c - Linux 上是否有映射到 IP 协议字段的标准枚举？

Question

我找不到一个，但很惊讶它不存在。是否有一个已经定义的枚举，其值（例如 TCP、UDP、ICMP）对应于 IP 标头的协议字段？

Answer 1

没有枚举，但有getprotoent(), getprotobyname()，getprotobynumber()如果你想从/etc/protocols.

Answer 2

检查linux/include/uapi/linux/in.h：

/* Standard well-defined IP protocols.  */
enum {
  IPPROTO_IP = 0,       /* Dummy protocol for TCP       */
#define IPPROTO_IP      IPPROTO_IP
  IPPROTO_ICMP = 1,     /* Internet Control Message Protocol    */
#define IPPROTO_ICMP        IPPROTO_ICMP
  IPPROTO_IGMP = 2,     /* Internet Group Management Protocol   */
#define IPPROTO_IGMP        IPPROTO_IGMP
  IPPROTO_IPIP = 4,     /* IPIP tunnels (older KA9Q tunnels use 94) */
#define IPPROTO_IPIP        IPPROTO_IPIP
  IPPROTO_TCP = 6,      /* Transmission Control Protocol    */
#define IPPROTO_TCP     IPPROTO_TCP
...