1 files changed, 131 insertions, 0 deletions
diff --git a/acl.go b/acl.go
new file mode 100644
index 0000000..3607d9c
--- /dev/null
+++ b/acl.go
@@ -0,0 +1,131 @@
+package main
+
+import (
+	"fmt"
+	"path"
+	"strings"
+)
+
+type Login struct {
+	user   string
+	groups []string
+}
+
+type ACL []ACLEntry
+
+type ACLEntry struct {
+	// The authenticated user (or ANONYMOUS if not authenticated) must match this string
+	user string
+	// For each of this groups, the authenticated user must belong to one group that matches
+	reqGroups []string
+	// The action requested must match one of these strings
+	actions []string
+	// The requested target must match this string. The special word SELF is replaced in the pattern by the user's dn before matching
+	target string
+	// All attributes requested must match one of these patterns
+	attributes []string
+	// All attributes requested must not match any of these patterns
+	exclAttributes []string
+}
+
+func splitNoEmpty(s string) []string {
+	if len(s) == 0 {
+		return []string{}
+	}
+	return strings.Split(s, " ")
+}
+
+func ParseACL(def []string) (ACL, error) {
+	acl := []ACLEntry{}
+	for _, item := range def {
+		parts := strings.Split(item, ":")
+		if len(parts) != 5 {
+			return nil, fmt.Errorf("Invalid ACL entry: %s", item)
+		}
+		attr, exclAttr := []string{}, []string{}
+		for _, s := range splitNoEmpty(parts[4]) {
+			if s[0] == '!' {
+				exclAttr = append(exclAttr, s)
+			} else {
+				attr = append(attr, s)
+			}
+		}
+		item_def := ACLEntry{
+			user:           parts[0],
+			reqGroups:      splitNoEmpty(parts[1]),
+			actions:        splitNoEmpty(parts[2]),
+			target:         parts[3],
+			attributes:     attr,
+			exclAttributes: exclAttr,
+		}
+		acl = append(acl, item_def)
+	}
+	return acl, nil
+}
+
+func (acl ACL) Check(login *Login, action string, target string, attributes []string) bool {
+	for _, item := range acl {
+		if item.Check(login, action, target, attributes) {
+			return true
+		}
+	}
+	return false
+}
+
+func (entry *ACLEntry) Check(login *Login, action string, target string, attributes []string) bool {
+	if !match(entry.user, login.user) {
+		return false
+	}
+
+	for _, grp := range entry.reqGroups {
+		if !matchAny(grp, login.groups) {
+			return false
+		}
+	}
+
+	rule_target_with_self := strings.ReplaceAll(entry.target, "SELF", login.user)
+	if !match(rule_target_with_self, target) {
+		return false
+	}
+
+	if !anyMatch(entry.actions, action) {
+		return false
+	}
+
+	for _, attrib := range attributes {
+		if !anyMatch(entry.attributes, attrib) {
+			return false
+		}
+	}
+
+	for _, exclAttr := range entry.exclAttributes {
+		if matchAny(exclAttr, attributes) {
+			return false
+		}
+	}
+
+	return true
+}
+
+func match(pattern string, val string) bool {
+	rv, err := path.Match(strings.ToLower(pattern), strings.ToLower(val))
+	return err == nil && rv
+}
+
+func matchAny(pattern string, vals []string) bool {
+	for _, val := range vals {
+		if match(pattern, val) {
+			return true
+		}
+	}
+	return false
+}
+
+func anyMatch(patterns []string, val string) bool {
+	for _, pattern := range patterns {
+		if match(pattern, val) {
+			return true
+		}
+	}
+	return false
+}