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  • (转）linux下和云端通讯的例程, ubuntu和openwrt下实验成功(二)

    前言: 上节用纯linux的函数实现了和云端通讯, 本节开始利用传说中的神器libcurl

    话说一个网络程序员对书法十分感兴趣，退休后决定在这方面有所建树。 于是花重金购买了上等的文房四宝。    
    一日，饭后突生雅兴，一番磨墨拟纸，  并点上了上好的檀香，颇有王羲之风范，  又具颜真卿气势，定神片刻，泼墨挥毫，    
    郑重地写下一行字：libcurl.

    由此可知libcurl的刻骨铭心!
    官方文档请参考这里 http://curl.haxx.se/libcurl/c/curl_easy_setopt.html

    刚接触 libcurl的时候, 自然的想到按照常规的思路来连接云端: 先连接Web, 再发送请求, 然后等待接受返回数据. 
    这样思路的代码如下

    点击(此处)折叠或打开

    1. /*----------------------------------------------------------------------------------------------------
    2. 名称: http_cloud_curl_simple.c
    3. 功能: 利用libcurl的API顺序实现云端通讯, 未利用回调机制
    4. -----------------------------------------------------------------------------------------------------*/
    5. #include <stdio.h>
    6. #include <stdlib.h>
    7. #include <string.h>
    8. #include <curl/curl.h>
    9. #include <assert.h>
    11. #include "../http_cloud.h"
    13. #define DBG printf
    15. //-----------------------------------------------------------------------------------------
    16. static void get_local_time(char *pc_str)
    17. {
    18.     time_t now;
    19.     struct tm *timenow;
    21.     assert(pc_str != NULL);
    23.     time(&now);
    24.     timenow = localtime(&now);
    25.     sprintf(pc_str, "%04d-%02d-%02dT%02d:%02d:%02d", timenow->tm_year+1900, timenow->tm_mon+1, timenow->tm_mday,
    26.                     timenow->tm_hour, timenow->tm_min, timenow->tm_sec);
    27. }
    29. /* Auxiliary function that waits on the socket. */
    30. static int wait_on_socket(curl_socket_t sockfd, int for_recv, long timeout_ms)
    31. {
    32.   struct timeval tv;
    33.   fd_set infd, outfd, errfd;
    34.   int res;
    36.   tv.tv_sec = timeout_ms / 1000;
    37.   tv.tv_usec= (timeout_ms % 1000) * 1000;
    39.   FD_ZERO(&infd);
    40.   FD_ZERO(&outfd);
    41.   FD_ZERO(&errfd);
    43.   FD_SET(sockfd, &errfd); /* always check for error */
    45.   if(for_recv) {
    46.     FD_SET(sockfd, &infd);
    47.   }
    48.   else {
    49.     FD_SET(sockfd, &outfd);
    50.   }
    52.   /* select() returns the number of signalled sockets or -1 */
    53.   res = select(sockfd + 1, &infd, &outfd, &errfd, &tv);
    54.   return res;
    55. }
    57. static char connect_cloud(char *pc_ret, const char *host_addr, const int portno, const char *request)
    58. {
    59.     CURL *curl;
    60.   CURLcode res;
    61.   /* Minimalistic http request */
    62.   //const char *request = "GET / HTTP/1.0 Host: example.com ";
    63.   //char request[1024] = "";
    64.   curl_socket_t sockfd; /* socket */
    65.   long sockextr;
    66.   size_t iolen;
    67.   curl_off_t nread;
    68.   int iLen = 0;
    69.   char cRet = 0;
    71.   assert((pc_ret != NULL) && (host_addr != NULL) && (request != NULL));
    73.   //curl_global_init(CURL_GLOBAL_DEFAULT);
    74.   curl = curl_easy_init();
    75.   if (!curl)    return 0;
    77.   //curl_easy_setopt(curl, CURLOPT_URL, "http://example.com");
    78.   curl_easy_setopt(curl, CURLOPT_URL, host_addr);
    79.   /* Do not do the transfer - only connect to host */
    80.   curl_easy_setopt(curl, CURLOPT_CONNECT_ONLY, 1L);
    81.   res = curl_easy_perform(curl);
    82.   if(CURLE_OK != res) {
    83.     printf("Error: %s ", strerror(res));
    84.     return -1;
    85.   }
    87.   /* Extract the socket from the curl handle - we'll need it for waiting.
    88.    * Note that this API takes a pointer to a 'long' while we use
    89.    * curl_socket_t for sockets otherwise.
    90.    */
    91.   res = curl_easy_getinfo(curl, CURLINFO_LASTSOCKET, &sockextr);
    92.   if(CURLE_OK != res) {
    93.     printf("Error: %s ", curl_easy_strerror(res));
    94.     return -2;
    95.   }
    97.   sockfd = sockextr;
    98.   /* wait for the socket to become ready for sending */
    99.   if(!wait_on_socket(sockfd, 0, 60000L)) {
    100.     printf("Error: timeout. ");
    101.     return -3;
    102.   }
    104.   /* Send the request. Real applications should check the iolen
    105.    * to see if all the request has been sent */
    106.   res = curl_easy_send(curl, request, strlen(request), &iolen);
    107.   if(CURLE_OK != res) {
    108.     printf("Error: %s ", curl_easy_strerror(res));
    109.     return -4;
    110.   }
    112.   /* read the response */
    113.   char buf[1024];
    114.   while(1) {
    115.     wait_on_socket(sockfd, 1, 60000L);
    116.     res = curl_easy_recv(curl, buf, 1024, &iolen);
    118.     if(CURLE_OK != res)
    119.       break;
    121.     nread = (curl_off_t)iolen;
    122.   }
    123.   buf[nread] = '';
    124.   DBG("Received (%" CURL_FORMAT_CURL_OFF_T "), %s ", nread, buf);
    126.   /* always cleanup */
    127.   curl_easy_cleanup(curl);
    129.   pc_ret = strstr(buf, " ");
    130.     if (pc_ret) {
    131.         pc_ret += 4;
    132.         DBG("ret = %s ", pc_ret);
    133.     }
    135.   return 1;
    136. }
    138. #if (YEELINK == 1)
    139. int yeelink_create_data(const int device_id, const int sensor_id, const float device_value)
    140. {
    141.     char pc_ret[200], request[1024], pc_json[100], pc_time[30], pc_host_file[100], pc_header[100], ret;
    142.     int len;
    144.     sprintf(pc_host_file, "v1.0/device/%d/sensor/%d/datapoints", device_id, sensor_id);
    145.     sprintf(pc_header, "U-ApiKey: %s", YEELINK_API_KEY);
    147.     get_local_time(pc_time);
    148.     sprintf(pc_json, "{"timestamp":"%s","value":%.2f}", pc_time, device_value);
    149.     len = strlen(pc_json);
    151.     sprintf(request, "POST /%s HTTP/1.1 Host: %s Accept: */* %s Content-Length: %d Content-Type: application/x-www-form-urlencoded Connection: Close %s ",
    152.         pc_host_file, YEELINK_HOST, pc_header, len, pc_json);
    153.     DBG("request = %s ", request);
    155.     ret = connect_cloud(pc_ret, YEELINK_HOST, YEELINK_PORT, request);
    157.     return(ret);
    158. }
    159. #endif
    161. #if (LEWEI50 == 1)
    162. //curl --request POST http://www.lewei50.com/api/V1/Gateway/UpdateSensors/01 --data "[{"Name":"T1","Value":"23.08"}]" --header "userkey:36be8ff22f794f1e8a0bee3336eef237"
    163. int lewei50_create_data(const char *device_id, const float device_value)
    164. {
    165.     char pc_ret[200], request[1024], pc_json[100], pc_header[100], ret;
    166.     int len;
    168.     assert(device_id != NULL);
    170.     sprintf(pc_header, "userkey: %s", LEWEI50_USER_KEY);
    171.     sprintf(pc_json, "[{"Name":"%s","Value":"%.2f"}]", device_id, device_value);
    172.     len = strlen(pc_json);
    174.     sprintf(request, "POST /%s HTTP/1.1 Host: %s Accept: */* %s Content-Length: %d Content-Type: application/x-www-form-urlencoded Connection: Close %s ",
    175.         LEWEI50_HOST_FILE, LEWEI50_HOST, pc_header, len, pc_json);
    176.     DBG("request = %s ", request);
    178.     ret = connect_cloud(pc_ret, LEWEI50_HOST, LEWEI50_PORT, request);
    180.     return(ret);
    181. }
    182. #endif
    184. //-------------------------------------------------------------------
    185. int main(void)
    186. {
    187.     float f_value = 15.02;
    188.     int i_tmp;
    190.     time_t t;
    191.   srand((unsigned)time(&t));    //初始化随机种子, 否则随机数不随机
    193.     i_tmp = rand();
    194.     i_tmp -= (i_tmp >> 4 << 4);
    195.   f_value += i_tmp;
    197. #if (YEELINK == 1)
    198.     yeelink_create_data(YEELINK_DEVICE_ID, YEELINK_SENSOR_ID, f_value);
    199. #endif
    201. #if (LEWEI50 == 1)
    202.     lewei50_create_data(LEWEI50_DEVICE_ID, f_value);
    203. #endif
    205.     return 1;
    206. }


    Makefile: 注意openwrt的连接参数要多加的, 为了这几个字母, 折腾了好长时间

    点击(此处)折叠或打开

    1. OPENWRT = 1
    3. ifeq ($(OPENWRT), 1)
    4.     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
    5.     CFLAGS += -I ~/openwrt-lib/include -L ~/openwrt-lib/lib
    6.     LFLAGS += -lcurl -lcrypto -lz -lssl
    8. else
    9.     CC = gcc
    10.     LFLAGS += -lcurl
    11. endif
    13. CFLAGS += -Wall -O2
    14. #CFLAGS += -g
    16. #可执行文件名和相关的obj文件
    17. APP_BINARY = http_cloud
    18. SRCS += http_cloud_curl_simple.c
    19. OBJS = $(SRCS:.c=.o)
    21. all: APP_FILE
    23. APP_FILE: $(OBJS)
    24.     $(CC) $(CFLAGS) $(OBJS) -o $(APP_BINARY) $(LFLAGS)
    26. .PHONY: clean
    27. clean:
    28.     @echo "cleanning project"
    29.     $(RM) *.a $(OBJS) *~ *.so *.lo $(APP_BINARY)
    30.     @echo "clean completed"

    openwrt下的运行结果如下
    root@OpenWrt:/xutest# ./http_cloud_libcurl
    yeelini ret = HTTP/1.1 200 OK
    Server: nginx/1.1.19
    Date: Thu, 07 Nov 2013 00:56:56 GMT
    Content-Type: text/html
    Transfer-Encoding: chunked
    Connection: close
    X-Powered-By: PHP/5.3.10-1ubuntu3.6
    Set-Cookie: CAKEPHP=dfvacsdpb8ls802dulnt695kk2; expires=Fri, 15-Nov-2013 08:56:56 GMT; path=/
    P3P: CP="NOI ADM DEV PSAi COM NAV OUR OTRo STP IND DEM"

    lewei50 ret = HTTP/1.1 200 OK
    Date: Thu, 07 Nov 2013 00:56:56 GMT
    Content-Type: application/json; charset=utf-8
    Content-Length: 44
    Connection: close
    Cache-Control: private
    Set-Cookie: SERVERID=a4a5b2bbca16d8c8b2ba6d5b6e55f36e|1383785816|1383785816;Path=/

    {"Successful":true,"Message":"Successful. "}

    root@OpenWrt:/xutest# 

    这仅仅是libcurl最最简单的应用, 本着'师夷长技以制夷'的原则, 继续看官方文档中......
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  • 原文地址：https://www.cnblogs.com/alljoyn/p/4739969.html
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