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DPDK用户态协议栈-Tcp Posix API 1

news 2025/7/13 1:35:54

和udp一样，我们需要实现和系统调用一样的接口来实现我们的tcp server。先来看看我们之前写的unix_tcp使用了哪些接口，这边我加上两个系统调用，分别是接收数据和发送数据。

#include <stdio.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <string.h>int main(int argc, char* argv) {int sock = socket(AF_INET, SOCK_STREAM, 0);struct sockaddr_in servaddr;servaddr.sin_addr.s_addr = htonl(INADDR_ANY);servaddr.sin_family = AF_INET;servaddr.sin_port = htons(9999);bind(sock, (struct sockaddr*)&servaddr, sizeof(struct sockaddr));listen(sock, 10);struct sockaddr_in clientaddr;socklen_t len = sizeof(clientaddr);char buffer[64] = {0};int fd = accept(sock, (struct sockaddr*)&clientaddr, &len);while (1) {int nb_recv = recv(fd, buffer, 64, 0);if (nb_recv > 0) {printf("tcp recv : %s\n", buffer);send(fd, buffer, nb_recv, 0);memset(buffer, 0, 64);}}return 0;
}

socket

bind

listen

recv

send

tcp的posix实现

bitmap

static struct localhost* get_host_fromfd(int sockfd) {struct localhost* htp = get_lhost_instance();struct localhost* host;for(host = htp; host != NULL; host = host->next) {if (host->fd == sockfd) {return host;}}struct ln_tcp_stream* stream;struct ln_tcp_table* table = get_tcp_table_instance();for(stream = table->streams; stream != NULL; stream = stream->next) {if (stream->fd == sockfd) {return stream;}}return NULL;
}

根据sockfd来搜索对应的控制块（tcp和udp同一个函数）。在之前的udp api实现的过程中实现了一个伪bitmap（后续会完善的）。现在加上了tcp，在函数中加上tcp控制块相关的遍历条件。

tcp server的最后两个状态

static int ln_tcp_handle_close_wait(struct ln_tcp_stream* stream, struct rte_tcp_hdr* tcphdr) {if (tcphdr->tcp_flags & RTE_TCP_FIN_FLAG) {if (stream->status == LN_TCP_STATUS_CLOSE_WAIT) {//}}return 0;
}static int ln_tcp_handle_last_ack(struct ln_tcp_stream* stream, struct rte_tcp_hdr* tcphdr) {if (tcphdr->tcp_flags & RTE_TCP_ACK_FLAG) {if (stream->status == LN_TCP_STATUS_LAST_ACK) {stream->status = LN_TCP_STATUS_CLOSED;struct ln_tcp_table* table = get_tcp_table_instance();LL_REMOVE(stream, table->streams);table->count--;rte_ring_free(stream->recvbuf);rte_ring_free(stream->sendbuf);rte_free(stream);}}return 0;
}

修改一些之前的API

由于tcp和udp都有创建套接字，绑定等通用的部分，所以我们要在之前写的api上做一些增加和修改，让TCP和UDP都可以使用他们。

socket创建套接字

static struct localhost* get_host_fromip_port(uint32_t ip, uint16_t port, uint8_t proto) {struct localhost* htp = get_lhost_instance();struct localhost* host;for(host = htp; host != NULL; host = host->next) {if (host->localip == ip && host->localport == port && host->protocol == proto) {return host;}}return NULL;
}int nsocket(__attribute__((unused)) int domain, int type, __attribute__((unused)) int protocol) {int fd = get_fd_frombitmap();if (type == SOCK_DGRAM) {struct localhost* host = rte_malloc("localhost", sizeof(struct localhost), 0);if (host == NULL) {return -1;}memset(host, 0, sizeof(struct localhost));host->fd = fd;if (type == SOCK_DGRAM) {host->protocol = IPPROTO_UDP;}host->recvbuf = rte_ring_create("recv buf", RING_SIZE, rte_socket_id(), RING_F_SC_DEQ | RING_F_SP_ENQ);if (host->recvbuf == NULL) {rte_free(host);return -1;}host->sendbuf = rte_ring_create("send buf", RING_SIZE, rte_socket_id(), RING_F_SC_DEQ | RING_F_SP_ENQ);if (host->sendbuf == NULL) {rte_ring_free(host->recvbuf);rte_free(host);return -1;}pthread_cond_t blank_cond = PTHREAD_COND_INITIALIZER;pthread_mutex_t blank_mutex = PTHREAD_MUTEX_INITIALIZER;rte_memcpy(&host->mutex, &blank_mutex, sizeof(pthread_mutex_t));rte_memcpy(&host->cond, &blank_cond, sizeof(pthread_cond_t));struct localhost* lhp = get_lhost_instance();LL_ADD(host, lhp);}else if (type == SOCK_STREAM) {struct ln_tcp_stream* stream = rte_malloc("ln_tcp_stream", sizeof(struct ln_tcp_stream), 0);if (stream == NULL) {return -1;}stream->fd = fd;stream->proto = IPPROTO_TCP;stream->next = stream->prev = NULL;stream->recvbuf = rte_ring_create("tcp recv buf", RING_SIZE, rte_socket_id(), RING_F_SC_DEQ | RING_F_SP_ENQ);if (stream->recvbuf == NULL) {rte_free(stream);return -1;}stream->sendbuf = rte_ring_create("tcp send buf", RING_SIZE, rte_socket_id(), RING_F_SC_DEQ | RING_F_SP_ENQ);if (stream->sendbuf == NULL) {rte_ring_free(stream->sendbuf);rte_free(stream);return -1;}pthread_cond_t blank_cond = PTHREAD_COND_INITIALIZER;pthread_mutex_t blank_mutex = PTHREAD_MUTEX_INITIALIZER;rte_memcpy(&stream->cond, &blank_cond, sizeof(pthread_cond_t));rte_memcpy(&stream->mutex, &blank_mutex, sizeof(pthread_mutex_t));struct ln_tcp_table* table - get_tcp_table_instance();LL_ADD(stream, table->streams);table->count++;}return fd;
}

bind绑定

int nbind(int sockfd, const struct sockaddr *addr, __attribute__((unused)) socklen_t addrlen) {void* hostinfo = get_host_fromfd(sockfd);if (hostinfo == NULL) {return -1;}struct localhost* host = (struct localhost*)hostinfo;if (host->protocol == IPPROTO_UDP) {if (host == NULL) {return -1;}const struct sockaddr_in* laddr = (const struct sockaddr_in*)addr;host->localport = laddr->sin_port;rte_memcpy(&host->localip, &laddr->sin_addr.s_addr, sizeof(uint32_t));rte_memcpy(host->localmac, nSrcMac, RTE_ETHER_ADDR_LEN);}else {struct ln_tcp_stream* stream = (struct ln_tcp_stream*)hostinfo;const struct sockaddr_in* laddr = (const struct sockaddr_in*)addr;stream->dport = laddr->sin_port;rte_memcpy(&stream->dip, &laddr->sin_addr.s_addr, sizeof(uint32_t));rte_memcpy(&stream->localmac, nSrcMac, RTE_ETHER_ADDR_LEN);stream->status = LN_TCP_STATUS_CLOSED;}return 0;
}

close

int nclose(int fd) {void* hostinfo = get_host_fromfd(fd);if (hostinfo == NULL) {return -1;}struct localhost* host = (struct localhost*)hostinfo;if (host->protocol == IPPROTO_UDP) {struct localhost* lhp = get_lhost_instance();LL_REMOVE(host, lhp);if (host->recvbuf) {rte_ring_free(host->recvbuf);}if (host->sendbuf) {rte_ring_free(host->sendbuf);}rte_free(host);set_fd_frombitmap(fd);}else if (host->protocol == IPPROTO_TCP){struct ln_tcp_stream* stream = (struct ln_tcp_stream*)hostinfo;if (stream->status != LN_TCP_STATUS_LISTEN) {struct ln_tcp_fragment* fragment = rte_malloc("close frag", sizeof(struct ln_tcp_fragment), 0);if (fragment == NULL) {return -1;}memset(fragment, 0, sizeof(struct ln_tcp_stream));fragment->sport = stream->dport;fragment->dport = stream->sport;fragment->acknum = stream->recv_next;fragment->seqnum = stream->recv_next;fragment->windows = LN_TCP_INITIAL_WINDOWS;fragment->hdr_off = 0x50;fragment->tcp_flags = RTE_TCP_FIN_FLAG | RTE_TCP_ACK_FLAG;rte_ring_mp_enqueue(stream->sendbuf, (void*)fragment);stream->status = LN_TCP_STATUS_LAST_ACK;set_fd_frombitmap(fd);}else {struct ln_tcp_table* tb = get_tcp_table_instance();LL_REMOVE(stream, tb->streams);rte_free(stream);}}return 0;
}

tcp的专有API

listen监听

int nlisten(int sockfd, __attribute__((unused))int backlog) {void* hostinfo = get_host_fromfd(sockfd);if (hostinfo == NULL) {return -1;}struct ln_tcp_stream* stream = (struct ln_tcp_stream*)hostinfo;if (stream->proto == IPPROTO_TCP) {stream->status = LN_TCP_STATUS_LISTEN;}return 0;
}

accept建立连接

int naccept(int sockfd, struct sockaddr *addr, __attribute__((unused))socklen_t *addrlen) {void* hostinfo = get_host_fromfd(sockfd);if (hostinfo == NULL) {return -1;}struct ln_tcp_stream* stream = (struct ln_tcp_stream*)hostinfo;if (stream->proto == IPPROTO_TCP) {struct ln_tcp_stream* apt = NULL;pthread_mutex_lock(&stream->mutex);while ((apt = ln_get_accept_stream(stream->dport)) == NULL) {pthread_cond_wait(&stream->cond, &stream->mutex);}pthread_mutex_unlock(&stream->mutex);struct sockaddr_in* addri = (struct sockaddr_in*)addr;addri->sin_port = apt->sport;rte_memcpy(&addri->sin_addr.s_addr, &apt->sip, sizeof(uint32_t));return apt->fd;}return -1;
}

参考资料：https://github.com/0voice

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