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conn_str.go
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conn_str.go
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package msdsn
import (
"crypto/tls"
"crypto/x509"
"encoding/pem"
"errors"
"fmt"
"net"
"net/url"
"os"
"path/filepath"
"strconv"
"strings"
"time"
"unicode"
)
type (
Encryption int
Log uint64
BrowserMsg byte
)
const (
DsnTypeURL = 1
DsnTypeOdbc = 2
DsnTypeAdo = 3
)
const (
EncryptionOff = 0
EncryptionRequired = 1
EncryptionDisabled = 3
EncryptionStrict = 4
)
const (
LogErrors Log = 1
LogMessages Log = 2
LogRows Log = 4
LogSQL Log = 8
LogParams Log = 16
LogTransaction Log = 32
LogDebug Log = 64
LogRetries Log = 128
)
const (
BrowserDefault BrowserMsg = 0
BrowserAllInstances BrowserMsg = 0x03
BrowserDAC BrowserMsg = 0x0f
)
const (
Database = "database"
Encrypt = "encrypt"
Password = "password"
ChangePassword = "change password"
UserID = "user id"
Port = "port"
TrustServerCertificate = "trustservercertificate"
Certificate = "certificate"
TLSMin = "tlsmin"
PacketSize = "packet size"
LogParam = "log"
ConnectionTimeout = "connection timeout"
HostNameInCertificate = "hostnameincertificate"
KeepAlive = "keepalive"
ServerSpn = "serverspn"
WorkstationID = "workstation id"
AppName = "app name"
ApplicationIntent = "applicationintent"
FailoverPartner = "failoverpartner"
FailOverPort = "failoverport"
DisableRetry = "disableretry"
Server = "server"
Protocol = "protocol"
DialTimeout = "dial timeout"
Pipe = "pipe"
MultiSubnetFailover = "multisubnetfailover"
)
type Config struct {
Port uint64
Host string
Instance string
Database string
User string
Password string
Encryption Encryption
TLSConfig *tls.Config
FailOverPartner string
FailOverPort uint64
// If true the TLSConfig servername should use the routed server.
HostInCertificateProvided bool
// Read Only intent for application database.
// NOTE: This does not make queries to most databases read-only.
ReadOnlyIntent bool
LogFlags Log
ServerSPN string
Workstation string
AppName string
// If true disables database/sql's automatic retry of queries
// that start on bad connections.
DisableRetry bool
// Do not use the following.
DialTimeout time.Duration // DialTimeout defaults to 15s per protocol. Set negative to disable.
ConnTimeout time.Duration // Use context for timeouts.
KeepAlive time.Duration // Leave at default.
PacketSize uint16
Parameters map[string]string
// Protocols is an ordered list of protocols to dial
Protocols []string
// ProtocolParameters are written by non-tcp ProtocolParser implementations
ProtocolParameters map[string]interface{}
// BrowserMsg is the message identifier to fetch instance data from SQL browser
BrowserMessage BrowserMsg
// ChangePassword is used to set the login's password during login. Ignored for non-SQL authentication.
ChangePassword string
//ColumnEncryption is true if the application needs to decrypt or encrypt Always Encrypted values
ColumnEncryption bool
// Attempt to connect to all IPs in parallel when MultiSubnetFailover is true
MultiSubnetFailover bool
}
func readDERFile(filename string) ([]byte, error) {
derBytes, err := os.ReadFile(filename)
if err != nil {
return nil, err
}
cert, err := x509.ParseCertificate(derBytes)
if err != nil {
return nil, err
}
pemBytes := pem.EncodeToMemory(&pem.Block{
Type: "CERTIFICATE",
Bytes: cert.Raw,
})
return pemBytes, nil
}
func readCertificate(certificate string) ([]byte, error) {
certType := strings.ToLower(filepath.Ext(certificate))
switch certType {
case ".pem":
return os.ReadFile(certificate)
case ".der":
return readDERFile(certificate)
default:
return nil, fmt.Errorf("certificate type %s is not supported", certType)
}
}
// Build a tls.Config object from the supplied certificate.
func SetupTLS(certificate string, insecureSkipVerify bool, hostInCertificate string, minTLSVersion string) (*tls.Config, error) {
config := tls.Config{
ServerName: hostInCertificate,
InsecureSkipVerify: insecureSkipVerify,
// fix for https://github.com/io1o/go-mssqldb/issues/166
// Go implementation of TLS payload size heuristic algorithm splits single TDS package to multiple TCP segments,
// while SQL Server seems to expect one TCP segment per encrypted TDS package.
// Setting DynamicRecordSizingDisabled to true disables that algorithm and uses 16384 bytes per TLS package
DynamicRecordSizingDisabled: true,
MinVersion: TLSVersionFromString(minTLSVersion),
}
if len(certificate) == 0 {
return &config, nil
}
pem, err := readCertificate(certificate)
if err != nil {
return nil, fmt.Errorf("cannot read certificate %q: %w", certificate, err)
}
if strings.Contains(config.ServerName, ":") && !insecureSkipVerify {
err := setupTLSCommonName(&config, pem)
if err != skipSetup {
return &config, err
}
}
certs := x509.NewCertPool()
certs.AppendCertsFromPEM(pem)
config.RootCAs = certs
return &config, nil
}
// Parse and handle encryption parameters. If encryption is desired, it returns the corresponding tls.Config object.
func parseTLS(params map[string]string, host string) (Encryption, *tls.Config, error) {
trustServerCert := false
var encryption Encryption = EncryptionOff
encrypt, ok := params[Encrypt]
if ok {
encrypt = strings.ToLower(encrypt)
switch encrypt {
case "mandatory", "yes", "1", "t", "true":
encryption = EncryptionRequired
case "disable":
encryption = EncryptionDisabled
case "strict":
encryption = EncryptionStrict
case "optional", "no", "0", "f", "false":
encryption = EncryptionOff
default:
f := "invalid encrypt '%s'"
return encryption, nil, fmt.Errorf(f, encrypt)
}
} else {
trustServerCert = true
}
trust, ok := params[TrustServerCertificate]
if ok {
var err error
trustServerCert, err = strconv.ParseBool(trust)
if err != nil {
f := "invalid trust server certificate '%s': %s"
return encryption, nil, fmt.Errorf(f, trust, err.Error())
}
}
certificate := params[Certificate]
if encryption != EncryptionDisabled {
tlsMin := params[TLSMin]
if encrypt == "strict" {
trustServerCert = false
}
tlsConfig, err := SetupTLS(certificate, trustServerCert, host, tlsMin)
if err != nil {
return encryption, nil, fmt.Errorf("failed to setup TLS: %w", err)
}
return encryption, tlsConfig, nil
}
return encryption, nil, nil
}
var skipSetup = errors.New("skip setting up TLS")
func getDsnType(dsn string) int {
if strings.HasPrefix(dsn, "sqlserver://") {
return DsnTypeURL
}
if strings.HasPrefix(dsn, "odbc:") {
return DsnTypeOdbc
}
return DsnTypeAdo
}
func getDsnParams(dsn string) (map[string]string, error) {
var params map[string]string
var err error
switch getDsnType(dsn) {
case DsnTypeOdbc:
params, err = splitConnectionStringOdbc(dsn[len("odbc:"):])
if err != nil {
return params, err
}
case DsnTypeURL:
params, err = splitConnectionStringURL(dsn)
if err != nil {
return params, err
}
default:
params = splitConnectionString(dsn)
}
return params, nil
}
func Parse(dsn string) (Config, error) {
p := Config{
ProtocolParameters: map[string]interface{}{},
Protocols: []string{},
}
var params map[string]string
var err error
params, err = getDsnParams(dsn)
if err != nil {
return p, err
}
p.Parameters = params
strlog, ok := params[LogParam]
if ok {
flags, err := strconv.ParseUint(strlog, 10, 64)
if err != nil {
return p, fmt.Errorf("invalid log parameter '%s': %s", strlog, err.Error())
}
p.LogFlags = Log(flags)
}
p.Database = params[Database]
p.User = params[UserID]
p.Password = params[Password]
p.ChangePassword = params[ChangePassword]
p.Port = 0
strport, ok := params[Port]
if ok {
var err error
p.Port, err = strconv.ParseUint(strport, 10, 16)
if err != nil {
f := "invalid tcp port '%v': %v"
return p, fmt.Errorf(f, strport, err.Error())
}
}
// https://docs.microsoft.com/en-us/sql/database-engine/configure-windows/configure-the-network-packet-size-server-configuration-option\
strpsize, ok := params[PacketSize]
if ok {
var err error
psize, err := strconv.ParseUint(strpsize, 0, 16)
if err != nil {
f := "invalid packet size '%v': %v"
return p, fmt.Errorf(f, strpsize, err.Error())
}
// Ensure packet size falls within the TDS protocol range of 512 to 32767 bytes
// NOTE: Encrypted connections have a maximum size of 16383 bytes. If you request
// a higher packet size, the server will respond with an ENVCHANGE request to
// alter the packet size to 16383 bytes.
p.PacketSize = uint16(psize)
if p.PacketSize < 512 {
p.PacketSize = 512
} else if p.PacketSize > 32767 {
p.PacketSize = 32767
}
}
// https://msdn.microsoft.com/en-us/library/dd341108.aspx
//
// Do not set a connection timeout. Use Context to manage such things.
// Default to zero, but still allow it to be set.
if strconntimeout, ok := params[ConnectionTimeout]; ok {
timeout, err := strconv.ParseUint(strconntimeout, 10, 64)
if err != nil {
f := "invalid connection timeout '%v': %v"
return p, fmt.Errorf(f, strconntimeout, err.Error())
}
p.ConnTimeout = time.Duration(timeout) * time.Second
}
// default keep alive should be 30 seconds according to spec:
// https://msdn.microsoft.com/en-us/library/dd341108.aspx
p.KeepAlive = 30 * time.Second
if keepAlive, ok := params[KeepAlive]; ok {
timeout, err := strconv.ParseUint(keepAlive, 10, 64)
if err != nil {
f := "invalid keepAlive value '%s': %s"
return p, fmt.Errorf(f, keepAlive, err.Error())
}
p.KeepAlive = time.Duration(timeout) * time.Second
}
serverSPN, ok := params[ServerSpn]
if ok {
p.ServerSPN = serverSPN
} // If not set by the app, ServerSPN will be set by the successful dialer.
workstation, ok := params[WorkstationID]
if ok {
p.Workstation = workstation
} else {
workstation, err := os.Hostname()
if err == nil {
p.Workstation = workstation
}
}
appname, ok := params[AppName]
if !ok {
appname = "go-mssqldb"
}
p.AppName = appname
appintent, ok := params[ApplicationIntent]
if ok {
if appintent == "ReadOnly" {
if p.Database == "" {
return p, fmt.Errorf("database must be specified when ApplicationIntent is ReadOnly")
}
p.ReadOnlyIntent = true
}
}
failOverPartner, ok := params[FailoverPartner]
if ok {
p.FailOverPartner = failOverPartner
}
failOverPort, ok := params[FailOverPort]
if ok {
var err error
p.FailOverPort, err = strconv.ParseUint(failOverPort, 0, 16)
if err != nil {
f := "invalid failover port '%v': %v"
return p, fmt.Errorf(f, failOverPort, err.Error())
}
}
disableRetry, ok := params[DisableRetry]
if ok {
var err error
p.DisableRetry, err = strconv.ParseBool(disableRetry)
if err != nil {
f := "invalid disableRetry '%s': %s"
return p, fmt.Errorf(f, disableRetry, err.Error())
}
} else {
p.DisableRetry = disableRetryDefault
}
server := params[Server]
protocol, ok := params[Protocol]
for _, parser := range ProtocolParsers {
if (!ok && !parser.Hidden()) || parser.Protocol() == protocol {
err = parser.ParseServer(server, &p)
if err != nil {
// if the caller only wants this protocol , fail right away
if ok {
return p, err
}
} else {
// Only enable a protocol if it can handle the server name
p.Protocols = append(p.Protocols, parser.Protocol())
}
}
}
if ok && len(p.Protocols) == 0 {
return p, fmt.Errorf("No protocol handler is available for protocol: '%s'", protocol)
}
f := len(p.Protocols)
if f == 0 {
f = 1
}
p.DialTimeout = time.Duration(15*f) * time.Second
if strdialtimeout, ok := params[DialTimeout]; ok {
timeout, err := strconv.ParseUint(strdialtimeout, 10, 64)
if err != nil {
f := "invalid dial timeout '%v': %v"
return p, fmt.Errorf(f, strdialtimeout, err.Error())
}
p.DialTimeout = time.Duration(timeout) * time.Second
}
hostInCertificate, ok := params[HostNameInCertificate]
if ok {
p.HostInCertificateProvided = true
} else {
hostInCertificate = p.Host
p.HostInCertificateProvided = false
}
p.Encryption, p.TLSConfig, err = parseTLS(params, hostInCertificate)
if err != nil {
return p, err
}
if c, ok := params["columnencryption"]; ok {
columnEncryption, err := strconv.ParseBool(c)
if err != nil {
if strings.EqualFold(c, "Enabled") {
columnEncryption = true
} else if strings.EqualFold(c, "Disabled") {
columnEncryption = false
} else {
return p, fmt.Errorf("invalid columnencryption '%v' : %v", columnEncryption, err.Error())
}
}
p.ColumnEncryption = columnEncryption
}
msf, ok := params[MultiSubnetFailover]
if ok {
multiSubnetFailover, err := strconv.ParseBool(msf)
if err != nil {
if strings.EqualFold(msf, "Enabled") {
multiSubnetFailover = true
} else if strings.EqualFold(msf, "Disabled") {
multiSubnetFailover = false
} else {
return p, fmt.Errorf("invalid multiSubnetFailover value '%v': %v", multiSubnetFailover, err.Error())
}
}
p.MultiSubnetFailover = multiSubnetFailover
} else {
// Defaulting to true to prevent breaking change although other client libraries default to false
p.MultiSubnetFailover = true
}
return p, nil
}
// convert connectionParams to url style connection string
// used mostly for testing
func (p Config) URL() *url.URL {
q := url.Values{}
if p.Database != "" {
q.Add(Database, p.Database)
}
if p.LogFlags != 0 {
q.Add(LogParam, strconv.FormatUint(uint64(p.LogFlags), 10))
}
host := p.Host
protocol := ""
// Can't just check for a : because of IPv6 host names
if strings.HasPrefix(host, "admin") || strings.HasPrefix(host, "np") || strings.HasPrefix(host, "sm") || strings.HasPrefix(host, "tcp") {
hostParts := strings.SplitN(p.Host, ":", 2)
if len(hostParts) > 1 {
host = hostParts[1]
protocol = hostParts[0]
}
}
if p.Port > 0 {
host = fmt.Sprintf("%s:%d", host, p.Port)
}
q.Add(DisableRetry, fmt.Sprintf("%t", p.DisableRetry))
protocolParam, ok := p.Parameters[Protocol]
if ok {
if protocol != "" && protocolParam != protocol {
panic("Mismatched protocol parameters!")
}
protocol = protocolParam
}
if protocol != "" {
q.Add(Protocol, protocol)
}
pipe, ok := p.Parameters[Pipe]
if ok {
q.Add(Pipe, pipe)
}
res := url.URL{
Scheme: "sqlserver",
Host: host,
User: url.UserPassword(p.User, p.Password),
}
if p.Instance != "" {
res.Path = p.Instance
}
q.Add(DialTimeout, strconv.FormatFloat(float64(p.DialTimeout.Seconds()), 'f', 0, 64))
switch p.Encryption {
case EncryptionDisabled:
q.Add(Encrypt, "DISABLE")
case EncryptionRequired:
q.Add(Encrypt, "true")
}
if p.ColumnEncryption {
q.Add("columnencryption", "true")
}
if len(q) > 0 {
res.RawQuery = q.Encode()
}
return &res
}
// ADO connection string keywords at https://github.com/dotnet/SqlClient/blob/main/src/Microsoft.Data.SqlClient/src/Microsoft/Data/Common/DbConnectionStringCommon.cs
var adoSynonyms = map[string]string{
"application name": AppName,
"data source": Server,
"address": Server,
"network address": Server,
"addr": Server,
"user": UserID,
"uid": UserID,
"initial catalog": Database,
"column encryption setting": "columnencryption",
}
func splitConnectionString(dsn string) (res map[string]string) {
res = map[string]string{}
parts := strings.Split(dsn, ";")
for _, part := range parts {
if len(part) == 0 {
continue
}
lst := strings.SplitN(part, "=", 2)
name := strings.TrimSpace(strings.ToLower(lst[0]))
if len(name) == 0 {
continue
}
var value string = ""
if len(lst) > 1 {
value = strings.TrimSpace(lst[1])
}
synonym, hasSynonym := adoSynonyms[name]
if hasSynonym {
name = synonym
}
// "server" in ADO can include a protocol and a port.
if name == Server {
for _, parser := range ProtocolParsers {
prot := parser.Protocol() + ":"
if strings.HasPrefix(value, prot) {
res[Protocol] = parser.Protocol()
}
value = strings.TrimPrefix(value, prot)
}
serverParts := strings.Split(value, ",")
if len(serverParts) == 2 && len(serverParts[1]) > 0 {
value = serverParts[0]
res[Port] = serverParts[1]
}
}
res[name] = value
}
return res
}
// Splits a URL of the form sqlserver://username:password@host/instance?param1=value¶m2=value
func splitConnectionStringURL(dsn string) (map[string]string, error) {
res := map[string]string{}
u, err := url.Parse(dsn)
if err != nil {
return res, err
}
if u.Scheme != "sqlserver" {
return res, fmt.Errorf("scheme %s is not recognized", u.Scheme)
}
if u.User != nil {
res[UserID] = u.User.Username()
p, exists := u.User.Password()
if exists {
res[Password] = p
}
}
host, port, err := net.SplitHostPort(u.Host)
if err != nil {
host = u.Host
}
if len(u.Path) > 0 {
res[Server] = host + "\\" + u.Path[1:]
} else {
res[Server] = host
}
if len(port) > 0 {
res[Port] = port
}
query := u.Query()
for k, v := range query {
if len(v) > 1 {
return res, fmt.Errorf("key %s provided more than once", k)
}
res[strings.ToLower(k)] = v[0]
}
return res, nil
}
// Splits a URL in the ODBC format
func splitConnectionStringOdbc(dsn string) (map[string]string, error) {
res := map[string]string{}
type parserState int
const (
// Before the start of a key
parserStateBeforeKey parserState = iota
// Inside a key
parserStateKey
// Beginning of a value. May be bare or braced
parserStateBeginValue
// Inside a bare value
parserStateBareValue
// Inside a braced value
parserStateBracedValue
// A closing brace inside a braced value.
// May be the end of the value or an escaped closing brace, depending on the next character
parserStateBracedValueClosingBrace
// After a value. Next character should be a semicolon or whitespace.
parserStateEndValue
)
var state = parserStateBeforeKey
var key string
var value string
for i, c := range dsn {
switch state {
case parserStateBeforeKey:
switch {
case c == '=':
return res, fmt.Errorf("unexpected character = at index %d. Expected start of key or semi-colon or whitespace", i)
case !unicode.IsSpace(c) && c != ';':
state = parserStateKey
key += string(c)
}
case parserStateKey:
switch c {
case '=':
key = normalizeOdbcKey(key)
state = parserStateBeginValue
case ';':
// Key without value
key = normalizeOdbcKey(key)
res[key] = value
key = ""
value = ""
state = parserStateBeforeKey
default:
key += string(c)
}
case parserStateBeginValue:
switch {
case c == '{':
state = parserStateBracedValue
case c == ';':
// Empty value
res[key] = value
key = ""
state = parserStateBeforeKey
case unicode.IsSpace(c):
// Ignore whitespace
default:
state = parserStateBareValue
value += string(c)
}
case parserStateBareValue:
if c == ';' {
res[key] = strings.TrimRightFunc(value, unicode.IsSpace)
key = ""
value = ""
state = parserStateBeforeKey
} else {
value += string(c)
}
case parserStateBracedValue:
if c == '}' {
state = parserStateBracedValueClosingBrace
} else {
value += string(c)
}
case parserStateBracedValueClosingBrace:
if c == '}' {
// Escaped closing brace
value += string(c)
state = parserStateBracedValue
continue
}
// End of braced value
res[key] = value
key = ""
value = ""
// This character is the first character past the end,
// so it needs to be parsed like the parserStateEndValue state.
state = parserStateEndValue
switch {
case c == ';':
state = parserStateBeforeKey
case unicode.IsSpace(c):
// Ignore whitespace
default:
return res, fmt.Errorf("unexpected character %c at index %d. Expected semi-colon or whitespace", c, i)
}
case parserStateEndValue:
switch {
case c == ';':
state = parserStateBeforeKey
case unicode.IsSpace(c):
// Ignore whitespace
default:
return res, fmt.Errorf("unexpected character %c at index %d. Expected semi-colon or whitespace", c, i)
}
}
}
switch state {
case parserStateBeforeKey: // Okay
case parserStateKey: // Unfinished key. Treat as key without value.
key = normalizeOdbcKey(key)
res[key] = value
case parserStateBeginValue: // Empty value
res[key] = value
case parserStateBareValue:
res[key] = strings.TrimRightFunc(value, unicode.IsSpace)
case parserStateBracedValue:
return res, fmt.Errorf("unexpected end of braced value at index %d", len(dsn))
case parserStateBracedValueClosingBrace: // End of braced value
res[key] = value
case parserStateEndValue: // Okay
}
return res, nil
}
// Normalizes the given string as an ODBC-format key
func normalizeOdbcKey(s string) string {
return strings.ToLower(strings.TrimRightFunc(s, unicode.IsSpace))
}
// ProtocolParser can populate Config with parameters to dial using its protocol
type ProtocolParser interface {
// ParseServer updates the Config with protocol properties from the server. Returns an error if the server isn't compatible.
ParseServer(server string, p *Config) error
// Protocol returns the name of the protocol dialer
Protocol() string
// Hidden returns true if this protocol must be explicitly chosen by the application
Hidden() bool
}
// ProtocolParsers is an ordered list of protocols that can be dialed. Each parser must have a corresponding Dialer in mssql.ProtocolDialers
var ProtocolParsers []ProtocolParser = []ProtocolParser{
tcpParser{Prefix: "tcp"},
tcpParser{Prefix: "admin"},
}
type tcpParser struct {
Prefix string
}
func (t tcpParser) Hidden() bool {
return t.Prefix == "admin"
}
func (t tcpParser) ParseServer(server string, p *Config) error {
// a server name can have different forms
parts := strings.SplitN(server, `\`, 2)
p.Host = parts[0]
if p.Host == "." || strings.ToUpper(p.Host) == "(LOCAL)" || p.Host == "" {
p.Host = "localhost"
}
if len(parts) > 1 {
p.Instance = parts[1]
}
if t.Prefix == "admin" {
if p.Instance == "" {
p.Port = 1434
}
p.BrowserMessage = BrowserDAC
} else {
p.BrowserMessage = BrowserAllInstances
}
return nil
}
func (t tcpParser) Protocol() string {
return t.Prefix
}