adding mod_proxy_http2 build support and some documentation

ChangeLog

@@ -1,5 +1,6 @@
 v1.5.0
 -------------------------------------------------------------------------------- 
+ * mod_proxy_http2 for backend HTTP/2 connections, currently cleartext only
  * new "bucket beam" technology to transport buckets across threads without 
    buffer copy. 
  * delaying response start until flush or enough body data has been accumulated.

README.md

@@ -3,10 +3,10 @@
 
 Copyright (C) 2015, 2016 greenbytes GmbH
 
-This repository contains the `mod_h[ttp]2` from Apache httpd as a standalone build. 
+This repository contains `mod_h[ttp]2` and `mod_proxy_h[ttp]2` from Apache httpd as a standalone build. 
 
 ##Status
-**An official Apache httpd module**, first released in 2.4.17. See [Apache downloads](https://httpd.apache.org/download.cgi) to get a released version.
+**`mod_h[ttp]2` is an official Apache httpd module**, first released in 2.4.17. See [Apache downloads](https://httpd.apache.org/download.cgi) to get a released version. `mod_proxy_h[ttp]2` is part of Apache httpd development, but has not been released yet.
 
 What you find here are **early experience versions** for people who like living on the edge and want to help me test not yet released changes.
 
@@ -38,6 +38,46 @@ If you do not have that or don't know how to get it, look at google, stackoverfl
 
 See ```ChangeLog``` for details.
 
+##`mod_proxy_http2`
+
+This module is part of the Apache httpd proxy architecture and functions similar to `mod_proxy_http` 
+and friends. To configure it, you need to use ```h2:``` or ```h2c:``` in the proxy URL. Example:
+(***Important***: against httpd 2.4.20, only ```h2c:``` connections will work!)
+```
+<Proxy "balancer://h2-local">
+    BalancerMember "h2://test.example.org:SUBST_PORT_HTTPS_SUBST"
+</Proxy>
+<Proxy "balancer://h2c-local">
+    BalancerMember "h2c://test.example.org:SUBST_PORT_HTTP_SUBST"
+</Proxy>
+
+<IfModule proxy_http2_module>
+    ProxyPass "/h2proxy" "balancer://h2-local"
+    ProxyPassReverse "/h2proxy" "balancer://h2-local"
+    ProxyPass "/h2cproxy" "balancer://h2c-local"
+    ProxyPassReverse "/h2cproxy" "balancer://h2c-local"
+</IfModule>
+```
+This will only work under the following conditions:
+* the backend speaks HTTP/2, the module will not fallback to HTTP/1.1
+* the backend supports HTTP/2 direct mode (see also ```H2Direct``` directive of ```mod_http2```)
+
+All other commond httpd ```proxy``` directives also apply.
+
+What it will ***not*** do and what is ***untested***:
+* fallback to HTTP/1.1
+* support TLS backend connections with Apache httpd 2.4.20 (some necessary changes for ALPN negotiation were not backported)
+* be very smart when the number of concurrent streams in the backend differs from the local settings
+* load balance between open connections dynamically
+* forward any HTTP/2 priority information
+* support HTTP/2 PUSH from the backend
+
+What it ***will*** do:
+* work with frontend HTTP/1.1 connections
+* reuse open HTTP/2 connections from the balancer
+* with a frontent HTTP/2 connection, all streams against the same backend will be handled in a single thread.
+
+
 ##Documenation
 There is the official [Apache documentation](https://httpd.apache.org/docs/2.4/en/mod/mod_http2.html) of the module, which you will not find here.
 
@@ -67,7 +107,7 @@ SPDY protocol. And without Tatsuhiro Tsujikawa excellent nghttp2 work, this
 would not have been possible.
 
 
-Münster, 18.04.2016,
+Münster, 19.04.2016,
 
 Stefan Eissing, greenbytes GmbH
 

mod-h2.xcodeproj/project.pbxproj

@@ -20,6 +20,10 @@
 		B25096C21CC4E66F002E8B04 /* h2.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = h2.h; sourceTree = "<group>"; };
 		B25096C41CC4F132002E8B04 /* h2_bucket_beam.c */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.c; path = h2_bucket_beam.c; sourceTree = "<group>"; };
 		B25096C51CC4F132002E8B04 /* h2_bucket_beam.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = h2_bucket_beam.h; sourceTree = "<group>"; };
+		B25096C61CC65E27002E8B04 /* h2_proxy_session.c */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.c; path = h2_proxy_session.c; sourceTree = "<group>"; };
+		B25096C71CC65E27002E8B04 /* h2_proxy_session.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = h2_proxy_session.h; sourceTree = "<group>"; };
+		B25096C81CC65E27002E8B04 /* mod_proxy_http2.c */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.c; path = mod_proxy_http2.c; sourceTree = "<group>"; };
+		B25096C91CC65E27002E8B04 /* mod_proxy_http2.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = mod_proxy_http2.h; sourceTree = "<group>"; };
 		B25574691BEB6EFC0058F97B /* config.h.in */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text; path = config.h.in; sourceTree = "<group>"; };
 		B255746A1BEB6EFC0058F97B /* h2_alt_svc.c */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.c; path = h2_alt_svc.c; sourceTree = "<group>"; };
 		B255746B1BEB6EFC0058F97B /* h2_alt_svc.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = h2_alt_svc.h; sourceTree = "<group>"; };
@@ -138,6 +142,8 @@
 				B25096C01CC4E66F002E8B04 /* h2_ngn_shed.c */,
 				B25096C11CC4E66F002E8B04 /* h2_ngn_shed.h */,
 				B25574821BEB6EFC0058F97B /* h2_private.h */,
+				B25096C61CC65E27002E8B04 /* h2_proxy_session.c */,
+				B25096C71CC65E27002E8B04 /* h2_proxy_session.h */,
 				B2AB9AB91C2ADBE100908DD6 /* h2_push.c */,
 				B2AB9ABA1C2ADBE100908DD6 /* h2_push.h */,
 				B25574831BEB6EFC0058F97B /* h2_request.c */,
@@ -167,6 +173,8 @@
 				B25574A41BEB6EFC0058F97B /* Makefile.am */,
 				B25574A71BEB6EFC0058F97B /* mod_http2.c */,
 				B2AB9ABC1C2ADBE100908DD6 /* mod_http2.h */,
+				B25096C81CC65E27002E8B04 /* mod_proxy_http2.c */,
+				B25096C91CC65E27002E8B04 /* mod_proxy_http2.h */,
 			);
 			path = mod_http2;
 			sourceTree = "<group>";

mod_http2/Makefile.am

@@ -16,11 +16,15 @@ SUBDIRS =
 
 ACLOCAL_AMFLAGS = -I m4
 
-lib_LTLIBRARIES    = mod_http2.la
+lib_LTLIBRARIES    = mod_http2.la \
+    mod_proxy_http2.la
 
 mod_http2_la_CPPFLAGS = -std=c99 -D_GNU_SOURCE -Werror
 mod_http2_la_LDFLAGS  = -module
 
+mod_proxy_http2_la_CPPFLAGS = -std=c99 -D_GNU_SOURCE -Werror
+mod_proxy_http2_la_LDFLAGS  = -module
+
 OBJECTS = \
     h2_alt_svc.c \
     h2_bucket_beam.c \
@@ -82,16 +86,32 @@ HFILES = \
     h2_workers.h \
     mod_http2.h
 
+PROXY_HFILES = \
+    h2.h \
+    h2_proxy_session.h \
+    h2_request.h \
+    h2_util.h \
+    mod_proxy_http2.h
+
+PROXY_OBJECTS = \
+    h2_proxy_session.c \
+    h2_request.c \
+    h2_util.c \
+    mod_proxy_http2.c
 
 mod_http2_la_SOURCES = $(HFILES) $(OBJECTS)
 
-all: mod_http2.la
+mod_proxy_http2_la_SOURCES = $(PROXY_HFILES) $(PROXY_OBJECTS)
+
+all: mod_http2.la \
+    mod_proxy_http2.la
 
 install-libLTLIBRARIES:
 	@: # override
 
-install-exec-local: mod_http2.la
+install-exec-local: mod_http2.la mod_proxy_http2.la
 	$(MKDIR_P) $(DESTDIR)/@LIBEXEC_DIR@
 	$(APXS) -i -S LIBEXECDIR=$(DESTDIR)/@LIBEXEC_DIR@ -n h2 mod_http2.la
+	$(APXS) -i -S LIBEXECDIR=$(DESTDIR)/@LIBEXEC_DIR@ -n h2 mod_proxy_http2.la
 
 

mod_http2/h2_proxy_session.c

@@ -211,7 +211,7 @@ static void process_proxy_header(request_rec *r, const char *n, const char *v)
     int i;
 
     for (i = 0; transform_hdrs[i].name; ++i) {
-        if (!ap_casecmpstr(transform_hdrs[i].name, n)) {
+        if (!h2_casecmpstr(transform_hdrs[i].name, n)) {
             dconf = ap_get_module_config(r->per_dir_config, &proxy_module);
             apr_table_add(r->headers_out, n,
                           (*transform_hdrs[i].func)(r, dconf, v));

mod_http2/h2_util.c

@@ -1430,3 +1430,123 @@ void h2_push_policy_determine(struct h2_request *req, apr_pool_t *p, int push_en
     req->push_policy = policy;
 }
 
+/*******************************************************************************
+ * ap_casecmpstr, when will it be backported?
+ ******************************************************************************/
+#if !APR_CHARSET_EBCDIC
+/*
+ * Provide our own known-fast implementation of str[n]casecmp()
+ * NOTE: Only ASCII alpha characters 41-5A are folded to 61-7A,
+ * other 8-bit latin alphabetics are never case-folded!
+ */
+static const unsigned char ucharmap[] = {
+    0x0,  0x1,  0x2,  0x3,  0x4,  0x5,  0x6,  0x7,
+    0x8,  0x9,  0xa,  0xb,  0xc,  0xd,  0xe,  0xf,
+    0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
+    0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
+    0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
+    0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
+    0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
+    0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
+    0x40,  'a',  'b',  'c',  'd',  'e',  'f',  'g',
+     'h',  'i',  'j',  'k',  'l',  'm',  'n',  'o',
+     'p',  'q',  'r',  's',  't',  'u',  'v',  'w',
+     'x',  'y',  'z', 0x5b, 0x5c, 0x5d, 0x5e, 0x5f,
+    0x60,  'a',  'b',  'c',  'd',  'e',  'f',  'g',
+     'h',  'i',  'j',  'k',  'l',  'm',  'n',  'o',
+     'p',  'q',  'r',  's',  't',  'u',  'v',  'w',
+     'x',  'y',  'z', 0x7b, 0x7c, 0x7d, 0x7e, 0x7f,
+    0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
+    0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
+    0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,
+    0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f,
+    0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
+    0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,
+    0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7,
+    0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf,
+    0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
+    0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf,
+    0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7,
+    0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf,
+    0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7,
+    0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef,
+    0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
+    0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff
+};
+
+#else /* APR_CHARSET_EBCDIC */
+/* Derived from apr-iconv/ccs/cp037.c for EBCDIC case comparison,
+   provides unique identity of every char value (strict ISO-646
+   conformance, arbitrary election of an ISO-8859-1 ordering, and
+   very arbitrary control code assignments into C1 to achieve
+   identity and a reversible mapping of code points),
+   then folding the equivalences of ASCII 41-5A into 61-7A, 
+   presenting comparison results in a somewhat ISO/IEC 10646
+   (ASCII-like) order, depending on the EBCDIC code page in use.
+ */
+static const unsigned char ucharmap[] = {
+	0x00, 0x01, 0x02, 0x03, 0x9C, 0x09, 0x86, 0x7F,
+	0x97, 0x8D, 0x8E, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,
+	0x10, 0x11, 0x12, 0x13, 0x9D, 0x85, 0x08, 0x87,
+	0x18, 0x19, 0x92, 0x8F, 0x1C, 0x1D, 0x1E, 0x1F,
+	0x80, 0x81, 0x82, 0x83, 0x84, 0x0A, 0x17, 0x1B,
+	0x88, 0x89, 0x8A, 0x8B, 0x8C, 0x05, 0x06, 0x07,
+	0x90, 0x91, 0x16, 0x93, 0x94, 0x95, 0x96, 0x04,
+	0x98, 0x99, 0x9A, 0x9B, 0x14, 0x15, 0x9E, 0x1A,
+	0x20, 0xA0, 0xE2, 0xE4, 0xE0, 0xE1, 0xE3, 0xE5,
+	0xE7, 0xF1, 0xA2, 0x2E, 0x3C, 0x28, 0x2B, 0x7C,
+	0x26, 0xE9, 0xEA, 0xEB, 0xE8, 0xED, 0xEE, 0xEF,
+	0xEC, 0xDF, 0x21, 0x24, 0x2A, 0x29, 0x3B, 0xAC,
+	0x2D, 0x2F, 0xC2, 0xC4, 0xC0, 0xC1, 0xC3, 0xC5,
+	0xC7, 0xD1, 0xA6, 0x2C, 0x25, 0x5F, 0x3E, 0x3F,
+	0xF8, 0xC9, 0xCA, 0xCB, 0xC8, 0xCD, 0xCE, 0xCF,
+	0xCC, 0x60, 0x3A, 0x23, 0x40, 0x27, 0x3D, 0x22,
+	0xD8, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,
+	0x68, 0x69, 0xAB, 0xBB, 0xF0, 0xFD, 0xFE, 0xB1,
+	0xB0, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x6F, 0x70,
+	0x71, 0x72, 0xAA, 0xBA, 0xE6, 0xB8, 0xC6, 0xA4,
+	0xB5, 0x7E, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78,
+	0x79, 0x7A, 0xA1, 0xBF, 0xD0, 0xDD, 0xDE, 0xAE,
+	0x5E, 0xA3, 0xA5, 0xB7, 0xA9, 0xA7, 0xB6, 0xBC,
+	0xBD, 0xBE, 0x5B, 0x5D, 0xAF, 0xA8, 0xB4, 0xD7,
+	0x7B, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,
+	0x68, 0x69, 0xAD, 0xF4, 0xF6, 0xF2, 0xF3, 0xF5,
+	0x7D, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x6F, 0x70,
+	0x71, 0x72, 0xB9, 0xFB, 0xFC, 0xF9, 0xFA, 0xFF,
+	0x5C, 0xF7, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78,
+	0x79, 0x7A, 0xB2, 0xD4, 0xD6, 0xD2, 0xD3, 0xD5,
+	0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
+	0x38, 0x39, 0xB3, 0xDB, 0xDC, 0xD9, 0xDA, 0x9F
+};
+#endif
+
+AP_DECLARE(int) h2_casecmpstr(const char *s1, const char *s2)
+{
+    const unsigned char *ps1 = (const unsigned char *) s1;
+    const unsigned char *ps2 = (const unsigned char *) s2;
+
+    while (ucharmap[*ps1] == ucharmap[*ps2]) {
+        if (*ps1++ == '\0') {
+            return (0);
+        }
+        ps2++;
+    }
+    return (ucharmap[*ps1] - ucharmap[*ps2]);
+}
+
+AP_DECLARE(int) h2_casecmpstrn(const char *s1, const char *s2, apr_size_t n)
+{
+    const unsigned char *ps1 = (const unsigned char *) s1;
+    const unsigned char *ps2 = (const unsigned char *) s2;
+    while (n--) {
+        if (ucharmap[*ps1] != ucharmap[*ps2]) {
+            return (ucharmap[*ps1] - ucharmap[*ps2]);
+        }
+        if (*ps1++ == '\0') {
+            break;
+        }
+        ps2++;
+    }
+    return (0);
+}
+

mod_http2/h2_util.h

@@ -383,4 +383,8 @@ apr_status_t h2_append_brigade(apr_bucket_brigade *to,
  */
 apr_off_t h2_brigade_mem_size(apr_bucket_brigade *bb);
 
+/* when will ap_casecmpstr() be backported finally? */
+int h2_casecmpstr(const char *s1, const char *s2);
+int h2_casecmpstrn(const char *s1, const char *s2, apr_size_t n);
+
 #endif /* defined(__mod_h2__h2_util__) */

mod_http2/mod_proxy_http2.c

@@ -125,12 +125,12 @@ static int proxy_http2_canon(request_rec *r, char *url)
     apr_port_t port, def_port;
 
     /* ap_port_of_scheme() */
-    if (ap_casecmpstrn(url, "h2c:", 4) == 0) {
+    if (h2_casecmpstrn(url, "h2c:", 4) == 0) {
         url += 4;
         scheme = "h2c";
         http_scheme = "http";
     }
-    else if (ap_casecmpstrn(url, "h2:", 3) == 0) {
+    else if (h2_casecmpstrn(url, "h2:", 3) == 0) {
         url += 3;
         scheme = "h2";
         http_scheme = "https";
@@ -604,7 +604,8 @@ static int proxy_http2_handler(request_rec *r,
         /* Still more to do, tear down old conn and start over */
         if (ctx->p_conn) {
             ctx->p_conn->close = 1;
-            proxy_run_detach_backend(r, ctx->p_conn);
+            /*only in trunk so far */
+            /*proxy_run_detach_backend(r, ctx->p_conn);*/
             ap_proxy_release_connection(ctx->proxy_func, ctx->p_conn, ctx->server);
             ctx->p_conn = NULL;
         }
@@ -617,7 +618,8 @@ static int proxy_http2_handler(request_rec *r,
             /* close socket when errors happened or session shut down (EOF) */
             ctx->p_conn->close = 1;
         }
-        proxy_run_detach_backend(ctx->rbase, ctx->p_conn);
+        /*only in trunk so far */
+        /*proxy_run_detach_backend(ctx->rbase, ctx->p_conn);*/
         ap_proxy_release_connection(ctx->proxy_func, ctx->p_conn, ctx->server);
         ctx->p_conn = NULL;
     }