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|
package main
import (
"errors"
"fmt"
"io"
"net"
"os"
"os/user"
"strings"
)
const TableName = "membership"
type Server struct {
HostName string
Groups []string
GroupsFile string
}
func ServeUnixSocket(listenner net.Listener, srv *Server) error {
for {
// Accept an incoming connection.
conn, err := listenner.Accept()
if errors.Is(err, net.ErrClosed) {
break
} else if err != nil {
fmt.Fprintln(os.Stderr, err.Error())
continue
}
go func(conn net.Conn) {
defer conn.Close()
err = srv.HandleConn(conn, conn)
if err != nil {
fmt.Fprintln(os.Stderr, err.Error())
}
}(conn)
}
return nil
}
func (s *Server) readGroupList() ([]string, error) {
f, err := os.Open(s.GroupsFile)
if err != nil {
return nil, err
}
buf, err := io.ReadAll(f)
if err != nil {
return nil, err
}
groups := strings.Split(string(buf), "\n")
return groups, nil
}
func (s *Server) HandleConn(w io.Writer, r io.Reader) error {
for {
var req Request
_, err := readNetString(r, &req)
if errors.Is(err, io.EOF) {
break
}
if req.Name != TableName {
if _, err = writeNetString(w, &ReplyPerm{Reason: "unexpected name"}); err != nil {
return err
}
return nil
}
strs := strings.SplitN(req.Key, "@", 2)
if len(strs) != 2 {
return fmt.Errorf("unexpected email address format")
}
userName := strs[0]
hostName := strs[1]
if hostName != s.HostName {
if _, err := writeNetString(w, &ReplyNotFound{}); err != nil {
return err
}
return nil
}
u, err := user.Lookup(userName)
if _, ok := err.(user.UnknownUserError); ok {
_, err := writeNetString(w, &ReplyNotFound{})
return err
} else if err != nil {
return err
}
groups, err := lookupGroupNames(u)
if err != nil {
return err
}
isListed := make(map[string]bool)
for _, v := range s.Groups {
isListed[v] = true
}
groupsFile, err := s.readGroupList()
if err != nil {
return fmt.Errorf("reading white list: %w", err)
}
for _, v := range groupsFile {
isListed[v] = true
}
found := false
for _, name := range groups {
found = isListed[name]
if found {
_, err = writeNetString(w, &ReplyOK{Data: "OK"})
return err
}
}
_, err = writeNetString(w, &ReplyNotFound{})
if err != nil {
return err
}
}
return nil
}
|
