c - 由于 HTTP header 中的奇怪字符，发送数据失败

Question

我使用以下代码创建了 hTTP header 并将其发送到服务器。然而，当它被接收时，它包含奇怪的字符。

 const char http_post_format[]=
 {
  "POST /%s HTTP/1.1\r\n\
  Host: %s\r\n\
  Content-Type: application/x-www-form-urlencoded\r\n\
  Content-Length:%s\r\n\r\n\
  %s\r\n"
 };

代码片段如下:

 int client_fd = -1;
 int len =- 1;
 char *ipstr=(char*)malloc(16);
 struct sockaddr_t addr;
 char *content_length=(char*)malloc(20);
 char *httpRequest = (char*)malloc(556);

 // cs_log("Free memory has %d bytes", MicoGetMemoryInfo()->free_memory) ;
 gethostbyname(http_host, (uint8_t *)ipstr, 16);
 cs_log("server address: host:%s, ip: %s", http_host, ipstr);

 client_fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
 addr.s_ip = inet_addr(ipstr);
 addr.s_port = http_port;
 connect(client_fd, &addr, sizeof(addr));

 Int2Str((uint8_t*)content_length, strlen(str_args));

 cs_log("content_length%s\n ",content_length);

 sprintf(httpRequest, http_post_format,
      http_post_url,
      http_host,
      content_length,
      str_args);

 len=write(client_fd,(uint8_t *)httpRequest, strlen(httpRequest));
 if(len == -1){
   memset(httpRequest,0,556);
 }
 cs_log("len%d\n%s\n ",len,httpRequest);

 free(httpRequest);
 httpRequest = NULL;
 close(client_fd);
 free(content_length);
 content_length=NULL;
 free(ipstr);
 ipstr =NULL;

预期可以解析的http headers如下:

POST /sensor/sensorinfo HTTP/1.1 
Host: 192.168.199.218
Content-Type: application/x-www-form-urlencoded
Content-Length:240

info={ "WIFI_INFO": { "WIFI": { "connected": "1", "strength": "80", "ip": "192.168.199.131", "mac": "d0bae4075913", "ssid": "chaosuan" } }, "DHT11_INFO": { "DHT": { "T": "28", "H": "43" } }, "DSM501A_INFO": { "DSM501A": { "VALUE": "0" } } }

实际收到的数据在Content-Length中包含一些奇怪的字符。

POST /sensor/sensorinfo HTTP/1.1
Host: 192.168.199.218
Content-Type: application/x-www-form-urlencoded
Content-Length:240棍*橪馭嶲誳3

info={ "WIFI_INFO": { "WIFI": { "connected": "1", "strength": "74", "ip": "192.168.199.131", "mac": "d0bae4075913", "ssid": "chaosuan" } }, "DHT11_INFO": { "DHT": { "T": "28", "H": "43" } }, "DSM501A_INFO": { "DSM501A": { "VALUE": "0" } } }

这里是 Int2Str 函数

 void Int2Str(uint8_t* str, int32_t intnum)
 {
 uint32_t i, Div = 1000000000, j = 0, Status = 0;

 for (i = 0; i < 10; i++)
 {
   str[j++] = (intnum / Div) + 48;

   intnum = intnum % Div;
   Div /= 10;
   if ((str[j-1] == '0') & (Status == 0))
   {
    j  = 0;
   }
   else
  {
    Status++;
  }
 } 
 }

Answer 1

你忘了在 Int2Str 中用 NUL 终止你的字符串:

这个函数的结尾应该是这样的:

   ...
   {
     Status++;
   }
  } 

  str[j] = 0;  // <<< add this
}

免责声明:未经测试的代码，可能存在更多问题。

对了，你为什么要写Int2Str？ itoa或更标准的 strtol功能做同样的工作。

您甚至可以直接使用 sprintf 和 %d 格式说明符，这样会更简单。

旁注

+ 48 不好。而是写 + '0'，这样就没有人会猜测 48 是 '0' 字符的 ASCII 码。