Remove newlines from wpa_supplicant config network output

Spurious newlines output while writing the config file can corrupt the
wpa_supplicant configuration. Avoid writing these for the network block
parameters. This is a generic filter that cover cases that may not have
been explicitly addressed with a more specific commit to avoid control
characters in the psk parameter.

Signed-off-by: Paul Stewart <pstew@google.com>

src/utils/common.c

@@ -709,6 +709,17 @@ int has_ctrl_char(const u8 *data, size_t len)
 }
 
 
+int has_newline(const char *str)
+{
+	while (*str) {
+		if (*str == '\n' || *str == '\r')
+			return 1;
+		str++;
+	}
+	return 0;
+}
+
+
 size_t merge_byte_arrays(u8 *res, size_t res_len,
 			 const u8 *src1, size_t src1_len,
 			 const u8 *src2, size_t src2_len)

src/utils/common.h

@@ -489,6 +489,7 @@ const char * wpa_ssid_txt(const u8 *ssid, size_t ssid_len);
 char * wpa_config_parse_string(const char *value, size_t *len);
 int is_hex(const u8 *data, size_t len);
 int has_ctrl_char(const u8 *data, size_t len);
+int has_newline(const char *str);
 size_t merge_byte_arrays(u8 *res, size_t res_len,
 			 const u8 *src1, size_t src1_len,
 			 const u8 *src2, size_t src2_len);

wpa_supplicant/config.c

@@ -2699,8 +2699,19 @@ char * wpa_config_get(struct wpa_ssid *ssid, const char *var)
 
 	for (i = 0; i < NUM_SSID_FIELDS; i++) {
 		const struct parse_data *field = &ssid_fields[i];
-		if (os_strcmp(var, field->name) == 0)
+		if (os_strcmp(var, field->name) == 0) {
-			return field->writer(field, ssid);
+			char *ret = field->writer(field, ssid);
+
+			if (ret && has_newline(ret)) {
+				wpa_printf(MSG_ERROR,
+					   "Found newline in value for %s; not returning it",
+					   var);
+				os_free(ret);
+				ret = NULL;
+			}
+
+			return ret;
+		}
 	}
 
 	return NULL;