-char *stringcopy(const char *s, int len);
-char *addr2string(struct sockaddr *addr, socklen_t len);
-void printfchars(char *prefixfmt, char *prefix, char *charfmt, char *chars, int len);
-int connectport(int type, char *host, char *port);
-int bindtoaddr(struct addrinfo *addrinfo, int family, int reuse, int v6only);