redir: Redirect tables

Open a redir block to bulk-specify a bunch of redirects that share a status code

config/setup/redir.go

@@ -22,49 +22,124 @@ func Redir(c *Controller) (middleware.Middleware, error) {
 func redirParse(c *Controller) ([]redirect.Rule, error) {
 	var redirects []redirect.Rule
 
+	// setRedirCode sets the redirect code for rule if it can, or returns an error
+	setRedirCode := func(code string, rule *redirect.Rule) error {
+		if code == "meta" {
+			rule.Meta = true
+		} else if codeNumber, ok := httpRedirs[code]; ok {
+			rule.Code = codeNumber
+		} else {
+			return c.Errf("Invalid redirect code '%v'", code)
+		}
+		return nil
+	}
+
+	// checkAndSaveRule checks the rule for validity (except the redir code)
+	// and saves it if it's valid, or returns an error.
+	checkAndSaveRule := func(rule redirect.Rule) error {
+		if rule.From == rule.To {
+			return c.Err("'from' and 'to' values of redirect rule cannot be the same")
+		}
+
+		for _, otherRule := range redirects {
+			if otherRule.From == rule.From {
+				return c.Errf("rule with duplicate 'from' value: %s -> %s", otherRule.From, otherRule.To)
+			}
+		}
+
+		redirects = append(redirects, rule)
+		return nil
+	}
+
 	for c.Next() {
-		var rule redirect.Rule
 		args := c.RemainingArgs()
 
-		// Always set the default Code, then overwrite
-		rule.Code = http.StatusMovedPermanently
-
-		switch len(args) {
-		case 1:
-			// To specified
-			rule.From = "/"
-			rule.To = args[0]
-		case 2:
-			// To and Code specified
-			rule.From = "/"
-			rule.To = args[0]
-			if "meta" == args[1] {
-				rule.Meta = true
-			} else if code, ok := httpRedirs[args[1]]; !ok {
-				return redirects, c.Err("Invalid redirect code '" + args[1] + "'")
+		var hadOptionalBlock bool
+		for c.NextBlock() {
+			hadOptionalBlock = true
+
+			var rule redirect.Rule
+
+			// Set initial redirect code
+			// BUG: If the code is specified for a whole block and that code is invalid,
+			// the line number will appear on the first line inside the block, even if that
+			// line overwrites the block-level code with a valid redirect code. The program
+			// still functions correctly, but the line number in the error reporting is
+			// misleading to the user.
+			if len(args) == 1 {
+				err := setRedirCode(args[0], &rule)
+				if err != nil {
+					return redirects, err
+				}
 			} else {
-				rule.Code = code
+				rule.Code = http.StatusMovedPermanently // default code
 			}
-		case 3:
-			// From, To, and Code specified
-			rule.From = args[0]
-			rule.To = args[1]
-			if "meta" == args[2] {
-				rule.Meta = true
-			} else if code, ok := httpRedirs[args[2]]; !ok {
-				return redirects, c.Err("Invalid redirect code '" + args[2] + "'")
-			} else {
-				rule.Code = code
+
+			// RemainingArgs only gets the values after the current token, but in our
+			// case we want to include the current token to get an accurate count.
+			insideArgs := append([]string{c.Val()}, c.RemainingArgs()...)
+
+			switch len(insideArgs) {
+			case 1:
+				// To specified (catch-all redirect)
+				rule.From = "/"
+				rule.To = insideArgs[0]
+			case 2:
+				// From and To specified
+				rule.From = insideArgs[0]
+				rule.To = insideArgs[1]
+			case 3:
+				// From, To, and Code specified
+				rule.From = insideArgs[0]
+				rule.To = insideArgs[1]
+				err := setRedirCode(insideArgs[2], &rule)
+				if err != nil {
+					return redirects, err
+				}
+			default:
+				return redirects, c.ArgErr()
 			}
-		default:
-			return redirects, c.ArgErr()
-		}
 
-		if rule.From == rule.To {
-			return redirects, c.Err("Redirect rule cannot allow From and To arguments to be the same.")
+			err := checkAndSaveRule(rule)
+			if err != nil {
+				return redirects, err
+			}
 		}
 
-		redirects = append(redirects, rule)
+		if !hadOptionalBlock {
+			var rule redirect.Rule
+			rule.Code = http.StatusMovedPermanently // default
+
+			switch len(args) {
+			case 1:
+				// To specified (catch-all redirect)
+				rule.From = "/"
+				rule.To = args[0]
+			case 2:
+				// To and Code specified (catch-all redirect)
+				rule.From = "/"
+				rule.To = args[0]
+				err := setRedirCode(args[1], &rule)
+				if err != nil {
+					return redirects, err
+				}
+			case 3:
+				// From, To, and Code specified
+				rule.From = args[0]
+				rule.To = args[1]
+				err := setRedirCode(args[2], &rule)
+				if err != nil {
+					return redirects, err
+				}
+			default:
+				return redirects, c.ArgErr()
+			}
+
+			err := checkAndSaveRule(rule)
+			if err != nil {
+				return redirects, err
+			}
+		}
 	}
 
 	return redirects, nil
@@ -72,12 +147,12 @@ func redirParse(c *Controller) ([]redirect.Rule, error) {
 
 // httpRedirs is a list of supported HTTP redirect codes.
 var httpRedirs = map[string]int{
-	"300": 300,
-	"301": 301,
-	"302": 302,
-	"303": 303,
-	"304": 304,
-	"305": 305,
-	"307": 307,
-	"308": 308,
+	"300": 300, // Multiple Choices
+	"301": 301, // Moved Permanently
+	"302": 302, // Found (NOT CORRECT for "Temporary Redirect", see 307)
+	"303": 303, // See Other
+	"304": 304, // Not Modified
+	"305": 305, // Use Proxy
+	"307": 307, // Temporary Redirect
+	"308": 308, // Permanent Redirect
 }