| 1 | package config |
| 2 | |
| 3 | import ( |
| 4 | "os" |
| 5 | "regexp" |
| 6 | "strings" |
| 7 | ) |
| 8 | |
| 9 | // varRef matches ${VAR} and ${VAR:-default}: a shell-style reference with an |
| 10 | // optional ":-default" fallback used when the variable is unset or empty. |
| 11 | var varRef = regexp.MustCompile(`\$\{([A-Za-z_][A-Za-z0-9_]*)(:-([^}]*))?\}`) |
| 12 | |
| 13 | type envLookup func(string) (string, bool) |
| 14 | |
| 15 | // ExpandVars substitutes ${VAR} / ${VAR:-default} references from the process |
| 16 | // environment. An unset variable with no default expands to "" (matching the |
| 17 | // MCP / Claude Code convention), so a missing secret yields an empty header |
| 18 | // rather than a literal "${TOKEN}" leaking onto the wire. |
| 19 | func ExpandVars(s string) string { |
| 20 | return expandVarsWithLookup(s, func(name string) (string, bool) { |
| 21 | v, ok := os.LookupEnv(name) |
| 22 | return v, ok && v != "" |
| 23 | }) |
| 24 | } |
| 25 | |
| 26 | func expandVarsWithLookup(s string, lookup envLookup) string { |
| 27 | if !strings.Contains(s, "${") { |
| 28 | return s |
| 29 | } |
| 30 | return varRef.ReplaceAllStringFunc(s, func(m string) string { |
| 31 | g := varRef.FindStringSubmatch(m) |
| 32 | name, hasDefault, def := g[1], g[2] != "", g[3] |
| 33 | if v, ok := lookup(name); ok { |
| 34 | return v |
| 35 | } |
| 36 | if hasDefault { |
| 37 | return def |
| 38 | } |
| 39 | return "" |
| 40 | }) |
| 41 | } |
| 42 | |
| 43 | func scopedEnvLookup(scoped map[string]string) envLookup { |
| 44 | return func(name string) (string, bool) { |
| 45 | if v, ok := os.LookupEnv(name); ok { |
| 46 | return v, v != "" |
| 47 | } |
| 48 | if v, ok := scoped[name]; ok && v != "" { |
| 49 | return v, true |
| 50 | } |
| 51 | return "", false |
| 52 | } |
| 53 | } |
| 54 | |
| 55 | func (c *Config) expandVars(s string) string { |
| 56 | if c == nil { |
| 57 | return ExpandVars(s) |
| 58 | } |
| 59 | return expandVarsWithLookup(s, scopedEnvLookup(c.expansionEnv)) |
| 60 | } |
| 61 | |
| 62 | // ExpandedPlugin returns a copy of e with ${VAR} references expanded across the |
| 63 | // command, args, env values, url, and header values — the fields Claude Code |
| 64 | // also expands. The entry itself is left untouched. |
| 65 | func (e PluginEntry) ExpandedPlugin() PluginEntry { |
| 66 | lookup := scopedEnvLookup(e.expansionEnv) |
| 67 | out := e |
| 68 | out.Command = expandVarsWithLookup(e.Command, lookup) |
| 69 | out.URL = expandVarsWithLookup(e.URL, lookup) |
| 70 | if len(e.Args) > 0 { |
| 71 | out.Args = make([]string, len(e.Args)) |
| 72 | for i, a := range e.Args { |
| 73 | out.Args[i] = expandVarsWithLookup(a, lookup) |
| 74 | } |
| 75 | } |
| 76 | out.Env = expandMap(e.Env, lookup) |
| 77 | out.Headers = expandMap(e.Headers, lookup) |
| 78 | return out |
| 79 | } |
| 80 | |
| 81 | func expandMap(m map[string]string, lookup envLookup) map[string]string { |
| 82 | if len(m) == 0 { |
| 83 | return m |
| 84 | } |
| 85 | out := make(map[string]string, len(m)) |
| 86 | for k, v := range m { |
| 87 | out[k] = expandVarsWithLookup(v, lookup) |
| 88 | } |
| 89 | return out |
| 90 | } |
| 91 |