You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
110 lines
3.0 KiB
C
110 lines
3.0 KiB
C
#include <string.h>
|
|
#include "fmt.h"
|
|
#include "textcode.h"
|
|
#include "str.h"
|
|
#include "scan.h"
|
|
#include "case.h"
|
|
#include "haveinline.h"
|
|
|
|
/* src is UTF-8 encoded */
|
|
size_t fmt_jsonescape(char* dest,const char* src,size_t len) {
|
|
register const unsigned char* s=(const unsigned char*) src;
|
|
size_t written=0,i;
|
|
char c;
|
|
for (i=0; i<len; ++i) {
|
|
switch (s[i]) {
|
|
case '<':
|
|
/* If you are outputting the json inside a <script> tag in HTML,
|
|
* and the string is attacker controlled and contains "</script>",
|
|
* that would allow cross site scripting. So we escape that here. */
|
|
if (len-i>=9 && case_equalb(s+i+1,8,"/script>"))
|
|
goto unicodeescape;
|
|
goto noneed;
|
|
case '\\':
|
|
case '"':
|
|
c=s[i];
|
|
escape:
|
|
if (dest) {
|
|
dest[written]='\\';
|
|
dest[written+1]=c;
|
|
}
|
|
written+=2;
|
|
break;
|
|
case '\n': c='n'; goto escape;
|
|
case '\r': c='r'; goto escape;
|
|
case '\b': c='b'; goto escape;
|
|
case '\t': c='t'; goto escape;
|
|
case '\f': c='f'; goto escape;
|
|
default:
|
|
if (s[i]<' ') {
|
|
unicodeescape:
|
|
if (dest) {
|
|
dest[written]='\\';
|
|
dest[written+1]='u';
|
|
dest[written+2]='0';
|
|
dest[written+3]='0';
|
|
dest[written+4]=fmt_tohex(s[i]>>4);
|
|
dest[written+5]=fmt_tohex(s[i]&0xf);
|
|
}
|
|
written+=6;
|
|
} else if (s[i]>0x7f) {
|
|
/* UTF-8! Convert to surrogate pair if needed. */
|
|
uint32_t u;
|
|
size_t j=scan_utf8_sem((const char*)s+i,len-i,&u);
|
|
if (j==0) { /* Invalid UTF-8! Try to limp on! */
|
|
written+=fmt_utf8(dest?dest+written:0,s[i]);
|
|
break;
|
|
}
|
|
/* It turns out we are not required to escape these.
|
|
* So we won't. */
|
|
#if 0
|
|
if (u>0xffff) {
|
|
if (dest) {
|
|
dest[written ]='\\';
|
|
dest[written+1]='u';
|
|
fmt_xlong(dest+written+2,0xd800 + ((u>>10) & 0x3bf));
|
|
dest[written+6]='\\';
|
|
dest[written+7]='u';
|
|
fmt_xlong(dest+written+8,0xdc00 + (u & 0x3ff));
|
|
}
|
|
written+=12;
|
|
} else
|
|
#endif
|
|
{
|
|
if (dest) memcpy(dest+written,s+i,j);
|
|
written+=j;
|
|
}
|
|
i+=j-1; /* -1 because the for loop will also add 1 */
|
|
break;
|
|
} else {
|
|
noneed:
|
|
if (dest) dest[written]=s[i];
|
|
++written;
|
|
}
|
|
break;
|
|
}
|
|
/* in case someone gives us malicious input */
|
|
if (written>((size_t)-1)/2) return (size_t)-1;
|
|
}
|
|
return written;
|
|
}
|
|
|
|
#ifdef UNITTEST
|
|
#include <assert.h>
|
|
#include <string.h>
|
|
|
|
int main() {
|
|
char buf[100];
|
|
/* test utf-8 pass-through and correct encoding of \t */
|
|
assert(fmt_jsonescape(buf,"\tfnörd",7)==8 && !memcmp(buf,"\\tfnörd",8));
|
|
/* test escaping of unprintable characters */
|
|
assert(fmt_jsonescape(buf,"\001x",2)==7 && !memcmp(buf,"\\u0001x",7));
|
|
/* test conversion of large UTF-8 chars to UTF-16 surrogate pairs (poop emoji) */
|
|
/* EDIT: this escaping is not actually needed, so we aren't doing it
|
|
* anymore. This test will fail now:
|
|
assert(fmt_jsonescape(buf,"\xf0\x9f\x92\xa9x",5)==13 && !memcmp(buf,"\\ud83d\\udca9x",13)); */
|
|
assert(fmt_jsonescape(buf,"a\x81x",3)==4 && !memcmp(buf,"a\xc2\x81x",4));
|
|
assert(fmt_jsonescape(buf,"</Script>",9)==14 && !memcmp(buf,"\\u003c/Script>",14));
|
|
}
|
|
#endif
|