iwinfo: Query hostapd for 'ssid2'

DAWN is reporting invalid results because it can't find the SSID of the
running networks. Reported by Elwin Huang in
https://github.com/berlin-open-wireless-lab/DAWN/issues/247#issuecomment-3327148254

It needs to be parsed like wpa_config_parse_string() does.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

diff --git a/iwinfo_nl80211.c b/iwinfo_nl80211.c
index cd801af0654f15c59e97600397e41bf0093d1de9..813678a8706ba9315335c4ee0fbb34405e2f8e27 100644 (file)
--- a/iwinfo_nl80211.c
+++ b/iwinfo_nl80211.c
@@ -1299,6 +1299,87 @@ static int nl80211_get_ssid_bssid_cb(struct nl_msg *msg, void *arg)
        }
 }
 
+/*
+ * This matches the behaviour of hostapd's wpa_config_parse_string
+ *
+ * (double quoted string, hexdump, printf-escaped string)
+ * ssid2="test"
+ * ssid2=74657374
+ * ssid2=P"hello\nthere"
+ */
+static int parse_ssid2(const char *value, char *buf, size_t buflen)
+{
+       const char *pos;
+       size_t len, i;
+
+       if (*value == '"') {
+               value++;
+               pos = strrchr(value, '"');
+               if (!pos || pos[1] != '\0')
+                       return -1;
+               len = pos - value;
+               if (len >= buflen)
+                       len = buflen - 1;
+               memcpy(buf, value, len);
+               buf[len] = '\0';
+               return 0;
+       } else if (*value == 'P' && value[1] == '"') {
+               value += 2;
+               pos = strrchr(value, '"');
+               if (!pos || pos[1] != '\0')
+                       return -1;
+               len = 0;
+               while (*value && value < pos && len < buflen - 1) {
+                       if (*value == '\\' && value + 1 < pos) {
+                               value++;
+                               if (*value == 'x' && value + 2 < pos) {
+                                       char hex[3] = {value[1], value[2], 0};
+                                       buf[len++] = strtol(hex, NULL, 16);
+                                       value += 3;
+                               } else if (*value >= '0' && *value <= '7' && value + 2 < pos &&
+                                          value[1] >= '0' && value[1] <= '7' &&
+                                          value[2] >= '0' && value[2] <= '7') {
+                                       buf[len++] = ((value[0] - '0') << 6) |
+                                                    ((value[1] - '0') << 3) |
+                                                    (value[2] - '0');
+                                       value += 3;
+                               } else {
+                                       switch (*value) {
+                                       case 'n': buf[len++] = '\n'; break;
+                                       case 'r': buf[len++] = '\r'; break;
+                                       case 't': buf[len++] = '\t'; break;
+                                       case '\\': buf[len++] = '\\'; break;
+                                       case '"': buf[len++] = '"'; break;
+                                       default: buf[len++] = *value; break;
+                                       }
+                                       value++;
+                               }
+                       } else {
+                               buf[len++] = *value++;
+                       }
+               }
+               buf[len] = '\0';
+               return 0;
+       } else {
+               len = strlen(value);
+               if (len & 1)
+                       return -1;
+               len /= 2;
+               if (len >= buflen)
+                       len = buflen - 1;
+               for (i = 0; i < len; i++) {
+                       char hex[3] = {value[i*2], value[i*2+1], 0};
+                       char *end;
+                       long val = strtol(hex, &end, 16);
+                       if (*end)
+                               return -1;
+                       buf[i] = val;
+               }
+               buf[len] = '\0';
+               return 0;
+       }
+}
+
 static int nl80211_get_ssid(const char *ifname, char *buf)
 {
        char *res;
@@ -1316,6 +1397,15 @@ static int nl80211_get_ssid(const char *ifname, char *buf)
                nl80211_hostapd_query(ifname, "ssid", sb.ssid,
                                      IWINFO_ESSID_MAX_SIZE + 1);
 
+       if (sb.ssid[0] == 0) {
+               /* ssid2 can be quoted, printf-encoded, or hex; needs parsing.
+                * Buffer sized for printf encoding (\xHH = 4 chars per byte) plus P"" wrapper. */
+               char ssid2_raw[IWINFO_ESSID_MAX_SIZE * 4 + 3];
+               ssid2_raw[0] = 0;
+               if (nl80211_hostapd_query(ifname, "ssid2", ssid2_raw, sizeof(ssid2_raw)))
+                       parse_ssid2(ssid2_raw, (char *)sb.ssid, IWINFO_ESSID_MAX_SIZE + 1);
+       }
+
        /* failed, try to obtain Mesh ID */
        if (sb.ssid[0] == 0)
                iwinfo_ubus_query(res ? res : ifname, "mesh_id",