gsm: Implement the size checking of the hello packet

[lcr.git] / gsm.cpp

diff --git a/gsm.cpp b/gsm.cpp
index 50ca2ea..5d4b64d 100644 (file)
--- a/gsm.cpp
+++ b/gsm.cpp
@@ -1334,6 +1334,7 @@ static int mncc_fd_read(struct lcr_fd *lfd, void *inst, int idx)
        int rc;
        static char buf[sizeof(struct gsm_mncc)+1024];
        struct gsm_mncc *mncc_prim = (struct gsm_mncc *) buf;
+       struct gsm_mncc_hello *hello = (struct gsm_mncc_hello *) buf;
 
        memset(buf, 0, sizeof(buf));
        rc = recv(lfd->fd, buf, sizeof(buf), 0);
@@ -1342,6 +1343,45 @@ static int mncc_fd_read(struct lcr_fd *lfd, void *inst, int idx)
        if (rc < 0)
                return rc;
 
+       /* TODO: size check? */
+       switch (mncc_prim->msg_type) {
+       case MNCC_SOCKET_HELLO:
+               if (hello->version != MNCC_SOCK_VERSION) {
+                       PERROR("MNCC version different. BSC version is %u\n", hello->version);
+                       mncc_fd_close(lcr_gsm, lfd);
+                       return 0;
+               }
+               if (hello->mncc_size != sizeof(struct gsm_mncc)) {
+                       PERROR("MNCC gsm_mncc size differs: %u %u\n",
+                               hello->mncc_size, sizeof(struct gsm_mncc));
+                       mncc_fd_close(lcr_gsm, lfd);
+                       return 0;
+               }
+               if (hello->data_frame_size != sizeof(struct gsm_data_frame)) {
+                       PERROR("MNCC gsm_mncc size differs: %u %u\n",
+                               hello->data_frame_size, sizeof(struct gsm_data_frame));
+                       mncc_fd_close(lcr_gsm, lfd);
+                       return 0;
+               }
+
+#define CHECK_OFFSET(hello, field, lcr_gsm, lfd)       \
+               if (hello->field ##_offset != __builtin_offsetof(struct gsm_mncc, field)) {     \
+                       PERROR("MNCC gsm_mncc offset of %s is %u %u\n",                         \
+                               #field, hello->field ##_offset,                                 \
+                               __builtin_offsetof(struct gsm_mncc, field));                    \
+                       mncc_fd_close(lcr_gsm, lfd);                                            \
+                       return 0;                                                               \
+               }
+
+               CHECK_OFFSET(hello, called, lcr_gsm, lfd);
+               CHECK_OFFSET(hello, signal, lcr_gsm, lfd);
+               CHECK_OFFSET(hello, emergency, lcr_gsm, lfd);
+               CHECK_OFFSET(hello, lchan_type, lcr_gsm, lfd);
+#undef CHECK_OFFSET
+
+               break;
+       }
+
        /* Hand the MNCC message into LCR */
        switch (lcr_gsm->type) {
 #ifdef WITH_GSM_BS