headers: New 'request_header' directive; handle Host header specially

Before this change, only response headers could be manipulated with the
Caddyfile's 'header' directive.

Also handle the request Host header specially, since the Go standard
library treats it separately from the other header fields...

1 files changed, 57 insertions, 16 deletions

diff --git a/modules/caddyhttp/headers/caddyfile.go b/modules/caddyhttp/headers/caddyfile.go
index 12ec8a0..d806005 100644
--- a/modules/caddyhttp/headers/caddyfile.go
+++ b/modules/caddyhttp/headers/caddyfile.go
@@ -24,9 +24,11 @@ import (
 
 func init() {
 	httpcaddyfile.RegisterHandlerDirective("headers", parseCaddyfile)
+	httpcaddyfile.RegisterHandlerDirective("request_header", parseReqHdrCaddyfile)
 }
 
-// parseCaddyfile sets up the handler from Caddyfile tokens. Syntax:
+// parseCaddyfile sets up the handler for response headers from
+// Caddyfile tokens. Syntax:
 //
 //     headers [<matcher>] [[+|-]<field> <value>] {
 //         [+][<field>] [<value>]
@@ -43,9 +45,11 @@ func parseCaddyfile(h httpcaddyfile.Helper) (caddyhttp.MiddlewareHandler, error)
 		if h.NextArg() {
 			hasArgs = true
 			field := h.Val()
-			h.NextArg()
-			value := h.Val()
-			processCaddyfileLine(hdr, field, value)
+			var value string
+			if h.NextArg() {
+				value = h.Val()
+			}
+			processCaddyfileLineRespHdr(hdr, field, value)
 		}
 
 		// if not, they should be in a block
@@ -58,31 +62,68 @@ func parseCaddyfile(h httpcaddyfile.Helper) (caddyhttp.MiddlewareHandler, error)
 			if h.NextArg() {
 				value = h.Val()
 			}
-			processCaddyfileLine(hdr, field, value)
+			processCaddyfileLineRespHdr(hdr, field, value)
 		}
 	}
 	return hdr, nil
 }
 
-func processCaddyfileLine(hdr *Headers, field, value string) {
-	if strings.HasPrefix(field, "+") {
-		if hdr.Response == nil {
-			hdr.Response = &RespHeaderOps{HeaderOps: new(HeaderOps)}
+// parseReqHdrCaddyfile sets up the handler for request headers
+// from Caddyfile tokens. Syntax:
+//
+//     request_header [<matcher>] [[+|-]<field> <value>]
+//
+func parseReqHdrCaddyfile(h httpcaddyfile.Helper) (caddyhttp.MiddlewareHandler, error) {
+	hdr := new(Headers)
+	for h.Next() {
+		if !h.NextArg() {
+			return nil, h.ArgErr()
+		}
+		field := h.Val()
+		var value string
+		if h.NextArg() {
+			value = h.Val()
+		}
+
+		if hdr.Request == nil {
+			hdr.Request = new(HeaderOps)
+		}
+		if strings.HasPrefix(field, "+") {
+			if hdr.Request.Add == nil {
+				hdr.Request.Add = make(http.Header)
+			}
+			hdr.Request.Add.Set(field[1:], value)
+		} else if strings.HasPrefix(field, "-") {
+			hdr.Request.Delete = append(hdr.Request.Delete, field[1:])
+		} else {
+			if hdr.Request.Set == nil {
+				hdr.Request.Set = make(http.Header)
+			}
+			hdr.Request.Set.Set(field, value)
+		}
+
+		if h.NextArg() {
+			return nil, h.ArgErr()
+		}
+	}
+	return hdr, nil
+}
+
+func processCaddyfileLineRespHdr(hdr *Headers, field, value string) {
+	if hdr.Response == nil {
+		hdr.Response = &RespHeaderOps{
+			HeaderOps: new(HeaderOps),
+			Deferred:  true,
 		}
+	}
+	if strings.HasPrefix(field, "+") {
 		if hdr.Response.Add == nil {
 			hdr.Response.Add = make(http.Header)
 		}
 		hdr.Response.Add.Set(field[1:], value)
 	} else if strings.HasPrefix(field, "-") {
-		if hdr.Response == nil {
-			hdr.Response = &RespHeaderOps{HeaderOps: new(HeaderOps)}
-		}
 		hdr.Response.Delete = append(hdr.Response.Delete, field[1:])
-		hdr.Response.Deferred = true
 	} else {
-		if hdr.Response == nil {
-			hdr.Response = &RespHeaderOps{HeaderOps: new(HeaderOps)}
-		}
 		if hdr.Response.Set == nil {
 			hdr.Response.Set = make(http.Header)
 		}