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parser.go
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parser.go
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package sshconfig
import (
"fmt"
"io/fs"
"io/ioutil"
"path/filepath"
"regexp"
"strconv"
"strings"
"github.com/mitchellh/go-homedir"
)
// SSHHost defines a single host entry in a ssh config
type SSHHost struct {
Host []string
HostName string
User string
Port int
ProxyCommand string
HostKeyAlgorithms string
IdentityFile string
LocalForwards []Forward
RemoteForwards []Forward
DynamicForwards []DynamicForward
Ciphers []string
MACs []string
}
// Forward defines a single port forward entry
type Forward struct {
InHost string
InPort int
OutHost string
OutPort int
}
// NewForward returns Forward object parsed from LocalForward or RemoteForward string
func NewForward(f string) (Forward, error) {
r := regexp.MustCompile(`((\S+):)?(\d+)\s+(\S+):(\d+)`)
m := r.FindStringSubmatch(f)
if len(m) < 6 {
return Forward{}, fmt.Errorf("Invalid forward: %#v", f)
}
InPort, err := strconv.Atoi(m[3])
if err != nil {
return Forward{}, err
}
OutPort, err := strconv.Atoi(m[5])
if err != nil {
return Forward{}, err
}
return Forward{
InHost: m[2],
InPort: InPort,
OutHost: m[4],
OutPort: OutPort,
}, nil
}
// DynamicForward defines a single dynamic port forward entry
type DynamicForward struct {
Host string
Port int
}
// NewDynamicForward returns DForward object parsed from DynamicForward string
func NewDynamicForward(f string) (DynamicForward, error) {
r := regexp.MustCompile(`((\S+):)?(\d+)`)
m := r.FindStringSubmatch(f)
if len(m) < 4 {
return DynamicForward{}, fmt.Errorf("Invalid dynamic forward: %#v", f)
}
InPort, err := strconv.Atoi(m[3])
if err != nil {
return DynamicForward{}, err
}
return DynamicForward{
Host: m[2],
Port: InPort,
}, nil
}
// MustParse must parse the SSH config given by path or it will panic
func MustParse(path string) []*SSHHost {
config, err := Parse(path)
if err != nil {
panic(err)
}
return config
}
// MustParseSSHConfig must parse the SSH config given by path or it will panic
// Deprecated: Use MustParse instead.
func MustParseSSHConfig(path string) []*SSHHost {
return MustParse(path)
}
// ParseSSHConfig parses a SSH config given by path.
// Deprecated: Use Parse instead.
func ParseSSHConfig(path string) ([]*SSHHost, error) {
return Parse(path)
}
// Parse parses a SSH config given by path.
func Parse(path string) ([]*SSHHost, error) {
// read config file
content, err := ioutil.ReadFile(path)
if err != nil {
return nil, err
}
return parse(string(content), path)
}
// ParseFS parses a SSH config given by path contained in fsys.
func ParseFS(fsys fs.FS, path string) ([]*SSHHost, error) {
// read config file
content, err := fs.ReadFile(fsys, path)
if err != nil {
return nil, err
}
return parse(string(content), path)
}
// parses an openssh config file
func parse(input string, path string) ([]*SSHHost, error) {
sshConfigs := []*SSHHost{}
var next item
var sshHost *SSHHost
var onlyIncludes bool = !strings.Contains(input, "Host ") && strings.Contains(input, "Include ");
lexer := lex(input)
Loop:
for {
token := lexer.nextItem()
if sshHost == nil {
if token.typ == itemEOF {
break Loop
}
if token.typ != itemHost && token.typ != itemInclude {
// File has no `Host` but has `Include`. Continue trying to parse it.
if onlyIncludes {
continue Loop
}
return nil, fmt.Errorf("%s:%d: config variable before Host variable", path, token.pos)
}
} else if token.typ == itemInclude {
return nil, fmt.Errorf("include not allowed in Host block")
}
switch token.typ {
case itemHost:
if sshHost != nil {
sshConfigs = append(sshConfigs, sshHost)
}
sshHost = &SSHHost{Host: []string{}, Port: 22}
case itemHostValue:
sshHost.Host = strings.Split(token.val, " ")
case itemHostName:
next = lexer.nextItem()
if next.typ != itemValue {
return nil, fmt.Errorf(next.val)
}
sshHost.HostName = next.val
case itemUser:
next = lexer.nextItem()
if next.typ != itemValue {
return nil, fmt.Errorf(next.val)
}
sshHost.User = next.val
case itemPort:
next = lexer.nextItem()
if next.typ != itemValue {
return nil, fmt.Errorf(next.val)
}
port, err := strconv.Atoi(next.val)
if err != nil {
return nil, err
}
sshHost.Port = port
case itemProxyCommand:
next = lexer.nextItem()
if next.typ != itemValue {
return nil, fmt.Errorf(next.val)
}
sshHost.ProxyCommand = next.val
case itemHostKeyAlgorithms:
next = lexer.nextItem()
if next.typ != itemValue {
return nil, fmt.Errorf(next.val)
}
sshHost.HostKeyAlgorithms = next.val
case itemIdentityFile:
next = lexer.nextItem()
if next.typ != itemValue {
return nil, fmt.Errorf(next.val)
}
sshHost.IdentityFile = next.val
case itemLocalForward:
next = lexer.nextItem()
f, err := NewForward(next.val)
if err != nil {
return nil, err
}
sshHost.LocalForwards = append(sshHost.LocalForwards, f)
case itemRemoteForward:
next = lexer.nextItem()
f, err := NewForward(next.val)
if err != nil {
return nil, err
}
sshHost.RemoteForwards = append(sshHost.RemoteForwards, f)
case itemDynamicForward:
next = lexer.nextItem()
f, err := NewDynamicForward(next.val)
if err != nil {
return nil, err
}
sshHost.DynamicForwards = append(sshHost.DynamicForwards, f)
case itemInclude:
next = lexer.nextItem()
if next.typ != itemValue {
return nil, fmt.Errorf(next.val)
}
includePath, err := parseIncludePath(path, next.val)
if err != nil {
return nil, err
}
files, err := filepath.Glob(includePath)
if err != nil {
return nil, err
}
if len(files) == 0 {
return nil, fmt.Errorf("no files found for include path %s", includePath)
}
for _, f := range files {
includeSshConfigs, err := Parse(f)
if err != nil {
return nil, err
}
sshConfigs = append(sshConfigs, includeSshConfigs...)
}
case itemCiphers:
next = lexer.nextItem()
if next.typ != itemValue {
return nil, fmt.Errorf(next.val)
}
sshHost.Ciphers = strings.Split(next.val, ",")
case itemMACs:
next = lexer.nextItem()
if next.typ != itemValue {
return nil, fmt.Errorf(next.val)
}
sshHost.MACs = strings.Split(next.val, ",")
case itemError:
return nil, fmt.Errorf("%s at pos %d", token.val, token.pos)
case itemEOF:
if sshHost != nil {
sshConfigs = append(sshConfigs, sshHost)
}
break Loop
default:
// continue onwards
}
}
return sshConfigs, nil
}
func parseIncludePath(currentPath string, includePath string) (string, error) {
if strings.HasPrefix(includePath, "~") {
expandedPath, err := homedir.Expand(includePath)
if err != nil {
return "", err
}
return expandedPath, nil
} else if !strings.HasPrefix(includePath, "/") {
return filepath.Join(filepath.Dir(currentPath), includePath), nil
}
return includePath, nil
}