dpvs中lvs核心处理函数：dp_vs_in

__dp_vs_in

• 开始进入lvs模块,这块代码非常复杂,简单说,对于存在proxy连接,判断方向(client->LB或是rs->LB),直接发送流量.新来的连接,查找virtual server,根据LB算法查找对应后端real server,建立连接,并保存这个会话

static int __dp_vs_in(void *priv, struct rte_mbuf *mbuf,const struct inet_hook_state *state, int af)
{struct dp_vs_iphdr  iph;struct dp_vs_proto *prot;struct dp_vs_conn * conn;int       dir, verdict, err, related;bool      drop = false;lcoreid_t cid, peer_cid;//获取L2层数据包类型eth_type_t etype = mbuf->packet_type; /* FIXME: use other field ? */assert(mbuf && state);//获取当前运行的lcore idcid = peer_cid = rte_lcore_id();//数据包不是发往本机的,直接返回ACCEPT,之后执行ipv4_rcv_finif (unlikely(etype != ETH_PKT_HOST)){return(INET_ACCEPT);}//填充内部dp_vs_iphdr,如果出错,主要是协议族不正确,直接返回ACCEPTif (dp_vs_fill_iphdr(af, mbuf, &iph) != EDPVS_OK){return(INET_ACCEPT);}//处理ICMP消息,类似于linux内核中icmp_error相关的处理逻辑,暂时不展开if (unlikely(iph.proto == IPPROTO_ICMP ||iph.proto == IPPROTO_ICMPV6)){/* handle related ICMP error to existing conn */verdict = dp_vs_in_icmp(af, mbuf, &related);if (related || verdict != INET_ACCEPT){return(verdict);}/* let unrelated and valid ICMP goes down,* may implement ICMP fwd in the futher. */}//查找四层处理协议,目前实现了tcp,udp和icmpprot = dp_vs_proto_lookup(iph.proto);//如果未找到相关的传输层proto,返回ACCEPTif (unlikely(!prot)){return(INET_ACCEPT);}/** Defrag ipvs-forwarding TCP/UDP is not supported for some reasons,** - RSS/flow-director do not support TCP/UDP fragments, means it's*   not able to direct frags to same lcore as original TCP/UDP packets.* - per-lcore conn table will miss if frags reachs wrong lcore.** If we redirect frags to "correct" lcore, it may cause performance* issue. Also it need to understand RSS algorithm. Moreover, for the* case frags in same flow are not occur in same lcore, a global lock is* needed, which is not a good idea.*///目前不支持ip分片,此处与flow director相关if (af == AF_INET && ip4_is_frag(ip4_hdr(mbuf))){RTE_LOG(DEBUG, IPVS, "%s: frag not support.\\n", __func__);return(INET_DROP);}/* packet belongs to existing connection ? *///调用proto相关conn_lookup函数查找会话,tcp中为tcp_conn_lookup。有可能会 drop 掉。dir 是设置数据流方向，从client到LB，//还是从real server到LB,peer_cid为查找时决定处理该连接的lcore idconn = prot->conn_lookup(prot, &iph, mbuf, &dir, false, &drop, &peer_cid);//如果决定drop,则直接判定为INET_DROP动作后返回if (unlikely(drop)){RTE_LOG(DEBUG, IPVS, "%s: deny ip try to visit.\\n", __func__);return(INET_DROP);}/** The connection is not locally found, however the redirect is found so* forward the packet to the remote redirect owner core.*///如果不在当前lcore上处理,则恢复mbuf->data_off指向L2 header后转发给其他lcore处理,此处ring enqueue成功后返回INET_STOLEN,//否则返回DROP丢弃数据包if (cid != peer_cid){/* recover mbuf.data_off to outer Ether header */rte_pktmbuf_prepend(mbuf, (uint16_t)sizeof(struct ether_hdr));return(dp_vs_redirect_pkt(mbuf, peer_cid));}//对于新建的连接,肯定是没有会话的,conn_sched根据请求选择一个后端real server建立连接if (unlikely(!conn)){/* try schedule RS and create new connection *///调用proto中conn_sched接口选择一个后端rs建立连接，如果创建连接失败，返回verdictif (prot->conn_sched(prot, &iph, mbuf, &conn, &verdict) != EDPVS_OK){/* RTE_LOG(DEBUG, IPVS, "%s: fail to schedule.\\n", __func__); */return(verdict);}/* only SNAT triggers connection by inside-outside traffic. *///snat模式，则是内部服务器访问外部服务，内网服务器--->dpvs--->外网服务器（baidu），所以设置dir=DPVS_CONN_DIR_OUTBOUNDif (conn->dest->fwdmode == DPVS_FWD_MODE_SNAT){dir = DPVS_CONN_DIR_OUTBOUND;}else{//其余模式设置dir=DPVS_CONN_DIR_INBOUNDdir = DPVS_CONN_DIR_INBOUND;}}//特殊处理,syn_proxyif (conn->flags & DPVS_CONN_F_SYNPROXY){if (dir == DPVS_CONN_DIR_INBOUND){/* Filter out-in ack packet when cp is at SYN_SENT state.* Drop it if not a valid packet, store it otherwise */if (0 == dp_vs_synproxy_filter_ack(mbuf, conn, prot,&iph, &verdict)){dp_vs_stats_in(conn, mbuf);dp_vs_conn_put(conn);return(verdict);}/* "Reuse" synproxy sessions.* "Reuse" means update syn_proxy_seq struct* and clean ack_mbuf etc. */if (0 != dp_vs_synproxy_ctrl_conn_reuse){if (0 == dp_vs_synproxy_reuse_conn(af, mbuf, conn, prot,&iph, &verdict)){dp_vs_stats_in(conn, mbuf);dp_vs_conn_put(conn);return(verdict);}}}else{/* Syn-proxy 3 logic: receive syn-ack from rs */if (dp_vs_synproxy_synack_rcv(mbuf, conn, prot,iph.len, &verdict) == 0){dp_vs_stats_out(conn, mbuf);dp_vs_conn_put(conn);return(verdict);}}}//状态迁移，tcp中为tcp_state_transif (prot->state_trans){err = prot->state_trans(prot, conn, mbuf, dir);if (err != EDPVS_OK){RTE_LOG(WARNING, IPVS, "%s: fail to trans state.", __func__);}}conn->old_state = conn->state;/* holding the conn, need a "put" later. *///根据流量方向dir,来选择如何写数据if (dir == DPVS_CONN_DIR_INBOUND){return(xmit_inbound(mbuf, prot, conn));}else{return(xmit_outbound(mbuf, prot, conn));}
}