HTTP: intern the version and avoid allocation

There are only a few possible reasonable values, and we can intern
them to avoid any allocations for it.  (We will probably do the same
for the HTTP method shortly as well.)

docs/man/nng_http_req_set_version.3http.adoc

@@ -1,6 +1,6 @@
 = nng_http_req_set_version(3http)
 //
-// Copyright 2018 Staysail Systems, Inc. <[email protected]>
+// Copyright 2024 Staysail Systems, Inc. <[email protected]>
 // Copyright 2018 Capitar IT Group BV <[email protected]>
 //
 // This document is supplied under the terms of the MIT License, a
@@ -20,6 +20,9 @@ nng_http_req_set_version - set HTTP request protocol version
 #include <nng/nng.h>
 #include <nng/supplemental/http/http.h>
 
+#define NNG_HTTP_VERSION_1_1 "HTTP/1.0"
+#define NNG_HTTP_VERSION_1_1 "HTTP/1.1"
+
 int nng_http_req_set_version(nng_http_req *req, const char *version);
 ----
 
@@ -33,12 +36,8 @@ The default value is "HTTP/1.1".
 
 A local copy of the _version_ is made in the request _req_.
 
-NOTE: No validation of the version supplied is performed.
-
 NOTE: The library does not contain support for versions of HTTP other than
 "HTTP/1.0" and "HTTP/1.1".
-Specifying any other version may result in unspecified behavior.
-
 
 == RETURN VALUES
 
@@ -48,7 +47,7 @@ This function returns 0 on success, and non-zero otherwise.
 
 [horizontal]
 `NNG_ENOMEM`:: Insufficient memory to perform the operation.
-`NNG_ENOTSUP`:: No support for HTTP in the library.
+`NNG_ENOTSUP`:: No support for HTTP in the library, or no support for the version specified.
 
 == SEE ALSO
 

docs/man/nng_http_res_set_version.3http.adoc

@@ -1,6 +1,6 @@
 = nng_http_res_set_version(3http)
 //
-// Copyright 2018 Staysail Systems, Inc. <[email protected]>
+// Copyright 2024 Staysail Systems, Inc. <[email protected]>
 // Copyright 2018 Capitar IT Group BV <[email protected]>
 //
 // This document is supplied under the terms of the MIT License, a
@@ -20,6 +20,9 @@ nng_http_res_set_version - set HTTP response protocol version
 #include <nng/nng.h>
 #include <nng/supplemental/http/http.h>
 
+#define NNG_HTTP_VERSION_1_1 "HTTP/1.0"
+#define NNG_HTTP_VERSION_1_1 "HTTP/1.1"
+
 int nng_http_res_set_version(nng_http_res *res, const char *version);
 ----
 
@@ -33,12 +36,8 @@ The default value is "HTTP/1.1".
 
 A local copy of the _version_ is made in the response _res_.
 
-NOTE: No validation of the version supplied is performed.
-
 NOTE: The library does not contain support for versions of HTTP other than
 "HTTP/1.0" and "HTTP/1.1".
-Specifying any other version may result in unspecified behavior.
-
 
 == RETURN VALUES
 
@@ -48,7 +47,7 @@ This function returns 0 on success, and non-zero otherwise.
 
 [horizontal]
 `NNG_ENOMEM`:: Insufficient memory to perform the operation.
-`NNG_ENOTSUP`:: No support for HTTP in the library.
+`NNG_ENOTSUP`:: No support for HTTP in the library, or no support for the version specified.
 
 == SEE ALSO
 

include/nng/supplemental/http/http.h

@@ -87,6 +87,11 @@ enum nng_http_status {
 	NNG_HTTP_STATUS_NETWORK_AUTH_REQUIRED    = 511,
 };
 
+#define NNG_HTTP_VERSION_1_0 "HTTP/1.0"
+#define NNG_HTTP_VERSION_1_1 "HTTP/1.1"
+#define NNG_HTTP_VERSION_2 "HTTP/2"
+#define NNG_HTTP_VERSION_3 "HTTP/3"
+
 // nng_http_req represents an HTTP request.
 typedef struct nng_http_req nng_http_req;
 

src/supplemental/http/http_msg.c

@@ -16,6 +16,7 @@
 
 #include "core/nng_impl.h"
 #include "http_api.h"
+#include "nng/supplemental/http/http.h"
 
 // Note that as we parse headers, the rule is that if a header is already
 // present, then we can append it to the existing header, separated by
@@ -39,7 +40,7 @@ struct nng_http_req {
 	nni_http_entity data;
 	char           *meth;
 	char           *uri;
-	char           *vers;
+	const char     *vers;
 	char           *buf;
 	size_t          bufsz;
 	bool            parsed;
@@ -50,7 +51,7 @@ struct nng_http_res {
 	nni_http_entity data;
 	uint16_t        code;
 	char           *rsn;
-	char           *vers;
+	const char     *vers;
 	char           *buf;
 	size_t          bufsz;
 	bool            parsed;
@@ -99,14 +100,14 @@ nni_http_req_reset(nni_http_req *req)
 {
 	http_headers_reset(&req->hdrs);
 	http_entity_reset(&req->data);
-	nni_strfree(req->vers);
 	nni_strfree(req->meth);
 	nni_strfree(req->uri);
-	req->vers = req->meth = req->uri = NULL;
+	req->meth = req->uri = NULL;
 	nni_free(req->buf, req->bufsz);
 	req->bufsz  = 0;
 	req->buf    = NULL;
 	req->parsed = false;
+	req->vers   = NNG_HTTP_VERSION_1_1;
 }
 
 void
@@ -115,8 +116,7 @@ nni_http_res_reset(nni_http_res *res)
 	http_headers_reset(&res->hdrs);
 	http_entity_reset(&res->data);
 	nni_strfree(res->rsn);
-	nni_strfree(res->vers);
-	res->vers   = NULL;
+	res->vers   = NNG_HTTP_VERSION_1_1;
 	res->rsn    = NULL;
 	res->code   = 0;
 	res->parsed = false;
@@ -532,8 +532,7 @@ http_req_prepare(nni_http_req *req)
 		return (NNG_EINVAL);
 	}
 	rv = http_asprintf(&req->buf, &req->bufsz, &req->hdrs, "%s %s %s\r\n",
-	    req->meth != NULL ? req->meth : "GET", req->uri,
-	    req->vers != NULL ? req->vers : "HTTP/1.1");
+	    req->meth != NULL ? req->meth : "GET", req->uri, req->vers);
 	return (rv);
 }
 
@@ -542,7 +541,7 @@ http_res_prepare(nni_http_res *res)
 {
 	int rv;
 	rv = http_asprintf(&res->buf, &res->bufsz, &res->hdrs, "%s %d %s\r\n",
-	    nni_http_res_get_version(res), nni_http_res_get_status(res),
+	    res->vers, nni_http_res_get_status(res),
 	    nni_http_res_get_reason(res));
 	return (rv);
 }
@@ -612,7 +611,7 @@ nni_http_req_alloc(nni_http_req **reqp, const nng_url *url)
 	req->data.data = NULL;
 	req->data.size = 0;
 	req->data.own  = false;
-	req->vers      = NULL;
+	req->vers      = NNG_HTTP_VERSION_1_1;
 	req->meth      = NULL;
 	req->uri       = NULL;
 	if (url != NULL) {
@@ -664,7 +663,7 @@ nni_http_res_alloc(nni_http_res **resp)
 	res->data.data = NULL;
 	res->data.size = 0;
 	res->data.own  = false;
-	res->vers      = NULL;
+	res->vers      = NNG_HTTP_VERSION_1_1;
 	res->rsn       = NULL;
 	res->code      = 0;
 	*resp          = res;
@@ -686,31 +685,48 @@ nni_http_req_get_uri(const nni_http_req *req)
 const char *
 nni_http_req_get_version(const nni_http_req *req)
 {
-	return (req->vers != NULL ? req->vers : "HTTP/1.1");
+	return (req->vers);
 }
 
 const char *
 nni_http_res_get_version(const nni_http_res *res)
 {
-	return (res->vers != NULL ? res->vers : "HTTP/1.1");
+	return (res->vers);
+}
+
+static const char *http_versions[] = {
+	// for efficiency, we order in most likely first
+	"HTTP/1.1",
+	"HTTP/2",
+	"HTTP/3",
+	"HTTP/1.0",
+	"HTTP/0.9",
+	NULL,
+};
+
+static int
+http_set_version(const char **ptr, const char *vers)
+{
+	vers = vers != NULL ? vers : NNG_HTTP_VERSION_1_1;
+	for (int i = 0; http_versions[i] != NULL; i++) {
+		if (strcmp(vers, http_versions[i]) == 0) {
+			*ptr = http_versions[i];
+			return (0);
+		}
+	}
+	return (NNG_ENOTSUP);
 }
 
 int
 nni_http_req_set_version(nni_http_req *req, const char *vers)
 {
-	if ((vers != NULL) && (strcmp(vers, "HTTP/1.1") == 0)) {
-		vers = NULL;
-	}
-	return (http_set_string(&req->vers, vers));
+	return (http_set_version(&req->vers, vers));
 }
 
 int
 nni_http_res_set_version(nni_http_res *res, const char *vers)
 {
-	if ((vers != NULL) && (strcmp(vers, "HTTP/1.1") == 0)) {
-		vers = NULL;
-	}
-	return (http_set_string(&res->vers, vers));
+	return (http_set_version(&res->vers, vers));
 }
 
 int