YAIP/src/proxy.c

#include "proxy.h"

Response *upstreamGetResponse(Request *request){
	//Here we pretend to be a client

	int client_fd = 0;
	struct sockaddr_in address;
	memset( &address, 0, sizeof(address) );
	struct hostent *host = gethostbyname(request->host);
	Response *rsp = NULL;

	if ((client_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0){
		perror("socket failed");
		return NULL;
	}


	address.sin_family = AF_INET;
	address.sin_port = htons( request->port );
	// We want the request to go out to whatever the host was resolved to
	memcpy( &address.sin_addr, host->h_addr_list[0], host->h_length );

	if((connect(client_fd, (struct sockaddr *)&address, sizeof(address)))<0)  {  
		perror("connect failed");
		return NULL;
	}

	char *toSend = requestToString(request);

	if ( write( client_fd, toSend, strlen(toSend) ) != strlen(toSend) ){
		perror( "Write Error" );
		return NULL;
	}

	rsp = newResponseFromSocket( client_fd );

	return rsp;
}

void sendConnectionEstablished(int client){
	// If it is a connect request, we are dealing with https

	// I am basically doing the same thing that mitmproxy does here
	// We start by responding with 200 Connection Established which
	// in a normal proxy would mean that we have established a
	// connection with the remote host. However, we haven't because we
	// are going to pretend to be the host to the client and pretend to
	// be the client to the host

	Response *response = newResponse();
	connectionEstablished(response);
	char *responseStr = responseToString(response);
	send(client , responseStr, strlen(responseStr) , 0 );
	freeResponse( response );
}

void proxyRequest(Request *request, int client, CertificateAutority *ca){
	if ( strcmp( request->method, "CONNECT" ) == 0 ){

		sendConnectionEstablished(client);

		// All we might need from the connect resquest is the host
		char *host = request->host;
		freeRequest( request );

		// If we already have a host cert for the domain we're dealing with use
		// it
		CertList *certItem = findCertListItem( ca->certs, host );
		if ( certItem == NULL ){
			// If we don't, generate a new one
			X509 *siteCert = generate_site_cert( ca->pkey, ca->cert, host );
			certItem = newCertListItem( host, ca->pkey, siteCert );
			if ( ca->certs == NULL ) ca->certs = certItem;
			else getLastCertListItem(ca->certs)->next = certItem;
		}


		SSL_CTX *ctx;
		SSL *ssl;
		char buf[1024] = {0};
		int bytes;
		Response *response;

		SSL_library_init();

		ctx = setup_ctx(certItem);

		ssl = SSL_new(ctx);
		SSL_set_fd( ssl, client );

		if ( SSL_accept(ssl) == -1 ){
			ERR_print_errors_fp(stderr);
		} else {
			bytes = SSL_read(ssl, buf, sizeof(buf));
			buf[bytes] = '\0';
			request = newRequestFromString( buf );
			//If this request doesn't contain a host, use the one from the
			//connect request
			if ( strlen( request->host ) == 0 ){
				free(request->host);
				request->host = strdup( host );
			}
			response = upstreamGetResponse(request);
			char *responseStr = responseToString( response );
			SSL_write( ssl, responseStr, strlen(responseStr) );
		}
		SSL_free(ssl);
		SSL_CTX_free(ctx);
		
	} else {
		Response *response = upstreamGetResponse(request);
		char *responseStr = responseToString( response );
		send(client , responseStr, strlen(responseStr) , 0 );
		free( responseStr );
		freeResponse( response );
	}
}