Deprecate Diffie-Hellman groups from RFC 5114

Also, change the way the standardized Diffie-Hellman groups are provided from
macro-based string-literals to global variables.
diff --git a/include/mbedtls/dhm.h b/include/mbedtls/dhm.h
index d7ab152..f3ee14f 100644
--- a/include/mbedtls/dhm.h
+++ b/include/mbedtls/dhm.h
@@ -38,6 +38,14 @@
 #define MBEDTLS_ERR_DHM_ALLOC_FAILED                      -0x3400  /**< Allocation of memory failed. */
 #define MBEDTLS_ERR_DHM_FILE_IO_ERROR                     -0x3480  /**< Read/write of file failed. */
 
+#if ! defined(MBEDTLS_DEPRECATED_REMOVED)
+#if defined(MBEDTLS_DEPRECATED_WARNING)
+#define MBEDTLS_DEPRECATED    __attribute__((deprecated))
+#else
+#define MBEDTLS_DEPRECATED
+#endif
+#endif
+
 /**
  * RFC 3526 defines a number of standardized Diffie-Hellman groups
  * for IKE.
@@ -51,93 +59,48 @@
  *  RFC 3526 4.    3072-bit MODP Group
  *  RFC 3526 5.    4096-bit MODP Group
  *  RFC 5114 2.2.  2048-bit MODP Group with 224-bit Prime Order Subgroup
+ * The constants with suffix "_p" denote the chosen prime moduli, while
+ * the constants with suffix "_g" denote the chosen generator
+ * of the associated prime field.
+ *
+ * All constants are represented as null-terminated strings containing the
+ * hexadecimal presentation of the respective numbers.
+ *
+ * \warning The origin of the primes in RFC 5114 is not documented and
+ *          their use therefore constitutes a security risk!
+ *
+ * \deprecated The primes from RFC 5114 are superseded by the primes
+ *             from RFC 3526 and RFC 7919 and should no longer be used.
+ *             They will be removed in the next major revision.
  */
-#define MBEDTLS_DHM_RFC3526_MODP_2048_P               \
-    "FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD1" \
-    "29024E088A67CC74020BBEA63B139B22514A08798E3404DD" \
-    "EF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245" \
-    "E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7ED" \
-    "EE386BFB5A899FA5AE9F24117C4B1FE649286651ECE45B3D" \
-    "C2007CB8A163BF0598DA48361C55D39A69163FA8FD24CF5F" \
-    "83655D23DCA3AD961C62F356208552BB9ED529077096966D" \
-    "670C354E4ABC9804F1746C08CA18217C32905E462E36CE3B" \
-    "E39E772C180E86039B2783A2EC07A28FB5C55DF06F4C52C9" \
-    "DE2BCBF6955817183995497CEA956AE515D2261898FA0510" \
-    "15728E5A8AACAA68FFFFFFFFFFFFFFFF"
 
-#define MBEDTLS_DHM_RFC3526_MODP_2048_G          "02"
+const char *mbedtls_dhm_rfc3526_modp_2048_p;
+const char *mbedtls_dhm_rfc3526_modp_2048_g;
+const char *mbedtls_dhm_rfc3526_modp_3072_p;
+const char *mbedtls_dhm_rfc3526_modp_3072_g;
+const char *mbedtls_dhm_rfc3526_modp_4096_p;
+const char *mbedtls_dhm_rfc3526_modp_4096_g;
 
-#define MBEDTLS_DHM_RFC3526_MODP_3072_P               \
-    "FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD1" \
-    "29024E088A67CC74020BBEA63B139B22514A08798E3404DD" \
-    "EF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245" \
-    "E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7ED" \
-    "EE386BFB5A899FA5AE9F24117C4B1FE649286651ECE45B3D" \
-    "C2007CB8A163BF0598DA48361C55D39A69163FA8FD24CF5F" \
-    "83655D23DCA3AD961C62F356208552BB9ED529077096966D" \
-    "670C354E4ABC9804F1746C08CA18217C32905E462E36CE3B" \
-    "E39E772C180E86039B2783A2EC07A28FB5C55DF06F4C52C9" \
-    "DE2BCBF6955817183995497CEA956AE515D2261898FA0510" \
-    "15728E5A8AAAC42DAD33170D04507A33A85521ABDF1CBA64" \
-    "ECFB850458DBEF0A8AEA71575D060C7DB3970F85A6E1E4C7" \
-    "ABF5AE8CDB0933D71E8C94E04A25619DCEE3D2261AD2EE6B" \
-    "F12FFA06D98A0864D87602733EC86A64521F2B18177B200C" \
-    "BBE117577A615D6C770988C0BAD946E208E24FA074E5AB31" \
-    "43DB5BFCE0FD108E4B82D120A93AD2CAFFFFFFFFFFFFFFFF"
 
-#define MBEDTLS_DHM_RFC3526_MODP_3072_G          "02"
+#if !defined(MBEDTLS_DEPRECATED_REMOVED)
+MBEDTLS_DEPRECATED const char *mbedtls_dhm_rfc5114_modp_2048_p;
+MBEDTLS_DEPRECATED const char *mbedtls_dhm_rfc5114_modp_2048_g;
+#endif
 
-#define MBEDTLS_DHM_RFC3526_MODP_4096_P                \
-    "FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD1" \
-    "29024E088A67CC74020BBEA63B139B22514A08798E3404DD" \
-    "EF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245" \
-    "E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7ED" \
-    "EE386BFB5A899FA5AE9F24117C4B1FE649286651ECE45B3D" \
-    "C2007CB8A163BF0598DA48361C55D39A69163FA8FD24CF5F" \
-    "83655D23DCA3AD961C62F356208552BB9ED529077096966D" \
-    "670C354E4ABC9804F1746C08CA18217C32905E462E36CE3B" \
-    "E39E772C180E86039B2783A2EC07A28FB5C55DF06F4C52C9" \
-    "DE2BCBF6955817183995497CEA956AE515D2261898FA0510" \
-    "15728E5A8AAAC42DAD33170D04507A33A85521ABDF1CBA64" \
-    "ECFB850458DBEF0A8AEA71575D060C7DB3970F85A6E1E4C7" \
-    "ABF5AE8CDB0933D71E8C94E04A25619DCEE3D2261AD2EE6B" \
-    "F12FFA06D98A0864D87602733EC86A64521F2B18177B200C" \
-    "BBE117577A615D6C770988C0BAD946E208E24FA074E5AB31" \
-    "43DB5BFCE0FD108E4B82D120A92108011A723C12A787E6D7" \
-    "88719A10BDBA5B2699C327186AF4E23C1A946834B6150BDA" \
-    "2583E9CA2AD44CE8DBBBC2DB04DE8EF92E8EFC141FBECAA6" \
-    "287C59474E6BC05D99B2964FA090C3A2233BA186515BE7ED" \
-    "1F612970CEE2D7AFB81BDD762170481CD0069127D5B05AA9" \
-    "93B4EA988D8FDDC186FFB7DC90A6C08F4DF435C934063199" \
-    "FFFFFFFFFFFFFFFF"
-
-#define MBEDTLS_DHM_RFC3526_MODP_4096_G          "02"
-
-#define MBEDTLS_DHM_RFC5114_MODP_2048_P               \
-    "AD107E1E9123A9D0D660FAA79559C51FA20D64E5683B9FD1" \
-    "B54B1597B61D0A75E6FA141DF95A56DBAF9A3C407BA1DF15" \
-    "EB3D688A309C180E1DE6B85A1274A0A66D3F8152AD6AC212" \
-    "9037C9EDEFDA4DF8D91E8FEF55B7394B7AD5B7D0B6C12207" \
-    "C9F98D11ED34DBF6C6BA0B2C8BBC27BE6A00E0A0B9C49708" \
-    "B3BF8A317091883681286130BC8985DB1602E714415D9330" \
-    "278273C7DE31EFDC7310F7121FD5A07415987D9ADC0A486D" \
-    "CDF93ACC44328387315D75E198C641A480CD86A1B9E587E8" \
-    "BE60E69CC928B2B9C52172E413042E9B23F10B0E16E79763" \
-    "C9B53DCF4BA80A29E3FB73C16B8E75B97EF363E2FFA31F71" \
-    "CF9DE5384E71B81C0AC4DFFE0C10E64F"
-
-#define MBEDTLS_DHM_RFC5114_MODP_2048_G              \
-    "AC4032EF4F2D9AE39DF30B5C8FFDAC506CDEBE7B89998CAF"\
-    "74866A08CFE4FFE3A6824A4E10B9A6F0DD921F01A70C4AFA"\
-    "AB739D7700C29F52C57DB17C620A8652BE5E9001A8D66AD7"\
-    "C17669101999024AF4D027275AC1348BB8A762D0521BC98A"\
-    "E247150422EA1ED409939D54DA7460CDB5F6C6B250717CBE"\
-    "F180EB34118E98D119529A45D6F834566E3025E316A330EF"\
-    "BB77A86F0C1AB15B051AE3D428C8F8ACB70A8137150B8EEB"\
-    "10E183EDD19963DDD9E263E4770589EF6AA21E7F5F2FF381"\
-    "B539CCE3409D13CD566AFBB48D6C019181E1BCFE94B30269"\
-    "EDFE72FE9B6AA4BD7B5A0F1C71CFFF4C19C418E1F6EC0179"\
-    "81BC087F2A7065B384B890D3191F2BFA"
+/**
+ * \deprecated These macros are superseded by direct access to the corresponding
+ *             global variables and will be removed in the next major revision.
+ */
+#if !defined(MBEDTLS_DEPRECATED_REMOVED)
+#define MBEDTLS_DHM_RFC5114_MODP_2048_P mbedtls_dhm_rfc5114_modp_2048_p
+#define MBEDTLS_DHM_RFC5114_MODP_2048_G mbedtls_dhm_rfc5114_modp_2048_g
+#define MBEDTLS_DHM_RFC3526_MODP_2048_P mbedtls_dhm_rfc3526_modp_2048_p
+#define MBEDTLS_DHM_RFC3526_MODP_2048_G mbedtls_dhm_rfc3526_modp_2048_g
+#define MBEDTLS_DHM_RFC3526_MODP_3072_P mbedtls_dhm_rfc3526_modp_3072_p
+#define MBEDTLS_DHM_RFC3526_MODP_3072_G mbedtls_dhm_rfc3526_modp_3072_g
+#define MBEDTLS_DHM_RFC3526_MODP_4096_P mbedtls_dhm_rfc3526_modp_4096_p
+#define MBEDTLS_DHM_RFC3526_MODP_4096_G mbedtls_dhm_rfc3526_modp_4096_g
+#endif
 
 #ifdef __cplusplus
 extern "C" {