wpa_supplicant 之检测外网连接

背景介绍

wpa_supplicant 和 wpa_cli 通讯成功之后,通过wpa_cli 连接网络之后,只能检测连接到网络, 并不能判断有没有连接互联网。说的通俗一点,预设一个场景: 

  • wpa_supplicant 成功连接到WiFi
  • 拔掉路由器网线, 并不是关闭路由器
  • 这种情况wpa_supplicant 并不能检测到 

针对以上的问题解决方案是增加外网检测,有两种方案如下

  • 通过ping 检测 
  • 通过curl 检测 

第一种方案一般用的比较多,也比较通用。通过命令的方式或通过裁剪busybox中ping.c的源码来实现。  第二种方案是通过看rokid项目发现, 通过curl 的方式实现,代码量很小,容易移植。 

解决方案

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <curl/curl.h>
int main()
{
    CURL *curl;
    CURLcode res;

    char addr[]="www.taobao.cn";
    int result = 0;
    curl = curl_easy_init();
    if (!curl) {
        return -1;
    }
    curl_easy_setopt(curl, CURLOPT_URL, addr);    
    curl_easy_setopt(curl, CURLOPT_NOBODY, 1L);    //做下载请求,而不会得到正文
    curl_easy_setopt(curl, CURLOPT_TIMEOUT, 1L);   // 设置超时时间s
    //curl_easy_setopt(curl, CURLOPT_TIMEOUT_MS, 500L);
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
    if (res != 0) {
        result = -2;
        printf("L(%d) fail code : %d\n",__LINE__,res);
    } else {
        result = 0;
        printf("L(%d) success\n",__LINE__);
    }
}
  • 编译

mipsel-linux-gcc curl.c -o ping-curl -I ./include -L ./lib -lcurl

  • 链接库

通过ldd 查看程序依赖库,发现curl 底层是通过nghttp2 进行http2通讯的

./ping-curl  : /usr/local/lib/libcurl.so.4: no version information available (required by ./a.out)
    linux-vdso.so.1 =>  (0x00007ffebfc93000)
    libcurl.so.4 => /usr/local/lib/libcurl.so.4 (0x00007f74ebac0000)
    libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f74eb6f6000)
    libnghttp2.so.14 => /usr/local/lib/libnghttp2.so.14 (0x00007f74eb4d0000)
    libssl.so.1.0.0 => /lib/x86_64-linux-gnu/libssl.so.1.0.0 (0x00007f74eb267000)
    libcrypto.so.1.0.0 => /lib/x86_64-linux-gnu/libcrypto.so.1.0.0 (0x00007f74eae23000)
    libz.so.1 => /usr/local/lib/libz.so.1 (0x00007f74eac07000)
    /lib64/ld-linux-x86-64.so.2 (0x00007f74ebd2c000)
    libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f74eaa03000)
  • 返回值对应的头文件 include/curl/curl.h
typedef enum {
  CURLE_OK = 0,
  CURLE_UNSUPPORTED_PROTOCOL,    /* 1 */
  CURLE_FAILED_INIT,             /* 2 */
  CURLE_URL_MALFORMAT,           /* 3 */
  CURLE_NOT_BUILT_IN,            /* 4 - [was obsoleted in August 2007 for
                                    7.17.0, reused in April 2011 for 7.21.5] */
  CURLE_COULDNT_RESOLVE_PROXY,   /* 5 */
  CURLE_COULDNT_RESOLVE_HOST,    /* 6 */
  CURLE_COULDNT_CONNECT,         /* 7 */
  CURLE_WEIRD_SERVER_REPLY,      /* 8 */
  CURLE_REMOTE_ACCESS_DENIED,    /* 9 a service was denied by the server
                                    due to lack of access - when login fails
                                    this is not returned. */
  CURLE_FTP_ACCEPT_FAILED,       /* 10 - [was obsoleted in April 2006 for
                                    7.15.4, reused in Dec 2011 for 7.24.0]*/
  CURLE_FTP_WEIRD_PASS_REPLY,    /* 11 */
  CURLE_FTP_ACCEPT_TIMEOUT,      /* 12 - timeout occurred accepting server
                                    [was obsoleted in August 2007 for 7.17.0,
                                    reused in Dec 2011 for 7.24.0]*/
  CURLE_FTP_WEIRD_PASV_REPLY,    /* 13 */
  CURLE_FTP_WEIRD_227_FORMAT,    /* 14 */
  CURLE_FTP_CANT_GET_HOST,       /* 15 */
  CURLE_HTTP2,                   /* 16 - A problem in the http2 framing layer.
                                    [was obsoleted in August 2007 for 7.17.0,
                                    reused in July 2014 for 7.38.0] */
  CURLE_FTP_COULDNT_SET_TYPE,    /* 17 */
  CURLE_PARTIAL_FILE,            /* 18 */
  CURLE_FTP_COULDNT_RETR_FILE,   /* 19 */
  CURLE_OBSOLETE20,              /* 20 - NOT USED */
  CURLE_QUOTE_ERROR,             /* 21 - quote command failure */
  CURLE_HTTP_RETURNED_ERROR,     /* 22 */
  CURLE_WRITE_ERROR,             /* 23 */
  CURLE_OBSOLETE24,              /* 24 - NOT USED */
  CURLE_UPLOAD_FAILED,           /* 25 - failed upload "command" */
  CURLE_READ_ERROR,              /* 26 - couldn't open/read from file */
  CURLE_OUT_OF_MEMORY,           /* 27 */
  /* Note: CURLE_OUT_OF_MEMORY may sometimes indicate a conversion error
           instead of a memory allocation error if CURL_DOES_CONVERSIONS
           is defined
  */
  CURLE_OPERATION_TIMEDOUT,      /* 28 - the timeout time was reached */
  CURLE_OBSOLETE29,              /* 29 - NOT USED */
  CURLE_FTP_PORT_FAILED,         /* 30 - FTP PORT operation failed */
  CURLE_FTP_COULDNT_USE_REST,    /* 31 - the REST command failed */
  CURLE_OBSOLETE32,              /* 32 - NOT USED */
  CURLE_RANGE_ERROR,             /* 33 - RANGE "command" didn't work */
  CURLE_HTTP_POST_ERROR,         /* 34 */
  CURLE_SSL_CONNECT_ERROR,       /* 35 - wrong when connecting with SSL */
  CURLE_BAD_DOWNLOAD_RESUME,     /* 36 - couldn't resume download */
  CURLE_FILE_COULDNT_READ_FILE,  /* 37 */
  CURLE_LDAP_CANNOT_BIND,        /* 38 */
  CURLE_LDAP_SEARCH_FAILED,      /* 39 */
  CURLE_OBSOLETE40,              /* 40 - NOT USED */
  CURLE_FUNCTION_NOT_FOUND,      /* 41 - NOT USED starting with 7.53.0 */
  CURLE_ABORTED_BY_CALLBACK,     /* 42 */
  CURLE_BAD_FUNCTION_ARGUMENT,   /* 43 */
  CURLE_OBSOLETE44,              /* 44 - NOT USED */
  CURLE_INTERFACE_FAILED,        /* 45 - CURLOPT_INTERFACE failed */
  CURLE_OBSOLETE46,              /* 46 - NOT USED */
  CURLE_TOO_MANY_REDIRECTS,      /* 47 - catch endless re-direct loops */
  CURLE_UNKNOWN_OPTION,          /* 48 - User specified an unknown option */
  CURLE_TELNET_OPTION_SYNTAX,    /* 49 - Malformed telnet option */
  CURLE_OBSOLETE50,              /* 50 - NOT USED */
  CURLE_PEER_FAILED_VERIFICATION, /* 51 - peer's certificate or fingerprint
                                     wasn't verified fine */
  CURLE_GOT_NOTHING,             /* 52 - when this is a specific error */
  CURLE_SSL_ENGINE_NOTFOUND,     /* 53 - SSL crypto engine not found */
  CURLE_SSL_ENGINE_SETFAILED,    /* 54 - can not set SSL crypto engine as
                                    default */
  CURLE_SEND_ERROR,              /* 55 - failed sending network data */
  CURLE_RECV_ERROR,              /* 56 - failure in receiving network data */
  CURLE_OBSOLETE57,              /* 57 - NOT IN USE */
  CURLE_SSL_CERTPROBLEM,         /* 58 - problem with the local certificate */
  CURLE_SSL_CIPHER,              /* 59 - couldn't use specified cipher */
  CURLE_SSL_CACERT,              /* 60 - problem with the CA cert (path?) */
  CURLE_BAD_CONTENT_ENCODING,    /* 61 - Unrecognized/bad encoding */
  CURLE_LDAP_INVALID_URL,        /* 62 - Invalid LDAP URL */
  CURLE_FILESIZE_EXCEEDED,       /* 63 - Maximum file size exceeded */
  CURLE_USE_SSL_FAILED,          /* 64 - Requested FTP SSL level failed */
  CURLE_SEND_FAIL_REWIND,        /* 65 - Sending the data requires a rewind
                                    that failed */
  CURLE_SSL_ENGINE_INITFAILED,   /* 66 - failed to initialise ENGINE */
  CURLE_LOGIN_DENIED,            /* 67 - user, password or similar was not
                                    accepted and we failed to login */
  CURLE_TFTP_NOTFOUND,           /* 68 - file not found on server */
  CURLE_TFTP_PERM,               /* 69 - permission problem on server */
  CURLE_REMOTE_DISK_FULL,        /* 70 - out of disk space on server */
  CURLE_TFTP_ILLEGAL,            /* 71 - Illegal TFTP operation */
  CURLE_TFTP_UNKNOWNID,          /* 72 - Unknown transfer ID */
  CURLE_REMOTE_FILE_EXISTS,      /* 73 - File already exists */
  CURLE_TFTP_NOSUCHUSER,         /* 74 - No such user */
  CURLE_CONV_FAILED,             /* 75 - conversion failed */
  CURLE_CONV_REQD,               /* 76 - caller must register conversion
                                    callbacks using curl_easy_setopt options
                                    CURLOPT_CONV_FROM_NETWORK_FUNCTION,
                                    CURLOPT_CONV_TO_NETWORK_FUNCTION, and
                                    CURLOPT_CONV_FROM_UTF8_FUNCTION */
  CURLE_SSL_CACERT_BADFILE,      /* 77 - could not load CACERT file, missing
                                    or wrong format */
  CURLE_REMOTE_FILE_NOT_FOUND,   /* 78 - remote file not found */
  CURLE_SSH,                     /* 79 - error from the SSH layer, somewhat
                                    generic so the error message will be of
                                    interest when this has happened */

  CURLE_SSL_SHUTDOWN_FAILED,     /* 80 - Failed to shut down the SSL
                                    connection */
  CURLE_AGAIN,                   /* 81 - socket is not ready for send/recv,
                                    wait till it's ready and try again (Added
                                    in 7.18.2) */
  CURLE_SSL_CRL_BADFILE,         /* 82 - could not load CRL file, missing or
                                    wrong format (Added in 7.19.0) */
  CURLE_SSL_ISSUER_ERROR,        /* 83 - Issuer check failed.  (Added in
                                    7.19.0) */
  CURLE_FTP_PRET_FAILED,         /* 84 - a PRET command failed */
  CURLE_RTSP_CSEQ_ERROR,         /* 85 - mismatch of RTSP CSeq numbers */
  CURLE_RTSP_SESSION_ERROR,      /* 86 - mismatch of RTSP Session Ids */
  CURLE_FTP_BAD_FILE_LIST,       /* 87 - unable to parse FTP file list */
  CURLE_CHUNK_FAILED,            /* 88 - chunk callback reported error */
  CURLE_NO_CONNECTION_AVAILABLE, /* 89 - No connection available, the
                                    session will be queued */
  CURLE_SSL_PINNEDPUBKEYNOTMATCH, /* 90 - specified pinned public key did not
                                     match */
  CURLE_SSL_INVALIDCERTSTATUS,   /* 91 - invalid certificate status */
  CURLE_HTTP2_STREAM,            /* 92 - stream error in HTTP/2 framing layer
                                    */
  CURLE_RECURSIVE_API_CALL,      /* 93 - an api function was called from
                                    inside a callback */
  CURL_LAST /* never use! */
} CURLcode;

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