Use chacha20-ietf as a default cipher instead of rc4-md5 (#2080)

* Use chacha20-ietf as a default cipher instead of rc4-md5

* Update tunnel.c

* Update utils.c

* Update ss-local.asciidoc

* Update ss-local.asciidoc

* Update tunnel.c

* Update ss-tunnel.asciidoc

* Update ss-manager.asciidoc

* Update ss-redir.asciidoc

* Update shadowsocks-libev.asciidoc

* Update aead.c

* Update local.c

* Update server.c

* Update utils.c

src/aead.c

@@ -719,8 +719,8 @@ aead_init(const char *pass, const char *key, const char *method)
                 break;
             }
         if (m >= AEAD_CIPHER_NUM) {
-            LOGE("Invalid cipher name: %s, use aes-256-gcm instead", method);
-            m = AES256GCM;
+            LOGE("Invalid cipher name: %s, use chacha20-ietf-poly1305 instead", method);
+            m = CHACHA20POLY1305IETF;
         }
     }
     return aead_key_init(m, pass, key);

src/local.c

@@ -1697,7 +1697,7 @@ main(int argc, char **argv)
     }
 
     if (method == NULL) {
-        method = "rc4-md5";
+        method = "chacha20-ietf-poly1305";
     }
 
     if (timeout == NULL) {

src/server.c

@@ -1860,7 +1860,7 @@ main(int argc, char **argv)
     }
 
     if (method == NULL) {
-        method = "rc4-md5";
+        method = "chacha20-ietf-poly1305";
     }
 
     if (timeout == NULL) {

src/stream.c

@@ -677,8 +677,8 @@ stream_init(const char *pass, const char *key, const char *method)
                 break;
             }
         if (m >= STREAM_CIPHER_NUM) {
-            LOGE("Invalid cipher name: %s, use rc4-md5 instead", method);
-            m = RC4_MD5;
+            LOGE("Invalid cipher name: %s, use chacha20-ietf instead", method);
+            m = CHACHA20IETF;
         }
     }
     if (m == TABLE) {

src/tunnel.c

@@ -1021,7 +1021,7 @@ main(int argc, char **argv)
     }
 
     if (method == NULL) {
-        method = "rc4-md5";
+        method = "chacha20-ietf-poly1305";
     }
 
     if (timeout == NULL) {

src/utils.c

@@ -317,7 +317,7 @@ usage()
     printf(
         "                                  salsa20, chacha20 and chacha20-ietf.\n");
     printf(
-        "                                  The default cipher is rc4-md5.\n");
+        "                                  The default cipher is chacha20-ietf-poly1305.\n");
     printf("\n");
     printf(
         "       [-a <user>]                Run as another user.\n");