Update BUILDING.md

Minecraft servers have a longstanding bug that omits newlines
when sending messages via RCON. This patch manually inserts
newlines to address the issue.

Reference: https://bugs.mojang.com/browse/MC-7569

Fixes #1

BUILDING.md

@@ -1,13 +1,18 @@
 Building and installing
 -----------------------
 
-#### Requirements & dependencies:
+### Prerequisites
+
 - GCC compatible compiler
-- POSIX getopt support from **<unistd.h>**
+- make
+- POSIX.1 support
+   * getopt()
+   * strcasecmp()
+   * tcflush()
 
 ---
 
-#### Compiling
+### Compiling
 
     cc -std=gnu99 -Wpedantic -Wall -Wextra -Wno-gnu-zero-variadic-macro-arguments -O2 -o mcrcon mcrcon.c
     

CHANGELOG.md

@@ -1,8 +1,12 @@
 #### Version history:
 
-###### 0.7.3
- - Add support to Valve style rcon authentication
+###### 0.8.0
+ - Implement support for multipacket responses
+ - Add support for Valve style rcon authentication
+ - Add experimental UTF-8 support for Windows
  - Change maximum packet size to correct value (4096 -> 4106)
+ - Attempt to add missing newlines in bugged Minecraft servers
+    * Implemented for responses to the 'help' command and unknown commands
  - Print auth failed message to stderr instead of stdout
  - Fail immediately if received packet size is out of spec
  - Return proper exit code from run_terminal_mode()
@@ -11,7 +15,7 @@
 ###### 0.7.2
  - Quit gracefully when Ctrl-D or Ctrl+C is pressed
  - Remove "exit" and "quit" as quitting commands
-    * these are actual rcon commands on some servers
+    * These are actual rcon commands on some servers
  - Suppress compiler warning (strncpy)
  - Fix erroneous string length in packet building function
  - Fix typo in ANSI escape sequence for LCYAN

Makefile

@@ -15,7 +15,7 @@ RM = rm -v -f
 
 CC ?= gcc
 CFLAGS = -std=gnu99 -Wall -Wextra -Wpedantic -Wno-gnu-zero-variadic-macro-arguments -O2
-EXTRAFLAGS ?= -fstack-protector-all
+EXTRAFLAGS ?= -fstack-protector-strong -D_FORTIFY_SOURCE=2 -fPIE -pie -Wl,-z,relro -Wl,-z,now -fno-common
 
 ifeq ($(OS), Windows_NT)
 	LINKER = -lws2_32

mcrcon.1

@@ -1,7 +1,7 @@
 .\" Process this file with
 .\" groff -man -Tascii mcrcon.1
 .\"
-.TH MCRCON 1 "November 2024" "Version 0.7.3"
+.TH MCRCON 1 "December 2024" "Version 0.8.0"
 .SH NAME 
 mcrcon \- send rcon commands to a Minecraft server
 .SH SYNOPSIS

mcrcon.c

@@ -31,17 +31,20 @@
 #include <errno.h>
 #include <unistd.h>
 
-
 #ifdef _WIN32
     #include <winsock2.h>
     #include <windows.h>
     #include <ws2tcpip.h>
+    #include <fcntl.h>
+    #include <wchar.h>
 #else
     #include <sys/socket.h>
+    #include <sys/select.h>
     #include <netdb.h>
+    #include <termios.h>
 #endif
 
-#define VERSION "0.7.3"
+#define VERSION "0.8.0"
 #define IN_NAME "mcrcon"
 #define VER_STR IN_NAME" "VERSION" (built: "__DATE__" "__TIME__")"
 
@@ -56,6 +59,8 @@
 #define MAX_PACKET_SIZE         4106 // id (4) + cmd (4) + DATA_BUFFSIZE
 #define MIN_PACKET_SIZE         10   // id (4) + cmd (4) + two empty strings (2)
 
+#define MAX_WAIT_TIME           600
+
 #define log_error(fmt, ...) fprintf(stderr, fmt,  ##__VA_ARGS__);
 
 // rcon packet structure
@@ -95,7 +100,6 @@ void        packet_print(rc_packet *packet);
 bool        rcon_auth(int sock, char *passwd);
 int         rcon_command(int sock, char *command);
 
-
 // =============================================
 //  GLOBAL VARIABLES
 // =============================================
@@ -104,11 +108,17 @@ static int flag_silent_mode = 0;
 static int  flag_disable_colors = 0;
 static int  flag_wait_seconds = 0;
 static int  global_connection_alive = 1;
+static bool global_valve_protocol = false;
+static bool global_minecraft_newline_fix = false;
 static int  global_rsock;
 
 #ifdef _WIN32
 // console coloring on windows
 HANDLE console_handle;
+
+// console code pages
+UINT old_output_codepage;
+UINT old_input_codepage;
 #endif
 
 // safety stuff (windows is still misbehaving)
@@ -116,6 +126,15 @@ void exit_proc(void)
 {
     if (global_rsock != -1)
         net_close(global_rsock);
+
+    #ifdef _WIN32
+    // Restore previous code pages
+    SetConsoleOutputCP(old_output_codepage);
+    SetConsoleCP(old_input_codepage);
+
+    // Set back to binary mode
+    _setmode(_fileno(stdin), _O_BINARY);
+    #endif
 }
 
 // TODO: check exact windows and linux behaviour
@@ -125,13 +144,9 @@ void sighandler(int sig)
         putchar('\n');
 
     global_connection_alive = 0;
-	#ifndef _WIN32
     exit(EXIT_SUCCESS);
-	#endif
 }
 
-#define MAX_WAIT_TIME 600
-
 unsigned int mcrcon_parse_seconds(char *str)
 {
     char *end;
@@ -166,10 +181,6 @@ int main(int argc, char *argv[])
     if (!port) port = "25575";
     if (!host) host = "localhost";
 
-	// disable output buffering (https://github.com/Tiiffi/mcrcon/pull/39)
-	setvbuf(stdout, NULL, _IONBF, 0);
-	setvbuf(stderr, NULL, _IONBF, 0);
-
     if(argc < 1 && pass == NULL) usage();
 
     // default getopt error handler enabled
@@ -223,6 +234,16 @@ int main(int argc, char *argv[])
     console_handle = GetStdHandle(STD_OUTPUT_HANDLE);
     if (console_handle == INVALID_HANDLE_VALUE)
         console_handle = NULL;
+
+    // Set the output and input code pages to utf-8
+    old_output_codepage = GetConsoleOutputCP();
+    old_input_codepage = GetConsoleCP();
+
+    SetConsoleOutputCP(CP_UTF8);
+    SetConsoleCP(CP_UTF8);
+
+    // Set the file translation mode to UTF16
+    _setmode(_fileno(stdin), _O_U16TEXT);
     #endif
 
     // open socket
@@ -389,6 +410,9 @@ bool net_send_packet(int sd, rc_packet *packet)
     return true;
 }
 
+
+// TODO: Fix the wonky behaviour when server quit/exit/stop/close
+//       command is issued. Client should close gracefully without errors.
 rc_packet *net_recv_packet(int sd)
 {
     int32_t psize;
@@ -481,52 +505,67 @@ void print_color(int color)
 void packet_print(rc_packet *packet)
 {
     uint8_t *data = packet->data;
+    int i;
 
     if (flag_raw_output == 1) {
-		for (int i = 0; data[i] != 0; ++i) {
-			putchar(data[i]);
-		}
+        fputs((char *) data, stdout);
         return;
     }
 
-	int i;
+    // Newline fix for Minecraft
+    if (global_valve_protocol == false) {
+        const char test[] = "Unknown or incomplete command, see below for error";
+        size_t test_size = sizeof test - 1;
+        if (strncmp((char *) data, test, test_size) == 0) {
+            fwrite(data, test_size, 1, stdout);
+            putchar('\n');
+            data = &data[test_size];
+        }
+    }
+
     int default_color = 0;
 
     #ifdef _WIN32
     CONSOLE_SCREEN_BUFFER_INFO console_info;
     if (GetConsoleScreenBufferInfo(console_handle, &console_info) != 0) {
         default_color = console_info.wAttributes + 0x30;
-		} else default_color = 0x37;
+    }
+    else default_color = 0x37;
     #endif
 
-	// colors enabled so try to handle the bukkit colors for terminal
-	if (flag_disable_colors == 0) {
-		for (i = 0; data[i] != 0; ++i) {
-			if (data[i] == 0x0A) print_color(default_color);
+    bool slash = false;
+    bool colors_detected = false;
+
+    for (i = 0; data[i] != 0; ++i)
+    {
+        if (data[i] == 0x0A) {
+            print_color(default_color);
+        }
         else if(data[i] == 0xc2 && data[i + 1] == 0xa7) {
+            // Disable new line fixes if Bukkit colors are detected
+            colors_detected = true;
             i += 2;
+            if (flag_disable_colors == 0) {
                 print_color(data[i]);
+            }
             continue;
         }
+
+        // Add missing newlines
+        if (colors_detected == false && global_minecraft_newline_fix && data[i] == '/') {
+            slash ? putchar('\n') : (slash = true);
+        }
+
         putchar(data[i]);
     }
     print_color(default_color); // cancel coloring
-	}
-	// strip colors
-	else {
-		for (i = 0; data[i] != 0; ++i) {
-			if (data[i] == 0xc2 && data[i + 1] == 0xa7) {
-				i += 2;
-				continue;
-			}	
-			putchar(data[i]);
-		}
-	}
 
     // print newline if string has no newline
-	if (data[i - 1] != 10 && data[i - 1] != 13) {
+    if (data[i - 1] != '\n') {
         putchar('\n');
     }
+
+    fflush(stdout);
 }
 
 rc_packet *packet_build(int id, int cmd, char s[static 1])
@@ -573,6 +612,7 @@ receive:
      * so we have to check packet type and try again if necessary.
      */
     if (packet->cmd != RCON_AUTH_RESPONSE) {
+        global_valve_protocol = true;
         goto receive;
     }
 
@@ -580,9 +620,11 @@ receive:
     return packet->id == -1 ? false : true;
 }
 
-// TODO: Add proper error handling and reporting!
 int rcon_command(int sock, char *command)
 {
+    if (global_valve_protocol == false && strcasecmp(command, "help") == 0)
+        global_minecraft_newline_fix = true;
+
     rc_packet *packet = packet_build(RCON_PID, RCON_EXEC_COMMAND, command);
     if (packet == NULL) {
         log_error("Error: packet build() failed!\n");
@@ -594,22 +636,61 @@ int rcon_command(int sock, char *command)
         return 0;
     }
 
+    // Workaround to handle valve multipacket responses
+    // This one does not require using select()
+    packet = packet_build(0xBADA55, 0xBADA55, "");
+    if (packet == NULL) {
+        log_error("Error: packet build() failed!\n");
+        return 0;
+    }
+
+    if (!net_send_packet(sock, packet)) {
+        log_error("Error: net_send_packet() failed!\n");
+        return 0;
+    }
+
+    // initialize stuff for select()
+    fd_set read_fds;
+    FD_ZERO(&read_fds);
+    FD_SET(sock, &read_fds);
+
+    // Set 5 second timeout
+    struct timeval timeout = {0};
+    timeout.tv_sec = 5;
+    timeout.tv_usec = 0;
+
+    int incoming = 0;
+
+    do {
         packet = net_recv_packet(sock);
         if (packet == NULL) {
             log_error("Error: net_recv_packet() failed!\n");
             return 0;
         }
 
-	if (packet->id != RCON_PID) {
+        // Check for packet id and multipacket guard id
+        if (packet->id != RCON_PID && packet->id != 0xBADA55) {
             log_error("Error: invalid packet id!\n");
             return 0;
         }
 
-	if (!flag_silent_mode) {
+        if (packet->id == 0xBADA55) break;
+
+        if (flag_silent_mode == false) {
             if (packet->size > 10)
                 packet_print(packet);
         }
 
+        int result = select(sock + 1, &read_fds, NULL, NULL, &timeout);
+        if (result == -1) {
+            log_error("Error: select() failed!\n");
+            return 0;
+        }
+
+        incoming = (result > 0 && FD_ISSET(sock, &read_fds));
+    }
+    while(incoming);
+
     return 1;
 }
 
@@ -641,16 +722,15 @@ int run_terminal_mode(int sock)
 {
     char command[MAX_COMMAND_LENGTH] = {0};
 
-	puts("Logged in.\nType 'Q' or press Ctrl-D / Ctrl-C to disconnect.");
+    puts("Logged in. Press Ctrl-D or Ctrl-C to disconnect.");
 
     while (global_connection_alive) {
         putchar('>');
+        fflush(stdout);
 
         int len = get_line(command, MAX_COMMAND_LENGTH);
         if (len < 1) continue;
 
-		if (strcasecmp(command, "Q") == 0) break;
-
         if (len > 0 && global_connection_alive) {
             if (!rcon_command(sock, command)) {
                 return EXIT_FAILURE;
@@ -660,22 +740,80 @@ int run_terminal_mode(int sock)
         /* Special case for "stop" command to prevent server-side bug.
          * https://bugs.mojang.com/browse/MC-154617
          *
-		 * NOTE: This is hacky workaround which should be handled better to
-		 *       ensure compatibility with other servers using source RCON.
-		 * NOTE: strcasecmp() is POSIX function.
+         * NOTE: Not sure if this still a problem?!
          */
-		if (strcasecmp(command, "stop") == 0) {
-			break;
+        if (global_valve_protocol == false && strcasecmp(command, "stop") == 0) {
+            // Timeout to before checking if connection was closed
+            #ifdef _WIN32
+            Sleep(2 * 1000);
+            #else
+            sleep(2);
+            #endif
+
+            char tmp[1];
+            #ifdef _WIN32
+            // TODO: More Windows side testing!
+            int result = recv(sock, tmp, sizeof(tmp), MSG_PEEK | 0);
+            #else
+            int result = recv(sock, tmp, sizeof(tmp), MSG_PEEK | MSG_DONTWAIT);
+            #endif
+            if (result == 0) {
+                break; // Connection closed
+            }
+            // TODO: Check for return values and errors!
         }
     }
 
     return EXIT_SUCCESS;
 }
 
+#ifdef _WIN32
+char *utf8_getline(char *buf, int size, FILE *stream)
+{
+    // Widechar fgets
+    wchar_t in[MAX_COMMAND_LENGTH] = {0};
+
+    wchar_t *result = fgetws(in, MAX_COMMAND_LENGTH, stream);
+    if (result == NULL) {
+        return NULL;
+    }
+
+    // Calculates UTF-8 buffer size
+    int required_size = WideCharToMultiByte(CP_UTF8, 0, in, -1, NULL, 0, NULL, NULL);
+    if (size < required_size) {
+        // TODO: Proper error handling & reporting
+        return NULL;
+    }
+
+    if (WideCharToMultiByte(CP_UTF8, 0, in, -1, buf, size, NULL, NULL) == 0) {
+        // TODO: Proper error handling & reporting
+        return NULL;
+    }
+
+    return buf;
+}
+#endif
+
+void flush_input(void)
+{
+    #ifdef _WIN32
+    FlushConsoleInputBuffer(console_handle);
+    #else
+    tcflush(STDIN_FILENO, TCIFLUSH);
+    #endif
+}
+
 // gets line from stdin and deals with rubbish left in the input buffer
 int get_line(char *buffer, int bsize)
 {
+    #ifdef _WIN32
+    char *ret = utf8_getline(buffer, bsize, stdin);
+    #else
     char *ret = fgets(buffer, bsize, stdin);
+    #endif
+
+    flush_input();
+
     if (ret == NULL) {
         if (ferror(stdin)) {
             log_error("Error %d: %s\n", errno, strerror(errno));
@@ -687,14 +825,7 @@ int get_line(char *buffer, int bsize)
 
     // remove unwanted characters from the buffer
     buffer[strcspn(buffer, "\r\n")] = '\0';
-
     int len = strlen(buffer);
 
-	// clean input buffer if needed 
-	if (len == bsize - 1) {
-		int ch;
-		while ((ch = getchar()) != '\n' && ch != EOF);
-	}
-
     return len;
 }