restrict usages of functions that require a workspace to VCL subs in

which a workspace is available

src/tests/usage.vtc

+# looks like -*- perl -*-
+
+varnishtest "test permitted use of functions in vcl_subs"
+
+varnish v1 -vcl { backend b { .host="${bad_ip}"; } } -start
+
+varnish v1 -errvcl {vmod convert error: decode() is illegal in vcl_init() and vcl_fini().vmod convert error: encode() is illegal in vcl_init() and vcl_fini().} {
+	import convert from "${vmod_topbuild}/src/.libs/libvmod_convert.so";
+	backend b { .host="${bad_ip}"; }
+	sub vcl_init {
+	  new err = convert.blob(IDENTITY,
+				 convert.encode(IDENTITY,
+						convert.decode(IDENTITY, "x")));
+	}
+}
+
+varnish v1 -errvcl {vmod convert error: transcode() is illegal in vcl_init() and vcl_fini().} {
+	import convert from "${vmod_topbuild}/src/.libs/libvmod_convert.so";
+	backend b { .host="${bad_ip}"; }
+	sub vcl_init {
+	  new err = convert.blob(IDENTITY,
+				 convert.transcode(IDENTITY, IDENTITY, "x"));
+	}
+}
+
+varnish v1 -errvcl {vmod convert error: encode() is illegal in vcl_init() and vcl_fini().} {
+	import convert from "${vmod_topbuild}/src/.libs/libvmod_convert.so";
+	backend b { .host="${bad_ip}"; }
+	sub vcl_init {
+	  new b1 = convert.blob(IDENTITY, "foo");
+	  new b2 = convert.blob(IDENTITY, convert.encode(IDENTITY, b1.get()));
+	}
+}
+
+# The *code() functions are legal in every other VCL sub
+varnish v1 -vcl {
+	import convert from "${vmod_topbuild}/src/.libs/libvmod_convert.so";
+	backend b { .host="${bad_ip}"; }
+
+	sub vcl_recv {
+	  set req.http.x = convert.encode(IDENTITY,
+					  convert.decode(IDENTITY, "foo"));
+	  set req.http.x = convert.transcode(IDENTITY, IDENTITY, "foo");
+	}
+
+	sub vcl_pipe {
+	  set req.http.x = convert.encode(IDENTITY,
+					  convert.decode(IDENTITY, "foo"));
+	  set req.http.x = convert.transcode(IDENTITY, IDENTITY, "foo");
+	}
+
+	sub vcl_pass {
+	  set req.http.x = convert.encode(IDENTITY,
+					  convert.decode(IDENTITY, "foo"));
+	  set req.http.x = convert.transcode(IDENTITY, IDENTITY, "foo");
+	}
+
+	sub vcl_hash {
+	  set req.http.x = convert.encode(IDENTITY,
+					  convert.decode(IDENTITY, "foo"));
+	  set req.http.x = convert.transcode(IDENTITY, IDENTITY, "foo");
+	}
+
+	sub vcl_miss {
+	  set req.http.x = convert.encode(IDENTITY,
+					  convert.decode(IDENTITY, "foo"));
+	  set req.http.x = convert.transcode(IDENTITY, IDENTITY, "foo");
+	}
+
+	sub vcl_hit {
+	  set req.http.x = convert.encode(IDENTITY,
+					  convert.decode(IDENTITY, "foo"));
+	  set req.http.x = convert.transcode(IDENTITY, IDENTITY, "foo");
+	}
+
+	sub vcl_purge {
+	  set req.http.x = convert.encode(IDENTITY,
+					  convert.decode(IDENTITY, "foo"));
+	  set req.http.x = convert.transcode(IDENTITY, IDENTITY, "foo");
+	}
+
+	sub vcl_deliver {
+	  set req.http.x = convert.encode(IDENTITY,
+					  convert.decode(IDENTITY, "foo"));
+	  set req.http.x = convert.transcode(IDENTITY, IDENTITY, "foo");
+	}
+
+	sub vcl_synth {
+	  set req.http.x = convert.encode(IDENTITY,
+					  convert.decode(IDENTITY, "foo"));
+	  set req.http.x = convert.transcode(IDENTITY, IDENTITY, "foo");
+	}
+
+	sub vcl_backend_fetch {
+	  set bereq.http.x = convert.encode(IDENTITY,
+					    convert.decode(IDENTITY, "foo"));
+	  set bereq.http.x = convert.transcode(IDENTITY, IDENTITY, "foo");
+	}
+
+	sub vcl_backend_response {
+	  set bereq.http.x = convert.encode(IDENTITY,
+					    convert.decode(IDENTITY, "foo"));
+	  set bereq.http.x = convert.transcode(IDENTITY, IDENTITY, "foo");
+	}
+
+	sub vcl_backend_error {
+	  set bereq.http.x = convert.encode(IDENTITY,
+					    convert.decode(IDENTITY, "foo"));
+	  set bereq.http.x = convert.transcode(IDENTITY, IDENTITY, "foo");
+	}
+
+}

src/vmod_convert.c

@@ -57,6 +57,11 @@ struct vmod_convert_blob {
 #define ERRNOMEM(ctx, msg) \
 	ERR((ctx), msg ", out of space")
 
+#define INIT_FINI(ctx) (((ctx)->method & (VCL_MET_INIT | VCL_MET_FINI)) != 0)
+
+#define ILLEGAL(ctx, m) \
+	ERR((ctx), m " is illegal in vcl_init() and vcl_fini().")
+
 static const struct vmod_priv const null_blob[1] =
 {
 	{
@@ -182,10 +187,11 @@ errmsg(VRT_CTX, const char *fmt, ...)
 		VSB_vprintf(ctx->msg, fmt, args);
 		VRT_handling(ctx, VCL_RET_FAIL);
 	}
-	else {
-		AN(ctx->vsl);
+	else if (ctx->vsl)
 		VSLbv(ctx->vsl, SLT_VCL_Error, fmt, args);
-	}
+	else
+		/* An error message in vcl_fini() cannot be formatted */
+		VSL(SLT_VCL_Error, 0, fmt);
 	va_end(args);
 }
 
@@ -308,6 +314,10 @@ vmod_decode(VRT_CTX, VCL_ENUM decs, const char *p, ...) {
 	ssize_t len;
 
 	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
+	if (INIT_FINI(ctx)) {
+		ILLEGAL(ctx, "decode()");
+		return NULL;
+	}
 
 	snap = WS_Snapshot(ctx->ws);
 	if ((b = WS_Alloc(ctx->ws, sizeof(struct vmod_priv))) == NULL) {
@@ -351,6 +361,10 @@ vmod_encode(VRT_CTX, VCL_ENUM encs, VCL_BLOB b) {
 	ssize_t len;
 
 	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
+	if (INIT_FINI(ctx)) {
+		ILLEGAL(ctx, "encode()");
+		return NULL;
+	}
 	if (b == NULL)
 		return NULL;
 
@@ -383,6 +397,10 @@ vmod_transcode(VRT_CTX, VCL_ENUM decs, VCL_ENUM encs, const char *p, ...) {
 	va_list ap;
 
 	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
+	if (INIT_FINI(ctx)) {
+		ILLEGAL(ctx, "transcode()");
+		return NULL;
+	}
 
 	/*
 	 * If the encoding and decoding are the same, just return the