组织tcp数据包
/*
* 函数名称: ln_tcp_encode
* 作 者: 黄彦杰 Lenn
* 设计日期: 2024-08-02
* 功能描述: 组织tcp数据包
* 返 回 值: 0
*/
static int ln_tcp_encode(uint8_t* pktbuf, uint32_t sip, uint32_t dip, uint8_t* smac, uint8_t* dmac, ln_tcp_fragment* fragment) {
unsigned int total_len = fragment->length + sizeof(struct rte_ether_hdr) + sizeof(struct rte_ipv4_hdr) +
sizeof(struct rte_tcp_hdr) + fragment->optlen * sizeof(uint32_t);
struct rte_ether_hdr* ehdr = (struct rte_ether_hdr*)pktbuf;
rte_memcpy(ehdr->s_addr.addr_bytes, smac, RTE_ETHER_ADDR_LEN);
rte_memcpy(ehdr->d_addr.addr_bytes, dmac, RTE_ETHER_ADDR_LEN);
ehdr->ether_type = htons(RTE_ETHER_TYPE_IPV4);
struct rte_ipv4_hdr* iphdr = (struct rte_ipv4_hdr*)(ehdr + 1);
iphdr->version_ihl = 0x45;
iphdr->type_of_service = 0;
iphdr->total_length = htons(total_len - sizeof(struct rte_ether_hdr));
iphdr->packet_id = htons(0);
iphdr->fragment_offset = htons(0);
iphdr->time_to_live = 64;
iphdr->next_proto_id = IPPROTO_TCP;
iphdr->src_addr = sip;
iphdr->dst_addr = dip;
iphdr->hdr_checksum = 0;
iphdr->hdr_checksum = rte_ipv4_cksum(iphdr);
struct rte_tcp_hdr* tcphdr = (struct rte_tcp_hdr*)(iphdr + 1);
tcphdr->src_port = fragment->sport;
tcphdr->dst_port = fragment->dport;
tcphdr->sent_seq = htonl(fragment->seqnum);
tcphdr->recv_ack = htonl(fragment->acknum);
tcphdr->data_off = fragment->hdr_off;
tcphdr->rx_win = fragment->windows;
tcphdr->tcp_urp = fragment->urp;
if (fragment->data != 0) {
uint8_t* payload = (uint8_t*)(tcphdr + 1) + fragment->optlen * sizeof(uint32_t);
rte_memcpy(payload, fragment->data, fragment->length);
}
tcphdr->cksum = 0;
tcphdr->cksum = rte_ipv4_udptcp_cksum(iphdr, tcphdr);
return 0;
}
/*
* 函数名称: ln_tcp_send
* 作 者: 黄彦杰 Lenn
* 设计日期: 2024-08-02
* 功能描述: tcp数据包发送
* 返 回 值: 存储tcp数据包的内存
*/
struct rte_mbuf* ln_tcp_send(struct rte_mempool* mbuf_pool, uint32_t sip, uint32_t dip, uint8_t* smac, uint8_t* dmac, ln_tcp_fragment* fragment) {
int total_len = fragment->length + sizeof(struct rte_ether_hdr) + sizeof(struct rte_ipv4_hdr) + sizeof(struct rte_tcp_hdr) + fragment->optlen * sizeof(uint32_t);
struct rte_mbuf* mbuf = rte_pktmbuf_alloc(mbuf_pool);
if (!mbuf) {
rte_exit(EXIT_FAILED, "Alloc tcp buf failed");
}
mbuf->pkt_len = total_len;
mbuf->data_len = total_len;
uint8_t* data = rte_pktmbuf_mtod(mbuf, uint8_t*);
ln_tcp_encode(data, sip, dip, smac, dmac, fragment);
return mbuf;
}
tcp状态控制
int ln_tcp_process(struct rte_mbuf* mbuf) {
struct rte_ipv4_hdr* iphdr = rte_pktmbuf_mtod_offset(mbuf, struct rte_ipv4_hdr*, struct rte_ether_hdr);
struct rte_tcp_hdr* tcphdr = (struct rte_tcp_hdr*)(iphdr + 1);
uint16_t cksum_cur = tcphdr->cksum;
tcphdr->cksum = 0;
tcphdr->cksum = rte_ipv4_udptcp_cksum(iphdr, tcphdr);
if (tcphdr->cksum != cksum_cur) {
printf("[check] cur sksum : %d, now cksum %d\n", cksum_cur, tcphdr->cksum);
return -1;
}
ln_tcp_stream* stream = ln_tcp_stream_search(iphdr->src_addr, iphdr->dst_addr, tcphdr->src_port, tcphdr->dst_port);
if (stream == NULL) {
stream = ln_tcp_stream_create(iphdr->src_addr, iphdr->dst_addr, tcphdr->src_port, tcphdr->dst_port);
if (stream == NULL) {
return -1;
}
}
switch (stream->status) {
case LN_TCP_STATUS_CLOSED: // client
break;
case LN_TCP_STATUS_LISTEN:
ln_tcp_handle_listen(stream, tcphdr);
break;
case LN_TCP_STATUS_SYN_RCVD:
ln_tcp_handle_syn_revd(stream, tcphdr);
break;
case LN_TCP_STATUS_SYN_SENT: // client
break;
case LN_TCP_STATUS_ESTABLISHED: // client | server
uint8_t hdrlen = tcphdr->data_off & 0xF0;
hdrlen = (hdrlen >> 4);
uint8_t* payload = (uint8_t*)(tcphdr + 1) + hdrlen * 4;
printf("--> tcp payload %s\n", padload);
break;
case LN_TCP_STATUS_FIN_WAIT_1: // client
break;
case LN_TCP_STATUS_FIN_WAIT_2: // client
break;
case LN_TCP_STATUS_CLOSING: // client
break;
case LN_TCP_STATUS_TIME_WAIT: // client
break;
case LN_TCP_STATUS_CLOSE_WAIT: // server
break;
case LN_TCP_STATUS_LAST_ACK: // server
break;
case default:
break;
}
}
首先，从接收到的
mbuf中提取出IP头（rte_ipv4_hdr* iphdr）和TCP头（rte_tcp_hdr* tcphdr）。这里使用了DPDK库函数rte_pktmbuf_mtod_offset()来获取指向特定位置的指针。接下来，保存当前的TCP校验和值，并将校验和字段置为0。然后通过调用
rte_ipv4_udptcp_cksum()计算新的TCP校验和，并与之前保存的值进行比较，以检查是否有校验和错误。然后，通过源IP地址、目标IP地址、源端口号和目标端口号在已建立的TCP流列表中搜索相应的流对象（
ln_tcp_stream* stream）。如果找不到匹配的流对象，则创建一个新的流对象。根据流对象当前状态，执行相应操作：
LN_TCP_STATUS_CLOSED：客户端状态。
LN_TCP_STATUS_LISTEN：监听状态，执行相关处理。
LN_TCP_STATUS_SYN_RCVD：同步收到状态，执行相关处理。
LN_TCP_STATUS_SYN_SENT：客户端状态。
LN_TCP_STATUS_ESTABLISHED：连接已建立状态（客户端或服务器），打印TCP负载信息。
其他状态暂未给出具体处理逻辑，可自行补充。
tcp数据包控制
int ln_tcp_out(struct rte_mempool* mbuf_pool) {
ln_tcp_table* table = get_tcp_table_instance();
ln_tcp_stream* stream;
for(stream = table->streams; stream != NULL; stream = stream->next) {
struct ln_tcp_fragment* fragment = NULL;
int nb_send = rte_ring_mc_dequeue(stream->sendbuf, (void**)&fragment);
if (nb_send < 0) {
continue;
}
uint8_t* dst_mac = ln_get_mac_from_arp(stream->sip);
if (dst_mac == NULL) {
struct rte_mbuf* arpbuf = ln_arp_send(mbuf_pool, RTE_ARP_OP_REQUEST, nDefaultArpMac, stream->dip, stream->sip);
struct inout_ring* ring = get_ioring_instance();
rte_ring_mp_enqueue_burst(ring->out, (void**)&arpbuf);
rte_ring_mp_enqueue(stream->sendbuf, (void*)fragment);
}
else {
struct rte_mbuf* tcpbuf = ln_tcp_send(mbuf_pool, stream->dip, stream->sip, stream->localmac, dst_mac, fragment);
struct inout_ring* ring = get_ioring_instance();
rte_ring_mp_enqueue_burst(ring->out, (void**)&tcpbuf);
rte_free(fragment);
}
}
return 0;
}
首先，获取全局的TCP连接表实例（
ln_tcp_table* table = get_tcp_table_instance();）。然后，遍历所有的TCP流对象（
stream），对每个流对象执行以下操作：从发送缓冲区（
sendbuf）中取出待发送的TCP片段（通过调用rte_ring_mc_dequeue()），存储在指针变量fragment中。如果没有可发送的数据包，则继续下一次循环。
获取目标MAC地址（dst_mac）：通过源IP地址查询ARP缓存，获取目标MAC地址。如果找不到目标MAC地址，则需要发送ARP请求，并将待发送的ARP请求包加入输出队列。
如果成功获取到目标MAC地址，则构建要发送的TCP数据包（通过调用
ln_tcp_send()），并将其加入输出队列。最后，释放已经处理过的TCP片段内存（通过调用
rte_free(fragment)）。整个函数遍历完所有流对象后返回。
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