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#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "query.h"
/*
* Return an allocated string containing the next parameter ("key=value").
* The method argument decides which data (GET or POST) to read from.
*
* If len is NULL, the string will be NUL-terminated; if len is non-NULL,
* the string will not be NUL-terminated, and len will be pointed to the
* length of the string.
*
* The string is truncated to max characters. If truncation occurred, the
* -1th character of the string is set to 1.
*/
char *
nextparam(enum method method, int *len, int max)
{
char *buf;
int i, sz;
static int j = 0;
/* Return NULL if at end of parameter string. */
if(method == GET && !query.string[j-1])
return NULL;
#define STEP 256
sz = STEP;
if(!(buf = malloc(1+sz))) /* Leave space for -1th character. */
err(1, "malloc");
/*
* buf's -1th character is set to 1 if the string
* has been truncated (i.e. if input exceeded max).
*/
buf++;
TRUNCATED(buf) = 0;
#define READ(b) (method == GET? \
(*(b) = query.string[j++]): \
fread(b, 1, 1, stdin))
/*
* The parameter is read in a rather lopsided loop, treating
* the first character specially.
*/
first:
/* Return NULL if at end of parameter string. */
if(!READ(buf))
return NULL;
/* Skip empty parameters. */
if(*buf == '&')
goto first;
i = 0;
goto rest;
for(; READ(buf+i); i++){
rest:
if(buf[i] == '&'){
buf[i] = 0;
break;
}
if(i+1 > max){
TRUNCATED(buf) = 1;
/* Skip ahead to next parameter. */
while(READ(buf+i+1) && buf[i+1] != '&') ;
break;
}
if(i+1 >= sz){
sz += STEP;
/* Remember to adjust for -1th character. */
if(buf--, buf = realloc(buf, 1+sz), !buf++)
err(1, "realloc");
}
}
if(len) *len = i;
else buf[i] = 0;
return buf;
}
/* Fill global query structure from CGI environment variables. */
void
setquery()
{
query.string = getenv("QUERY_STRING");
if(!query.string){
fprintf(stderr, "no QUERY_STRING\n");
exit(1);
}
query.method = strcmp(getenv("REQUEST_METHOD"), "POST")? GET: POST;
if(query.method == POST)
query.length = atoi(getenv("CONTENT_LENGTH"));
}
/*
* Split parameter string on equals sign and return value portion;
* return NULL if none found. For example, v = split(p) results in
* p pointing to the parameter key and v pointing to the value.
*/
char *
split(char *param)
{
int n;
n = strcspn(param, "=");
if(!param[n])
return NULL;
param[n] = 0;
return param+n+1;
}
/*
* Decode a URL-encoded string in place. If len is negative, the string
* is assumed to be NUL-terminated. The length of the new string is
* returned. Note that the new string is NOT NUL-terminated! To produce
* a NUL-terminated string, use s[urldecode(s, -1)] = 0.
*/
int
urldecode(char *s, int len)
{
unsigned int code, i, j;
if(len < 0)
len = strlen(s);
for(i = j = 0; i < len; i++, j++){
if(s[i] == '+')
s[j] = ' ';
else if(s[i] == '%'){
if(!sscanf(s+i+1, "%2x", &code))
code = '?';
s[j] = code;
i += 2;
}else
s[j] = s[i];
}
return j;
}
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