Sunshow Life » C http://blog.sunshow.net 回到最初的美好 Mon, 16 Aug 2010 03:49:02 +0000 en hourly 1 http://wordpress.org/?v=3.0.1 libcurl与CLOSE_WAIT http://blog.sunshow.net/2010/03/libcurl-and-close-wait/ http://blog.sunshow.net/2010/03/libcurl-and-close-wait/#comments Tue, 02 Mar 2010 05:41:49 +0000 Sunshow http://blog.sunshow.net/?p=730 调用libcurl下载，然后使用netstat查看发现有大量的TCP连接保持在CLOSE_WAIT状态
查看libcurl的文档说明，有这样一个选项：

CURLOPT_FORBID_REUSE

Pass a long. Set to 1 to make the next transfer explicitly close the connection when done. Normally, libcurl keeps all connections alive when done with one transfer in case a succeeding one follows that can re-use them. This option should be used with caution and only if you understand what it does. Set to 0 to have libcurl keep the connection open for possible later re-use (default behavior).

也就是说，默认情况下libcurl完成一个任务以后，出于重用连接的考虑不会马上关闭
如果没有新的TCP请求来重用这个连接，那么只能等到CLOSE_WAIT超时，这个时间默认在7200秒甚至更高，太多的CLOSE_WAIT连接会导致性能问题

解决方法：

curl_easy_setopt(curl, CURLOPT_FORBID_REUSE, 1);

最好再修改一下TCP参数调低CLOSE_WAIT和TIME_WAIT的超时时间

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相关日志 ]]> http://blog.sunshow.net/2010/03/libcurl-and-close-wait/feed/ 0 url的encode和decode http://blog.sunshow.net/2009/11/url-encode-decode/ http://blog.sunshow.net/2009/11/url-encode-decode/#comments Sat, 14 Nov 2009 08:34:39 +0000 Sunshow http://blog.sunshow.net/?p=716 相关RFC：http://curl.haxx.se/rfc/rfc2396.txt

  1. /* ---------------------------------------------------------------------------
  2. * Encode URL by converting special characters to %XX (where XX are hexadecimal digits)
  3. * Don't forget to free the return value.
  4. */
  5. char *urlencode(const char *url)
  6. {
  7. #define COPY_TO_ENCODE_URL(c) \
  8.         if (outlen < pos) { \
  9.             outlen += 10; \
  10.             out = realloc(out, outlen + 1); \
  11.         } \
  12.         out[pos ++] = c; \
  13.        
  14.     size_t i, len = strlen(url), outlen;
  15.     outlen = len;
  16.     char *out = malloc(outlen + 1);
  17.     int pos;
  18.  
  19.     for (i = 0, pos = 0; i < len; i ++) {
  20.         if ((url[i] >= 48 && url[i] <= 57)  // 0-9
  21.                 || (url[i] >= 65 && url[i] <= 90)   //a-z
  22.                 || (url[i] >= 97 && url[i] <= 122)  //A-Z
  23.                 || url[i] == ';' || url[i] == '/' || url[i] == '?'
  24.                 || url[i] == ':' || url[i] == '@' || url[i] == '&'
  25.                 || url[i] == '=' || url[i] == '+' || url[i] == '$'
  26.                 || url[i] == ',' || url[i] == '-' || url[i] == '_'
  27.                 || url[i] == '.' || url[i] == '!' || url[i] == '~'
  28.                 || url[i] == '*' || url[i] == '\'' || url[i] == '('
  29.                 || url[i] == ')') {
  30.             /* straight copy */
  31.             COPY_TO_ENCODE_URL(url[i]);
  32.         }
  33.         else {
  34.             #undef HEX_TO_DIGIT
  35.             char dig1 = (url[i] & 0xF0) >> 4;
  36.             char dig2 = (url[i] & 0x0F);
  37.             if (dig1 >= 0 && dig1 <= 9) dig1 += 48;    //0,48inascii
  38.             if (dig1 >= 10 && dig1 <= 15) dig1 += 65 - 10;    //A,65inascii
  39.             if (dig2 >= 0 && dig2 <= 9) dig2 += 48;
  40.             if (dig2 >= 10 && dig2 <= 15) dig2 += 65 - 10;
  41.  
  42.             COPY_TO_ENCODE_URL('%');
  43.             COPY_TO_ENCODE_URL(dig1);
  44.             COPY_TO_ENCODE_URL(dig2);
  45.         }
  46.     }
  47.     out[pos] = '\0';
  48.     return (out);
  49. }
  50.  
  51. /* ---------------------------------------------------------------------------
  52. * Decode URL by converting %XX (where XX are hexadecimal digits) to the
  53. * character it represents.  Don't forget to free the return value.
  54. */
  55. char *urldecode(const char *url)
  56. {
  57.     size_t i, len = strlen(url);
  58.     char *out = malloc(len + 1);
  59.     int pos;
  60.  
  61.     for (i = 0, pos = 0; i < len; i ++) {
  62.         if (url[i] == '%' && i+2 < len &&
  63.             isxdigit(url[i + 1]) && isxdigit(url[i + 2])) {
  64.             /* decode %XX */
  65.             #define HEX_TO_DIGIT(hex) ( \
  66.                 ((hex) >= 'A' && (hex) <= 'F') ? ((hex) - 'A' + 10): \
  67.                 ((hex) >= 'a' && (hex) <= 'f') ? ((hex) - 'a' + 10): \
  68.                 ((hex) - '0') )
  69.  
  70.             out[pos ++] = HEX_TO_DIGIT(url[i + 1]) * 16 +
  71.                          HEX_TO_DIGIT(url[i + 2]);
  72.             i += 2;
  73.  
  74.             #undef HEX_TO_DIGIT
  75.         }
  76.         else {
  77.             /* straight copy */
  78.             out[pos ++] = url[i];
  79.         }
  80.     }
  81.     out[pos] = '\0';
  82.     return (out);
  83. }
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相关日志 ]]> http://blog.sunshow.net/2009/11/url-encode-decode/feed/ 0 [Socket]获取客户端IP http://blog.sunshow.net/2009/07/get-client-ip-from-socket/ http://blog.sunshow.net/2009/07/get-client-ip-from-socket/#comments Thu, 16 Jul 2009 05:41:47 +0000 Sunshow http://blog.sunshow.net/?p=709 有两种方法，一种是在accept的时候获取，一种是通过getpeername获取

#include <sys/socket.h>
 
int accept(int socket, struct sockaddr *restrict address,
       socklen_t *restrict address_len);
 
int getpeername(int socket, struct sockaddr *restrict address,
       socklen_t *restrict address_len);

两者区别主要在取IP的fd不一样，前者是在监听的fd，后者是在连接建立的fd

struct sockaddr_in addr;
socklen_t addr_len;
int32_t listen_fd, sock_fd;
 
/* create listening port */
 
addr_len = sizeof(addr);
 
memset(&addr, 0, addr_len);
sock_fd = accept(listen_fd, (struct sockaddr *)&addr, &addr_len);
printf("%d\n", addr.sin_addr.s_addr);
 
memset(&addr, 0, addr_len);
getpeername(sock_fd, (struct sockaddr *)&addr, &addr_len);
printf("%d\n", addr.sin_addr.s_addr);

当然这种长整型格式的IP不一定是我们想要的，可以通过inet_ntoa转换

#include <arpa/inet.h>
 
in_addr_t inet_addr(const char *cp);
char *inet_ntoa(struct in_addr in);
printf("%s\n", inet_ntoa(addr));
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