fix: correctly expand default bash env syntax

Signed-off-by: Valery Piashchynski <[email protected]>

1 files changed, 133 insertions, 6 deletions

diff --git a/internal/rpc/client.go b/internal/rpc/client.go
index 2fe63407..7b3d8f5d 100644
--- a/internal/rpc/client.go
+++ b/internal/rpc/client.go
@@ -18,6 +18,8 @@ import (
 const (
 	prefix string = "rr"
 	rpcKey string = "rpc.listen"
+	// default envs
+	envDefault = ":-"
 )
 
 // NewClient creates client ONLY for internal usage (communication between our application with RR side).
@@ -35,12 +37,7 @@ func NewClient(cfg string, flags []string) (*rpc.Client, error) {
 	}
 
 	// automatically inject ENV variables using ${ENV} pattern
-	for _, key := range v.AllKeys() {
-		val := v.Get(key)
-		if s, ok := val.(string); ok {
-			v.Set(key, os.ExpandEnv(s))
-		}
-	}
+	expandEnvViper(v)
 
 	// override config Flags
 	if len(flags) > 0 {
@@ -108,3 +105,133 @@ func parseValue(value string) string {
 
 	return value
 }
+
+// ExpandVal replaces ${var} or $var in the string based on the mapping function.
+// For example, os.ExpandEnv(s) is equivalent to os.Expand(s, os.Getenv).
+func ExpandVal(s string, mapping func(string) string) string {
+	var buf []byte
+	// ${} is all ASCII, so bytes are fine for this operation.
+	i := 0
+	for j := 0; j < len(s); j++ {
+		if s[j] == '$' && j+1 < len(s) {
+			if buf == nil {
+				buf = make([]byte, 0, 2*len(s))
+			}
+			buf = append(buf, s[i:j]...)
+			name, w := getShellName(s[j+1:])
+			if name == "" && w > 0 { //nolint:revive
+				// Encountered invalid syntax; eat the
+				// characters.
+			} else if name == "" {
+				// Valid syntax, but $ was not followed by a
+				// name. Leave the dollar character untouched.
+				buf = append(buf, s[j])
+				// parse default syntax
+			} else if idx := strings.Index(s, envDefault); idx != -1 {
+				// ${key:=default} or ${key:-val}
+				substr := strings.Split(name, envDefault)
+				if len(substr) != 2 {
+					return ""
+				}
+
+				key := substr[0]
+				defaultVal := substr[1]
+
+				res := mapping(key)
+				if res == "" {
+					res = defaultVal
+				}
+
+				buf = append(buf, res...)
+			} else {
+				buf = append(buf, mapping(name)...)
+			}
+			j += w
+			i = j + 1
+		}
+	}
+	if buf == nil {
+		return s
+	}
+	return string(buf) + s[i:]
+}
+
+// getShellName returns the name that begins the string and the number of bytes
+// consumed to extract it. If the name is enclosed in {}, it's part of a ${}
+// expansion and two more bytes are needed than the length of the name.
+func getShellName(s string) (string, int) {
+	switch {
+	case s[0] == '{':
+		if len(s) > 2 && isShellSpecialVar(s[1]) && s[2] == '}' {
+			return s[1:2], 3
+		}
+		// Scan to closing brace
+		for i := 1; i < len(s); i++ {
+			if s[i] == '}' {
+				if i == 1 {
+					return "", 2 // Bad syntax; eat "${}"
+				}
+				return s[1:i], i + 1
+			}
+		}
+		return "", 1 // Bad syntax; eat "${"
+	case isShellSpecialVar(s[0]):
+		return s[0:1], 1
+	}
+	// Scan alphanumerics.
+	var i int
+	for i = 0; i < len(s) && isAlphaNum(s[i]); i++ { //nolint:revive
+
+	}
+	return s[:i], i
+}
+
+func expandEnvViper(v *viper.Viper) {
+	for _, key := range v.AllKeys() {
+		val := v.Get(key)
+		switch t := val.(type) {
+		case string:
+			// for string expand it
+			v.Set(key, parseEnvDefault(t))
+		case []any:
+			// for slice -> check if it's a slice of strings
+			strArr := make([]string, 0, len(t))
+			for i := 0; i < len(t); i++ {
+				if valStr, ok := t[i].(string); ok {
+					strArr = append(strArr, parseEnvDefault(valStr))
+					continue
+				}
+
+				v.Set(key, val)
+			}
+
+			// we should set the whole array
+			if len(strArr) > 0 {
+				v.Set(key, strArr)
+			}
+		default:
+			v.Set(key, val)
+		}
+	}
+}
+
+// isShellSpecialVar reports whether the character identifies a special
+// shell variable such as $*.
+func isShellSpecialVar(c uint8) bool {
+	switch c {
+	case '*', '#', '$', '@', '!', '?', '-', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
+		return true
+	}
+	return false
+}
+
+// isAlphaNum reports whether the byte is an ASCII letter, number, or underscore.
+func isAlphaNum(c uint8) bool {
+	return c == '_' || '0' <= c && c <= '9' || 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z'
+}
+
+func parseEnvDefault(val string) string {
+	// tcp://127.0.0.1:${RPC_PORT:-36643}
+	// for envs like this, part would be tcp://127.0.0.1:
+	return ExpandVal(val, os.Getenv)
+}