HTTP handler: limit host names to 256 bytes (RFC 1035 specifies 253.)

This also makes `nng_http_handler_set_host` never fail (API break).

7 files changed, 39 insertions, 49 deletions

diff --git a/docs/man/nng_http_handler_set_host.3http.adoc b/docs/man/nng_http_handler_set_host.3http.adoc
index 0deae488..3f25172f 100644
--- a/docs/man/nng_http_handler_set_host.3http.adoc
+++ b/docs/man/nng_http_handler_set_host.3http.adoc
@@ -1,6 +1,6 @@
 = nng_http_handler_set_host(3http)
 //
-// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2024 Staysail Systems, Inc. <info@staysail.tech>
 // Copyright 2018 Capitar IT Group BV <info@capitar.com>
 //
 // This document is supplied under the terms of the MIT License, a
@@ -20,7 +20,7 @@ nng_http_handler_set_host - set host for HTTP handler
 #include <nng/nng.h>
 #include <nng/supplemental/http/http.h>
 
-int nng_http_handler_set_host(nng_http_handler *handler, const char *host);
+void nng_http_handler_set_host(nng_http_handler *handler, const char *host);
 ----
 
 == DESCRIPTION
@@ -41,15 +41,8 @@ ports, the port number can be elided.
 The matching test only considers
 the hostname or IP address, and ignores any trailing port number.
 
-== RETURN VALUES
-
-This function returns 0 on success, and non-zero otherwise.
-
-== ERRORS
-
-[horizontal]
-`NNG_ENOMEM`:: Insufficient free memory to perform the operation.
-`NNG_ENOTSUP`:: No support for HTTP in the library.
+NOTE: This should not be used with an IP address normally, as `Host:` header
+is used with virtual hosts in HTTP/1.1, and not supported for HTTP/1.0.
 
 == SEE ALSO
 
diff --git a/docs/ref/migrate/nng1.md b/docs/ref/migrate/nng1.md
index 8a1af631..544f15b6 100644
--- a/docs/ref/migrate/nng1.md
+++ b/docs/ref/migrate/nng1.md
@@ -221,8 +221,19 @@ accessors functions are provided:
 
 ## HTTP API
 
-- [`nng_http_req_set_method`] no longer returns a value. It never fails, but it may truncate an unreasonably long value.
+A few limits on string lengths of certain values are now applied, which allows us to preallocate values
+and eliminate certain unreasonable error paths. If values longer than these are supplied in certain APIs
+they may be silently truncated to the limit:
+
+- Hostnames are limited per RFC 1035 to 253 characters (not including terminating "." or zero byte.)
+- HTTP Method names are limited to 32 bytes (the longest IANA registered method is currently 18 bytes, used for WebDAV.)
+- The fixed part of URI pathnames used with HTTP handlers is limited to 1024 bytes.
+
+The following API changes are present:
+
+- [`nng_http_req_set_method`] no longer returns a value, and cannot fail.
 - [`nng_http_res_set_status`] no longer returns a value, and cannot fail.
+- [`nng_http_handler_set_host`] no longer returns a value and cannot fail.
 
 ## Security Descriptors (Windows Only)
 
diff --git a/include/nng/supplemental/http/http.h b/include/nng/supplemental/http/http.h
index fa485243..729e25ad 100644
--- a/include/nng/supplemental/http/http.h
+++ b/include/nng/supplemental/http/http.h
@@ -362,7 +362,7 @@ NNG_DECL int nng_http_handler_set_method(nng_http_handler *, const char *);
 // default, then the Host: header is not considered when matching the
 // handler.)  Note that the Host: header must match *exactly* (except
 // that case is not considered.)
-NNG_DECL int nng_http_handler_set_host(nng_http_handler *, const char *);
+NNG_DECL void nng_http_handler_set_host(nng_http_handler *, const char *);
 
 // nng_http_handler_collect_body is used to indicate the server should
 // check for, and process, data sent by the client, which will be attached
diff --git a/src/supplemental/http/http_api.h b/src/supplemental/http/http_api.h
index 349f3a49..d759e27b 100644
--- a/src/supplemental/http/http_api.h
+++ b/src/supplemental/http/http_api.h
@@ -322,7 +322,7 @@ extern int nni_http_handler_set_tree_exclusive(nni_http_handler *);
 // on port number as we assume that clients MUST have gotten that part right
 // as we do not support virtual hosting on multiple separate ports; the
 // server only listens on a single port.
-extern int nni_http_handler_set_host(nni_http_handler *, const char *);
+extern void nni_http_handler_set_host(nni_http_handler *, const char *);
 
 // nni_http_handler_set_method limits the handler to only being called
 // for the given HTTP method.  By default a handler is called for GET
diff --git a/src/supplemental/http/http_public.c b/src/supplemental/http/http_public.c
index e3093d45..a60743fd 100644
--- a/src/supplemental/http/http_public.c
+++ b/src/supplemental/http/http_public.c
@@ -609,15 +609,14 @@ nng_http_handler_collect_body(nng_http_handler *h, bool want, size_t len)
 #endif
 }
 
-int
+void
 nng_http_handler_set_host(nng_http_handler *h, const char *host)
 {
 #ifdef NNG_SUPP_HTTP
-	return (nni_http_handler_set_host(h, host));
+	nni_http_handler_set_host(h, host);
 #else
 	NNI_ARG_UNUSED(h);
 	NNI_ARG_UNUSED(host);
-	return (NNG_ENOTSUP);
 #endif
 }
 
diff --git a/src/supplemental/http/http_server.c b/src/supplemental/http/http_server.c
index fa9ad2f4..e9c8bea3 100644
--- a/src/supplemental/http/http_server.c
+++ b/src/supplemental/http/http_server.c
@@ -26,7 +26,7 @@ struct nng_http_handler {
 	nni_list_node   node;
 	char           *uri;
 	char            method[32];
-	char           *host;
+	char            host[256]; // RFC 1035
 	nng_sockaddr    host_addr;
 	bool            host_ip;
 	bool            tree;
@@ -122,12 +122,12 @@ nni_http_handler_init(
 	h->cb             = cb;
 	h->data           = NULL;
 	h->dtor           = NULL;
-	h->host           = NULL;
 	h->tree           = false;
 	h->tree_exclusive = false;
 	h->maxbody        = 1024 * 1024; // Up to 1MB of body
 	h->getbody        = true;
-	strcpy(h->method, "GET");
+	(void) strcpy(h->method, "GET");
+	(void) strcpy(h->host, "");
 	*hp = h;
 	return (0);
 }
@@ -143,7 +143,6 @@ nni_http_handler_fini(nni_http_handler *h)
 	if (h->dtor != NULL) {
 		h->dtor(h->data);
 	}
-	nni_strfree(h->host);
 	nni_strfree(h->uri);
 	NNI_FREE_STRUCT(h);
 }
@@ -203,19 +202,15 @@ nni_http_handler_set_tree_exclusive(nni_http_handler *h)
 	return (0);
 }
 
-int
+void
 nni_http_handler_set_host(nni_http_handler *h, const char *host)
 {
-	char *dup;
+	NNI_ASSERT(!nni_atomic_get_bool(&h->busy));
 
-	if (nni_atomic_get_bool(&h->busy) != 0) {
-		return (NNG_EBUSY);
-	}
 	if ((host == NULL) || (strcmp(host, "*") == 0) ||
 	    strcmp(host, "") == 0) {
-		nni_strfree(h->host);
-		h->host = NULL;
-		return (0);
+		(void) strcpy(h->host, "");
+		return;
 	}
 	if (nni_parse_ip(host, &h->host_addr) == 0) {
 		uint8_t wild[16] = { 0 };
@@ -224,28 +219,21 @@ nni_http_handler_set_host(nni_http_handler *h, const char *host)
 		switch (h->host_addr.s_family) {
 		case NNG_AF_INET:
 			if (h->host_addr.s_in.sa_addr == 0) {
-				nni_strfree(h->host);
-				h->host = NULL;
-				return (0);
+				(void) strcpy(h->host, "");
+				return;
 			}
 			break;
 		case NNG_AF_INET6:
 			if (memcmp(h->host_addr.s_in6.sa_addr, wild, 16) ==
 			    0) {
-				nni_strfree(h->host);
-				h->host = NULL;
-				return (0);
+				(void) strcpy(h->host, "");
+				return;
 			}
 			break;
 		}
 		h->host_ip = true;
 	}
-	if ((dup = nni_strdup(host)) == NULL) {
-		return (NNG_ENOMEM);
-	}
-	nni_strfree(h->host);
-	h->host = dup;
-	return (0);
+	(void) snprintf(h->host, sizeof(h->host), "%s", host);
 }
 
 int
@@ -499,7 +487,7 @@ http_handler_host_match(nni_http_handler *h, const char *host)
 	nng_sockaddr sa;
 	size_t       len;
 
-	if (h->host == NULL) {
+	if ((len = strlen(h->host)) == '\0') {
 		return (true);
 	}
 	if (host == NULL) {
@@ -529,8 +517,6 @@ http_handler_host_match(nni_http_handler *h, const char *host)
 		}
 	}
 
-	len = strlen(h->host);
-
 	if ((nni_strncasecmp(host, h->host, len) != 0)) {
 		return (false);
 	}
@@ -1205,13 +1191,13 @@ nni_http_server_add_handler(nni_http_server *s, nni_http_handler *h)
 	NNI_LIST_FOREACH (&s->handlers, h2) {
 		size_t len2;
 
-		if ((h2->host != NULL) && (h->host != NULL) &&
+		if ((h2->host[0] != 0) && (h->host[0] != 0) &&
 		    (nni_strcasecmp(h2->host, h->host) != 0)) {
 			// Hosts don't match, so we are safe.
 			continue;
 		}
-		if (((h2->host == NULL) && (h->host != NULL)) ||
-		    ((h->host == NULL) && (h2->host != NULL))) {
+		if (((h2->host[0] == 0) && (h->host[0] != 0)) ||
+		    ((h->host[0] == 0) && (h2->host[0] != 0))) {
 			continue; // Host specified for just one.
 		}
 		if (((h->method[0] == 0) && (h2->method[0] != 0)) ||
diff --git a/src/supplemental/websocket/websocket.c b/src/supplemental/websocket/websocket.c
index 3dfb3e8e..ba304149 100644
--- a/src/supplemental/websocket/websocket.c
+++ b/src/supplemental/websocket/websocket.c
@@ -2150,8 +2150,9 @@ nni_ws_listener_alloc(nng_stream_listener **wslp, const nng_url *url)
 		return (rv);
 	}
 
-	if (((rv = nni_http_handler_set_host(l->handler, host)) != 0) ||
-	    ((rv = nni_http_handler_set_data(l->handler, l, 0)) != 0) ||
+	nni_http_handler_set_host(l->handler, host);
+
+	if (((rv = nni_http_handler_set_data(l->handler, l, 0)) != 0) ||
 	    ((rv = nni_http_server_init(&l->server, url)) != 0)) {
 		ws_listener_free(l);
 		return (rv);