一种简单的UDP服务器框架

代码组织：

进入lib，

socket.h

/**
  @file   socket.h
  @brief  Socket API header file

  UDP socket utility functions, it provides simple functions that helps
  to build UDP client/server.

  @author wangzhicheng
 */
#ifndef SOCKET_H
#define SOCKET_H

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <resolv.h>
#include <fcntl.h>

int UDPServerInit(int port, int *serverfd);
int UDPClientInit(int *clientfd);
int UDPRecv(int sockfd, void *buf, size_t size, char *from_ip, int *port);
int UDPSend(int sockfd, const void *buf, size_t size, const char *to_ip, const int *port);
int UDPClose(int sockfd);

#endif

socket.c

#include "socket.h"
/*
 * @brief   initialize UDP server
 * @port    port number for socket
 * @serverfd  server socket fd
 * return server socked fd for success, on error return error code
 * */
int UDPServerInit(int port, int *serverfd) {
  struct sockaddr_in server;
  // create socket , same as client
  *serverfd = socket(AF_INET, SOCK_DGRAM, 0);
  if(*serverfd < 0) return -1;
  /// initialize structure dest
  memset((void*)&server, '\0', sizeof(server));
  server.sin_family = AF_INET;
  server.sin_port = htons(port);
  server.sin_addr.s_addr = INADDR_ANY;
  // Assign a port number to socket
  bind(*serverfd, (struct sockaddr*)&server, sizeof(server));

  return *serverfd;
}
/*
 * @brief initialize UDP client
 * @clientfd  client socket fd
 * return client socked fd for success, on error return error code
 */
int UDPClientInit(int *clientfd) {
  *clientfd = socket(AF_INET, SOCK_DGRAM, 0);

  return *clientfd;
}
/*
 * @brief   UDPRecv from UDP socket
 * @clientfd  socket fd
 * @buf       receving buffer
 * @size    buffer size
 * @from_ip   the client ip address of requested from UDP
 * return     the length of receive data
 */
int UDPRecv(int sockfd, void *buf, size_t size, char *from_ip, int *port) {
  struct sockaddr_in client;
  size_t addrlen = 0;
  int rc;
  memset(&client, '\0', sizeof(client));
  addrlen = sizeof(client);
  rc = recvfrom(sockfd, buf, size, 0, (struct sockaddr *)&client, &addrlen);
  strcpy(from_ip, (const char *)inet_ntoa(client.sin_addr));
  *port = htons(client.sin_port);

  return rc;
  
}
/*
 * @brief   UDPSend from UDP socket
 * @clientfd  socket fd
 * @buf       sending buffer
 * @size    buffer size
 * @to_ip   the ip address of target server
 * return     the length of sending data
 */
int UDPSend(int sockfd, const void *buf, size_t size, const char *to_ip, const int *port) {
  struct sockaddr_in server;
  memset(&server, '\0', sizeof(server));
  server.sin_family = AF_INET;
  server.sin_port = htons(*port);
  inet_aton(to_ip, &server.sin_addr);

  return sendto(sockfd, buf, size, 0, (struct sockaddr *)&server, sizeof(server));
}
/*
 * close the socket
 * */
int UDPClose(int sockfd) {
  return close(sockfd);
}

进入server

server.c

/*************************************************************************
    > File Name: server.c
    > Author: ma6174
    > Mail: 
    > Created Time: Sat 04 Oct 2014 09:46:30 PM WST
 ************************************************************************/

#include "socket.h"

int UDPPORT = 4001;
#define SIZE 256

int main() {
    int serverfd = -1;
    char buf[SIZE];
    char from_ip[SIZE];
    int port, num;
    if(UDPServerInit(UDPPORT, &serverfd) < 0) {
        perror("can init UDP server...!\n");
        exit(EXIT_FAILURE);
    }
    while(1) {
        num = UDPRecv(serverfd, buf, SIZE, from_ip, &port);
        if(num < 0) {
            perror("receving error...!\n");
            exit(EXIT_FAILURE);
        }
        buf[num] = '\0';
        printf("You got a message %s from client ..\n Its ip is %s, port is %d\n", buf, from_ip, port);
        if(!strcmp(buf, "bye")) {
            break;
        }
//      sleep(1);
    }
    UDPClose(serverfd);

    return 0;
}

Makefile

CC=gcc
LIBRARY=../lib
CFLAGS=-I$(LIBRARY)
CXXFLAGS=
OBJS1=server.o  socket.o 

all:  server


server: $(OBJS1)
  $(CC) -o   $@ $(OBJS1)  

socket.o: $(LIBRARY)/socket.c
  $(CC) -c $(LIBRARY)/socket.c

clean:
  rm *.o server  > /dev/null 2>&1

进入client

client.c

/*************************************************************************
    > File Name: client.c
    > Author: ma6174
    > Mail: 
    > Created Time: Sat 04 Oct 2014 09:46:30 PM WST
 ************************************************************************/

#include "socket.h"

#define SIZE 256
int UDPPORT = 4001;
const char *serveraddr = "127.0.0.1";

int main() {
    int clientfd = -1;
    char buf[SIZE];
    size_t  num;
    UDPClientInit(&clientfd);
    if(clientfd < 0) {
        perror("UDP client init failed...!\n");
        exit(EXIT_FAILURE);
    }
    while(1) {
        puts("sending message...:");
        scanf("%s", buf);
        UDPSend(clientfd, buf, strlen(buf), serveraddr, &UDPPORT);
//      sleep(1);
    }
    return 0;
}

Makefile

CC=gcc
LIBRARY=../lib
CFLAGS=-I$(LIBRARY)
CXXFLAGS=
OBJS1=client.o  socket.o 

all:  client


client: $(OBJS1)
  $(CC) -o   $@ $(OBJS1) 

socket.o: $(LIBRARY)/socket.c
  $(CC) -c $(LIBRARY)/socket.c

clean:
  rm *.o client  > /dev/null 2>&1

测试：