Use a union to read an old lease.

diff --git a/dhcp.c b/dhcp.c
index 3f4295de5fe774edaa15f4e349f3cfb1b7505c5a..298bc90d7953381f5472d1a6f30372e88b8b678e 100644 (file)
--- a/dhcp.c
+++ b/dhcp.c
@@ -1117,7 +1117,10 @@ read_lease(struct interface *ifp)
 {
        int fd;
        bool fd_opened;
-       struct dhcp_message *dhcp;
+       union {
+               uint8_t *buf;
+               struct dhcp_message *dhcp;
+       } u;
        struct dhcp_state *state = D_STATE(ifp);
        ssize_t bytes;
        const uint8_t *auth;
@@ -1142,42 +1145,42 @@ read_lease(struct interface *ifp)
        else
                logger(ifp->ctx, LOG_DEBUG, "%s: reading lease `%s'",
                    ifp->name, state->leasefile);
-       dhcp = calloc(1, sizeof(*dhcp));
-       if (dhcp == NULL) {
+       u.buf = calloc(1, sizeof(*u.dhcp));
+       if (u.buf == NULL) {
                if (fd_opened)
                        close(fd);
                return NULL;
        }
-       bytes = read(fd, (char *)dhcp, sizeof(*dhcp));
+       bytes = read(fd, u.buf, sizeof(*u.dhcp));
        if (fd_opened)
                close(fd);
        if (bytes == -1) {
-               free(dhcp);
+               free(u.buf);
                return NULL;
        }
        if ((size_t)bytes < offsetof(struct dhcp_message, cookie)) {
-               free(dhcp);
+               free(u.buf);
                errno = EINVAL;
                return NULL;
        }
 
        if (ifp->ctx->options & DHCPCD_DUMPLEASE)
-               return dhcp;
+               return u.dhcp;
 
        /* We may have found a BOOTP server */
-       if (get_option_uint8(ifp->ctx, &type, dhcp, DHO_MESSAGETYPE) == -1)
+       if (get_option_uint8(ifp->ctx, &type, u.dhcp, DHO_MESSAGETYPE) == -1)
                type = 0;
 
        /* Authenticate the message */
-       auth = get_option(ifp->ctx, dhcp, DHO_AUTHENTICATION, &auth_len);
+       auth = get_option(ifp->ctx, u.dhcp, DHO_AUTHENTICATION, &auth_len);
        if (auth) {
                if (dhcp_auth_validate(&state->auth, &ifp->options->auth,
-                   (uint8_t *)dhcp, sizeof(*dhcp), 4, type,
+                   (uint8_t *)u.dhcp, sizeof(*u.dhcp), 4, type,
                    auth, auth_len) == NULL)
                {
                        logger(ifp->ctx, LOG_DEBUG,
                            "%s: dhcp_auth_validate: %m", ifp->name);
-                       free(dhcp);
+                       free(u.buf);
                        return NULL;
                }
                if (state->auth.token)
@@ -1192,11 +1195,11 @@ read_lease(struct interface *ifp)
        {
                logger(ifp->ctx, LOG_ERR,
                    "%s: authentication now required", ifp->name);
-               free(dhcp);
+               free(u.buf);
                return NULL;
        }
 
-       return dhcp;
+       return u.dhcp;
 }
 
 static const struct dhcp_opt *