Abstract out random generation

Still depending on gcrypt for hashing, but this is a step towards
making that dependency optional.

7 files changed, 67 insertions, 7 deletions

diff --git a/configure.ac b/configure.ac
index 656eb7d..270f989 100644
--- a/configure.ac
+++ b/configure.ac
@@ -38,7 +38,10 @@ AM_CONDITIONAL([USE_RUST], [test "x$with_rust" == "xyes"])
 LT_INIT
 
 
-AM_PATH_LIBGCRYPT
+# Libgcrypt
+
+AM_PATH_LIBGCRYPT([],
+        [AC_DEFINE([HAVE_GCRYPT], [1], [Libgcrypt is available])])
 
 # libnice (+ glib) and libsrtp for media calls, optional
 
diff --git a/src/Makefile.am b/src/Makefile.am
index 5bf0f1a..44b6702 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -15,12 +15,14 @@ librexmpp_la_SOURCES = rexmpp_roster.h rexmpp_roster.c \
 	rexmpp_base64.h rexmpp_base64.c \
 	rexmpp_sasl.h rexmpp_sasl.c \
 	rexmpp_xml.h rexmpp_xml.c \
-	rexmpp_utf8.h
+	rexmpp_utf8.h \
+	rexmpp_random.h rexmpp_random.c
 
 include_HEADERS = config.h rexmpp_roster.h rexmpp_tcp.h rexmpp_socks.h rexmpp.h \
 	rexmpp_dns.h rexmpp_tls.h rexmpp_jid.h rexmpp_openpgp.h rexmpp_console.h \
 	rexmpp_pubsub.h rexmpp_http_upload.h rexmpp_jingle.h rexmpp_base64.h \
-	rexmpp_sasl.h rexmpp_xml.h rexmpp_utf8.h rexmpp_xml_parser.h
+	rexmpp_sasl.h rexmpp_xml.h rexmpp_utf8.h rexmpp_xml_parser.h \
+	rexmpp_random.h
 librexmpp_la_CFLAGS = $(AM_CFLAGS) $(LIBXML2_CFLAGS) $(EXPAT_CFLAGS) \
 	$(GNUTLS_CFLAGS) $(LIBDANE_CFLAGS) $(OPENSSL_CFLAGS) \
 	$(GSASL_CFLAGS) $(UNBOUND_CFLAGS) $(CARES_CFLAGS) $(GPGME_CFLAGS) \
diff --git a/src/rexmpp.c b/src/rexmpp.c
index 7194d87..beb2762 100644
--- a/src/rexmpp.c
+++ b/src/rexmpp.c
@@ -17,8 +17,12 @@
 
 #include "config.h"
 
+#ifdef HAVE_GCRYPT
 #include <gcrypt.h>
+#endif
+#ifdef USE_UNBOUND
 #include <unbound.h>
+#endif
 #ifdef HAVE_GPGME
 #include <gpgme.h>
 #endif
@@ -39,6 +43,7 @@
 #include "rexmpp_jingle.h"
 #include "rexmpp_base64.h"
 #include "rexmpp_sasl.h"
+#include "rexmpp_random.h"
 
 struct rexmpp_iq_cacher {
   rexmpp_iq_callback_t cb;
@@ -817,7 +822,7 @@ void rexmpp_schedule_reconnect (rexmpp_t *s) {
     return;
   }
   if (s->reconnect_number == 0) {
-    gcry_create_nonce((char*)&s->reconnect_seconds, sizeof(time_t));
+    rexmpp_random_buf((char*)&s->reconnect_seconds, sizeof(time_t));
     if (s->reconnect_seconds < 0) {
       s->reconnect_seconds = - s->reconnect_seconds;
     }
@@ -852,7 +857,7 @@ char *rexmpp_gen_id (rexmpp_t *s) {
   (void)s;
   char buf_raw[18], *buf_base64 = NULL;
   size_t buf_base64_len = 0;
-  gcry_create_nonce(buf_raw, 18);
+  rexmpp_random_buf(buf_raw, 18);
   rexmpp_base64_to(buf_raw, 18, &buf_base64, &buf_base64_len);
   return buf_base64;
 }
diff --git a/src/rexmpp_openpgp.c b/src/rexmpp_openpgp.c
index c11d031..4ef7335 100644
--- a/src/rexmpp_openpgp.c
+++ b/src/rexmpp_openpgp.c
@@ -55,6 +55,7 @@ Possible future improvements:
 #include "rexmpp_jid.h"
 #include "rexmpp_pubsub.h"
 #include "rexmpp_base64.h"
+#include "rexmpp_random.h"
 
 
 #ifdef HAVE_GPGME
@@ -739,9 +740,9 @@ char *rexmpp_openpgp_payload (rexmpp_t *s,
 
     /* A random-length random-content padding. */
     char *rand_str, rand[256];
-    gcry_create_nonce(rand, 1);
+    rexmpp_random_buf(rand, 1);
     size_t rand_str_len = 0, rand_len = (unsigned char)rand[0] % (255 - 16) + 16;
-    gcry_create_nonce(rand, rand_len);
+    rexmpp_random_buf(rand, rand_len);
     rexmpp_base64_to(rand, rand_len, &rand_str, &rand_str_len);
 
     rexmpp_xml_t *rpad =
diff --git a/src/rexmpp_random.c b/src/rexmpp_random.c
new file mode 100644
index 0000000..8efabd3
--- /dev/null
+++ b/src/rexmpp_random.c
@@ -0,0 +1,25 @@
+/**
+   @file rexmpp_random.c
+   @brief Random generation
+   @author defanor <defanor@uberspace.net>
+   @date 2023
+   @copyright MIT license.
+*/
+
+#include "config.h"
+
+#ifdef HAVE_GCRYPT
+#include <gcrypt.h>
+#else
+#define _GNU_SOURCE
+#include <stdlib.h>
+#endif
+
+
+void rexmpp_random_buf (void *buf, size_t len) {
+#ifdef HAVE_GCRYPT
+  gcry_create_nonce(buf, len);
+#else
+  arc4random_buf(buf, len);
+#endif
+}
diff --git a/src/rexmpp_random.h b/src/rexmpp_random.h
new file mode 100644
index 0000000..1b21001
--- /dev/null
+++ b/src/rexmpp_random.h
@@ -0,0 +1,22 @@
+/**
+   @file rexmpp_random.h
+   @brief Random generation
+   @author defanor <defanor@uberspace.net>
+   @date 2023
+   @copyright MIT license.
+*/
+
+#ifndef REXMPP_RANDOM_H
+#define REXMPP_RANDOM_H
+
+/**
+   @brief Fills a buffer with cryptographically-secure random data.
+   @param[out] buf A buffer to write into.
+   @param[in] len The number of bytes to fill.
+
+   Uses arc4random_buf or gcry_create_nonce, depending on what is
+   available.
+*/
+void rexmpp_random_buf (void *buf, size_t len);
+
+#endif
diff --git a/src/rexmpp_xml_parser.c b/src/rexmpp_xml_parser.c
index b2eaf8b..e00c70c 100644
--- a/src/rexmpp_xml_parser.c
+++ b/src/rexmpp_xml_parser.c
@@ -6,6 +6,8 @@
    @copyright MIT license.
 */
 
+#include <string.h>
+
 #include "rexmpp.h"
 #include "rexmpp_xml.h"
 #include "rexmpp_xml_parser.h"