added skeleton code for a complex jail protocol (instead of a raw tcp2pty communication)

Signed-off-by: lns <matzeton@googlemail.com>

1 files changed, 149 insertions, 0 deletions

diff --git a/src/jail_protocol.c b/src/jail_protocol.c
new file mode 100644
index 0000000..4b6ebdd
--- /dev/null
+++ b/src/jail_protocol.c
@@ -0,0 +1,149 @@
+/*
+ * jail_protocol.c
+ * potd is licensed under the BSD license:
+ *
+ * Copyright (c) 2018 Toni Uhlig <matzeton@googlemail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ *
+ * - Neither the name of the Yellow Lemon Software nor the names of its
+ *   contributors may be used to endorse or promote products derived from this
+ *   software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <arpa/inet.h>
+#include <assert.h>
+
+#include "jail_protocol.h"
+#include "utils.h"
+
+typedef struct jail_event {
+    jail_data *data;
+    int sock_fd;
+    int tty_fd;
+} jail_event;
+
+static int
+handshake_read_loop(event_ctx *ev_ctx, int src_fd, void *user_data);
+
+
+ssize_t jail_protocol_readhdr(jail_data *dst, unsigned char *buf,
+                              size_t bufsiz)
+{
+    jail_protocol_hdr *hdr;
+    size_t data_siz, min_siz;
+
+    assert(dst);
+
+    if (bufsiz < sizeof(*hdr))
+        return -1;
+    hdr = (jail_protocol_hdr *) buf;
+    if (ntohl(hdr->magic) != PROTO_MAGIC)
+        return -1;
+    data_siz = bufsiz - sizeof(*hdr);
+    if (ntohl(hdr->size) != data_siz)
+        return -1;
+
+    switch (ntohl(hdr->type)) {
+        case PROTO_TYPE_USER:
+            min_siz = MIN(data_siz, USER_LEN);
+            memcpy(dst->user, (char *) buf + sizeof(*hdr), min_siz);
+            dst->user[min_siz] = 0;
+            break;
+        case PROTO_TYPE_PASS:
+            min_siz = MIN(data_siz, PASS_LEN);
+            memcpy(dst->pass, (char *) buf + sizeof(*hdr), min_siz);
+            dst->pass[min_siz] = 0;
+            break;
+        case PROTO_TYPE_DATA:
+            break;
+        default:
+            break;
+    }
+
+    return data_siz;
+}
+
+ssize_t jail_protocol_writehdr(jail_protocol_hdr *src, int type,
+							   unsigned char *buf, size_t bufsiz)
+{
+    jail_protocol_hdr *hdr;
+    size_t data_siz;
+
+    assert(src && buf);
+
+    hdr = (jail_protocol_hdr *) buf;
+    hdr->magic = htonl(PROTO_MAGIC);
+    hdr->type = htonl(type);
+    data_siz = bufsiz - sizeof(*hdr);
+    hdr->size = data_siz;
+
+    return data_siz;
+}
+
+static int
+handshake_read_loop(event_ctx *ev_ctx, int src_fd, void *user_data)
+{
+    jail_event *ev_jail = (jail_event *) user_data;
+    int siz, rc, dst_fd;
+    unsigned char buf[BUFSIZ] = {0};
+
+    (void) ev_ctx;
+
+    if (src_fd == ev_jail->sock_fd)
+        dst_fd = ev_jail->tty_fd;
+    else if (src_fd == ev_jail->tty_fd)
+        dst_fd = ev_jail->sock_fd;
+    else
+        goto error;
+
+    siz = read(src_fd, buf, sizeof buf);
+    if (siz <= 0)
+        goto error;
+    rc = jail_protocol_readhdr(ev_jail->data, buf, sizeof buf);
+    if (rc < 0) {
+        rc = write(dst_fd, buf, siz);
+        goto error;
+    }
+
+    return 1;
+error:
+    ev_ctx->active = 0;
+    return 1;
+}
+
+int jail_protocol_handshake_read(event_ctx *ev_client, int client_fd,
+                                 int tty_fd, jail_data *dst)
+{
+    jail_event ev_jail = {0,0,0};
+    int rc;
+
+    ev_jail.data = dst;
+    ev_jail.sock_fd = client_fd;
+    ev_jail.tty_fd = tty_fd;
+    rc = event_loop(ev_client, handshake_read_loop, &ev_jail);
+
+    return rc || !ev_client->active;
+}