问题:如何扩展之前的通信框架,使其支持 UDP 通信,进而成为一个完善的网络通讯框架?
UDP 通讯扩展
UDP 通信实体概要设计
- 每个 UDP Point 地位对等(因为不必主动发起连接),可通过 ip 地址和 port 号进行通讯
- UDP Point 数据收发单位为: Message 或 Byte
- 在接受口设计上,与 TcpClient 保持一致(框架接口一致性)
- 目标:封装原生 socket 细节,关注 UDP 通信逻辑
UDP 通讯实体接口设计
typedef void UdpPoint;
UdpPoint *UdpPoint_New(int port);
UdpPoint *UdpPoint_From(int fd);
void UdpPoint_Del(UdpPoint *point);
int UdpPoint_SendMsg(UdpPoint *point, Message *msg, const char *remote, int port);
int UdpPoint_SendRaw(UdpPoint *point, const char *buf, int length, const char *remote, int port);
Message *UdpPoint_RecvMsg(UdpPoint *point, char *remote, int *port);
int UdpPoint_RecvRaw((UdpPoint *point, const char *buf, int length, char *remote, int *port);
int UdpPoint_Available(UdpPoint *point);
void UdpPoint_SetData(UdpPoint *point, void *data);
void *UdpPoint_GetData(UdpPoint *point);
int UdpPoint_SetOpt(UdpPoint *point, int levle, int optname, const void *optval, unsigned int optlen);
int UdpPoint_GetOpt(UdpPoint *point, int levle, int optname, void *optval, unsigned int *optlen);
关键代码实现
- 由于 UDP 是以数据报方式进行通讯(非数据流方式,报文间有明显边界)
- 因此,不能直接通过 MParser_ReadFd(...) 解析出消息
- 必须先将报文完整接收到内存中,再进行从内存中解析出消息
- 即通过 MParser_ReadMeme(...) 间接完成消息解析
关于上述的补充
UDP 套接字的收发报文要用 sendto 和 recvfrom(可以类比 TCP 套接字的 connect 和 accept),参数里面会标识要发往的对端,或者要接收的对端的 IP 地址和端口;
对 UDP 套接字 connect 的行为也只会告诉内核:”帮我做个过滤,我只关心这个对端的报文“,已”连接“的UDP套接字可以利用 read, write, recv, send 函数,通常如果确定了该实体只与一个对端进行通讯,那么就选择 connect;
[更重要的是 UDP 套接字的缓冲区是以一个个报文为单位进行排队的]
,调用一次 recvfrom 表示提取一个报文,和基于 TCP 基于字节流的方式是不同的。基于这样的原因我们不能在 UDP 中先读取一定的应用层 header, 而后再根据头部长度字段来优雅的读取具体数量的数据,这样会出错,发生混乱,而在 TCP 中经常这么做。
编程实验: UDP 通讯端设计与实现
udp_point.h
#ifndef UDP_POINT_H
#define UDP_POINT_H
#include "message.h"
typedef void UdpPoint;
UdpPoint *UdpPoint_New(int port);
UdpPoint *UdpPoint_From(int fd);
void UdpPoint_Del(UdpPoint *point);
int UdpPoint_SendMsg(UdpPoint *point, Message *msg, const char *remote, int port);
int UdpPoint_SendRaw(UdpPoint *point, const char *buf, int length, const char *remote, int port);
Message *UdpPoint_RecvMsg(UdpPoint *point, char *remote, int *port);
int UdpPoint_RecvRaw(UdpPoint *point, char *buf, int length, char *remote, int *port);
int UdpPoint_Available(UdpPoint *point);
void UdpPoint_SetData(UdpPoint *point, void *data);
void *UdpPoint_GetData(UdpPoint *point);
int UdpPoint_SetOpt(UdpPoint *point, int levle, int optname, const void *optval, unsigned int optlen);
int UdpPoint_GetOpt(UdpPoint *point, int levle, int optname, void *optval, unsigned int *optlen);
#endif // UDP_POINT_H
udp_point.c
#include "udp_point.h"
#include "msg_parser.h"
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <malloc.h>
#include <string.h>
typedef struct udp_point {
int fd;
MParser *parser;
void *data;
}Point;
static char g_temp[1024 * 4] = {0};
static void ParserAddr(struct sockaddr_in addr, char *ip, int *port)
{
if (ip) {
strcpy(ip, inet_ntoa(addr.sin_addr));
}
if (port) {
*port = ntohs(addr.sin_port);
}
}
UdpPoint *UdpPoint_New(int port)
{
Point *ret = malloc(sizeof(Point));
struct sockaddr_in addr = {0};
int ok = !! ret;
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = htonl(INADDR_ANY);
addr.sin_port = htons(port);
ok = ok && ((ret->parser = MParser_New()) != NULL);
ok = ok && ((ret->fd = socket(PF_INET, SOCK_DGRAM, 0)) != -1);
ok = ok && (bind(ret->fd, (struct sockaddr*)&addr, sizeof(addr)) != -1);
if (ok) {
ret->data = NULL;
} else {
ret ? (MParser_Del(ret->parser), NULL) : NULL;
ret ? close(ret->fd) : -1;
free(ret);
ret = NULL;
}
return ret;
}
UdpPoint *UdpPoint_From(int fd)
{
Point *ret = malloc(sizeof(Point));
if (ret) {
ret->fd = fd;
ret->parser = MParser_New();
ret->data = NULL;
}
return (ret && ret->parser) ? ret : (free(ret), NULL);
}
void UdpPoint_Del(UdpPoint *point)
{
Point *c = (Point*)point;
if (c) {
close(c->fd);
MParser_Del(c->parser);
free(c);
}
}
int UdpPoint_SendMsg(UdpPoint *point, Message *msg, const char *remote, int port)
{
int ret = 0;
Point *c = (Point*)point;
if (c && msg && remote) {
int len = Message_Size(msg);
char *data = (char*)Message_H2N(msg);
ret = UdpPoint_SendRaw(point, data, len, remote, port);
Message_N2H(msg);
}
return ret;
}
int UdpPoint_SendRaw(UdpPoint *point, const char *buf, int length, const char *remote, int port)
{
int ret = 0;
Point *c = (Point*)point;
if (c && buf && remote) {
struct sockaddr_in raddr = {0};
int addrlen = sizeof(raddr);
raddr.sin_family = AF_INET;
raddr.sin_addr.s_addr = inet_addr(remote);
raddr.sin_port = htons(port);
ret = (sendto(c->fd, buf, length, 0, (struct sockaddr*)&raddr, addrlen) != -1);
}
return ret;
}
Message *UdpPoint_RecvMsg(UdpPoint *point, char *remote, int *port)
{
Message *ret = NULL;
Point *c = (Point*)point;
if (c) {
struct sockaddr_in raddr = {0};
int addrlen = sizeof(raddr);
int length = recvfrom(c->fd, g_temp, sizeof(g_temp), MSG_PEEK, (struct sockaddr*)&raddr, &addrlen);
char *buf = (length > 0) ? malloc(length) : NULL;
length = recvfrom(c->fd, buf, length, 0, (struct sockaddr*)&raddr, &addrlen);
if (length > 0) {
ret = MParser_ReadMem(c->parser, buf, length);
}
if (ret) {
ParserAddr(raddr, remote, port);
}
free(buf);
}
return ret;
}
int UdpPoint_RecvRaw(UdpPoint *point, char *buf, int length, char *remote, int *port)
{
int ret = 0;
Point *c = (Point*)point;
if (c && buf) {
struct sockaddr_in raddr = {0};
int addrlen = sizeof(raddr);
printf("===============================\n");
ret = recvfrom(c->fd, buf, length, 0, (struct sockaddr*)&raddr, &addrlen);
printf("===============================\n");
if (ret != -1) {
ParserAddr(raddr, remote, port);
}
}
return ret;
}
int UdpPoint_Available(UdpPoint *point)
{
int ret = -1;
Point *c = (Point*)point;
if (c) {
struct sockaddr_in raddr = {0};
int len = sizeof(raddr);
ret = recvfrom(c->fd, g_temp, sizeof(g_temp), MSG_PEEK | MSG_DONTWAIT, (struct sockaddr*)&raddr, &len);
}
return ret;
}
void UdpPoint_SetData(UdpPoint *point, void *data)
{
Point *c = (Point*)point;
if (c) {
c->data = data;
}
}
void *UdpPoint_GetData(UdpPoint *point)
{
void *ret = NULL;
Point *c = (Point*)point;
if (c) {
ret = c->data;
}
return ret;
}
int UdpPoint_SetOpt(UdpPoint *point, int levle, int optname, const void *optval, unsigned int optlen)
{
int ret = -1;
Point *c = (Point*)point;
if (c) {
ret = setsockopt(c->fd, levle, optname, optval, optlen);
}
return ret;
}
int UdpPoint_GetOpt(UdpPoint *point, int levle, int optname, void *optval, unsigned int *optlen)
{
int ret = -1;
Point *c = (Point*)point;
if (c) {
ret = getsockopt(c->fd, levle, optname, optval, optlen);
}
return ret;
}
输出:
p = 0x55bd81ba4260
ip: 192.168.2.24, port: 7777
msg: 0x55bd81ba46e0
msg->type = 1
msg->cmd = 2
msg->index = 3
msg->total = 4
03 02 01
tcp_client 添加属性相关操作
int TcpClient_SetOpt(TcpClient *client, int levle, int optname, const void *optval, unsigned int optlen);
int TcpClient_GetOpt(TcpClient *client, int levle, int optname, void *optval, unsigned int *optlen);
// ...
int TcpClient_SetOpt(TcpClient *client, int levle, int optname, const void *optval, unsigned int optlen)
{
int ret = -1;
Client *c = (Client*)client;
if (c) {
ret = setsockopt(c->fd, levle, optname, optval, optlen);
}
return ret;
}
int TcpClient_GetOpt(TcpClient *client, int levle, int optname, void *optval, unsigned int *optlen)
{
int ret = -1;
Client *c = (Client*)client;
if (c) {
ret = getsockopt(c->fd, levle, optname, optval, optlen);
}
return ret;
}
tcp_server 添加属性相关操作
int TcpClient_SetOpt(TcpServer *server, int levle, int optname, const void *optval, unsigned int optlen);
int TcpClient_GetOpt(TcpServer *server, int levle, int optname, void *optval, unsigned int *optlen);
// ...
int TcpServer_SetOpt(TcpServer *server, int levle, int optname, const void *optval, unsigned int optlen)
{
int ret = -1;
Server *s = (Server*)server;
if (s) {
ret = setsockopt(s->fd, levle, optname, optval, optlen);
}
return ret;
}
int TcpServer_GetOpt(TcpServer *server, int levle, int optname, void *optval, unsigned int *optlen)
{
int ret = -1;
Server *s = (Server*)server;
if (s) {
ret = getsockopt(s->fd, levle, optname, optval, optlen);
}
return ret;
}
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