libipsec: Enforce a minimum of 256 for SPIs

RFC 4303 reserves the SPIs between 1 and 255 for future use.  This also
avoids an overflow and a division by zero if spi_min is 0 and spi_max is
0xffffffff.

diff --git a/src/libipsec/ipsec_sa_mgr.c b/src/libipsec/ipsec_sa_mgr.c
index 314785f67e46c06d7dd9567488ea8414c4abbe68..a1fa23e287c60d8f22bfad7a9e152140d07e9d7a 100644 (file)
--- a/src/libipsec/ipsec_sa_mgr.c
+++ b/src/libipsec/ipsec_sa_mgr.c
@@ -401,7 +401,7 @@ METHOD(ipsec_sa_mgr_t, get_spi, status_t,
        uint32_t spi_min, spi_max, spi_new;
 
        spi_min = lib->settings->get_int(lib->settings, "%s.spi_min",
-                                                                        0x00000000, lib->ns);
+                                                                        0x00000100, lib->ns);
        spi_max = lib->settings->get_int(lib->settings, "%s.spi_max",
                                                                         0xffffffff, lib->ns);
        if (spi_min > spi_max)
@@ -410,6 +410,9 @@ METHOD(ipsec_sa_mgr_t, get_spi, status_t,
                spi_min = spi_max;
                spi_max = spi_new;
        }
+       /* make sure the SPI is valid (not in range 0-255) */
+       spi_min = max(spi_min, 0x00000100);
+       spi_max = max(spi_max, 0x00000100);
 
        this->mutex->lock(this->mutex);
        if (!this->rng)
@@ -433,8 +436,6 @@ METHOD(ipsec_sa_mgr_t, get_spi, status_t,
                        return FAILED;
                }
                spi_new = spi_min + spi_new % (spi_max - spi_min + 1);
-               /* make sure the SPI is valid (not in range 0-255) */
-               spi_new |= 0x00000100;
                spi_new = htonl(spi_new);
        }
        while (!allocate_spi(this, spi_new));