获取url参数值以某种格式编码

getting url param value encoded in some format

本文关键字：格式 编码 url 参数 获取      更新时间：2023-10-16

我写了下面的C代码来获取url参数的值

char *param(char *attribute_name) {
    char *query_str = getenv("QUERY_STRING");
    urlDecode(query_str);
    printf("qstr = %s<br/>", query_str);
    int i;
    char *param_value;
    char *temp = malloc(strlen(attribute_name) + 3);
    char *x;
    strcpy(temp, "?");
    strcat(temp, attribute_name);
    strcat(temp, "=");
    x = strstr(query_str, temp);
    attribute_name = strdup(attribute_name);
    if (x == NULL) {
        free(temp);
        temp = malloc(strlen(attribute_name) + 3);
        strcpy(temp, "&");
        strcat(temp, attribute_name);
        strcat(temp, "=");
        x = strstr(query_str, temp);
    }
    if (x != NULL) {
        param_value = malloc(strlen(x) - strlen(temp) + 1);
        int s = strlen(x) - strlen(temp);
        int t = strlen(x) - s;
        strncpy(param_value, &x[t], 1);
        for (i = strlen(temp) + 1; i <= strlen(x); i++) {
            if (x[i] != '&') {
                strncat(param_value, &x[i], 1);
            } else {
                break;
            }
        }
    }
    free(temp);
    return param_value;
}

int urlDecode(char *str) {
    unsigned int i;
    char tmp[BUFSIZ];
    char *ptr = tmp;
    memset(tmp, 0, sizeof(tmp));
    for (i=0; i < strlen(str); i++) {
        if (str[i] != '%') {
            *ptr++ = str[i];
            continue;
        }
        if (!isdigit(str[i+1]) || !isdigit(str[i+2])) {
            *ptr++ = str[i];
            continue;
        }
        *ptr++ = ((str[i+1] - '0') << 4) | (str[i+2] - '0');
        i += 2;
   }
   *ptr = '';
   strcpy(str, tmp);
   return 0;
}
下面是main()函数: 
int main() {
    printf("Content-type: text/htmlnrnr");
    printf("<!Doctype html>");
    printf("<html>");
    printf("<meta charset="UTF-8"><meta http-equiv="Content-type" content="text/html; charset=UTF-8">");
    printf("<body>");
    char attr[] = "u";
    char *value = param(attr);
    puts(value);
    //free(value);
    printf("</body></html>");
    return 0;
}

下面是我点击url: http://example.com/cgi-bin/cgi_param?u=1212&sa=232%203&sdd=jdwjdjw

后在浏览器上收到的输出

qstr = u=1212&sa=232 3&sdd=jdwjdjw

�l12�

请纠正我哪里做错了?由于

这是我使用strstr strchr和memchr所做的快速函数。这就是你要找的。

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
char *find_param(char *param, char *query_str) {
    char *p, *p2, *value;
    p = strchr(query_str, '?');
    if (!p)
        return NULL;
    do {
        p = strstr(p+1, param);
    } while (p && p[strlen(param)] != '=');
    if (!p)
        return NULL;
    p += (1 + strlen(param));
    p2 = memchr (p, '&', strlen(p));
    if (!p2)
        p2 = p + strlen(p);
    value = malloc(p2 - p + 1);
    strcpy(value, p);
    value[p2 - p] = '';
    return value;
}
int main() {
    printf("%s", find_param("u", "http://example.com/cgi-bin/cgi_param?u=1212&sa=232%203&sdd=jdwjdjw"));
    return 0;
}

打印:

1212

也适用于sa和sdd。

我的代码中有一个逻辑错误。在做了以下修改后，运行正常。

来自:

strcpy(temp, "?");

: 

strcpy(temp, "");

谢谢你的建议

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