基于libcurl使用c语言实现http客户端的基础框架

http客户端实现

主要使用的几个api接口：
1、curl_easy_init
2、curl_slist_append
3、curl_formadd
4、curl_easy_setopt
5、curl_easy_perform
6、curl_easy_getinfo

7、curl_slist_free_all
8、curl_formfree
9、curl_easy_cleanup

下面代码中使用的一些libcurl选项，如果需要详细了解，可以访问 https://curl.se/libcurl/ 自行学习

typedef struct _stHttpUserInfo
{
   
    int nOperation;                 /* 操作类型, 参考 HTTP_SEND_HEARTBIT */
    int nSubOperation;              /* 子操作类型, 参考 HTTP_UPLOADRESULT_TYPE_SNAPIMG */
    int ucFlag;                     /* 用以区分头部还是内容部分，默认为0-->只需要body部分 */ 
    int nSedSize;                   /* 发送数据大小 */ 
    int nRcvBufLen;                 /* 缓冲区长度 */ 
    int nRcvSize;                   /* 接收body数据大小 */ 
    
    void *pRcvBuffer;               /* 指向用户用来存储数据的buf */ 
    void *pSendBuffer;              /* 指向用户发送数据的buf */ 
}stHttpUserInfo;

typedef struct _stHttpClientInfo
{
   
    int nClientPort;                /* http服务器监听端口号 */ 
    char szClientIP[32];            /* http服务器IP */ 
    char szClientPath[64];          /* http服务器文件路径 */ 
    char szUserName[32];            /* http服务器登录用户 */ 
    char szUserPassWord[32];        /* http服务器登录密码 */ 
    char szUrl[128];                /* http服务器url */ 
    
    char szWorkDir[128];            /* 工作目录, 需要保存文件的路径 */ 

    stHttpUserInfo stHttpUserHead;
    stHttpUserInfo stHttpUserBody;
}stHttpClientInfo;

#define FREE(x) \
{
     \
    if (NULL != x)\
    {
     \
        free(x);\
        x = NULL;\
    }\
}

/**************************************************************************
    函数名称: httpClient_WriteBack
    功能描述: http写数据回调 
    输入参数: IN void *pContents,                       http返回的数据
              IN size_t size,                       单个数据的大小
              IN size_t nmemb,                      数据的个数
              OUT void *stream                      存放接收消息的结构
    输出参数: OUT void *stream                          存放接收消息的结构
    注 意 点: 返回值为接收的长度
***************************************************************************/
size_t httpClient_WriteBack(IN void *pContents, IN size_t size, IN size_t nmemb, OUT void *stream)
{
   
    int nRealSize = 0;
    char *pcTmp = NULL;
    stHttpUserInfo *pstChunk = NULL;

    if ((NULL == pContents) || (NULL == stream))
    {
   
        printf("[CURL]Invalid parameter\n");
        return 0;
    }

    nRealSize = size * nmemb;
    pstChunk = (stHttpUserInfo *)stream;
    pcTmp = pstChunk->pRcvBuffer;
    pstChunk->pRcvBuffer = (char *)realloc(pstChunk->pRcvBuffer, pstChunk->nRcvSize + nRealSize + 1);
    if (NULL == pstChunk->pRcvBuffer) 
    {
   
        FREE(pcTmp);
        printf("[CURL]realloc memory failed, lenth[%d]\n", pstChunk->nRcvSize + nRealSize + 1);
        return 0;
    }

    /* 因为需要保存之前的数据，所以realloc后不能memset */
    memcpy((char *)pstChunk->pRcvBuffer + pstChunk->nRcvSize, (void *)pContents, (size_t)nRealSize);
    pstChunk->nRcvSize += nRealSize;
    
    return nRealSize;
}

/**************************************************************************
    函数名称: Http_Client
    功能描述: 发送http请求 
    输入参数: IN stHttpClientInfo *pstUserArg            客户端结构              
    输出参数: 
    注 意 点: 
***************************************************************************/
Http_Client(IN stHttpClientInfo *pstUserArg)
{
   
    int nRet = 0;
    int timeout = 10;           /* http请求的超时时间, 默认10s */
    CURL *pstCurl = NULL;
    CURLcode code = 0;
    long response_code = -1;
    struct curl_slist *pstHeaderlist = NULL;
    struct curl_httppost *pstForm = NULL;
    struct curl_httppost *pstLast  = NULL;
    
    /* 1. 初始化curl */
    pstCurl = curl_easy_init();
    if (NULL == pstCurl)
    {
   
        printf("[CURL]init curl fail\n");
        return ERR_COMMON_NO_MEMORY;
    }
    
    /* 2. 初始化头信息 */
    pstHeaderlist = curl_slist_append(pstHeaderlist, "Connection:keep-alive");
    pstHeaderlist = curl_slist_append(pstHeaderlist, "Accept: */*");
    pstHeaderlist = curl_slist_append(pstHeaderlist, "Cache-Control:no-cache");
    pstHeaderlist = curl_slist_append(pstHeaderlist, "Expect:");

    /* 根据类型填充表单 */
    switch(pstUserArg->stHttpUserHead.nOperation)
    {
   
        /* 表单--数据流, pstUserArg->stHttpUserBody.pSendBuffer存放的字符串 */
        case 0:
        {
   
            pstHeaderlist = curl_slist_append(pstHeaderlist, "Content-Type: multipart/form-data");
            
            curl_formadd(&pstForm, &pstLast, 
                         CURLFORM_COPYNAME, "json",
                         CURLFORM_PTRCONTENTS, pstUserArg->stHttpUserBody.pSendBuffer,
                         CURLFORM_END);
            
            timeout = strlen(pstUserArg->stHttpUserBody.pSendBuffer)/(200 * 1024);  /* 按照200k/s计算上传的超时时间 */
            curl_easy_setopt(pstCurl, CURLOPT_HTTPPOST, pstForm);         /* 替换表单数据 */
            break;
        }
        
        /* 表单--文件流, pstUserArg->stHttpUserBody.pSendBuffer存放的文件绝对路径 */
        case 1:
        {
   
            pstHeaderlist = curl_slist_append(pstHeaderlist, "Content-Type: multipart/form-data");
            
            curl_formadd(&pstForm, &pstLast, 
                         CURLFORM_COPYNAME, "file",
                         CURLFORM_FILE, pstUserArg->stHttpUserBody.pSendBuffer,
                         CURLFORM_END);
            
            timeout = 60;  /* 自行计算文件大小, 然后按照200k/s计算上传的超时时间 */
            curl_easy_setopt(pstCurl, CURLOPT_HTTPPOST, pstForm);         /* 替换表单数据 */
            break;
        }

        /* get请求 */
        case 2:
        {
   
            curl_easy_setopt(pstCurl, CURLOPT_HTTPGET, 1L);
            timeout = 30;
            break;
        }

        /* psot, body中存放json数据 */
        case 3:
        {
   
            pstHeaderlist = curl_slist_append(pstHeaderlist, "Content-Type: application/json");

            curl_easy_setopt(pstCurl, CURLOPT_POSTFIELDSIZE, strlen(pstUserArg->stHttpUserBody.pSendBuffer)); /* 设置上传数据的大小,也可以设置-1让libcurl使用strlen计算数据大小 */
            curl_easy_setopt(pstCurl, CURLOPT_POSTFIELDS, pstUserArg->stHttpUserBody.pSendBuffer);
            timeout = strlen(pstUserArg->stHttpUserBody.pSendBuffer)/(200 * 1024);  /* 按照200k/s计算上传的超时时间 */
            break;
        }
        
        default:
        {
   
            curl_easy_cleanup(pstCurl);
            pstCurl = NULL;
            
            curl_slist_free_all(pstHeaderlist);
            pstHeaderlist = NULL;
            
            printf("[CURL]not support msg type[%d]\n", pstUserArg->stHttpUserHead.nOperation);
            return ERR_COMMON_NOT_SUPPORT;
        }
    }
    
    curl_easy_setopt(pstCurl, CURLOPT_HTTPHEADER, pstHeaderlist);
    
    /* 3. 初始化存放接收数据需要用到的缓存 */
    pstUserArg->stHttpUserBody.nRcvBufLen = 0;
    pstUserArg->stHttpUserBody.pRcvBuffer = (char *)calloc(1, 1);
    if (NULL == pstUserArg->stHttpUserBody.pRcvBuffer)
    {
   
        printf("[CURL]calloc fail\n");
        curl_formfree(pstForm);
        pstForm = NULL;
        
        curl_slist_free_all(pstHeaderlist);
        pstHeaderlist = NULL;
        
        curl_easy_cleanup(pstCurl);
        pstCurl = NULL;
        
        return ERR_COMMON_NO_MEMORY;
    }
    
    /* 4. 填充相关请求信息 */
    if (NULL != strstr(pstUserArg->szUrl, "https"))         /* 设定为不验证证书和HOST */
    {
   
        curl_easy_setopt(pstCurl, CURLOPT_SSL_VERIFYPEER, 0);
        curl_easy_setopt(pstCurl, CURLOPT_SSL_VERIFYHOST, 0);
    }
    
    curl_easy_setopt(pstCurl, CURLOPT_URL, pstUserArg->szUrl);                  /* 设置URL路径 */
    curl_easy_setopt(pstCurl, CURLOPT_NOSIGNAL, 1L);                            /* 屏蔽库内部由于多线程导致的信号中断 */
    curl_easy_setopt(pstCurl, CURLOPT_WRITEFUNCTION, httpClient_WriteBack);     /* 设置用于接收响应body的处理函数*/
    curl_easy_setopt(pstCurl, CURLOPT_WRITEDATA, &pstUserArg->stHttpUserBody);  /* 设置回调函数的第四个参数 */
    
    if (1 == pstUserArg->stHttpUserHead.ucFlag)
    {
   
        pstUserArg->stHttpUserHead.nRcvBufLen = 0;
        pstUserArg->stHttpUserHead.pRcvBuffer = (char *)calloc(1, 1);
        if (NULL == pstUserArg->stHttpUserHead.pRcvBuffer)
        {
   
            printf("[CURL]calloc fail\n");
            curl_formfree(pstForm);
            pstForm = NULL;
            
            curl_easy_cleanup(pstCurl);
            pstCurl = NULL;
            
            curl_slist_free_all(pstHeaderlist);
            pstHeaderlist = NULL;
            
            FREE(pstUserArg->stHttpUserBody.pRcvBuffer);
            return ERR_COMMON_NO_MEMORY;
        }
        
        curl_easy_setopt(pstCurl, CURLOPT_HEADERFUNCTION,httpClient_WriteBack);         /* 设置用于接收响应header的处理函数 */
        curl_easy_setopt(pstCurl, CURLOPT_WRITEHEADER, &pstUserArg->stHttpUserHead);    /* 接收头部分 */
    }
    
    curl_easy_setopt(pstCurl, CURLOPT_TIMEOUT, timeout);          /* 设置接收超时时间，单位：秒 */

    /* 5. 发送http请求 */
    code = curl_easy_perform(pstCurl);
    if(code != CURLE_OK)
    {
   
        printf("[CURL]http[%s] fail[%d:%s]\n", pstUserArg->szUrl, code, curl_easy_strerror(code));

        FREE(pstUserArg->stHttpUserBody.pRcvBuffer);
        FREE(pstUserArg->stHttpUserHead.pRcvBuffer);
        
        curl_slist_free_all(pstHeaderlist);
        pstHeaderlist = NULL;
        
        curl_formfree(pstForm);
        pstForm = NULL;
        
        curl_easy_cleanup(pstCurl);
        pstCurl = NULL;
        
        return ERR_COMMON_FAIL;
    }

    /* 6. 获取http响应的错误码 */
    curl_easy_getinfo(pstCurl, CURLINFO_RESPONSE_CODE, &response_code);
    
    /* 7. 处理HTTP响应 */
    if ((200 != response_code) && (201 != response_code))
    {
   
        printf("[CURL]curl_easy_getinfo RESPONSE_CODE: %ld(%s)\n", response_code, curl_easy_strerror(response_code));
        nRet = ERR_COMMON_FAIL;
    }
    else
    {
   
        /* 自行添加http的处理回调 */
        {
   
            
        }
        
        if (ERR_COMMON_SUCCEED != nRet)
        {
   
            printf("[CURL]proc Http Response fail[%d]\n", nRet);
        }
    }
    
    /* 8. 释放资源 */
    FREE(pstUserArg->stHttpUserBody.pRcvBuffer);
    FREE(pstUserArg->stHttpUserHead.pRcvBuffer);
    
    curl_slist_free_all(pstHeaderlist);
    pstHeaderlist = NULL;
    
    curl_formfree(pstForm);
    pstForm = NULL;
    
    curl_easy_cleanup(pstCurl);
    pstCurl = NULL;

    return nRet;
}