
+		}
+		if hostLen != ctrLen {
+			return newPort, errors.Errorf("host and container port ranges have different lengths: %d vs %d", hostLen, ctrLen)
+		}
+		newPort.HostPort = hostStart
+	}
+
+	hport := newPort.HostPort
+	if hport == 0 {
+		hport = newPort.ContainerPort
+	}
+	logrus.Debugf("Adding port mapping from %d to %d length %d protocol %q", hport, newPort.ContainerPort, newPort.Range, newPort.Protocol)
+
+	return newPort, nil
+}
+
+// Parse and validate a port range.
+// Returns start port, length of range, error.
+func parseAndValidateRange(portRange string) (uint16, uint16, error) {
+	splitRange := strings.Split(portRange, "-")
+	if len(splitRange) > 2 {
+		return 0, 0, errors.Errorf("invalid port format - port ranges are formatted as startPort-stopPort")
+	}
+
+	if splitRange[0] == "" {
+		return 0, 0, errors.Errorf("port numbers cannot be negative")
+	}
+
+	startPort, err := parseAndValidatePort(splitRange[0])
+	if err != nil {
+		return 0, 0, err
+	}
+
+	var rangeLen uint16 = 1
+	if len(splitRange) == 2 {
+		if splitRange[1] == "" {
+			return 0, 0, errors.Errorf("must provide ending number for port range")
+		}
+		endPort, err := parseAndValidatePort(splitRange[1])
+		if err != nil {
+			return 0, 0, err
+		}
+		if endPort <= startPort {
+			return 0, 0, errors.Errorf("the end port of a range must be higher than the start port - %d is not higher than %d", endPort, startPort)
+		}
+		// Our range is the total number of ports
+		// involved, so we need to add 1 (8080:8081 is
+		// 2 ports, for example, not 1)
+		rangeLen = endPort - startPort + 1
+	}
+
+	return startPort, rangeLen, nil
+}
+
+// Turn a single string into a valid U16 port.
+func parseAndValidatePort(port string) (uint16, error) {
+	num, err := strconv.Atoi(port)
+	if err != nil {
+		return 0, errors.Wrapf(err, "cannot parse %q as a port number", port)
+	}
+	if num < 1 || num > 65535 {
+		return 0, errors.Errorf("port numbers must be between 1 and 65535 (inclusive), got %d", num)
 	}
-	return portBindings, nil
+	return uint16(num), nil
 }