网络协议栈函数.docVIP

(以下文件路径都是在2.6.28.7内核之下，在其它内核下有可能源码的位置不一样) 输出过程： 1、(sock_sendmsg在 kernel/net/socket.c) int sock_sendmsg(struct socket *sock, struct msghdr *msg, size_t size) { struct kiocb iocb; struct sock_iocb siocb; int ret; init_sync_kiocb(iocb, NULL); iocb.private = siocb; ret = __sock_sendmsg(iocb, sock, msg, size); if (-EIOCBQUEUED == ret) ret = wait_on_sync_kiocb(iocb); return ret; } tcp_sendmsg在 kernel/net/ipv4/tcp.c下 int tcp_sendmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg, size_t size) { struct sock *sk = sock-sk; struct iovec *iov; struct tcp_sock *tp = tcp_sk(sk); struct sk_buff *skb; int iovlen, flags; int mss_now, size_goal; int err, copied; long timeo; lock_sock(sk); TCP_CHECK_TIMER(sk); flags = msg-msg_flags; timeo = sock_sndtimeo(sk, flags MSG_DONTWAIT); /* Wait for a connection to finish. */ if ((1 sk-sk_state) ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) if ((err = sk_stream_wait_connect(sk, timeo)) != 0) goto out_err; /* This should be in poll */ clear_bit(SOCK_ASYNC_NOSPACE, sk-sk_socket-flags); mss_now = tcp_current_mss(sk, !(flagsMSG_OOB)); size_goal = tp-xmit_size_goal; /* Ok commence sending. */ iovlen = msg-msg_iovlen; iov = msg-msg_iov; copied = 0; err = -EPIPE; if (sk-sk_err || (sk-sk_shutdown SEND_SHUTDOWN)) goto do_error; while (--iovlen = 0) { int seglen = iov-iov_len; unsigned char __user *from = iov-iov_base; iov++; while (seglen 0) { int copy; skb = tcp_write_queue_tail(sk); if (!tcp_send_head(sk) || (copy = size_goal - skb-len) = 0) { new_segment: /* Allocate new segment. If the interface is SG, * allocate skb fitting to single page. */ if (!sk_stream_memory_free(sk)) goto wait_for_sndbuf; skb = sk_stream_alloc_skb(sk, select_size(sk), sk-sk_allocation); if (!skb) goto wait_for_memory; /* * Check whether we can use HW checksum. */ if (sk-sk_route_caps NETIF_F_ALL_CSUM) skb-ip_summed = CHECKSUM_