Condition upgrades (if, if_op) for rewrite, redir (#889)

* checkpoint

* Added RequestMatcher interface. Extract 'if' condition into a RequestMatcher.

* Added tests for IfMatcher

* Minor refactors

* Refactors

* Use if_op

* conform with new 0.9 beta function changes.

caddyhttp/httpserver/condition.go

@@ -0,0 +1,199 @@
+package httpserver
+
+import (
+	"fmt"
+	"net/http"
+	"regexp"
+	"strings"
+
+	"github.com/mholt/caddy/caddyfile"
+)
+
+// SetupIfMatcher parses `if` or `if_type` in the current dispenser block.
+// It returns a RequestMatcher and an error if any.
+func SetupIfMatcher(c caddyfile.Dispenser) (RequestMatcher, error) {
+	var matcher IfMatcher
+	for c.NextBlock() {
+		switch c.Val() {
+		case "if":
+			args1 := c.RemainingArgs()
+			if len(args1) != 3 {
+				return matcher, c.ArgErr()
+			}
+			ifc, err := newIfCond(args1[0], args1[1], args1[2])
+			if err != nil {
+				return matcher, err
+			}
+			matcher.ifs = append(matcher.ifs, ifc)
+		case "if_op":
+			if !c.NextArg() {
+				return matcher, c.ArgErr()
+			}
+			switch c.Val() {
+			case "and":
+				matcher.isOr = false
+			case "or":
+				matcher.isOr = true
+			default:
+				return matcher, c.ArgErr()
+			}
+		}
+	}
+	return matcher, nil
+}
+
+// operators
+const (
+	isOp         = "is"
+	notOp        = "not"
+	hasOp        = "has"
+	notHasOp     = "not_has"
+	startsWithOp = "starts_with"
+	endsWithOp   = "ends_with"
+	matchOp      = "match"
+	notMatchOp   = "not_match"
+)
+
+func operatorError(operator string) error {
+	return fmt.Errorf("Invalid operator %v", operator)
+}
+
+// ifCondition is a 'if' condition.
+type ifCondition func(string, string) bool
+
+var ifConditions = map[string]ifCondition{
+	isOp:         isFunc,
+	notOp:        notFunc,
+	hasOp:        hasFunc,
+	notHasOp:     notHasFunc,
+	startsWithOp: startsWithFunc,
+	endsWithOp:   endsWithFunc,
+	matchOp:      matchFunc,
+	notMatchOp:   notMatchFunc,
+}
+
+// isFunc is condition for Is operator.
+// It checks for equality.
+func isFunc(a, b string) bool {
+	return a == b
+}
+
+// notFunc is condition for Not operator.
+// It checks for inequality.
+func notFunc(a, b string) bool {
+	return a != b
+}
+
+// hasFunc is condition for Has operator.
+// It checks if b is a substring of a.
+func hasFunc(a, b string) bool {
+	return strings.Contains(a, b)
+}
+
+// notHasFunc is condition for NotHas operator.
+// It checks if b is not a substring of a.
+func notHasFunc(a, b string) bool {
+	return !strings.Contains(a, b)
+}
+
+// startsWithFunc is condition for StartsWith operator.
+// It checks if b is a prefix of a.
+func startsWithFunc(a, b string) bool {
+	return strings.HasPrefix(a, b)
+}
+
+// endsWithFunc is condition for EndsWith operator.
+// It checks if b is a suffix of a.
+func endsWithFunc(a, b string) bool {
+	return strings.HasSuffix(a, b)
+}
+
+// matchFunc is condition for Match operator.
+// It does regexp matching of a against pattern in b
+// and returns if they match.
+func matchFunc(a, b string) bool {
+	matched, _ := regexp.MatchString(b, a)
+	return matched
+}
+
+// notMatchFunc is condition for NotMatch operator.
+// It does regexp matching of a against pattern in b
+// and returns if they do not match.
+func notMatchFunc(a, b string) bool {
+	matched, _ := regexp.MatchString(b, a)
+	return !matched
+}
+
+// ifCond is statement for a IfMatcher condition.
+type ifCond struct {
+	a  string
+	op string
+	b  string
+}
+
+// newIfCond creates a new If condition.
+func newIfCond(a, operator, b string) (ifCond, error) {
+	if _, ok := ifConditions[operator]; !ok {
+		return ifCond{}, operatorError(operator)
+	}
+	return ifCond{
+		a:  a,
+		op: operator,
+		b:  b,
+	}, nil
+}
+
+// True returns true if the condition is true and false otherwise.
+// If r is not nil, it replaces placeholders before comparison.
+func (i ifCond) True(r *http.Request) bool {
+	if c, ok := ifConditions[i.op]; ok {
+		a, b := i.a, i.b
+		if r != nil {
+			replacer := NewReplacer(r, nil, "")
+			a = replacer.Replace(i.a)
+			b = replacer.Replace(i.b)
+		}
+		return c(a, b)
+	}
+	return false
+}
+
+// IfMatcher is a RequestMatcher for 'if' conditions.
+type IfMatcher struct {
+	ifs  []ifCond // list of If
+	isOr bool     // if true, conditions are 'or' instead of 'and'
+}
+
+// Match satisfies RequestMatcher interface.
+// It returns true if the conditions in m are true.
+func (m IfMatcher) Match(r *http.Request) bool {
+	if m.isOr {
+		return m.Or(r)
+	}
+	return m.And(r)
+}
+
+// And returns true if all conditions in m are true.
+func (m IfMatcher) And(r *http.Request) bool {
+	for _, i := range m.ifs {
+		if !i.True(r) {
+			return false
+		}
+	}
+	return true
+}
+
+// Or returns true if any of the conditions in m is true.
+func (m IfMatcher) Or(r *http.Request) bool {
+	for _, i := range m.ifs {
+		if i.True(r) {
+			return true
+		}
+	}
+	return false
+}
+
+// IfMatcherKeyword returns if k is a keyword for 'if' config block.
+func IfMatcherKeyword(k string) bool {
+	return k == "if" || k == "if_cond"
+}