关于名称和地址族课件.pptVIP

第三章;目标 ;将名字映射到数字（1）;将名字映射到数字（2）;DNS;访问名称服务;GetAddrInfo.c; struct addrinfo addrCriteria; memset(addrCriteria, 0, sizeof(addrCriteria)); addrCriteria.ai_family = AF_UNSPEC; addrCriteria.ai_socktype = SOCK_STREAM; addrCriteria.ai_protocol = IPPROTO_TCP; struct addrinfo *addrList; int rtnVal = getaddrinfo(addrString, portString, addrCriteria, addrList); if (rtnVal != 0) DieWithUserMessage(getaddrinfo() failed, gai_strerror(rtnVal));;for (struct addrinfo *addr = addrList; addr != NULL; addr = addr-ai_next) { PrintSocketAddress(addr-ai_addr, stdout); fputc(\n, stdout); } freeaddrinfo(addrList); // Free addrinfo allocated in getaddrinfo() exit(0); };运行结果;addrinfo结构体;详细信息;编写地址通用的代码; switch (address-sa_family) { case AF_INET: numericAddress = ((struct sockaddr_in *) address)-sin_addr; port = ntohs(((struct sockaddr_in *) address)-sin_port); break; case AF_INET6: numericAddress = ((struct sockaddr_in6 *) address)-sin6_addr; port = ntohs(((struct sockaddr_in6 *) address)-sin6_port); break; default: fputs([unknown type], stream); // Unhandled type return; };if (inet_ntop(address-sa_family, numericAddress, addrBuffer, sizeof(addrBuffer)) == NULL) fputs([invalid address], stream); // Unable to convert else { fprintf(stream, %s, addrBuffer); if (port != 0) // Zero not valid in any socket addr fprintf(stream, -%u, port); } };通用的TCP客户;通用的TCP服务器;IPv4与IPv6之间互操作;从数字获取名称