libcurl 库的ftp上传和下载代码

昨天考虑好了IM传送图片的方式，用的是FTP做缓存来传递图片，以减少聊天服务器的压力，用的是libcurl库，自己下载了一个Server-U 服务器，下面是测试程序，上传和下载都跑通了，剩下的就是在程序中写逻辑来实现具体的功能了。

上传代码：

//ftp上传实例
// 服务器地址：192.168.0.185 账号：spider 密码：spider
// 在服务器路径 a上建立一个a.txt ，本地文件是test.txt
// 命令行参数192.168.0.185 spider spider a a.txt D:/test.txt
//#include <stdlib.h>  
//#include <stdio.h>  
//#include <curl/curl.h>  
//#include <string.h>  
//
//int debugFun(CURL* curl, curl_infotype type, char* str, size_t len, void* stream)  
//{  
//    //只打印CURLINFO_TEXT类型的信息 
//    if(type == CURLINFO_TEXT)  
//    {  
//        fwrite(str, 1, len, (FILE*)stream);  
//    }  
//    return 0;
//}  
//
//int main(int argc, char** argv)  
//{  
//    CURL* curl;  
//    CURLcode res;  
//    char errorBuf[CURL_ERROR_SIZE];  
//    FILE *sendFile, *debugFile;  
//    char ftpurl[256 + 1];  
//    char usrpasswd[64 + 1];  
//
//    curl_slist *slist=NULL;  
//
//    if(argc != 7)  
//    {  
//        printf("Usage:\n\t./ftp ip username password ftpPath destFileName srcFile");  
//        return -1;  
//    }  
//
//    //将相关的调试信息打印到dubugFile.txt中 
//    if(NULL == (debugFile = fopen("debugFile.txt", "a+")))  
//        return -1;  
//
//    //打开ftp上传的源文件 
//    if(NULL == (sendFile = fopen(argv[6], "r")))  
//    {  
//        fclose(debugFile);  
//        return -1;  
//    }  
//
//    //获取需要发送文件的大小 
//    fseek(sendFile, 0, SEEK_END);  
//    int sendSize = ftell(sendFile);  
//    if(sendSize < 0)  
//    {  
//        fclose(debugFile);  
//        fclose(sendFile);  
//        return -1;  
//    }  
//    fseek(sendFile, 0L, SEEK_SET);  
//
//    if((res = curl_global_init(CURL_GLOBAL_ALL)) != 0)  
//    {  
//        fclose(debugFile);  
//        fclose(sendFile);  
//        return -1;  
//    }  
//    if((curl = curl_easy_init()) == NULL)  
//    {  
//        fclose(debugFile);  
//        fclose(sendFile);  
//        curl_global_cleanup();  
//        return -1;  
//    }  
//
//    if(argv[4][strlen(argv[4]) - 1] != '/')  
//        sprintf(ftpurl, "ftp://%s/%s/%s", argv[1], argv[4], argv[5]);  
//    else 
//        sprintf(ftpurl, "ftp://%s/%s%s", argv[1], argv[4], argv[5]);  
//    curl_easy_setopt(curl, CURLOPT_URL, ftpurl);  
//    //设置ftp上传url,组成如下的URL  
//    //ftp://192.168.31.145//root/subdir/curl/testftp.txt  
//
//    sprintf(usrpasswd, "%s:%s", argv[2], argv[3]);  
//    curl_easy_setopt(curl, CURLOPT_USERPWD, usrpasswd);  
//
//    curl_easy_setopt(curl, CURLOPT_VERBOSE, 1);  
//    curl_easy_setopt(curl, CURLOPT_DEBUGDATA, debugFile);  
//
//    curl_easy_setopt(curl, CURLOPT_READDATA, sendFile);  
//    curl_easy_setopt(curl, CURLOPT_UPLOAD, 1);  
//    curl_easy_setopt(curl, CURLOPT_INFILESIZE, sendSize);  
//    curl_easy_setopt(curl, CURLOPT_FTP_CREATE_MISSING_DIRS, 1);  
//
//    curl_easy_setopt(curl, CURLOPT_DEBUGFUNCTION, debugFun);  
//
//    res = curl_easy_perform(curl);  
//    if(0 != res)  
//    {  
//        fclose(sendFile);  
//        fclose(debugFile);  
//        curl_easy_cleanup(curl);  
//        curl_global_cleanup();  
//        return -1;  
//    }  
//
//    curl_easy_cleanup(curl);  
//    fclose(sendFile);  
//    fclose(debugFile);    
//    curl_global_cleanup();  
//    getchar();
//    return 0;     
//} 

下载代码如下：

//ftp下载实例
#include <stdio.h>; 
#include <curl/curl.h>; 
#include <curl/types.h>; 
#include <curl/easy.h>; 
 
struct FtpFile   //定义一个结构为了传递给my_fwrite函数.可用curl_easy_setopt的CURLOPT_WRITEDATA选项传递
{ 
        char *filename; 
        FILE *stream; 
}; 
 
int my_fwrite(void *buffer, size_t size, size_t nmemb, void *stream) 
{ 
        struct FtpFile *out=(struct FtpFile *)stream; // stream指针其实就是指向struct FtpFile ftpfile的
        if(out && !out->stream) 
        { 
                out->stream=fopen(out->filename, "wb"); //没有这个流的话就创建一个名字是out->filename. 
                if(!out->stream) 
                return -1; 
        } 
        return fwrite(buffer, size, nmemb, out->stream); 
} 
 
int main(int argc, char *argv[]) 
{ 
        CURL *curl; 
        CURLcode res;  
        struct FtpFile ftpfile={"D:/Success.txt",NULL}; //初始化一个FtpFile结构 
        curl_global_init(CURL_GLOBAL_DEFAULT); 
 
        curl = curl_easy_init(); 
        if(curl) 
        { 
                curl_easy_setopt(curl, CURLOPT_URL,"ftp://192.168.0.185/a/a.txt");  
 
                curl_easy_setopt(curl, CURLOPT_USERPWD,"spider:spider");
                curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, my_fwrite); 
                curl_easy_setopt(curl, CURLOPT_WRITEDATA, &ftpfile); //给相关函数的第四个参数传递一个结构体的指针
                curl_easy_setopt(curl, CURLOPT_VERBOSE, TRUE);//CURLOPT_VERBOSE 这个选项很常用用来在屏幕上显示对服务器相关操作返回的信息
 
                res = curl_easy_perform(curl); 
                curl_easy_cleanup(curl); 
 
                if(CURLE_OK != res) 
                        fprintf(stderr, "curl told us %d\n", res); 
        } 
        if(ftpfile.stream) 
        fclose(ftpfile.stream); 
        curl_global_cleanup(); 
 
        return 0; 
}

最后记录一个比较好用的：

#include <stdlib.h>
#include <stdio.h>
#include <curl/curl.h>
#include <sys/stat.h>
/* parse headers for Content-Length */
size_t getcontentlengthfunc(void *ptr, size_t size, size_t nmemb, void *stream) 
{
    int r;
    long len = 0;
    /* _snscanf() is Win32 specific */
    //r = _snscanf(ptr, size * nmemb, "Content-Length: %ld\n", &len);
    r = sscanf((const char*)ptr, "Content-Length: %ld\n", &len);
    if (r) /* Microsoft: we don't read the specs */
        *((long *) stream) = len;
    return size * nmemb;
}
/* discard downloaded data */
size_t discardfunc(void *ptr, size_t size, size_t nmemb, void *stream) 
{
    return size * nmemb;
}
//write data to upload
size_t writefunc(void *ptr, size_t size, size_t nmemb, void *stream)
{
    return fwrite(ptr, size, nmemb, (FILE*)stream);
}
/* read data to upload */
size_t readfunc(void *ptr, size_t size, size_t nmemb, void *stream)
{
    FILE *f = (FILE*)stream;
    size_t n;
    if (ferror(f))
        return CURL_READFUNC_ABORT;
    n = fread(ptr, size, nmemb, f) * size;
    return n;
}
int upload(CURL *curlhandle, const char * remotepath, const char * localpath, long timeout, long tries)
{
    FILE *f;
    long uploaded_len = 0;
    CURLcode r = CURLE_GOT_NOTHING;
    int c;
    f = fopen(localpath, "rb");
    if (f == NULL) {
        perror(NULL);
        return 0;
    }
    curl_easy_setopt(curlhandle, CURLOPT_UPLOAD, 1L);
    curl_easy_setopt(curlhandle, CURLOPT_URL, remotepath);
    curl_easy_setopt(curlhandle, CURLOPT_USERPWD, "spider:spider");   
    if (timeout)
        curl_easy_setopt(curlhandle, CURLOPT_FTP_RESPONSE_TIMEOUT, timeout);
    curl_easy_setopt(curlhandle, CURLOPT_HEADERFUNCTION, getcontentlengthfunc);
    curl_easy_setopt(curlhandle, CURLOPT_HEADERDATA, &uploaded_len);
    curl_easy_setopt(curlhandle, CURLOPT_WRITEFUNCTION, discardfunc);
    curl_easy_setopt(curlhandle, CURLOPT_READFUNCTION, readfunc);
    curl_easy_setopt(curlhandle, CURLOPT_READDATA, f);
    curl_easy_setopt(curlhandle, CURLOPT_FTPPORT, "-"); /* disable passive mode */
    curl_easy_setopt(curlhandle, CURLOPT_FTP_CREATE_MISSING_DIRS, 1L);
    curl_easy_setopt(curlhandle, CURLOPT_VERBOSE, 1L);
    for (c = 0; (r != CURLE_OK) && (c < tries); c++) {
        /* are we resuming? */
        if (c) { /* yes */
            /* determine the length of the file already written */
            /*
            * With NOBODY and NOHEADER, libcurl will issue a SIZE
            * command, but the only way to retrieve the result is
            * to parse the returned Content-Length header. Thus,
            * getcontentlengthfunc(). We need discardfunc() above
            * because HEADER will dump the headers to stdout
            * without it.
            */
            curl_easy_setopt(curlhandle, CURLOPT_NOBODY, 1L);
            curl_easy_setopt(curlhandle, CURLOPT_HEADER, 1L);
            r = curl_easy_perform(curlhandle);
            if (r != CURLE_OK)
                continue;
            curl_easy_setopt(curlhandle, CURLOPT_NOBODY, 0L);
            curl_easy_setopt(curlhandle, CURLOPT_HEADER, 0L);
            fseek(f, uploaded_len, SEEK_SET);
            curl_easy_setopt(curlhandle, CURLOPT_APPEND, 1L);
        }
        else { /* no */
            curl_easy_setopt(curlhandle, CURLOPT_APPEND, 0L);
        }
        r = curl_easy_perform(curlhandle);
    }
    fclose(f);
    if (r == CURLE_OK)
        return 1;
    else {
        fprintf(stderr, "%s\n", curl_easy_strerror(r));
        return 0;
    }
}
// 下载
int download(CURL *curlhandle, const char * remotepath, const char * localpath, long timeout, long tries)
{
    FILE *f;
    curl_off_t local_file_len = -1 ;
    long filesize =0 ;
    CURLcode r = CURLE_GOT_NOTHING;
    struct stat file_info;
    int use_resume = 0;
    //获取本地文件大小信息
    if(stat(localpath, &file_info) == 0)
    {
        local_file_len = file_info.st_size; 
        use_resume = 1;
    }
    //追加方式打开文件，实现断点续传
    f = fopen(localpath, "ab+");
    if (f == NULL) {
        perror(NULL);
        return 0;
    }
    curl_easy_setopt(curlhandle, CURLOPT_URL, remotepath);
    curl_easy_setopt(curlhandle, CURLOPT_USERPWD, "spider:spider");   
    //连接超时设置
    curl_easy_setopt(curlhandle, CURLOPT_CONNECTTIMEOUT, timeout);
    //设置头处理函数
    curl_easy_setopt(curlhandle, CURLOPT_HEADERFUNCTION, getcontentlengthfunc);
    curl_easy_setopt(curlhandle, CURLOPT_HEADERDATA, &filesize);
    // 设置断点续传
    curl_easy_setopt(curlhandle, CURLOPT_RESUME_FROM_LARGE, use_resume?local_file_len:0);
    curl_easy_setopt(curlhandle, CURLOPT_WRITEFUNCTION, writefunc);
    curl_easy_setopt(curlhandle, CURLOPT_WRITEDATA, f);
    curl_easy_setopt(curlhandle, CURLOPT_NOPROGRESS, 1L);
    curl_easy_setopt(curlhandle, CURLOPT_VERBOSE, 1L);
    r = curl_easy_perform(curlhandle);
    fclose(f);
    if (r == CURLE_OK)
        return 1;
    else {
        fprintf(stderr, "%s\n", curl_easy_strerror(r));
        return 0;
    }
}
int main(int c, char **argv) 
{
    CURL *curlhandle = NULL;
    CURL *curldwn = NULL;
    curl_global_init(CURL_GLOBAL_ALL);
    curlhandle = curl_easy_init();
    curldwn = curl_easy_init();
    upload(curlhandle, "ftp://192.168.0.185/a/success", "D:/abc.jpg", 1, 3);
    download(curldwn, "ftp://192.168.0.185/a/success", "D:/abc1.jpg", 1, 3);
    curl_easy_cleanup(curlhandle);
    curl_easy_cleanup(curldwn);
    curl_global_cleanup();
    return 0;
}