网站备案在哪里找,如何推广外贸网站,杭州网站seo优化,wordpress果酱主题原创文章是freas_1990#xff0c;转载请注明出处#xff1a;http://blog.csdn.net/freas_1990/article/details/23795587 在Linux 2.6一旦#xff08;不包含2.6#xff0c;对于更详细的调查是不是版本号#xff09;#xff0c;控制块的概念#xff0c;各种协议的状态管理… 原创文章是freas_1990转载请注明出处http://blog.csdn.net/freas_1990/article/details/23795587 在Linux 2.6一旦不包含2.6对于更详细的调查是不是版本号控制块的概念各种协议的状态管理还出于比較混乱的状态。 Linux 2.6以后。传输控制块机制使代码看起来比較规整了。 创建传输控制块 /** Create an inet socket.*/static int inet_create(struct socket *sock, int protocol)
{struct sock *sk;struct list_head *p;struct inet_protosw *answer;struct inet_opt *inet;int err -ENOBUFS;sock-state SS_UNCONNECTED;sk sk_alloc(PF_INET, GFP_KERNEL, inet_sk_size(protocol),inet_sk_slab(protocol));if (!sk)goto out;/* Look for the requested type/protocol pair. */answer NULL;rcu_read_lock();list_for_each_rcu(p, inetsw[sock-type]) {answer list_entry(p, struct inet_protosw, list);/* Check the non-wild match. */if (protocol answer-protocol) {if (protocol ! IPPROTO_IP)break;} else {/* Check for the two wild cases. */if (IPPROTO_IP protocol) {protocol answer-protocol;break;}if (IPPROTO_IP answer-protocol)break;}answer NULL;}err -ESOCKTNOSUPPORT;if (!answer)goto out_sk_free;err -EPERM;if (answer-capability 0 !capable(answer-capability))goto out_sk_free;err -EPROTONOSUPPORT;if (!protocol)goto out_sk_free;err 0;sock-ops answer-ops;sk-sk_prot answer-prot;sk-sk_no_check answer-no_check;if (INET_PROTOSW_REUSE answer-flags)sk-sk_reuse 1;rcu_read_unlock();inet inet_sk(sk);if (SOCK_RAW sock-type) {inet-num protocol;if (IPPROTO_RAW protocol)inet-hdrincl 1;}if (ipv4_config.no_pmtu_disc)inet-pmtudisc IP_PMTUDISC_DONT;elseinet-pmtudisc IP_PMTUDISC_WANT;inet-id 0;sock_init_data(sock, sk);sk_set_owner(sk, THIS_MODULE);sk-sk_destruct inet_sock_destruct;sk-sk_zapped 0;sk-sk_family PF_INET;sk-sk_protocol protocol;sk-sk_backlog_rcv sk-sk_prot-backlog_rcv;inet-uc_ttl -1;inet-mc_loop 1;inet-mc_ttl 1;inet-mc_index 0;inet-mc_list NULL;#ifdef INET_REFCNT_DEBUGatomic_inc(inet_sock_nr);
#endifif (inet-num) {/* It assumes that any protocol which allows* the user to assign a number at socket* creation time automatically* shares.*/inet-sport htons(inet-num);/* Add to protocol hash chains. */sk-sk_prot-hash(sk);}if (sk-sk_prot-init) {err sk-sk_prot-init(sk);if (err)inet_sock_release(sk);}
out:return err;
out_sk_free:rcu_read_unlock();sk_free(sk);goto out;
} 这里的sk_alloc是重点 sk sk_alloc(PF_INET, GFP_KERNEL, inet_sk_size(protocol),inet_sk_slab(protocol)); inet_sk_size定义例如以下 static __inline__ int inet_sk_size(int protocol)
{int rc sizeof(struct tcp_sock);if (protocol IPPROTO_UDP)rc sizeof(struct udp_sock);else if (protocol IPPROTO_RAW)rc sizeof(struct raw_sock);return rc;
} 它会依据详细的传输层协议定义返回对应的传输控制块的大小。 在socket里sock指针仅仅是一个“泛型”它可能指向struct sockstruct tcp_sockstruct udp_sock根据该协议的细节。 版权声明本文博客原创文章博客未经同意不得转载。
