c语言解析http请求表单内容,基于C语言的CGI开发

原文地址 http://www.oschina.net/code/snippet_924296_25837
cgi.h

复制代码 代码如下:

#ifndef CGI_H

#define CGI_H

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

typedef struct Node{

 char *name;

 char *value;

 struct Node *next;

}Node;

typedef struct Index{

 Node *head;

 char *buffer;

}Index;

Index *get_input();

void free_input(Index *);

Node *analyze(char *);

Node *analy_a(char *);

Node *analy_m(char *, char *);

char *get_value(Node *, char *);

char fun1(char);

#endif

get_input.c

复制代码 代码如下:

#include "cgi.h"

Index *get_input() {

 //获得表单发送方法

 char *get_method = getenv("REQUEST_METHOD");

 Index *input = (Index *)malloc(sizeof(Index));

 Node *head;

 char *buffer;

 if (strcmp(get_method,"GET") == 0) {

  char *get_str = getenv("QUERY_STRING");

  if (get_str == NULL || *get_str == 0) {

   return NULL;

  }

  //get方法，通过环境变量得到内容

  buffer = (char *)malloc(strlen(get_str) + 1);

  strcpy(buffer, get_str);

  //对内容进行解析，以链表的形式存在

  head = analy_a(buffer);

 } else if (strcmp(get_method,"POST") == 0){

  int get_len = atoi(getenv("CONTENT_LENGTH"));

  if (get_len == 0) {

   return NULL;

  }

  //post方法，通过标准输入读取内容

  buffer = (char *)malloc(get_len + 1);

  memset(buffer,0,get_len + 1);

  int n = fread(buffer, 1,get_len, stdin);

  if (n != get_len) {

   fprintf(stderr,"Read error!");

  }

  head = analyze(buffer);

 }

 //链表头

 input -> head = head;

 //接受到的字符串

 input -> buffer = buffer;

 return input;

}

analyze.c

复制代码 代码如下:

#include "cgi.h"

//post方法获取的内容进行解析

Node *analyze(char *buffer)

{

 //获取内容格式

 char *c_type = getenv("CONTENT_TYPE");

 char *bound;

 fprintf(stderr,"debug:c_type is %s\n",c_type);

 if (strcmp("application/x-www-form-urlencoded",c_type) == 0) {

  //该格式表明获取内容为"name=value"形式

  return analy_a(buffer);  

 } else if (strcmp("text/plain", c_type) == 0) {

  //此种编码格式暂不讨论

 } else {

  //编码格式为multipart/form-data，适用大流量数据传送

  //获取等号后面的分隔符

  bound = index(c_type,'=') + 1;

  fprintf(stderr,"debug:bound is %s\n",bound);

  return analy_m(buffer, bound);

 }

}

analy_a.c

复制代码 代码如下:

#include "cgi.h"

//编码格式为'application/x-www-form-urlencoded'的内容

Node *analy_a(char *buffer)

{

 //创建第一个节点

 Node *head = (Node *)malloc(sizeof(Node));

 Node *temp = head;

 temp -> name = buffer;

 char *b_temp = buffer;

 //通过移动、改变部分字符来分离字符串

 while (*buffer != 0) {

  if (*buffer == '=') {

   //'='，则表示name已经结束，value将开始

   *b_temp = 0;

   temp -> value = b_temp + 1; 

  }else if (*buffer == '+') {

   //'+'代表空格

   *b_temp = ' ';

  }else if (*buffer == '%') {

   //'%'则紧跟两位十六进制表示的特殊字符

   *b_temp = fun1(*(buffer + 1)) * 16 + fun1(*(buffer + 2));

   buffer += 2;

  }

  else if (*buffer == '&') {

   //'&'表示value已经结束，name即将开始

   *b_temp = 0;

   //重新申请内存，存储新内容地址

   temp -> next = (Node *)malloc(sizeof(Node));

   temp = temp -> next;

   temp -> name = b_temp + 1; 

  }else {

   *b_temp = *buffer;

  }

  buffer++;

  b_temp++;   

 }

 //最后一个结束符

 *b_temp = 0;

 return head;

}

analy_m.c

复制代码 代码如下:

#include "cgi.h"

//编码格式为'multipart/form-data'的内容

Node *analy_m(char *buffer, char *bound)

{

 char *start;

 char *end;

 //第一个节点

 Node *head = (Node*)malloc(sizeof(Node));

 Node *temp = head;

 fprintf(stderr,"debug:buffer is %s\n", buffer);

 //开始解析内容，name在两个双引号之间(详见编码格式)

 temp -> name = index(buffer, '"') + 1;

 end = index(temp -> name, '"');

 *end = 0;

 fprintf(stderr,"debug:temp->name is %s\n", temp -> name);

 //中间间隔了两个"\r\n"

 temp -> value = end + 5;

 buffer = strstr(temp -> value, bound);

 //到下一个间隔符，上面间隔两个"\r\n"

 *(buffer - 4) = 0;

 fprintf(stderr,"debug:temp->valu is %s\n", temp -> value);

 while ((start = strstr(buffer,"name=")) != NULL) {

  //循环获取name与value地址，直到没有name为止

  temp -> next = (Node *)malloc(sizeof(Node));

  temp = temp -> next;

  temp -> name = index(start, '"') + 1;

  end = index(temp -> name, '"');

  *end = 0;

  fprintf(stderr,"debug:temp->name is %s\n", temp -> name);

  temp -> value = end + 5;

  buffer = strstr(temp -> value, bound);

  *(buffer - 4) = 0;

  fprintf(stderr,"debug:temp->valu is %s\n", temp -> value);

 }

 return head;

}

fun1.c

复制代码 代码如下:

//将十六进制字符转化为十进制数

char fun1(char ch)

{

 char buffer;

 if (ch < 'A') {

  buffer = ch - 48;       

 }else if (ch < 'a'){

  buffer = ch - 55;

 }else {

  buffer = ch - 87;

 }

 return buffer; 

}

get_value.c

复制代码 代码如下:

#include "cgi.h"

//根据name获取相应的value

char *get_value(Node *head, char *name)

{ 

 Node *p;

 while (head != NULL) {

  if (strcmp(head -> name, name) == 0) {

   return head -> value;

  }

  p = head -> next;

  head = p;

 }

 return NULL;

}

free_input.c

复制代码 代码如下:

#include "cgi.h"

//释放动态获取的内存

void free_input(Index *index)

{

 Node *temp = index -> head;

 Node *p;

 while (temp != NULL) {

  p = temp -> next;

  free(temp);

  temp = p;

 }

 free(index -> buffer);

 free(index);

}