Throw exception on TCP bind failure instead of exiting immediately.

This makes it possible to choose another port when trying to construct an rpcs on a random port.

rpc/connection.cc

@@ -298,8 +298,7 @@ tcpsconn::tcpsconn(chanmgr *m1, int port, int lossytest)
 	setsockopt(tcp_, IPPROTO_TCP, TCP_NODELAY, &yes, sizeof(yes));
 
 	if(bind(tcp_, (sockaddr *)&sin, sizeof(sin)) < 0){
-		perror("accept_loop tcp bind:");
-		assert(0);
+        throw PortBusyException(std::string("accept_loop tcp bind error: ") + std::string(strerror(errno))); 
 	}
 
 	if(listen(tcp_, 1000) < 0) {

rpc/connection.h

@@ -7,11 +7,16 @@
 #include <netinet/in.h>
 
 #include <map>
+#include <stdexcept>
 
 #include "pollmgr.h"
 
 class connection;
 
+class PortBusyException : public std::runtime_error {
+   using runtime_error::runtime_error;
+};
+
 class chanmgr {
 	public:
 		virtual bool got_pdu(connection *c, char *b, int sz) = 0;