Socket functions

Byte Order Conversion

• htons() host to network short
• htonl() host to network long
• ntohs() network to host short
• ntohl() network to host long

IP address conversion

struct sockaddr_in sa; // IPv4
struct sockaddr_in6 sa6; // IPv6

inet_pton(AF_INET, "192.0.2.1", &(sa.sin_addr)); // IPv4
inet_pton(AF_INET6, "2001:db8:63b3:1::3490", &(sa6.sin6_addr)); // IPv6

// IPv4: char ip4[INET_ADDRSTRLEN]; struct sockaddr_in sa; // space to hold the IPv4 string // pretend this is loaded with something inet_ntop(AF_INET, &(sa.sin_addr), ip4, INET_ADDRSTRLEN); printf("The IPv4 address is: %s\n", ip4); // IPv6: char ip6[INET6_ADDRSTRLEN]; // space to hold the IPv6 string struct sockaddr_in6 sa6; // pretend this is loaded with something inet_ntop(AF_INET6, &(sa6.sin6_addr), ip6, INET6_ADDRSTRLEN); printf("The address is: %s\n", ip6);

getaddrinfo()

int getaddrinfo(const char *node, // e.g. "www.example.com" or IP
  const char *service, // e.g. "http" or port number
  const struct addrinfo *hints,
  struct addrinfo **res);