fixes #745 HTTP server redirect handler

7 files changed, 358 insertions, 66 deletions

diff --git a/docs/man/nng_http_handler_alloc.3http.adoc b/docs/man/nng_http_handler_alloc.3http.adoc
index d5861d14..c01cd51b 100644
--- a/docs/man/nng_http_handler_alloc.3http.adoc
+++ b/docs/man/nng_http_handler_alloc.3http.adoc
@@ -31,6 +31,9 @@ int nng_http_handler_alloc_directory(nng_http_handler **hp, const char *path,
 int nng_http_handler_alloc_file(nng_http_handler **hp, const char *path,
     const char *filename);
 
+int nng_http_handler_alloc_redirect(nng_http_handler **hp, const char *path,
+    uint16_t status, const char *location);
+
 int nng_http_handler_alloc_static(nng_http_handler **hp, const char *path,
     const void *data, size_t size, const char *content_type);
 ----
@@ -48,7 +51,7 @@ Only the path component of the Request URI is
 considered when determining whether the handler should be called.
 
 Additionally each handler has a method it is registered to handle
-(the default is "GET", see
+(the default is `GET`, see
 `<<nng_http_handler_set_method.3http#,nng_http_handler_set_method()>>`), and
 optionally a 'Host' header it can be matched against (see
 `<<nng_http_handler_set_host.3http#,nng_http_handler_set_host()>>`).
@@ -123,9 +126,30 @@ of the requested file name.
 If a content type cannot be determined from
 the extension, then `application/octet-stream` is used.
 
+=== Redirect Handler
+
+The fourth member is used to arrange for a server redirect from one
+URL to another.
+The reply will be with status code __status__, which should be a 3XX
+code such as 301, and a `Location:` header will contain the URL
+referenced by __location__, with any residual suffix from the request
+URI appended.
+
+TIP: Use `<<nng_http_handler_set_tree#,nng_http_handler_set_tree()>>`
+to redirect an entire tree.
+For example, it is possible to redirect an entire HTTP site to another
+HTTPS site by specifying `/` as the path and then using the base
+of the new site, such as `https://newsite.example.com` as the
+new location.
+
+TIP: Be sure to use the appropriate value for __status__.
+Permanent redirection should use 301 and temporary redirections should use 307.
+In REST APIs, using a redirection to supply the new location of an object
+created with `POST` should use 303.
+
 === Static Handler
 
-The fourth member of this family, `nng_http_handler_alloc_static()`, creates
+The fifth member of this family, `nng_http_handler_alloc_static()`, creates
 a handler to serve up fixed content located in program data.
 The client is
 sent the _data_, with `Content-Length` of _size_ bytes, and `Content-Type` of
@@ -133,7 +157,7 @@ __content_type__.
 
 == RETURN VALUES
 
-This function returns 0 on success, and non-zero otherwise.
+These functions return 0 on success, and non-zero otherwise.
 
 == ERRORS
 
diff --git a/src/supplemental/http/http.h b/src/supplemental/http/http.h
index d9edd5c8..d0854981 100644
--- a/src/supplemental/http/http.h
+++ b/src/supplemental/http/http.h
@@ -328,6 +328,12 @@ NNG_DECL int nng_http_handler_alloc_file(
 NNG_DECL int nng_http_handler_alloc_static(
     nng_http_handler **, const char *, const void *, size_t, const char *);
 
+// nng_http_handler_alloc_redirect creates an HTTP redirect handler.
+// The status is given, along with the new URL.  If the status is 0,
+// then 301 will be used instead.
+NNG_DECL int nng_http_handler_alloc_redirect(
+    nng_http_handler **, const char *, uint16_t, const char *);
+
 // nng_http_handler_alloc_file creates a "directory" based handler, that
 // serves up static content from the given directory tree.  Directories
 // that contain an index.html or index.htm file use that file for the
diff --git a/src/supplemental/http/http_api.h b/src/supplemental/http/http_api.h
index a30399d2..14e842be 100644
--- a/src/supplemental/http/http_api.h
+++ b/src/supplemental/http/http_api.h
@@ -121,6 +121,13 @@ extern int         nni_http_res_set_reason(nni_http_res *, const char *);
 // the HTML body with customized content if it exists.
 extern bool nni_http_res_is_error(nni_http_res *);
 
+// nni_http_alloc_html_error allocates a string corresponding to an
+// HTML error.  This can be set as the body of the res.  The status
+// will be looked up using HTTP status code lookups, but the details
+// will be added if present as further body text.  The result can
+// be freed with nni_strfree() later.
+extern int nni_http_alloc_html_error(char **, uint16_t, const char *);
+
 extern void nni_http_read(nni_http_conn *, nni_aio *);
 extern void nni_http_read_full(nni_http_conn *, nni_aio *);
 extern void nni_http_write(nni_http_conn *, nni_aio *);
@@ -214,7 +221,7 @@ extern int nni_http_hijack(nni_http_conn *);
 //
 // The callback function will receive the following arguments (via
 // nng_aio_get_input(): nni_http_request *, nni_http_handler *, and
-// nni_http_context_t *.  The first is a request object, for convenience.
+// nni_http_conn_t *.  The first is a request object, for convenience.
 // The second is the handler, from which the callback can obtain any other
 // data it has set.  The final is the http context, from which its possible
 // to hijack the session.
@@ -244,6 +251,10 @@ extern int nni_http_handler_init_directory(
 extern int nni_http_handler_init_static(
     nni_http_handler **, const char *, const void *, size_t, const char *);
 
+// nni_http_handler_init_redirect creates a handler that redirects the request.
+extern int nni_http_handler_init_redirect(
+    nni_http_handler **, const char *, uint16_t, const char *);
+
 // nni_http_handler_fini destroys a handler.  This should only be done before
 // the handler is added, or after it is deleted.  The server automatically
 // calls this for any handlers still registered with it if it is destroyed.
diff --git a/src/supplemental/http/http_msg.c b/src/supplemental/http/http_msg.c
index 3b78a2a9..da60c746 100644
--- a/src/supplemental/http/http_msg.c
+++ b/src/supplemental/http/http_msg.c
@@ -128,15 +128,19 @@ nni_http_res_reset(nni_http_res *res)
 void
 nni_http_req_free(nni_http_req *req)
 {
-	nni_http_req_reset(req);
-	NNI_FREE_STRUCT(req);
+	if (req != NULL) {
+		nni_http_req_reset(req);
+		NNI_FREE_STRUCT(req);
+	}
 }
 
 void
 nni_http_res_free(nni_http_res *res)
 {
-	nni_http_res_reset(res);
-	NNI_FREE_STRUCT(res);
+	if (res != NULL) {
+		nni_http_res_reset(res);
+		NNI_FREE_STRUCT(res);
+	}
 }
 
 static int
@@ -1012,36 +1016,49 @@ nni_http_res_set_reason(nni_http_res *res, const char *reason)
 }
 
 int
+nni_http_alloc_html_error(char **html, uint16_t code, const char *details)
+{
+	const char *rsn = nni_http_reason(code);
+
+	return (nni_asprintf(html,
+	    "<!DOCTYPE html>\n"
+	    "<html><head><title>%d %s</title>\n"
+	    "<style>"
+	    "body { font-family: Arial, sans serif; text-align: center }\n"
+	    "h1 { font-size: 36px; }"
+	    "span { background-color: gray; color: white; padding: 7px; "
+	    "border-radius: 5px }"
+	    "h2 { font-size: 24px; }"
+	    "p { font-size: 20px; }"
+	    "</style></head>"
+	    "<body><p>&nbsp;</p>"
+	    "<h1><span>%d</span></h1>"
+	    "<h2>%s</h2>"
+	    "<p>%s</p>"
+	    "</body></html>",
+	    code, rsn, code, rsn, details != NULL ? details : ""));
+}
+
+int
 nni_http_res_alloc_error(nni_http_res **resp, uint16_t err)
 {
-	char          html[512];
+	char *        html = NULL;
+	nni_http_res *res  = NULL;
 	int           rv;
-	nni_http_res *res;
 
-	if ((rv = nni_http_res_alloc(&res)) != 0) {
-		return (rv);
-	}
-
-	// very simple builtin error page
-	(void) snprintf(html, sizeof(html),
-	    "<head><title>%d %s</title></head>"
-	    "<body><p/><h1 align=\"center\">"
-	    "<span style=\"font-size: 36px; border-radius: 5px; "
-	    "background-color: black; color: white; padding: 7px; "
-	    "font-family: Arial, sans serif;\">%d</span></h1>"
-	    "<p align=\"center\">"
-	    "<span style=\"font-size: 24px; font-family: Arial, sans serif;\">"
-	    "%s</span></p></body>",
-	    err, nni_http_reason(err), err, nni_http_reason(err));
-
-	res->code = err;
-	if (((rv = nni_http_res_set_header(
+	if (((rv = nni_http_res_alloc(&res)) != 0) ||
+	    ((rv = nni_http_alloc_html_error(&html, err, NULL)) != 0) ||
+	    ((rv = nni_http_res_set_header(
 	          res, "Content-Type", "text/html; charset=UTF-8")) != 0) ||
 	    ((rv = nni_http_res_copy_data(res, html, strlen(html))) != 0)) {
+		nni_strfree(html);
 		nni_http_res_free(res);
 	} else {
+		nni_strfree(html);
+		res->code  = err;
 		res->iserr = true;
 		*resp      = res;
 	}
+
 	return (rv);
 }
diff --git a/src/supplemental/http/http_public.c b/src/supplemental/http/http_public.c
index b86521b0..50ef03fa 100644
--- a/src/supplemental/http/http_public.c
+++ b/src/supplemental/http/http_public.c
@@ -559,6 +559,21 @@ nng_http_handler_alloc_directory(
 }
 
 int
+nng_http_handler_alloc_redirect(
+    nng_http_handler **hp, const char *uri, uint16_t status, const char *where)
+{
+#ifdef NNG_SUPP_HTTP
+	return (nni_http_handler_init_redirect(hp, uri, status, where));
+#else
+	NNI_ARG_UNUSED(hp);
+	NNI_ARG_UNUSED(uri);
+	NNI_ARG_UNUSED(status);
+	NNI_ARG_UNUSED(where);
+	return (NNG_ENOTSUP);
+#endif
+}
+
+int
 nng_http_handler_alloc_static(nng_http_handler **hp, const char *uri,
     const void *data, size_t size, const char *ctype)
 {
diff --git a/src/supplemental/http/http_server.c b/src/supplemental/http/http_server.c
index 1a7f2c25..44c338f4 100644
--- a/src/supplemental/http/http_server.c
+++ b/src/supplemental/http/http_server.c
@@ -229,12 +229,8 @@ http_sconn_reap(void *arg)
 	if (sc->conn != NULL) {
 		nni_http_conn_fini(sc->conn);
 	}
-	if (sc->req != NULL) {
-		nni_http_req_free(sc->req);
-	}
-	if (sc->res != NULL) {
-		nni_http_res_free(sc->res);
-	}
+	nni_http_req_free(sc->req);
+	nni_http_res_free(sc->res);
 	nni_aio_fini(sc->rxaio);
 	nni_aio_fini(sc->txaio);
 	nni_aio_fini(sc->txdataio);
@@ -294,10 +290,8 @@ http_sconn_txdatdone(void *arg)
 		return;
 	}
 
-	if (sc->res != NULL) {
-		nni_http_res_free(sc->res);
-		sc->res = NULL;
-	}
+	nni_http_res_free(sc->res);
+	sc->res = NULL;
 
 	if (sc->close) {
 		http_sconn_close(sc);
@@ -325,10 +319,8 @@ http_sconn_txdone(void *arg)
 		return;
 	}
 
-	if (sc->res != NULL) {
-		nni_http_res_free(sc->res);
-		sc->res = NULL;
-	}
+	nni_http_res_free(sc->res);
+	sc->res     = NULL;
 	sc->handler = NULL;
 	nni_http_req_reset(sc->req);
 	nni_http_read_req(sc->conn, sc->req, sc->rxaio);
@@ -1089,10 +1081,10 @@ nni_http_server_res_error(nni_http_server *s, nni_http_res *res)
 {
 	http_error *epage;
 	char *      body = NULL;
+	char *      html = NULL;
 	size_t      len;
 	uint16_t    code = nni_http_res_get_status(res);
 	int         rv;
-	char        html[512];
 
 	nni_mtx_lock(&s->errors_mtx);
 	NNI_LIST_FOREACH (&s->errors, epage) {
@@ -1102,23 +1094,16 @@ nni_http_server_res_error(nni_http_server *s, nni_http_res *res)
 			break;
 		}
 	}
+	nni_mtx_unlock(&s->errors_mtx);
+
 	if (body == NULL) {
-		const char *reason = nni_http_reason(code);
-		// very simple builtin error page
-		(void) snprintf(html, sizeof(html),
-		    "<head><title>%d %s</title></head>"
-		    "<body><p/><h1 align=\"center\">"
-		    "<span style=\"font-size: 36px; border-radius: 5px; "
-		    "background-color: black; color: white; padding: 7px; "
-		    "font-family: Arial, sans serif;\">%d</span></h1>"
-		    "<p align=\"center\">"
-		    "<span style=\"font-size: 24px; font-family: Arial, sans "
-		    "serif;\">"
-		    "%s</span></p></body>",
-		    code, reason, code, reason);
+		if ((rv = nni_http_alloc_html_error(&html, code, NULL)) != 0) {
+			return (rv);
+		}
 		body = html;
 		len  = strlen(body);
 	}
+
 	// NB: The server lock has to be held here to guard against the
 	// error page being tossed or changed.
 	if (((rv = nni_http_res_copy_data(res, body, len)) == 0) &&
@@ -1126,8 +1111,8 @@ nni_http_server_res_error(nni_http_server *s, nni_http_res *res)
 	          res, "Content-Type", "text/html; charset=UTF-8")) == 0)) {
 		nni_http_res_set_status(res, code);
 	}
+	nni_strfree(html);
 
-	nni_mtx_unlock(&s->errors_mtx);
 	return (rv);
 }
 
@@ -1335,9 +1320,7 @@ http_handle_file(nni_aio *aio)
 	    ((rv = nni_http_res_set_header(res, "Content-Type", ctype)) !=
 	        0) ||
 	    ((rv = nni_http_res_copy_data(res, data, size)) != 0)) {
-		if (res != NULL) {
-			nni_http_res_free(res);
-		}
+		nni_http_res_free(res);
 		nni_free(data, size);
 		nni_aio_finish_error(aio, rv);
 		return;
@@ -1526,9 +1509,7 @@ http_handle_dir(nni_aio *aio)
 	    ((rv = nni_http_res_set_header(res, "Content-Type", ctype)) !=
 	        0) ||
 	    ((rv = nni_http_res_copy_data(res, data, size)) != 0)) {
-		if (res != NULL) {
-			nni_http_res_free(res);
-		}
+		nni_http_res_free(res);
 		nni_free(data, size);
 		nni_aio_finish_error(aio, rv);
 		return;
@@ -1573,6 +1554,130 @@ nni_http_handler_init_directory(
 	return (0);
 }
 
+typedef struct http_redirect {
+	uint16_t code;
+	char *   where;
+} http_redirect;
+
+static void
+http_handle_redirect(nni_aio *aio)
+{
+	nni_http_res *    r    = NULL;
+	char *            html = NULL;
+	char *            msg  = NULL;
+	char *            loc  = NULL;
+	http_redirect *   hr;
+	nni_http_handler *h;
+	int               rv;
+	nni_http_req *    req;
+	const char *      base;
+	const char *      uri;
+
+	req  = nni_aio_get_input(aio, 0);
+	h    = nni_aio_get_input(aio, 1);
+	base = nni_http_handler_get_uri(h); // base uri
+	uri  = nni_http_req_get_uri(req);
+
+	hr = nni_http_handler_get_data(h);
+
+	// If we are doing a full tree, then include the entire suffix.
+	if (strncmp(uri, base, strlen(base)) == 0) {
+		rv = nni_asprintf(&loc, "%s%s", hr->where, uri + strlen(base));
+		if (rv != 0) {
+			nni_aio_finish_error(aio, rv);
+			return;
+		}
+	} else {
+		loc = hr->where;
+	}
+
+	// Builtin redirect page
+	rv = nni_asprintf(&msg,
+	    "You should be automatically redirected to <a href=\"%s\">%s</a>.",
+	    loc, loc);
+
+	// Build a response.  We always close the connection for redirects,
+	// because it is probably going to another server.  This also
+	// keeps us from having to consume the entity body, we can just
+	// discard it.
+	if ((rv != 0) || ((rv = nni_http_res_alloc(&r)) != 0) ||
+	    ((rv = nni_http_alloc_html_error(&html, hr->code, msg)) != 0) ||
+	    ((rv = nni_http_res_set_status(r, hr->code)) != 0) ||
+	    ((rv = nni_http_res_set_header(r, "Connection", "close")) != 0) ||
+	    ((rv = nni_http_res_set_header(
+	          r, "Content-Type", "text/html; charset=UTF-8")) != 0) ||
+	    ((rv = nni_http_res_set_header(r, "Location", loc)) != 0) ||
+	    ((rv = nni_http_res_copy_data(r, html, strlen(html))) != 0)) {
+		if (loc != hr->where) {
+			nni_strfree(loc);
+		}
+		nni_strfree(msg);
+		nni_strfree(html);
+		nni_http_res_free(r);
+		nni_aio_finish_error(aio, rv);
+		return;
+	}
+	if (loc != hr->where) {
+		nni_strfree(loc);
+	}
+	nni_strfree(msg);
+	nni_strfree(html);
+	nni_aio_set_output(aio, 0, r);
+	nni_aio_finish(aio, 0, 0);
+}
+
+static void
+http_redirect_free(void *arg)
+{
+	http_redirect *hr;
+
+	if ((hr = arg) != NULL) {
+		nni_strfree(hr->where);
+		NNI_FREE_STRUCT(hr);
+	}
+}
+
+int
+nni_http_handler_init_redirect(nni_http_handler **hpp, const char *uri,
+    uint16_t status, const char *where)
+{
+	nni_http_handler *h;
+	int               rv;
+	http_redirect *   hr;
+
+	if ((hr = NNI_ALLOC_STRUCT(hr)) == NULL) {
+		return (NNG_ENOMEM);
+	}
+	if ((hr->where = nni_strdup(where)) == NULL) {
+		NNI_FREE_STRUCT(hr);
+		return (NNG_ENOMEM);
+	}
+	if (status == 0) {
+		status = NNG_HTTP_STATUS_STATUS_MOVED_PERMANENTLY;
+	}
+	hr->code = status;
+
+	if ((rv = nni_http_handler_init(&h, uri, http_handle_redirect)) != 0) {
+		http_redirect_free(hr);
+		return (rv);
+	}
+
+	if (((rv = nni_http_handler_set_method(h, NULL)) != 0) ||
+	    ((rv = nni_http_handler_set_data(h, hr, http_redirect_free)) !=
+	        0)) {
+		http_redirect_free(hr);
+		nni_http_handler_fini(h);
+		return (rv);
+	}
+
+	// We don't need to collect the body at all, because the handler
+	// just discards the content and closes the connection.
+	nni_http_handler_collect_body(h, false, 0);
+
+	*hpp = h;
+	return (0);
+}
+
 typedef struct http_static {
 	void * data;
 	size_t size;
@@ -1599,9 +1704,7 @@ http_handle_static(nni_aio *aio)
 	    ((rv = nni_http_res_set_header(r, "Content-Type", ctype)) != 0) ||
 	    ((rv = nni_http_res_set_status(r, NNG_HTTP_STATUS_OK)) != 0) ||
 	    ((rv = nni_http_res_set_data(r, hs->data, hs->size)) != 0)) {
-		if (r != NULL) {
-			nni_http_res_free(r);
-		}
+		nni_http_res_free(r);
 		nni_aio_finish_error(aio, rv);
 		return;
 	}
diff --git a/tests/httpserver.c b/tests/httpserver.c
index 21b961b8..1bf88f12 100644
--- a/tests/httpserver.c
+++ b/tests/httpserver.c
@@ -550,4 +550,120 @@ TestMain("HTTP Server", {
 			nng_url_free(curl);
 		});
 	});
+
+	Convey("Redirect handler works", {
+		char     urlstr[32];
+		nng_url *url;
+
+		trantest_next_address(urlstr, "http://127.0.0.1:%u");
+		So(nng_url_parse(&url, urlstr) == 0);
+		So(nng_http_server_hold(&s, url) == 0);
+
+		Reset({
+			nng_http_server_release(s);
+			nng_url_free(url);
+		});
+
+		Convey("GET redirect works", {
+			char          fullurl[256];
+			nng_http_req *req;
+			nng_http_res *res;
+			nng_url *     curl;
+			const char *  dest;
+			void *        data;
+			size_t        size;
+
+			So(nng_http_handler_alloc_redirect(&h, "/here", 301,
+			       "http://127.0.0.1/there") == 0);
+			So(nng_http_server_add_handler(s, h) == 0);
+			So(nng_http_server_start(s) == 0);
+			nng_msleep(100);
+
+			So(nng_http_res_alloc(&res) == 0);
+			snprintf(fullurl, sizeof(fullurl), "%s/here", urlstr);
+			So(nng_url_parse(&curl, fullurl) == 0);
+			So(nng_http_req_alloc(&req, curl) == 0);
+			So(nng_http_req_set_method(req, "GET") == 0);
+
+			So(httpdo(curl, req, res, &data, &size) == 0);
+			So(nng_http_res_get_status(res) == 301);
+			So((dest = nng_http_res_get_header(res, "Location")) !=
+			    NULL);
+			So(strcmp(dest, "http://127.0.0.1/there") == 0);
+			So(data != NULL);
+			So(size > 0);
+			nng_http_req_free(req);
+			nng_http_res_free(res);
+			nng_url_free(curl);
+		});
+
+		Convey("Tree redirect works", {
+			char          fullurl[256];
+			nng_http_req *req;
+			nng_http_res *res;
+			nng_url *     curl;
+			const char *  dest;
+			void *        data;
+			size_t        size;
+
+			// We'll use a 303 to ensure codes carry thru
+			So(nng_http_handler_alloc_redirect(&h, "/here", 303,
+			       "http://127.0.0.1/there") == 0);
+			So(nng_http_handler_set_tree(h) == 0);
+			So(nng_http_server_add_handler(s, h) == 0);
+			So(nng_http_server_start(s) == 0);
+			nng_msleep(100);
+
+			So(nng_http_res_alloc(&res) == 0);
+			snprintf(fullurl, sizeof(fullurl),
+			    "%s/here/i/go/again", urlstr);
+			So(nng_url_parse(&curl, fullurl) == 0);
+			So(nng_http_req_alloc(&req, curl) == 0);
+			So(nng_http_req_set_method(req, "GET") == 0);
+
+			So(httpdo(curl, req, res, &data, &size) == 0);
+			So(nng_http_res_get_status(res) == 303);
+			So((dest = nng_http_res_get_header(res, "Location")) !=
+			    NULL);
+			So(strcmp(dest, "http://127.0.0.1/there/i/go/again") ==
+			    0);
+			nng_http_req_free(req);
+			nng_http_res_free(res);
+			nng_url_free(curl);
+		});
+
+		Convey("POST Redirect works", {
+			char          fullurl[256];
+			size_t        size;
+			nng_http_req *req;
+			nng_http_res *res;
+			nng_url *     curl;
+			char          txdata[5];
+			const char *  dest;
+			void *        data;
+
+			So(nng_http_handler_alloc_redirect(&h, "/here", 301,
+			       "http://127.0.0.1/there") == 0);
+			So(nng_http_server_add_handler(s, h) == 0);
+			So(nng_http_server_start(s) == 0);
+			nng_msleep(100);
+
+			snprintf(txdata, sizeof(txdata), "1234");
+			So(nng_http_res_alloc(&res) == 0);
+			snprintf(fullurl, sizeof(fullurl), "%s/here", urlstr);
+			So(nng_url_parse(&curl, fullurl) == 0);
+			So(nng_http_req_alloc(&req, curl) == 0);
+			nng_http_req_set_data(req, txdata, strlen(txdata));
+			So(nng_http_req_set_method(req, "POST") == 0);
+			So(httpdo(curl, req, res, (void **) &data, &size) ==
+			    0);
+			So(nng_http_res_get_status(res) == 301);
+			So((dest = nng_http_res_get_header(res, "Location")) !=
+			    NULL);
+			So(strcmp(dest, "http://127.0.0.1/there") == 0);
+			nng_http_req_free(req);
+			nng_http_res_free(res);
+			nng_url_free(curl);
+		});
+	});
 })