diff --git a/src/core/ddsc/src/dds_participant.c b/src/core/ddsc/src/dds_participant.c
index 3cbb48d..5d84fb8 100644
--- a/src/core/ddsc/src/dds_participant.c
+++ b/src/core/ddsc/src/dds_participant.c
@@ -96,7 +96,7 @@ dds_entity_t dds_create_participant (const dds_domainid_t domain, const dds_qos_
   dds_participant * pp;
   ddsi_plist_t plist;
   dds_qos_t *new_qos = NULL;
-  char *config = "";
+  const char *config = "";
 
   /* Make sure DDS instance is initialized. */
   if ((ret = dds_init ()) < 0)
diff --git a/src/core/ddsc/tests/config.c b/src/core/ddsc/tests/config.c
index a7d2bec..546062a 100644
--- a/src/core/ddsc/tests/config.c
+++ b/src/core/ddsc/tests/config.c
@@ -29,7 +29,7 @@
 
 static void config__check_env (const char *env_variable, const char *expected_value)
 {
-  char *env_uri = NULL;
+  const char *env_uri = NULL;
   ddsrt_getenv (env_variable, &env_uri);
 #ifdef FORCE_ENV
   {
diff --git a/src/core/ddsc/tests/participant.c b/src/core/ddsc/tests/participant.c
index 6100f5d..70697a5 100644
--- a/src/core/ddsc/tests/participant.c
+++ b/src/core/ddsc/tests/participant.c
@@ -111,7 +111,7 @@ CU_Test(ddsc_participant, create_with_conf_no_env) {
     ddsrt_setenv(DDS_PROJECT_NAME_NOSPACE_CAPS"_URI", CONFIG_ENV_SIMPLE_UDP);
     ddsrt_setenv("MAX_PARTICIPANTS", CONFIG_ENV_MAX_PARTICIPANTS);
 
-    char * env_uri = NULL;
+    const char * env_uri = NULL;
     ddsrt_getenv(DDS_PROJECT_NAME_NOSPACE_CAPS"_URI", &env_uri);
     CU_ASSERT_PTR_NOT_EQUAL_FATAL(env_uri, NULL);
 
diff --git a/src/ddsrt/CMakeLists.txt b/src/ddsrt/CMakeLists.txt
index 6efefdd..b81f86b 100644
--- a/src/ddsrt/CMakeLists.txt
+++ b/src/ddsrt/CMakeLists.txt
@@ -131,7 +131,8 @@ list(APPEND sources
   "${source_path}/strtol.c"
   "${source_path}/mh3.c"
   "${source_path}/avl.c"
-  "${source_path}/expand_envvars.c"
+  "${source_path}/environ.c"
+  "${source_path}/expand_vars.c"
   "${source_path}/fibheap.c"
   "${source_path}/hopscotch.c"
   "${source_path}/thread_pool.c"
diff --git a/src/ddsrt/include/dds/ddsrt/environ.h b/src/ddsrt/include/dds/ddsrt/environ.h
index d5d895e..dd65f01 100644
--- a/src/ddsrt/include/dds/ddsrt/environ.h
+++ b/src/ddsrt/include/dds/ddsrt/environ.h
@@ -14,6 +14,7 @@
 
 #include "dds/export.h"
 #include "dds/ddsrt/attributes.h"
+#include "dds/ddsrt/expand_vars.h"
 #include "dds/ddsrt/retcode.h"
 
 #if defined(__cplusplus)
@@ -42,7 +43,7 @@ extern "C" {
 DDS_EXPORT dds_return_t
 ddsrt_getenv(
   const char *name,
-  char **value)
+  const char **value)
 ddsrt_nonnull_all;
 
 /**
diff --git a/src/ddsrt/include/dds/ddsrt/expand_vars.h b/src/ddsrt/include/dds/ddsrt/expand_vars.h
new file mode 100644
index 0000000..78b2326
--- /dev/null
+++ b/src/ddsrt/include/dds/ddsrt/expand_vars.h
@@ -0,0 +1,78 @@
+/*
+ * Copyright(c) 2006 to 2018 ADLINK Technology Limited and others
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0, or the Eclipse Distribution License
+ * v. 1.0 which is available at
+ * http://www.eclipse.org/org/documents/edl-v10.php.
+ *
+ * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
+ */
+#ifndef DDSRT_EXPAND_VARS_H
+#define DDSRT_EXPAND_VARS_H
+
+#include "dds/export.h"
+#include "dds/ddsrt/attributes.h"
+#include "dds/ddsrt/retcode.h"
+
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+typedef const char * (*expand_lookup_fn)(const char *name, void *data);
+
+/**
+ * @brief Expand variables within string.
+ *
+ * Expands ${X}, ${X:-Y}, ${X:+Y}, ${X:?Y} forms, but not $X.
+ *
+ * The result string should be freed with ddsrt_free().
+ *
+ * @param[in]  string  String to expand.
+ * @param[in]  lookup  Lookup function to retrieve replacement value
+ * @param[in]  data    Data passed to lookup function
+ *
+ * @returns Allocated char*.
+ *
+ * @retval NULL
+ *             Expansion failed.
+ * @retval Pointer
+ *             Copy of the string argument with the variables expanded.
+ */
+DDS_EXPORT char*
+ddsrt_expand_vars(
+  const char *string,
+  expand_lookup_fn lookup,
+  void * data);
+
+/**
+ * @brief Expand variables within string.
+ *
+ * Expands $X, ${X}, ${X:-Y}, ${X:+Y}, ${X:?Y} forms, $ and \
+ * can be escaped with \.
+ *
+ * The result string should be freed with ddsrt_free().
+ *
+ * @param[in]  string  String to expand.
+ * @param[in]  lookup  Lookup function to retrieve replacement value
+ * @param[in]  data    Data passed to lookup function
+ *
+ * @returns Allocated char*.
+ *
+ * @retval NULL
+ *             Expansion failed.
+ * @retval Pointer
+ *             Copy of the string argument with the variables expanded.
+ */
+DDS_EXPORT char*
+ddsrt_expand_vars_sh(
+  const char *string,
+  expand_lookup_fn lookup,
+  void * data);
+
+#if defined(__cplusplus)
+}
+#endif
+
+#endif /* DDSRT_EXPAND_VARS_H */
diff --git a/src/ddsrt/src/environ.c b/src/ddsrt/src/environ.c
new file mode 100644
index 0000000..501d92b
--- /dev/null
+++ b/src/ddsrt/src/environ.c
@@ -0,0 +1,59 @@
+/*
+ * Copyright(c) 2006 to 2018 ADLINK Technology Limited and others
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0, or the Eclipse Distribution License
+ * v. 1.0 which is available at
+ * http://www.eclipse.org/org/documents/edl-v10.php.
+ *
+ * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
+ */
+#include <stdio.h>
+#include <ctype.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <string.h>
+
+#include "dds/ddsrt/expand_vars.h"
+#include "dds/ddsrt/environ.h"
+#include "dds/ddsrt/heap.h"
+#include "dds/ddsrt/log.h"
+#include "dds/ddsrt/string.h"
+#include "dds/ddsrt/process.h"
+
+struct expand_env_data
+{
+    uint32_t domid;
+    char idstr[20];
+};
+
+static const char * expand_lookup_env(const char *name, void * data)
+{
+    const char *env = NULL;
+    struct expand_env_data * env_data = data;
+
+    if (ddsrt_getenv (name, &env) == DDS_RETCODE_OK) {
+        /* ok */
+    } else if (strcmp (name, "$") == 0 || strcmp (name, "CYCLONEDDS_PID") == 0) {
+        (void) snprintf (env_data->idstr, sizeof (env_data->idstr), "%"PRIdPID, ddsrt_getpid ());
+        env = env_data->idstr;
+    } else if (strcmp (name, "CYCLONEDDS_DOMAIN_ID") == 0 && env_data->domid != UINT32_MAX) {
+        (void) snprintf (env_data->idstr, sizeof (env_data->idstr), "%"PRIu32, env_data->domid);
+        env = env_data->idstr;
+    }
+    return env;
+}
+
+char *ddsrt_expand_envvars_sh (const char *src0, uint32_t domid)
+{
+    struct expand_env_data env = { .domid = domid, .idstr = "" };
+    return ddsrt_expand_vars_sh(src0, &expand_lookup_env, &env);
+}
+
+char *ddsrt_expand_envvars (const char *src0, uint32_t domid)
+{
+    struct expand_env_data env = { .domid = domid, .idstr = "" };
+    return ddsrt_expand_vars(src0, &expand_lookup_env, &env);
+}
+
diff --git a/src/ddsrt/src/environ/posix/environ.c b/src/ddsrt/src/environ/posix/environ.c
index 1f8b84f..c2e61a9 100644
--- a/src/ddsrt/src/environ/posix/environ.c
+++ b/src/ddsrt/src/environ/posix/environ.c
@@ -24,7 +24,7 @@ isenvvar(const char *name)
 }
 
 dds_return_t
-ddsrt_getenv(const char *name, char **value)
+ddsrt_getenv(const char *name, const char **value)
 {
   char *env;
 
diff --git a/src/ddsrt/src/environ/solaris2.6/environ.c b/src/ddsrt/src/environ/solaris2.6/environ.c
index 83f0d8f..07d113a 100644
--- a/src/ddsrt/src/environ/solaris2.6/environ.c
+++ b/src/ddsrt/src/environ/solaris2.6/environ.c
@@ -27,7 +27,7 @@ isenvvar(const char *name)
 }
 
 dds_return_t
-ddsrt_getenv(const char *name, char **value)
+ddsrt_getenv(const char *name, const char **value)
 {
   char *env;
 
diff --git a/src/ddsrt/src/environ/windows/environ.c b/src/ddsrt/src/environ/windows/environ.c
index a5b2f90..7589545 100644
--- a/src/ddsrt/src/environ/windows/environ.c
+++ b/src/ddsrt/src/environ/windows/environ.c
@@ -26,7 +26,7 @@ isenvvar(const char *name)
 
 DDSRT_WARNING_MSVC_OFF(4996)
 dds_return_t
-ddsrt_getenv(const char *name, char **value)
+ddsrt_getenv(const char *name, const char **value)
 {
   char *env;
 
diff --git a/src/ddsrt/src/expand_envvars.c b/src/ddsrt/src/expand_vars.c
similarity index 72%
rename from src/ddsrt/src/expand_envvars.c
rename to src/ddsrt/src/expand_vars.c
index faa166a..e0396bd 100644
--- a/src/ddsrt/src/expand_envvars.c
+++ b/src/ddsrt/src/expand_vars.c
@@ -15,13 +15,13 @@
 #include <assert.h>
 #include <string.h>
 
-#include "dds/ddsrt/environ.h"
+#include "dds/ddsrt/expand_vars.h"
 #include "dds/ddsrt/heap.h"
 #include "dds/ddsrt/log.h"
 #include "dds/ddsrt/string.h"
 #include "dds/ddsrt/process.h"
 
-typedef char * (*expand_fn)(const char *src0, uint32_t domid);
+typedef char * (*expand_fn)(const char *src0, expand_lookup_fn lookup, void * data);
 
 static void expand_append (char **dst, size_t *sz, size_t *pos, char c)
 {
@@ -33,46 +33,33 @@ static void expand_append (char **dst, size_t *sz, size_t *pos, char c)
     (*pos)++;
 }
 
-static char *expand_env (const char *name, char op, const char *alt, expand_fn expand, uint32_t domid)
+static char *expand_var (const char *name, char op, const char *alt, expand_fn expand, expand_lookup_fn lookup, void * data)
 {
-    char idstr[20];
-    char *env = NULL;
-    dds_return_t ret;
-
-    if ((ret = ddsrt_getenv (name, &env)) == DDS_RETCODE_OK) {
-        /* ok */
-    } else if (strcmp (name, "$") == 0 || strcmp (name, "CYCLONEDDS_PID") == 0) {
-        (void) snprintf (idstr, sizeof (idstr), "%"PRIdPID, ddsrt_getpid ());
-        env = idstr;
-    } else if (strcmp (name, "CYCLONEDDS_DOMAIN_ID") == 0 && domid != UINT32_MAX) {
-        (void) snprintf (idstr, sizeof (idstr), "%"PRIu32, domid);
-        env = idstr;
-    }
-
+    const char *val = lookup (name, data);
     switch (op)
     {
         case 0:
-            return ddsrt_strdup (env ? env : "");
+            return ddsrt_strdup (val ? val : "");
         case '-':
-            return env && *env ? ddsrt_strdup (env) : expand (alt, domid);
+            return val && *val ? ddsrt_strdup (val) : expand (alt, lookup, data);
         case '?':
-            if (env && *env) {
-                return ddsrt_strdup (env);
+            if (val && *val) {
+                return ddsrt_strdup (val);
             } else {
-                char *altx = expand (alt, domid);
-                DDS_ILOG (DDS_LC_ERROR, domid, "%s: %s\n", name, altx);
+                char *altx = expand (alt, lookup, data);
+                DDS_LOG (DDS_LC_ERROR, "%s: %s\n", name, altx);
                 ddsrt_free (altx);
                 return NULL;
             }
         case '+':
-            return env && *env ? expand (alt, domid) : ddsrt_strdup ("");
+            return val && *val ? expand (alt, lookup, data) : ddsrt_strdup ("");
         default:
             abort ();
             return NULL;
     }
 }
 
-static char *expand_envbrace (const char **src, expand_fn expand, uint32_t domid)
+static char *expand_varbrace (const char **src, expand_fn expand, expand_lookup_fn lookup, void * data)
 {
     const char *start = *src + 1;
     char *name, *x;
@@ -89,7 +76,7 @@ static char *expand_envbrace (const char **src, expand_fn expand, uint32_t domid
     name[*src - start] = 0;
     if (**src == '}') {
         (*src)++;
-        x = expand_env (name, 0, NULL, expand, domid);
+        x = expand_var (name, 0, NULL, expand, lookup, data);
         ddsrt_free (name);
         return x;
     } else {
@@ -133,7 +120,7 @@ static char *expand_envbrace (const char **src, expand_fn expand, uint32_t domid
         memcpy (alt, altstart, (size_t) (*src - altstart));
         alt[*src - altstart] = 0;
         (*src)++;
-        x = expand_env (name, op, alt, expand, domid);
+        x = expand_var (name, op, alt, expand, lookup, data);
         ddsrt_free (alt);
         ddsrt_free (name);
         return x;
@@ -143,7 +130,7 @@ err:
     return NULL;
 }
 
-static char *expand_envsimple (const char **src, expand_fn expand, uint32_t domid)
+static char *expand_varsimple (const char **src, expand_fn expand, expand_lookup_fn lookup, void * data)
 {
     const char *start = *src;
     char *name, *x;
@@ -154,22 +141,22 @@ static char *expand_envsimple (const char **src, expand_fn expand, uint32_t domi
     name = ddsrt_malloc ((size_t) (*src - start) + 1);
     memcpy (name, start, (size_t) (*src - start));
     name[*src - start] = 0;
-    x = expand_env (name, 0, NULL, expand, domid);
+    x = expand_var (name, 0, NULL, expand, lookup, data);
     ddsrt_free (name);
     return x;
 }
 
-static char *expand_envchar (const char **src, expand_fn expand, uint32_t domid)
+static char *expand_varchar (const char **src, expand_fn expand, expand_lookup_fn lookup, void * data)
 {
     char name[2];
     assert (**src);
     name[0] = **src;
     name[1] = 0;
     (*src)++;
-    return expand_env (name, 0, NULL, expand, domid);
+    return expand_var (name, 0, NULL, expand, lookup, data);
 }
 
-char *ddsrt_expand_envvars_sh (const char *src0, uint32_t domid)
+char *ddsrt_expand_vars_sh (const char *src0, expand_lookup_fn lookup, void * data)
 {
     /* Expands $X, ${X}, ${X:-Y}, ${X:+Y}, ${X:?Y} forms; $ and \ can be escaped with \ */
     const char *src = src0;
@@ -192,11 +179,11 @@ char *ddsrt_expand_envvars_sh (const char *src0, uint32_t domid)
                 ddsrt_free(dst);
                 return NULL;
             } else if (*src == '{') {
-                x = expand_envbrace (&src, &ddsrt_expand_envvars_sh, domid);
+                x = expand_varbrace (&src, &ddsrt_expand_vars_sh, lookup, data);
             } else if (isalnum ((unsigned char) *src) || *src == '_') {
-                x = expand_envsimple (&src, &ddsrt_expand_envvars_sh, domid);
+                x = expand_varsimple (&src, &ddsrt_expand_vars_sh, lookup, data);
             } else {
-                x = expand_envchar (&src, &ddsrt_expand_envvars_sh, domid);
+                x = expand_varchar (&src, &ddsrt_expand_vars_sh, lookup, data);
             }
             if (x == NULL) {
                 ddsrt_free(dst);
@@ -215,7 +202,7 @@ char *ddsrt_expand_envvars_sh (const char *src0, uint32_t domid)
     return dst;
 }
 
-char *ddsrt_expand_envvars (const char *src0, uint32_t domid)
+char *ddsrt_expand_vars (const char *src0, expand_lookup_fn lookup, void * data)
 {
     /* Expands ${X}, ${X:-Y}, ${X:+Y}, ${X:?Y} forms, but not $X */
     const char *src = src0;
@@ -225,7 +212,7 @@ char *ddsrt_expand_envvars (const char *src0, uint32_t domid)
         if (*src == '$' && *(src + 1) == '{') {
             char *x, *xp;
             src++;
-            x = expand_envbrace (&src, &ddsrt_expand_envvars, domid);
+            x = expand_varbrace (&src, &ddsrt_expand_vars, lookup, data);
             if (x == NULL) {
                 ddsrt_free(dst);
                 return NULL;
@@ -242,3 +229,4 @@ char *ddsrt_expand_envvars (const char *src0, uint32_t domid)
     expand_append (&dst, &sz, &pos, 0);
     return dst;
 }
+
diff --git a/src/ddsrt/src/xmlparser.c b/src/ddsrt/src/xmlparser.c
index 873aa0d..8820b71 100644
--- a/src/ddsrt/src/xmlparser.c
+++ b/src/ddsrt/src/xmlparser.c
@@ -27,9 +27,12 @@
 #define TOK_CLOSE_TAG -5
 #define TOK_SHORTHAND_CLOSE_TAG -6
 #define TOK_ERROR -7
+#define TOK_CDATA -8
 
 #define NOMARKER (~(size_t)0)
 
+static const char *cdata_magic = "<![CDATA[";
+
 struct ddsrt_xmlp_state {
     size_t cbufp; /* current position in cbuf */
     size_t cbufn; /* number of bytes in cbuf (cbufp <= cbufn) */
@@ -559,6 +562,8 @@ static int next_token (struct ddsrt_xmlp_state *st, char **payload)
         } else if (peek_chars (st, "<?", 1)) {
             processing_instruction (st, "?>");
             return next_token (st, payload);
+        } else if (peek_chars (st, cdata_magic, 0)) {
+            tok = TOK_CDATA;
         } else if (peek_chars (st, "<!", 1)) {
             processing_instruction (st, ">");
             return next_token (st, payload);
@@ -652,7 +657,6 @@ static int parse_element (struct ddsrt_xmlp_state *st, uintptr_t parentinfo)
                 }
             } else {
                 /* text */
-                static const char *cdata_magic = "<![CDATA[";
                 char *content;
                 int cmt = 0;
                 rewind_to_input_marker (st);
diff --git a/src/ddsrt/tests/environ.c b/src/ddsrt/tests/environ.c
index 0a11334..564445b 100644
--- a/src/ddsrt/tests/environ.c
+++ b/src/ddsrt/tests/environ.c
@@ -26,7 +26,7 @@ CU_Theory((const char *name), ddsrt_environ, bad_name)
   dds_return_t rc;
   static const char value[] = "bar";
   static char dummy[] = "foobar";
-  char *ptr;
+  const char *ptr;
 
   rc = ddsrt_setenv(name, value);
   CU_ASSERT_EQUAL(rc, DDS_RETCODE_BAD_PARAMETER);
@@ -71,7 +71,7 @@ CU_Test(ddsrt_environ, getenv)
   static const char name[] = "foo";
   static const char value[] = "bar";
   static char dummy[] = "foobar";
-  char *ptr;
+  const char *ptr;
 
   /* Ensure "not found" is returned. */
   rc = ddsrt_unsetenv(name);
diff --git a/src/ddsrt/tests/process_app.c b/src/ddsrt/tests/process_app.c
index 1613391..9251a72 100644
--- a/src/ddsrt/tests/process_app.c
+++ b/src/ddsrt/tests/process_app.c
@@ -57,7 +57,7 @@ static int test_pid(void)
 static int test_env(void)
 {
   int ret = TEST_EXIT_FAILURE;
-  char *envptr = NULL;
+  const char *envptr = NULL;
   if (ddsrt_getenv(TEST_ENV_VAR_NAME, &envptr) == DDS_RETCODE_OK) {
     printf(" Process: env %s=%s.\n", TEST_ENV_VAR_NAME, envptr);
     if (strcmp(envptr, TEST_ENV_VAR_VALUE) == 0) {