Add support for using nettle instead of gcrypt as gnutls backend

configure.ac

@@ -1799,17 +1799,30 @@ if test "$OPENSSL_ENABLED" != "1"; then
 fi dnl OPENSSL != 1
 
 dnl ---
-dnl If GnuTLS is enabled, we MUST verify that it uses libgcrypt since
-dnl curl code relies on that but recent GnuTLS versions can in fact build
-dnl with different crypto libraries which curl right now cannot handle
+dnl Check which crypto backend GnuTLS uses
 dnl ---
 
 if test "$GNUTLS_ENABLED" = "1"; then
-  AC_CHECK_LIB(gcrypt,
-               gcry_control, ,
-    [
-      AC_MSG_ERROR([need GnuTLS built with gcrypt to function with GnuTLS])
-    ])
+  USE_GNUTLS_NETTLE=
+  # First check if we can detect either crypto library via transitive linking
+  AC_CHECK_LIB(gnutls, nettle_MD5Init, [ USE_GNUTLS_NETTLE=1 ])
+  if test "$USE_GNUTLS_NETTLE" = ""; then
+    AC_CHECK_LIB(gnutls, gcry_control, [ USE_GNUTLS_NETTLE=0 ])
+  fi
+  # If not, try linking directly to both of them to see if they are available
+  if test "$USE_GNUTLS_NETTLE" = ""; then
+    AC_CHECK_LIB(nettle, nettle_MD5Init, [ USE_GNUTLS_NETTLE=1 ])
+  fi
+  if test "$USE_GNUTLS_NETTLE" = ""; then
+    AC_CHECK_LIB(gcrypt, gcry_control, [ USE_GNUTLS_NETTLE=0 ])
+  fi
+  if test "$USE_GNUTLS_NETTLE" = ""; then
+    AC_MSG_ERROR([GnuTLS found, but neither gcrypt nor nettle found])
+  fi
+  if test "$USE_GNUTLS_NETTLE" = "1"; then
+    AC_DEFINE(USE_GNUTLS_NETTLE, 1, [if GnuTLS uses nettle as crypto backend])
+    AC_SUBST(USE_GNUTLS_NETTLE, [1])
+  fi
 fi
 
 dnl ---

lib/curl_ntlm_core.c

@@ -63,6 +63,11 @@
 #    define DESKEY(x) &x
 #  endif
 
+#elif defined(USE_GNUTLS_NETTLE)
+
+#  include <nettle/des.h>
+#  include <nettle/md4.h>
+
 #elif defined(USE_GNUTLS)
 
 #  include <gcrypt.h>
@@ -133,7 +138,17 @@ static void extend_key_56_to_64(const unsigned char *key_56, char *key)
   key[7] = (unsigned char) ((key_56[6] << 1) & 0xFF);
 }
 
-#if defined(USE_GNUTLS)
+#if defined(USE_GNUTLS_NETTLE)
+
+static void setup_des_key(const unsigned char *key_56,
+                          struct des_ctx *des)
+{
+  char key[8];
+  extend_key_56_to_64(key_56, key);
+  des_set_key(des, key);
+}
+
+#elif defined(USE_GNUTLS)
 
 /*
  * Turns a 56 bit key into the 64 bit, odd parity key and sets the key.
@@ -233,6 +248,14 @@ void Curl_ntlm_core_lm_resp(const unsigned char *keys,
   setup_des_key(keys + 14, DESKEY(ks));
   DES_ecb_encrypt((DES_cblock*) plaintext, (DES_cblock*) (results + 16),
                   DESKEY(ks), DES_ENCRYPT);
+#elif defined(USE_GNUTLS_NETTLE)
+  struct des_ctx des;
+  setup_des_key(keys, &des);
+  des_encrypt(&des, 8, results, plaintext);
+  setup_des_key(keys + 7, &des);
+  des_encrypt(&des, 8, results + 8, plaintext);
+  setup_des_key(keys + 14, &des);
+  des_encrypt(&des, 8, results + 16, plaintext);
 #elif defined(USE_GNUTLS)
   gcry_cipher_hd_t des;
 
@@ -295,6 +318,12 @@ void Curl_ntlm_core_mk_lm_hash(struct SessionHandle *data,
     setup_des_key(pw + 7, DESKEY(ks));
     DES_ecb_encrypt((DES_cblock *)magic, (DES_cblock *)(lmbuffer + 8),
                     DESKEY(ks), DES_ENCRYPT);
+#elif defined(USE_GNUTLS_NETTLE)
+    struct des_ctx des;
+    setup_des_key(pw, &des);
+    des_encrypt(&des, 8, lmbuffer, magic);
+    setup_des_key(pw + 7, &des);
+    des_encrypt(&des, 8, lmbuffer + 8, magic);
 #elif defined(USE_GNUTLS)
     gcry_cipher_hd_t des;
 
@@ -357,6 +386,11 @@ CURLcode Curl_ntlm_core_mk_nt_hash(struct SessionHandle *data,
     MD4_Init(&MD4pw);
     MD4_Update(&MD4pw, pw, 2 * len);
     MD4_Final(ntbuffer, &MD4pw);
+#elif defined(USE_GNUTLS_NETTLE)
+    struct md4_ctx MD4pw;
+    md4_init(&MD4pw);
+    md4_update(&MD4pw, 2 * len, pw);
+    md4_digest(&MD4pw, MD4_DIGEST_SIZE, ntbuffer);
 #elif defined(USE_GNUTLS)
     gcry_md_hd_t MD4pw;
     gcry_md_open(&MD4pw, GCRY_MD_MD4, 0);

lib/curl_ntlm_msgs.c

@@ -54,6 +54,13 @@
 #  endif
 #  include "ssluse.h"
 
+#elif defined(USE_GNUTLS_NETTLE)
+
+#  include <nettle/md5.h>
+#  include <gnutls/gnutls.h>
+#  include <gnutls/crypto.h>
+#  define MD5_DIGEST_LENGTH 16
+
 #elif defined(USE_GNUTLS)
 
 #  include <gcrypt.h>
@@ -714,6 +721,9 @@ CURLcode Curl_ntlm_create_type3_message(struct SessionHandle *data,
     MD5_CTX MD5pw;
     Curl_ossl_seed(data); /* Initiate the seed if not already done */
     RAND_bytes(entropy, 8);
+#elif defined(USE_GNUTLS_NETTLE)
+    struct md5_ctx MD5pw;
+    gnutls_rnd(GNUTLS_RND_RANDOM, entropy, 8);
 #elif defined(USE_GNUTLS)
     gcry_md_hd_t MD5pw;
     Curl_gtls_seed(data); /* Initiate the seed if not already done */
@@ -739,6 +749,10 @@ CURLcode Curl_ntlm_create_type3_message(struct SessionHandle *data,
     MD5_Init(&MD5pw);
     MD5_Update(&MD5pw, tmp, 16);
     MD5_Final(md5sum, &MD5pw);
+#elif defined(USE_GNUTLS_NETTLE)
+    md5_init(&MD5pw);
+    md5_update(&MD5pw, 16, tmp);
+    md5_digest(&MD5pw, 16, md5sum);
 #elif defined(USE_GNUTLS)
     gcry_md_open(&MD5pw, GCRY_MD_MD5, 0);
     gcry_md_write(MD5pw, tmp, MD5_DIGEST_LENGTH);

lib/gtls.c

@@ -34,7 +34,9 @@
 
 #include <gnutls/gnutls.h>
 #include <gnutls/x509.h>
+#ifndef USE_GNUTLS_NETTLE
 #include <gcrypt.h>
+#endif
 
 #ifdef HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
@@ -1032,7 +1034,9 @@ int Curl_gtls_seed(struct SessionHandle *data)
   static bool ssl_seeded = FALSE;
 
   /* Quickly add a bit of entropy */
+#ifndef USE_GNUTLS_NETTLE
   gcry_fast_random_poll();
+#endif
 
   if(!ssl_seeded || data->set.str[STRING_SSL_RANDOM_FILE] ||
      data->set.str[STRING_SSL_EGDSOCKET]) {

lib/md5.c

@@ -27,6 +27,30 @@
 #include "curl_md5.h"
 #include "curl_hmac.h"
 
+#ifdef USE_GNUTLS_NETTLE
+
+#include <nettle/md5.h>
+
+typedef struct md5_ctx MD5_CTX;
+
+static void MD5_Init(MD5_CTX * ctx)
+{
+  md5_init(ctx);
+}
+
+static void MD5_Update(MD5_CTX * ctx,
+                       const unsigned char * input,
+                       unsigned int inputLen)
+{
+  md5_update(ctx, inputLen, input);
+}
+
+static void MD5_Final(unsigned char digest[16], MD5_CTX * ctx)
+{
+  md5_digest(ctx, 16, digest);
+}
+#else
+
 #ifdef USE_GNUTLS
 
 #include <gcrypt.h>
@@ -369,6 +393,8 @@ static void Decode (UINT4 *output,
 
 #endif /* USE_GNUTLS */
 
+#endif /* USE_GNUTLS_NETTLE */
+
 const HMAC_params Curl_HMAC_MD5[] = {
   {
     (HMAC_hinit_func) MD5_Init,           /* Hash initialization function. */