Fix curl crash when DNS does not resolve.

dep/Makefile

@@ -131,7 +131,7 @@ curl-7.79.1:
 	rm curl-7.79.1.tar.gz
 
 CURL_FLAGS += --enable-symbol-hiding --enable-shared=no
-CURL_FLAGS += --enable-http --disable-ftp --disable-file --disable-ldap --disable-ldaps --disable-rtsp --enable-proxy --disable-dict --disable-telnet --disable-tftp --disable-pop3 --disable-imap --disable-smb --disable-smtp --disable-gopher --disable-mqtt --disable-manual --disable-threaded-resolver --disable-pthreads --disable-verbose --disable-sspi --disable-ntlm --disable-ntlm-wb --disable-tls-srp --disable-unix-sockets --disable-doh --disable-mime --disable-dateparse --disable-netrc --disable-progress-meter --disable-alt-svc
+CURL_FLAGS += --enable-http --disable-ftp --disable-file --disable-ldap --disable-ldaps --disable-rtsp --enable-proxy --disable-dict --disable-telnet --disable-tftp --disable-pop3 --disable-imap --disable-smb --disable-smtp --disable-gopher --disable-mqtt --disable-manual --enable-threaded-resolver --enable-pthreads --disable-verbose --disable-sspi --disable-ntlm --disable-ntlm-wb --disable-tls-srp --disable-unix-sockets --disable-doh --disable-mime --disable-dateparse --disable-netrc --disable-progress-meter --disable-alt-svc
 CURL_FLAGS += --without-hyper --without-zlib --without-brotli --without-zstd --without-libpsl --without-libgsasl --without-libssh2 --without-librtmp --without-winidn --without-libidn2 --without-nghttp2 --without-ngtcp2 --without-nghttp3 --without-quiche
 CURL_FLAGS += --with-ssl="$(DEP_PATH)"
 

src/network.cpp

@@ -27,6 +27,11 @@ static CURL* createCurl() {
 	// 15 second timeout for requests
 	curl_easy_setopt(curl, CURLOPT_TIMEOUT, 15);
 
+	// If curl can't resolve a DNS entry, it sends a signal to interrupt the process.
+	// However, since we use curl on non-main thread, this crashes the application.
+	// So tell curl not to signal.
+	curl_easy_setopt(curl, CURLOPT_NOSIGNAL, 1);
+
 	std::string caPath = asset::system("cacert.pem");
 	curl_easy_setopt(curl, CURLOPT_CAINFO, caPath.c_str());