ipc: read trailing responses after set operation

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

diff --git a/src/ipc-uapi.h b/src/ipc-uapi.h
index d2ba522a02d7e1c54ff905884559dd3e120fb583..f582916ecc9f93c601739c3f92e4391e7543f00a 100644 (file)
--- a/src/ipc-uapi.h
+++ b/src/ipc-uapi.h
@@ -5,6 +5,7 @@
 
 #include <arpa/inet.h>
 #include <errno.h>
+#include <limits.h>
 #include <net/if.h>
 #include <netdb.h>
 #include <netinet/in.h>
@@ -30,8 +31,10 @@ static int userspace_set_device(struct wgdevice *dev)
        struct wgpeer *peer;
        struct wgallowedip *allowedip;
        FILE *f;
-       int ret;
+       int ret, set_errno = -EPROTO;
        socklen_t addr_len;
+       size_t line_buffer_len = 0, line_len;
+       char *key = NULL, *value;
 
        f = userspace_interface_file(dev->name);
        if (!f)
@@ -92,10 +95,30 @@ static int userspace_set_device(struct wgdevice *dev)
        fprintf(f, "\n");
        fflush(f);
 
-       if (fscanf(f, "errno=%d", &ret) != 1)
-               ret = errno ? -errno : -EPROTO;
-       if (getc(f) != '\n' || getc(f) != '\n')
-               ret = -EPROTO;
+       while (getline(&key, &line_buffer_len, f) > 0) {
+               line_len = strlen(key);
+               ret = set_errno;
+               if (line_len == 1 && key[0] == '\n')
+                       goto out;
+               value = strchr(key, '=');
+               if (!value || line_len == 0 || key[line_len - 1] != '\n')
+                       break;
+               *value++ = key[--line_len] = '\0';
+
+               if (!strcmp(key, "errno")) {
+                       long long num;
+                       char *end;
+                       if (value[0] != '-' && !char_is_digit(value[0]))
+                               break;
+                       num = strtoll(value, &end, 10);
+                       if (*end || num > INT_MAX || num < INT_MIN)
+                               break;
+                       set_errno = num;
+               }
+       }
+       ret = errno ? -errno : -EPROTO;
+out:
+       free(key);
        fclose(f);
        errno = -ret;
        return ret;