How to use http request to parse form content in C language
What this article shares to you is about how to use http request to parse the form content in the c language, the editor thinks it is very practical, so I share it with you to learn. I hope you can get something after reading this article.
The code is as follows:
# ifndef CGI_H#define CGI_H
# include # include # include
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
The code is as follows:
# include "cgi.h"
Index * get_input () {/ / get the form delivery method 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 method, through the environment variable to get the content buffer = (char *) malloc (strlen (get_str) + 1); strcpy (buffer, get_str); / / A pair of content is parsed, and head = analy_a (buffer) exists in the form of a linked list
} else if (strcmp (get_method, "POST") = = 0) {int get_len = atoi (getenv ("CONTENT_LENGTH")); if (get_len = = 0) {return NULL;} / / post method, read through standard input buffer = (char *) malloc (get_len + 1); memset (buffer,0,get_len + 1); int n = fread (buffer, 1m GetWorlen, stdin); if (n! = get_len) {fprintf (stderr, "Read error!") } head = analyze (buffer);} / / chain header input-> head = head;// received string input-> buffer = buffer;return input;}
Analyze.c
The code is as follows:
Parse the content obtained by # include "cgi.h" / / post method Node * analyze (char * buffer) {/ / get the content format 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) {/ / this format indicates that the acquired content is in the form of "name=value" return analy_a (buffer) } else if (strcmp ("text/plain", c_type) = = 0) {/ / this encoding format will not be discussed for the time being} else {/ / the encoding format is multipart/form-data, which is suitable for large traffic data transmission / / acquisition of the delimiter bound = index after the equal sign (stderr, "debug:bound is% s\ n", bound); return analy_m (buffer, bound);}}
Analy_a.c
The code is as follows:
# include "cgi.h" / / Encoding the content in 'application/x-www-form-urlencoded' Node * analy_a (char * buffer) {/ / create the first node Node * head = (Node *) malloc (sizeof (Node)); Node * temp = head;temp-> name = buffer;char * b_temp = buffer / / separating the string while (* buffer! = 0) {if (* buffer = ='=') {/ /'=') {/ /'='by moving and changing some characters means that name has ended and value will start * b_temp = 0 else if-> value = b_temp + 1;} else if (* buffer = ='+') {/ /'+ 'represents a space * b_temp ='' } else if (* buffer = ='%') {/ /'%'is followed by the special character * b_temp = fun1 (* (buffer + 1)) * 16 + fun1 (* (buffer + 2)); buffer + = 2;} else if (* buffer = ='&') {/ /'& 'indicates that value is over and name is about to begin * b_temp = 0 / / re-apply for memory and store the new content address temp-> next = (Node *) malloc (sizeof (Node)); temp = temp-> next;temp-> name = breadtemp + 1;} else {* b_temp = * buffer;} buffer++;b_temp++;} / / the last Terminator * b_temp = 0position return head;}
Analy_m.c
The code is as follows:
# include "cgi.h" / / content Node* analy_m (char * buffer, char * bound) {char * start;char * end;// first node Node* head = (Node*) malloc (sizeof (Node)); Node* temp = head;fprintf (stderr, "debug:buffer is% s\ n", buffer) / / start parsing the content, with name between two double quotes (see encoding format) temp- > name = index (buffer,'") + 1 end = index (temp- > name,'"'"); * end = 0 stderr fprintf (stderr," debug:temp- > name is% s\ n ", temp- > name); / / separated by two"\ r\ n "temp- > value = end + 5 buffer = strstr (temp- > value, bound) / / to the next spacer, separated by two "\ r\ n" * (buffer-4) = 0politics fprintf (stderr, "debug:temp- > valu is% s\ n", temp- > value); while ((start = strstr (buffer, "name=")! = NULL) {/ / cycle to obtain name and value addresses until there is no name temp- > next = (Node *) malloc (sizeof (Node); temp = temp- > next) Temp- > name = index (start,'"') + 1 position 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 position fprintf (stderr," debug:temp- > valu is% s\ n ", temp- > value);} return head;}
Fun1.c
The code is as follows:
/ / convert hexadecimal characters to decimal numbers 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 代码如下: #include "cgi.h"//根据name获取相应的valuechar *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
The code is as follows:
# include "cgi.h" / / release dynamically acquired memory void free_input (Index * index) {Node * temp = index-> head;Node * ppolitics while (temp! = NULL) {p = temp-> next;free (temp); temp = p;} free (index-> buffer); free (index);}
The above is how to parse the form content using http request in c language. The editor believes that there are some knowledge points that we may see or use in our daily work. I hope you can learn more from this article. For more details, please follow the industry information channel.
