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url.go
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/
url.go
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package ldaputil
import (
"fmt"
"net"
"net/url"
"strings"
"gopkg.in/ldap.v2"
)
// Scheme is a valid ldap scheme
type Scheme string
const (
SchemeLDAP Scheme = "ldap"
SchemeLDAPS Scheme = "ldaps"
)
// Scope is a valid LDAP search scope
type Scope int
const (
ScopeWholeSubtree Scope = ldap.ScopeWholeSubtree
ScopeSingleLevel Scope = ldap.ScopeSingleLevel
ScopeBaseObject Scope = ldap.ScopeBaseObject
)
// DerefAliases is a valid LDAP alias dereference parameter
type DerefAliases int
const (
DerefAliasesNever = ldap.NeverDerefAliases
DerefAliasesSearching = ldap.DerefInSearching
DerefAliasesFinding = ldap.DerefFindingBaseObj
DerefAliasesAlways = ldap.DerefAlways
)
const (
defaultLDAPPort = "389"
defaultLDAPSPort = "636"
defaultHost = "localhost"
defaultQueryAttribute = "uid"
defaultFilter = "(objectClass=*)"
scopeWholeSubtreeString = "sub"
scopeSingleLevelString = "one"
scopeBaseObjectString = "base"
criticalExtensionPrefix = "!"
)
// LDAPURL holds a parsed RFC 2255 URL
type LDAPURL struct {
// Scheme is ldap or ldaps
Scheme Scheme
// Host is the host:port of the LDAP server
Host string
// The DN of the branch of the directory where all searches should start from
BaseDN string
// The attribute to search for
QueryAttribute string
// The scope of the search. Can be ldap.ScopeWholeSubtree, ldap.ScopeSingleLevel, or ldap.ScopeBaseObject
Scope Scope
// A valid LDAP search filter (e.g. "(objectClass=*)")
Filter string
}
// ParseURL parsed the given ldapURL as an RFC 2255 URL
// The syntax of the URL is ldap://host:port/basedn?attribute?scope?filter
func ParseURL(ldapURL string) (LDAPURL, error) {
// Must be a valid URL to start
parsedURL, err := url.Parse(ldapURL)
if err != nil {
return LDAPURL{}, err
}
opts := LDAPURL{}
determinedScheme, err := DetermineLDAPScheme(parsedURL.Scheme)
if err != nil {
return LDAPURL{}, err
}
opts.Scheme = determinedScheme
determinedHost, err := DetermineLDAPHost(parsedURL.Host, opts.Scheme)
if err != nil {
return LDAPURL{}, err
}
opts.Host = determinedHost
// Set base dn (default to "")
// url.Parse() already percent-decodes the path
opts.BaseDN = strings.TrimLeft(parsedURL.Path, "/")
attributes, scope, filter, extensions, err := SplitLDAPQuery(parsedURL.RawQuery)
if err != nil {
return LDAPURL{}, err
}
// Attributes contains comma-separated attributes
// Set query attribute to first attribute
// Default to uid to match mod_auth_ldap
opts.QueryAttribute = strings.Split(attributes, ",")[0]
if len(opts.QueryAttribute) == 0 {
opts.QueryAttribute = defaultQueryAttribute
}
determinedScope, err := DetermineLDAPScope(scope)
if err != nil {
return LDAPURL{}, err
}
opts.Scope = determinedScope
determinedFilter, err := DetermineLDAPFilter(filter)
if err != nil {
return LDAPURL{}, err
}
opts.Filter = determinedFilter
// Extensions are in "name=value,name2=value2" form
// Critical extensions are prefixed with a !
// Optional extensions are ignored, per RFC
// Fail if there are any critical extensions, since we don't support any
if len(extensions) > 0 {
for _, extension := range strings.Split(extensions, ",") {
exttype := strings.SplitN(extension, "=", 2)[0]
if strings.HasPrefix(exttype, criticalExtensionPrefix) {
return LDAPURL{}, fmt.Errorf("unsupported critical extension %s", extension)
}
}
}
return opts, nil
}
// DetermineLDAPScheme determines the LDAP connection scheme. Scheme is one of "ldap" or "ldaps"
// Default to "ldap"
func DetermineLDAPScheme(scheme string) (Scheme, error) {
switch Scheme(scheme) {
case SchemeLDAP, SchemeLDAPS:
return Scheme(scheme), nil
default:
return "", fmt.Errorf("invalid scheme %q", scheme)
}
}
// DetermineLDAPHost determines the host and port for the LDAP connection.
// The default host is localhost; the default port for scheme "ldap" is 389, for "ldaps" is 686
func DetermineLDAPHost(hostport string, scheme Scheme) (string, error) {
if len(hostport) == 0 {
hostport = defaultHost
}
// add port if missing
if _, _, err := net.SplitHostPort(hostport); err != nil {
switch scheme {
case SchemeLDAPS:
return net.JoinHostPort(hostport, defaultLDAPSPort), nil
case SchemeLDAP:
return net.JoinHostPort(hostport, defaultLDAPPort), nil
default:
return "", fmt.Errorf("no default port for scheme %q", scheme)
}
}
// nothing needed to be done
return hostport, nil
}
// SplitLDAPQuery splits the query in the URL into the substituent parts. All sections are optional.
// Query syntax is attribute?scope?filter?extensions
func SplitLDAPQuery(query string) (attributes, scope, filter, extensions string, err error) {
parts := strings.Split(query, "?")
switch len(parts) {
case 4:
extensions = parts[3]
fallthrough
case 3:
if v, err := url.QueryUnescape(parts[2]); err != nil {
return "", "", "", "", err
} else {
filter = v
}
fallthrough
case 2:
if v, err := url.QueryUnescape(parts[1]); err != nil {
return "", "", "", "", err
} else {
scope = v
}
fallthrough
case 1:
if v, err := url.QueryUnescape(parts[0]); err != nil {
return "", "", "", "", err
} else {
attributes = v
}
return attributes, scope, filter, extensions, nil
case 0:
return
default:
err = fmt.Errorf("too many query options %q", query)
return "", "", "", "", err
}
}
// DeterminmeLDAPScope determines the LDAP search scope. Scope is one of "sub", "one", or "base"
// Default to "sub" to match mod_auth_ldap
func DetermineLDAPScope(scope string) (Scope, error) {
switch scope {
case "", scopeWholeSubtreeString:
return ScopeWholeSubtree, nil
case scopeSingleLevelString:
return ScopeSingleLevel, nil
case scopeBaseObjectString:
return ScopeBaseObject, nil
default:
return -1, fmt.Errorf("invalid scope %q", scope)
}
}
// DetermineLDAPFilter determines the LDAP search filter. Filter is a valid LDAP filter
// Default to "(objectClass=*)" per RFC
func DetermineLDAPFilter(filter string) (string, error) {
if len(filter) == 0 {
return defaultFilter, nil
}
if _, err := ldap.CompileFilter(filter); err != nil {
return "", fmt.Errorf("invalid filter: %v", err)
}
return filter, nil
}
func DetermineDerefAliasesBehavior(derefAliasesString string) (DerefAliases, error) {
mapping := map[string]DerefAliases{
"never": DerefAliasesNever,
"search": DerefAliasesSearching,
"base": DerefAliasesFinding,
"always": DerefAliasesAlways,
}
derefAliases, exists := mapping[derefAliasesString]
if !exists {
return -1, fmt.Errorf("not a valid LDAP alias dereferncing behavior: %s", derefAliasesString)
}
return derefAliases, nil
}