Add VCC support for backend probe specifications.

It is possible to specify just the URL to be probed, or to specify the
entire HTTP request:

	backend b0 {
		.host = "127.0.0.1";
		.probe = {
			.url = "/test.jpg";
			.timeout = 224 ms;
		}
	}

	backend b1 {
		.host = "127.0.0.1";
		.probe = {
			# NB: \r\n automatically inserted after each string!
			.request =
			    "GET / HTTP/1.1"
			    "Host: www.foo.bar"
			    "Connection: close";
			.timeout = 0.3 s;
		}
	}

If the full request has not been completed within the timeout, the
backend will be set to down.


git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@2902 d4fa192b-c00b-0410-8231-f00ffab90ce4

bin/varnishtest/tests/v00005.vtc

+# $Id$
+
+test "VCL: test backend probe syntax"
+
+# Check url definition
+varnish v1 -vcl {
+	backend b1 {
+		.host = "localhost";
+		.probe = {
+			.url = "/";
+		}
+	}
+}
+
+# Check request definition
+varnish v1 -vcl {
+	backend b1 {
+		.host = "localhost";
+		.probe = {
+			.request = 
+			    "GET / HTTP/1.1"
+			    "Host: foo.bar" ;
+		}
+	}
+}
+
+# Check redefinition
+varnish v1 -badvcl {
+	backend b1 {
+		.host = "localhost";
+		.probe = {
+			.url = "/";
+			.request = 
+			    "GET / HTTP/1.1"
+			    "Host: foo.bar" ;
+		}
+	}
+}
+
+# Check redefinition the other way
+varnish v1 -badvcl {
+	backend b1 {
+		.host = "localhost";
+		.probe = {
+			.request = 
+			    "GET / HTTP/1.1"
+			    "Host: foo.bar" ;
+			.url = "/";
+		}
+	}
+}

include/vrt.h

@@ -41,15 +41,25 @@ struct director;
 struct VCL_conf;
 struct sockaddr;
 
+/*
+ * A backend probe specification
+ */
+
+struct vrt_backend_probe {
+	char		*request;
+	double		timeout;
+};
+
 /*
  * A backend is a host+port somewhere on the network
  */
 struct vrt_backend {
-	char		*portname;
-	char		*hostname;
-	char		*vcl_name;
-	char		*ident;
-	double		connect_timeout;
+	char				*portname;
+	char				*hostname;
+	char				*vcl_name;
+	char				*ident;
+	double				connect_timeout;
+	struct vrt_backend_probe 	probe;
 };
 
 /*

lib/libvcl/vcc_backend.c

@@ -216,6 +216,89 @@ vcc_FieldsOk(struct tokenlist *tl, const struct fld_spec *fs)
 	}
 }
 
+/*--------------------------------------------------------------------
+ * Parse a backend probe specification
+ */
+
+static void
+vcc_ProbeRedef(struct tokenlist *tl, struct token **t_did, struct token *t_field)
+{
+	if (*t_did != NULL) {
+		vsb_printf(tl->sb,
+		    "Probe request redefinition at:\n");
+		vcc_ErrWhere(tl, t_field);
+		vsb_printf(tl->sb,
+		    "Previous definition:\n");
+		vcc_ErrWhere(tl, *t_did);
+		return;
+	}
+	*t_did = t_field;
+}
+
+static void
+vcc_ParseProbe(struct tokenlist *tl)
+{
+	struct fld_spec *fs;
+	struct token *t_field;
+	struct token *t_did = NULL;
+
+	fs = vcc_FldSpec(tl, "?url", "?request", "?timeout", NULL);
+
+	ExpectErr(tl, '{');
+	vcc_NextToken(tl);
+
+	Fh(tl, 0, "\t.probe = {\n");
+	while (tl->t->tok != '}') {
+
+		vcc_IsField(tl, &t_field, fs);
+		ERRCHK(tl);
+		if (tl->err)
+			break;
+		if (vcc_IdIs(t_field, "url")) {
+			vcc_ProbeRedef(tl, &t_did, t_field);
+			ERRCHK(tl);
+			ExpectErr(tl, CSTR);
+			Fh(tl, 0, "\t\t.request =\n");
+			Fh(tl, 0, "\t\t\t\"GET \" ");
+			EncToken(tl->fh, tl->t);
+			Fh(tl, 0, " \" /HTTP/1.1\\r\\n\"\n");
+			Fh(tl, 0, "\t\t\t\"Connection: close\\r\\n\"\n");
+			Fh(tl, 0, "\t\t\t\"\\r\\n\",\n");
+			vcc_NextToken(tl);
+		} else if (vcc_IdIs(t_field, "request")) {
+			vcc_ProbeRedef(tl, &t_did, t_field);
+			ERRCHK(tl);
+			ExpectErr(tl, CSTR);
+			Fh(tl, 0, "\t\t.request =\n");
+			while (tl->t->tok == CSTR) {
+				Fh(tl, 0, "\t\t\t");
+				EncToken(tl->fh, tl->t);
+				Fh(tl, 0, " \"\\r\\n\"\n");
+				vcc_NextToken(tl);
+			}
+			Fh(tl, 0, "\t\t\t\"\\r\\n\",\n");
+		} else if (vcc_IdIs(t_field, "timeout")) {
+			Fh(tl, 0, "\t\t.timeout = ");
+			tl->fb = tl->fh;
+			vcc_TimeVal(tl);
+			tl->fb = NULL;
+			ERRCHK(tl);
+			Fh(tl, 0, ",\n");
+		} else {
+			vcc_ErrToken(tl, t_field);
+			vcc_ErrWhere(tl, t_field);
+			ErrInternal(tl);
+			return;
+		}
+
+		ExpectErr(tl, ';');
+		vcc_NextToken(tl);
+	}
+	Fh(tl, 0, "\t},\n");
+	ExpectErr(tl, '}');
+	vcc_NextToken(tl);
+}
+
 /*--------------------------------------------------------------------
  * Parse and emit a backend host definition 
  *
@@ -244,7 +327,8 @@ vcc_ParseHostDef(struct tokenlist *tl, int *nbh, const struct token *name, const
 	const char *ep;
 	struct fld_spec *fs;
 
-	fs = vcc_FldSpec(tl, "!host", "?port", "?connect_timeout", NULL);
+	fs = vcc_FldSpec(tl,
+	    "!host", "?port", "?connect_timeout", "?probe", NULL);
 	t_first = tl->t;
 
 	ExpectErr(tl, '{');
@@ -276,11 +360,15 @@ vcc_ParseHostDef(struct tokenlist *tl, int *nbh, const struct token *name, const
 			assert(tl->t->dec != NULL);
 			t_host = tl->t;
 			vcc_NextToken(tl);
+			ExpectErr(tl, ';');
+			vcc_NextToken(tl);
 		} else if (vcc_IdIs(t_field, "port")) {
 			ExpectErr(tl, CSTR);
 			assert(tl->t->dec != NULL);
 			t_port = tl->t;
 			vcc_NextToken(tl);
+			ExpectErr(tl, ';');
+			vcc_NextToken(tl);
 		} else if (vcc_IdIs(t_field, "connect_timeout")) {
 			Fh(tl, 0, "\t.connect_timeout = ");
 			tl->fb = tl->fh;
@@ -288,13 +376,16 @@ vcc_ParseHostDef(struct tokenlist *tl, int *nbh, const struct token *name, const
 			tl->fb = NULL;
 			ERRCHK(tl);
 			Fh(tl, 0, ",\n");
+			ExpectErr(tl, ';');
+			vcc_NextToken(tl);
+		} else if (vcc_IdIs(t_field, "probe")) {
+			vcc_ParseProbe(tl);
+			ERRCHK(tl);
 		} else {
 			ErrInternal(tl);
 			return;
 		}
 
-		ExpectErr(tl, ';');
-		vcc_NextToken(tl);
 	}
 
 	vcc_FieldsOk(tl, fs);

lib/libvcl/vcc_fixed_token.c

@@ -380,14 +380,24 @@ vcl_output_lang_h(struct vsb *sb)
 	vsb_cat(sb, "struct sockaddr;\n");
 	vsb_cat(sb, "\n");
 	vsb_cat(sb, "/*\n");
+	vsb_cat(sb, " * A backend probe specification\n");
+	vsb_cat(sb, " */\n");
+	vsb_cat(sb, "\n");
+	vsb_cat(sb, "struct vrt_backend_probe {\n");
+	vsb_cat(sb, "	char		*request;\n");
+	vsb_cat(sb, "	double		timeout;\n");
+	vsb_cat(sb, "};\n");
+	vsb_cat(sb, "\n");
+	vsb_cat(sb, "/*\n");
 	vsb_cat(sb, " * A backend is a host+port somewhere on the network\n");
 	vsb_cat(sb, " */\n");
 	vsb_cat(sb, "struct vrt_backend {\n");
-	vsb_cat(sb, "	char		*portname;\n");
-	vsb_cat(sb, "	char		*hostname;\n");
-	vsb_cat(sb, "	char		*vcl_name;\n");
-	vsb_cat(sb, "	char		*ident;\n");
-	vsb_cat(sb, "	double		connect_timeout;\n");
+	vsb_cat(sb, "	char				*portname;\n");
+	vsb_cat(sb, "	char				*hostname;\n");
+	vsb_cat(sb, "	char				*vcl_name;\n");
+	vsb_cat(sb, "	char				*ident;\n");
+	vsb_cat(sb, "	double				connect_timeout;\n");
+	vsb_cat(sb, "	struct vrt_backend_probe 	probe;\n");
 	vsb_cat(sb, "};\n");
 	vsb_cat(sb, "\n");
 	vsb_cat(sb, "/*\n");