利用libcurl和国内著名的两个物联网云端通讯的例程, ubuntu和openwrt下调试成功(四)

1. libcurl 的参考文档如下

CURLOPT_HEADERFUNCTION

Pass a pointer to a function that matches the following prototype: size_t function( void *ptr, size_t size, size_t nmemb, void *userdata);. This function gets called by libcurl as soon as it has received header data. The header callback will be called once for each header and only complete header lines are passed on to the callback. Parsing headers is very easy using this. The size of the data pointed to by ptr is sizemultiplied with nmemb. Do not assume that the header line is zero terminated! The pointer named userdata is the one you set with the CURLOPT_WRITEHEADER option. The callback function must return the number of bytes actually taken care of. If that amount differs from the amount passed to your function, it'll signal an error to the library. This will abort the transfer and return CURL_WRITE_ERROR.

A complete HTTP header that is passed to this function can be up to CURL_MAX_HTTP_HEADER (100K) bytes.

If this option is not set, or if it is set to NULL, but CURLOPT_HEADERDATA (CURLOPT_WRITEHEADER) is set to anything but NULL, the function used to accept response data will be used instead. That is, it will be the function specified with CURLOPT_WRITEFUNCTION, or if it is not specified or NULL - the default, stream-writing function.

It's important to note that the callback will be invoked for the headers of all responses received after initiating a request and not just the final response. This includes all responses which occur during authentication negotiation. If you need to operate on only the headers from the final response, you will need to collect headers in the callback yourself and use HTTP status lines, for example, to delimit response boundaries.

When a server sends a chunked encoded transfer, it may contain a trailer. That trailer is identical to a HTTP header and if such a trailer is received it is passed to the application using this callback as well. There are several ways to detect it being a trailer and not an ordinary header: 1) it comes after the response-body. 2) it comes after the final header line (CR LF) 3) a Trailer: header among the regular response-headers mention what header(s) to expect in the trailer.

For non-HTTP protocols like FTP, POP3, IMAP and SMTP this function will get called with the server responses to the commands that libcurl sends.

CURLOPT_WRITEHEADER

(This option is also known as CURLOPT_HEADERDATA) Pass a pointer to be used to write the header part of the received data to. If you don't use CURLOPT_WRITEFUNCTION or CURLOPT_HEADERFUNCTIONto take care of the writing, this must be a valid FILE * as the internal default will then be a plain fwrite(). See also the CURLOPT_HEADERFUNCTION option above on how to set a custom get-all-headers callback.

2. 完整code如下

/*------------------------------------------------------------------------------------------
名称: http_cloud_curl_callbak.c
利用libcurl的API的回调机制实现云端通讯. http://curl.haxx.se/libcurl/c/curl_easy_setopt.html

CURLOPT_HEADERFUNCTION, CURLOPT_HEADERDATA: 只处理HTTP头部数据,处理与下载数据回调的处理相同.
    sina的股票接口因为无HTTP头部返回因此不能应用此.
-------------------------------------------------------------------------------------------*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <curl/curl.h>
#include <assert.h>

#include "../http_cloud.h"

#define CURL_HEADER (1)    //0=利用 CURLOPT_WRITEFUNCTION, 1=利用 CURLOPT_HEADERFUNCTION
#define DBG printf
#define CURL_DBG (0)    //1=开启curl的调试

//-----------------------------------------------------------------------------------------
static void get_local_time(char *pc_str)
{
    time_t now;
    struct tm *timenow;

    assert(pc_str != NULL);

    time(&now);
    timenow = localtime(&now);
    sprintf(pc_str, "%04d-%02d-%02dT%02d:%02d:%02d", timenow->tm_year+1900, timenow->tm_mon+1, timenow->tm_mday,
                    timenow->tm_hour, timenow->tm_min, timenow->tm_sec);
}

size_t callback_get_head(void *ptr, size_t size, size_t nmemb, void *userp)
{
    DBG("ptr = %s, userp = %s\n", ptr, userp);
    strcat(userp, ptr);

    return size * nmemb; //必须返回这个大小, 否则只回调一次
}

static char connect_cloud(char *pc_ret, const char *host_addr, const int portno,
        const char *pc_method, struct curl_slist *http_headers)
{
    CURL *curl;
    CURLcode res = CURLE_GOT_NOTHING;

  assert((pc_ret != NULL) && (host_addr != NULL) && (http_headers != NULL) && (pc_method != NULL));

  //curl_global_init(CURL_GLOBAL_DEFAULT);
  curl = curl_easy_init();
  if (!curl)    {
      fprintf(stderr, "--- curl init Error!\n");
      return 0;
  }

  curl_easy_setopt(curl, CURLOPT_URL, host_addr);
  curl_easy_setopt(curl, CURL_HTTP_VERSION_1_1, 1L);    //HTTP 1.1
  curl_easy_setopt(curl, CURLOPT_TIMEOUT, 3);     //设置超时, 单位为秒
    //curl_easy_setopt(curl, CURLOPT_NOSIGNAL, 1);     //屏蔽其它信号, makes libcurl NOT ask the system to ignore SIGPIPE signals

#if (CURL_DBG == 1)
  curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);    //调试用: 显示交互明细,
    //curl_easy_setopt(curl, CURLOPT_HEADER, 1L);    //调试用: 只显示头行的返回
#endif

#if 1
    curl_easy_setopt(curl, CURLOPT_CUSTOMREQUEST, pc_method);

#if (CURL_HEADER == 0)
    curl_easy_setopt(curl, CURLOPT_HEADER, 1);         //下载数据包括HTTP头部, The default value for this parameter is 0.
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, callback_get_head); //下载数据的回调函数
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, pc_ret);                                //下载数据的指针

#else
    curl_easy_setopt(curl, CURLOPT_HEADERFUNCTION, callback_get_head); //头部数据的回调函数
    curl_easy_setopt(curl, CURLOPT_HEADERDATA, pc_ret);                                //头部数据的指针
#endif

    curl_easy_setopt(curl, CURLOPT_HTTPHEADER, http_headers);    //多行的HTTP头部
#endif

  res = curl_easy_perform(curl);
  if(res != CURLE_OK)
      fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(res));

    curl_easy_cleanup(curl);

  return 1;
}

#if (YEELINK == 1)
int yeelink_create_data(const int device_id, const int sensor_id, const float device_value)
{
    char pc_ret[500], request[1024], pc_json[100], pc_time[30], pc_host_file[100], pc_header[100], pc_url[200], ret;
    int len;

    sprintf(pc_host_file, "v1.0/device/%d/sensor/%d/datapoints", device_id, sensor_id);
    sprintf(pc_header, "U-ApiKey: %s", YEELINK_API_KEY);

    get_local_time(pc_time);
    sprintf(pc_json, "{\"timestamp\":\"%s\",\"value\":%.2f}", pc_time, device_value);
    len = strlen(pc_json);

    //sprintf(request, "POST /%s HTTP/1.1\r\nHost: %s\r\nAccept: */*\r\n%s\r\nContent-Length: %d\r\nContent-Type: application/x-www-form-urlencoded\r\nConnection: Close\r\n\r\n%s\r\n",
    //    pc_host_file, YEELINK_HOST, pc_header, len, pc_json);
    //DBG("request = %s\n", request);

    //组织请求头部, 自动末尾添加'\r\n'
    struct curl_slist *http_headers = NULL;

    //sprintf(request, "POST /%s HTTP/1.1", pc_host_file);
    //http_headers = curl_slist_append(http_headers, request);    //此部分在url中体现

    sprintf(request, "Host: %s", YEELINK_HOST);
    http_headers = curl_slist_append(http_headers, request);

    sprintf(request, "%s", pc_header);
    http_headers = curl_slist_append(http_headers, request);

    sprintf(request, "%s", "Accept: */*");
    http_headers = curl_slist_append(http_headers, request);

    sprintf(request, "Content-Length: %d", len);
    http_headers = curl_slist_append(http_headers, request);

    sprintf(request, "%s", "Content-Type: application/x-www-form-urlencoded");
    http_headers = curl_slist_append(http_headers, request);

    sprintf(request, "%s", "Connection: Close");
    http_headers = curl_slist_append(http_headers, request);

    sprintf(request, "\r\n%s", pc_json);
    http_headers = curl_slist_append(http_headers, request);

#if 0
    struct curl_slist *tmp = http_headers;
    printf("HTTP request = ");
    while(tmp) {
        printf("%s\n", tmp->data);
        tmp = tmp->next;
    }
#endif

    //发送请求, 再判断返回值
    //url = api.yeelink.net/v1.0/device/391/sensor/497/datapoints
    sprintf(pc_url, "%s/%s", YEELINK_HOST, pc_host_file);
    ret = connect_cloud(pc_ret, pc_url, YEELINK_PORT, HTTP_POST, http_headers);

    //释放 http_headers资源
    curl_slist_free_all(http_headers);

    DBG("yeelini ret = %s\n", pc_ret);

    return(ret);
}
#endif

#if (LEWEI50 == 1)
//curl --request POST http://www.lewei50.com/api/V1/Gateway/UpdateSensors/01 --data "[{\"Name\":\"T1\",\"Value\":\"23.08\"}]" --header "userkey:36be8ff22f794f1e8a0bee3336eef237"
int lewei50_create_data(const char *device_id, const float device_value)
{
    char pc_ret[500], request[1024], pc_json[100], pc_header[100], pc_url[200], *pc_data, ret;
    int len;

    assert(device_id != NULL);

    sprintf(pc_header, "userkey: %s", LEWEI50_USER_KEY);
    sprintf(pc_json, "[{\"Name\":\"%s\",\"Value\":\"%.2f\"}]", device_id, device_value);
    len = strlen(pc_json);

    //sprintf(request, "POST /%s HTTP/1.1\r\nHost: %s\r\nAccept: */*\r\n%s\r\nContent-Length: %d\r\nContent-Type: application/x-www-form-urlencoded\r\nConnection: Close\r\n\r\n%s\r\n",
    //    LEWEI50_HOST_FILE, LEWEI50_HOST, pc_header, len, pc_json);
    //DBG("request = %s\n", request);

    //组织请求头部, 自动末尾添加'\r\n'
    struct curl_slist *http_headers = NULL;

    //sprintf(request, "POST /%s HTTP/1.1", pc_host_file);
    //http_headers = curl_slist_append(http_headers, request);    //此部分在url中体现

    sprintf(request, "Host: %s", LEWEI50_HOST);
    http_headers = curl_slist_append(http_headers, request);

    sprintf(request, "%s", pc_header);
    http_headers = curl_slist_append(http_headers, request);

    sprintf(request, "%s", "Accept: */*");
    http_headers = curl_slist_append(http_headers, request);

    sprintf(request, "Content-Length: %d", len);
    http_headers = curl_slist_append(http_headers, request);

    sprintf(request, "%s", "Content-Type: application/x-www-form-urlencoded");
    http_headers = curl_slist_append(http_headers, request);

    sprintf(request, "%s", "Connection: Close");
    http_headers = curl_slist_append(http_headers, request);

    sprintf(request, "\r\n%s", pc_json);
    http_headers = curl_slist_append(http_headers, request);

    //发送请求, 再判断返回值
    //url = www.lewei50.com/api/V1/gateway/UpdateSensors/01
    sprintf(pc_url, "%s/%s", LEWEI50_HOST, LEWEI50_HOST_FILE);
    ret = connect_cloud(pc_ret, pc_url, LEWEI50_PORT, HTTP_POST, http_headers);
    //释放 http_headers资源
    curl_slist_free_all(http_headers);

    //{"Successful":true,"Message":"Successful. "}, 模式不同此返回数据的位置也不同.
    DBG("lewei50 ret = %s\n", pc_ret);
    ret = 0;
    pc_data = strstr(pc_ret, HTTP_RET_OK);
    if (pc_data) {
        pc_data += strlen(HTTP_RET_OK);

        //只返回最后的 json数据
        pc_data = strstr(pc_data, "\r\n\r\n");
        if (pc_data) {
            pc_data += 4;
            ret = 1;
            DBG("lewei50 data = %s\n", pc_data);
        }
    }

    return(ret);
}
#endif

//-------------------------------------------------------------------
int main(void)
{
    float f_value = 15.02;
    int i_tmp;

    time_t t;
  srand((unsigned)time(&t));    //初始化随机种子, 否则随机数不随机

    i_tmp = rand();
    i_tmp -= (i_tmp >> 4 << 4);
  f_value += i_tmp;

#if (YEELINK == 1)
    yeelink_create_data(YEELINK_DEVICE_ID, YEELINK_SENSOR_ID, f_value);
#endif

#if (LEWEI50 == 1)
    lewei50_create_data(LEWEI50_DEVICE_ID, f_value);
#endif

    return 1;
}

3.  Makefile如下

OPENWRT = 1

ifeq ($(OPENWRT), 1)
    CC = ~/OpenWrt-SDK-ar71xx-for-linux-i486-gcc-4.6-linaro_uClibc-0.9.33.2/staging_dir/toolchain-mips_r2_gcc-4.6-linaro_uClibc-0.9.33.2/bin/mips-openwrt-linux-gcc
    CFLAGS += -I ~/openwrt-lib/include -L ~/openwrt-lib/lib
    LFLAGS += -lcurl -lcrypto -lz -lssl

else
    CC = gcc
    LFLAGS += -lcurl
endif

CFLAGS += -Wall -O2
#CFLAGS += -g

#可执行文件名和相关的obj文件
APP_BINARY = http_cloud
SRCS += http_cloud_curl_callback.c
OBJS = $(SRCS:.c=.o)

all: APP_FILE

APP_FILE: $(OBJS)
    $(CC) $(CFLAGS) $(OBJS) -o $(APP_BINARY) $(LFLAGS)

.PHONY: clean
clean:
    @echo "cleanning project"
    $(RM) *.a $(OBJS) *~ *.so *.lo $(APP_BINARY)
    @echo "clean completed"

4. 运行结果如下
xxg@xxg-desktop:~/1-wire/http_cloud/libcurl$ ./http_cloud
ptr = HTTP/1.1 200 OK
, userp = 
ptr = Server: nginx/1.1.19
, userp = HTTP/1.1 200 OK

ptr = Date: Mon, 25 Nov 2013 01:29:37 GMT
, userp = HTTP/1.1 200 OK
Server: nginx/1.1.19

ptr = Content-Type: text/html
, userp = HTTP/1.1 200 OK
Server: nginx/1.1.19
Date: Mon, 25 Nov 2013 01:29:37 GMT

ptr = Transfer-Encoding: chunked
, userp = HTTP/1.1 200 OK
Server: nginx/1.1.19
Date: Mon, 25 Nov 2013 01:29:37 GMT
Content-Type: text/html

ptr = Connection: close
, userp = HTTP/1.1 200 OK
Server: nginx/1.1.19
Date: Mon, 25 Nov 2013 01:29:37 GMT
Content-Type: text/html
Transfer-Encoding: chunked

ptr = X-Powered-By: PHP/5.3.10-1ubuntu3.6
, userp = HTTP/1.1 200 OK
Server: nginx/1.1.19
Date: Mon, 25 Nov 2013 01:29:37 GMT
Content-Type: text/html
Transfer-Encoding: chunked
Connection: close

ptr = Set-Cookie: CAKEPHP=kgqv6b4rnbbtn1h1ndda514936; expires=Tue, 03-Dec-2013 09:29:37 GMT; path=/
, userp = HTTP/1.1 200 OK
Server: nginx/1.1.19
Date: Mon, 25 Nov 2013 01:29:37 GMT
Content-Type: text/html
Transfer-Encoding: chunked
Connection: close
X-Powered-By: PHP/5.3.10-1ubuntu3.6

ptr = P3P: CP="NOI ADM DEV PSAi COM NAV OUR OTRo STP IND DEM"
, userp = HTTP/1.1 200 OK
Server: nginx/1.1.19
Date: Mon, 25 Nov 2013 01:29:37 GMT
Content-Type: text/html
Transfer-Encoding: chunked
Connection: close
X-Powered-By: PHP/5.3.10-1ubuntu3.6
Set-Cookie: CAKEPHP=kgqv6b4rnbbtn1h1ndda514936; expires=Tue, 03-Dec-2013 09:29:37 GMT; path=/

ptr = 
, userp = HTTP/1.1 200 OK
Server: nginx/1.1.19
Date: Mon, 25 Nov 2013 01:29:37 GMT
Content-Type: text/html
Transfer-Encoding: chunked
Connection: close
X-Powered-By: PHP/5.3.10-1ubuntu3.6
Set-Cookie: CAKEPHP=kgqv6b4rnbbtn1h1ndda514936; expires=Tue, 03-Dec-2013 09:29:37 GMT; path=/
P3P: CP="NOI ADM DEV PSAi COM NAV OUR OTRo STP IND DEM"

yeelini ret = HTTP/1.1 200 OK
Server: nginx/1.1.19
Date: Mon, 25 Nov 2013 01:29:37 GMT
Content-Type: text/html
Transfer-Encoding: chunked
Connection: close
X-Powered-By: PHP/5.3.10-1ubuntu3.6
Set-Cookie: CAKEPHP=kgqv6b4rnbbtn1h1ndda514936; expires=Tue, 03-Dec-2013 09:29:37 GMT; path=/
P3P: CP="NOI ADM DEV PSAi COM NAV OUR OTRo STP IND DEM"

ptr = HTTP/1.1 200 OK
, userp = onnection: close
X-Powered-By: PHP/5.3.10-1ubuntu3.6
Set-Cookie: CAKEPHP=kgqv6b4rnbbtn1h1ndda514936; expires=Tue, 03-Dec-2013 09:29:37 GMT; path=/
P3P: CP="NOI ADM DEV PSAi COM NAV OUR OTRo STP IND DEM"


ptr = Date: Mon, 25 Nov 2013 01:29:37 GMT
, userp = onnection: close
X-Powered-By: PHP/5.3.10-1ubuntu3.6
Set-Cookie: CAKEPHP=kgqv6b4rnbbtn1h1ndda514936; expires=Tue, 03-Dec-2013 09:29:37 GMT; path=/
P3P: CP="NOI ADM DEV PSAi COM NAV OUR OTRo STP IND DEM"

HTTP/1.1 200 OK

ptr = Content-Type: application/json; charset=utf-8
, userp = onnection: close
X-Powered-By: PHP/5.3.10-1ubuntu3.6
Set-Cookie: CAKEPHP=kgqv6b4rnbbtn1h1ndda514936; expires=Tue, 03-Dec-2013 09:29:37 GMT; path=/
P3P: CP="NOI ADM DEV PSAi COM NAV OUR OTRo STP IND DEM"

HTTP/1.1 200 OK
Date: Mon, 25 Nov 2013 01:29:37 GMT

ptr = Content-Length: 44
, userp = onnection: close
X-Powered-By: PHP/5.3.10-1ubuntu3.6
Set-Cookie: CAKEPHP=kgqv6b4rnbbtn1h1ndda514936; expires=Tue, 03-Dec-2013 09:29:37 GMT; path=/
P3P: CP="NOI ADM DEV PSAi COM NAV OUR OTRo STP IND DEM"

HTTP/1.1 200 OK
Date: Mon, 25 Nov 2013 01:29:37 GMT
Content-Type: application/json; charset=utf-8

ptr = Connection: close
, userp = onnection: close
X-Powered-By: PHP/5.3.10-1ubuntu3.6
Set-Cookie: CAKEPHP=kgqv6b4rnbbtn1h1ndda514936; expires=Tue, 03-Dec-2013 09:29:37 GMT; path=/
P3P: CP="NOI ADM DEV PSAi COM NAV OUR OTRo STP IND DEM"

HTTP/1.1 200 OK
Date: Mon, 25 Nov 2013 01:29:37 GMT
Content-Type: application/json; charset=utf-8
Content-Length: 44

ptr = Cache-Control: private
, userp = onnection: close
X-Powered-By: PHP/5.3.10-1ubuntu3.6
Set-Cookie: CAKEPHP=kgqv6b4rnbbtn1h1ndda514936; expires=Tue, 03-Dec-2013 09:29:37 GMT; path=/
P3P: CP="NOI ADM DEV PSAi COM NAV OUR OTRo STP IND DEM"

HTTP/1.1 200 OK
Date: Mon, 25 Nov 2013 01:29:37 GMT
Content-Type: application/json; charset=utf-8
Content-Length: 44
Connection: close

ptr = Set-Cookie: SERVERID=a4a5b2bbca16d8c8b2ba6d5b6e55f36e|1385342977|1385342977;Path=/
, userp = onnection: close
X-Powered-By: PHP/5.3.10-1ubuntu3.6
Set-Cookie: CAKEPHP=kgqv6b4rnbbtn1h1ndda514936; expires=Tue, 03-Dec-2013 09:29:37 GMT; path=/
P3P: CP="NOI ADM DEV PSAi COM NAV OUR OTRo STP IND DEM"

HTTP/1.1 200 OK
Date: Mon, 25 Nov 2013 01:29:37 GMT
Content-Type: application/json; charset=utf-8
Content-Length: 44
Connection: close
Cache-Control: private

ptr = 
, userp = onnection: close
X-Powered-By: PHP/5.3.10-1ubuntu3.6
Set-Cookie: CAKEPHP=kgqv6b4rnbbtn1h1ndda514936; expires=Tue, 03-Dec-2013 09:29:37 GMT; path=/
P3P: CP="NOI ADM DEV PSAi COM NAV OUR OTRo STP IND DEM"


HTTP/1.1 200 OK
Date: Mon, 25 Nov 2013 01:29:37 GMT
Content-Type: application/json; charset=utf-8
Content-Length: 44
Connection: close
Cache-Control: private
Set-Cookie: SERVERID=a4a5b2bbca16d8c8b2ba6d5b6e55f36e|1385342977|1385342977;Path=/


{"Successful":true,"Message":"Successful. "}lewei50 ret = onnection: close
X-Powered-By: PHP/5.3.10-1ubuntu3.6
Set-Cookie: CAKEPHP=kgqv6b4rnbbtn1h1ndda514936; expires=Tue, 03-Dec-2013 09:29:37 GMT; path=/
P3P: CP="NOI ADM DEV PSAi COM NAV OUR OTRo STP IND DEM"


HTTP/1.1 200 OK
Date: Mon, 25 Nov 2013 01:29:37 GMT
Content-Type: application/json; charset=utf-8
Content-Length: 44
Connection: close
Cache-Control: private
Set-Cookie: SERVERID=a4a5b2bbca16d8c8b2ba6d5b6e55f36e|1385342977|1385342977;Path=/

lewei50 data = 

xxg@xxg-desktop:~/1-wire/http_cloud/libcurl$ 

---