#include <stdlib.h>
#include <stdarg.h>
#include <time.h>
#include <ctype.h>
#include "asn1.h"
#include <string.h>
size_t scan_asn1generic(const char* src,const char* max,const char* fmt,...) {
size_t curlen,seqlen;
const char* maxstack[100];
size_t curmax=0;
va_list args;
int optional=0;
unsigned long* application=NULL;
unsigned long tag;
enum asn1_tagclass tc;
enum asn1_tagtype tt;
unsigned int wantedtag;
unsigned long* desttag=NULL;
const char* orig=src;
va_start(args,fmt);
maxstack[0]=max;
while (*fmt) {
switch (*fmt) {
case '?': // ? = rest is optional (until end of sequence)
optional=1;
break;
case 'i': // i = INTEGER
{
long* dest=va_arg(args,long*);
*dest=0;
curlen=scan_asn1int(src,maxstack[curmax],&tc,&tt,&tag,dest);
if (application) {
if (tc!=APPLICATION) return 0;
*application=tag;
} else {
if (tc!=UNIVERSAL || tt!=PRIMITIVE || tag!=INTEGER)
return 0;
}
if (!curlen) { if (optional) break; else return 0; }
src+=curlen;
application=NULL;
break;
}
case 'I': // I = INTEGER, but for bignum integers; writes to an array of size_t, first one contains number of digits after it
{
size_t* dest=va_arg(args,size_t*);
size_t len,tmp,tlen,j,t;
if (!(len=scan_asn1tag(src,maxstack[curmax],&tc,&tt,&tag))) return 0;
if (!(tmp=scan_asn1length(src+len,maxstack[curmax],&tlen))) return 0;
len+=tmp;
j=0; t=1;
src+=len;
/* asn.1 sends n bytes, most significant first.
* we want m digits, most significant first.
* if n is not a multiple of sizeof(digit) then we need to
* insert a few 0 bytes in the first word
*/
while (tlen) {
j=(j<<8)+(unsigned char)(*src);
++src;
--tlen;
if ((tlen%sizeof(j))==0 && (j || t>1)) {
dest[t]=j;
j=0;
++t;
}
}
if (j) dest[t++]=j;
dest[0]=t-1;
break;
}
case 'b':
wantedtag=BIT_STRING; goto stringmain;
case 'u':
wantedtag=UTCTIME; goto stringmain;
case 'p':
wantedtag=PrintableString; goto stringmain;
case 'a':
wantedtag=IA5String; goto stringmain;
case 's':
wantedtag=OCTET_STRING; goto stringmain;
stringmain:
{
struct string* dest;
struct string temp;
time_t* desttime=NULL;
size_t i;
if (wantedtag==UTCTIME) {
dest=&temp;
desttime=va_arg(args,time_t*);
} else
dest=va_arg(args,struct string*);
dest->l=0;
dest->s=0;
curlen=scan_asn1string(src,maxstack[curmax],&tc,&tt,&tag,&dest->s,&dest->l);
if (!curlen) { if (optional) break; else return 0; }
if (application) {
if (tc!=APPLICATION) return 0;
*application=tag;
} else {
if (tc!=UNIVERSAL || tt!=PRIMITIVE || tag!=wantedtag)
return 0;
}
if (wantedtag==BIT_STRING) { // additional checks for bit strings
if (dest->l==0 || // length can't be 0 because the format starts with 1 octet that contains the number of unused bits in the last octet
((unsigned char)(dest->s[0])>7) || // it's the number of unused bits in an octet, must be [0..7]
(dest->l==1 && dest->s[0])) return 0; // if there is no last octet, there can't be any unused bits in there
dest->l=(dest->l-1)*8-dest->s[0];
dest->s+=1;
} else if (wantedtag==PrintableString) {
for (i=0; i<dest->l; ++i) // RFC 2252 section 4.1 production p
if (!isalnum(dest->s[i])
&& dest->s[i]!='"'
&& dest->s[i]!='('
&& dest->s[i]!=')'
&& dest->s[i]!='+'
&& dest->s[i]!=','
&& dest->s[i]!='-'
&& dest->s[i]!='.'
&& dest->s[i]!='/'
&& dest->s[i]!=':'
&& dest->s[i]!='?'
&& dest->s[i]!=' ') return 0;
} else if (wantedtag==IA5String) {
for (i=0; i<dest->l; ++i) // IA5String is an ASCII string, which means 0 <= s[i] <= 127
if ((unsigned char)(dest->s[i]) > 127) return 0;
} else if (wantedtag==UTCTIME) {
size_t j;
struct tm t;
memset(&t,0,sizeof(t));
/*
YYMMDDhhmmZ
YYMMDDhhmm+hh'mm'
YYMMDDhhmm-hh'mm'
YYMMDDhhmmssZ
YYMMDDhhmmss+hh'mm'
YYMMDDhhmmss-hh'mm'
*/
if (dest->l<11 || dest->l>17) return 0;
j=(dest->s[0]-'0')*10+dest->s[1]-'0';
t.tm_year=j+(j<70)*100;
for (i=0; i<10; ++i)
if (!isdigit(dest->s[i])) return 0;
j=(dest->s[2]-'0')*10+dest->s[3]-'0'; // is the month plausible?
if (j<1 || j>12) return 0;
t.tm_mon=j-1;
j=(dest->s[4]-'0')*10+dest->s[5]-'0'; // is the day plausible?
if (j<1 || j>31) return 0;
t.tm_mday=j;
j=(dest->s[6]-'0')*10+dest->s[7]-'0'; // is the hour plausible?
if (j>23) return 0;
t.tm_hour=j;
j=(dest->s[8]-'0')*10+dest->s[9]-'0'; // is the minutes plausible?
if (j>59) return 0;
t.tm_min=j;
i=10;
if (isdigit(dest->s[10])) {
i+=2;
j=(dest->s[10]-'0')*10+dest->s[11]-'0'; // is the seconds plausible?
if (j>59) return 0;
t.tm_sec=j;
}
*desttime=mktime(&t);
if (dest->s[i]=='+' || dest->s[i]=='-') {
size_t j;
if (dest->l!=15) return 0;
for (j=i; j<i+4; ++j)
if (!isdigit(dest->s[j])) return 0;
j=(dest->s[i]-'0')*10+dest->s[i+1]-'0'; // is the offset minutes plausible?
if (j>59) return 0;
if (dest->s[i]=='+')
*desttime+=j*60;
else
*desttime-=j*60;
j=(dest->s[i+2]-'0')*10+dest->s[i+3]-'0'; // is the offset seconds plausible?
if (j>59) return 0;
if (dest->s[i]=='+')
*desttime+=j;
else
*desttime-=j;
} else if (dest->s[i]!='Z') return 0;
}
src+=curlen;
application=NULL;
break;
}
case 'o': // o == OID
{
struct string* dest=va_arg(args,struct string*);
curlen=scan_asn1tag(src,maxstack[curmax],&tc,&tt,&tag);
if (!curlen) { if (optional) break; else return 0; }
if (application) {
if (tc!=APPLICATION) return 0;
*application=tag;
} else {
if (tc!=UNIVERSAL || tt!=PRIMITIVE || tag!=OBJECT_IDENTIFIER)
return 0;
}
src+=curlen;
curlen=scan_asn1length(src,maxstack[curmax],&seqlen);
if (!curlen) return 0;
src+=curlen;
dest->s=src;
dest->l=seqlen;
src+=seqlen;
application=NULL;
break;
}
case '*': // next tag class is APPLICATION instead of UNIVERSAL; write tag to unsigned long*
{
application=va_arg(args,unsigned long*);
break;
}
case 'c': // c = context specific; PRIVATE CONSTRUCTED 0, close with '}'
desttag=va_arg(args,unsigned long*);
// fall through
case '[': // [ = SET
case '{': // { = SEQUENCE
{
curlen=scan_asn1tag(src,maxstack[curmax],&tc,&tt,&tag);
if (!curlen) { if (optional) break; else return 0; }
if (application) {
if (tc!=APPLICATION || tt!=CONSTRUCTED) return 0;
*application=tag;
} else {
if (*fmt=='c') {
if (tc!=PRIVATE || tt!=CONSTRUCTED)
return 0;
*desttag=tag;
} else {
if (tc!=UNIVERSAL || tt!=CONSTRUCTED || tag!=(*fmt=='{'?SEQUENCE_OF:SET_OF))
return 0;
}
}
src+=curlen;
curlen=scan_asn1length(src,maxstack[curmax],&seqlen);
if (!curlen) return 0;
if (curmax>99) return 0;
maxstack[++curmax]=src+curlen+seqlen;
src+=curlen;
application=NULL;
break;
}
case '!': // save current src and max-src into struct string*
// useful for optional parts or CHOICEs
{
struct string* dest=va_arg(args,struct string*);
dest->s=src;
dest->l=maxstack[curmax]-src;
break;
}
case ']': // ] = end of SET
case '}': // } = end of SEQUENCE
{
optional=0;
if (curmax==0) return 0;
src=maxstack[curmax];
--curmax;
break;
}
default:
return 0;
}
++fmt;
}
va_end(args);
return src-orig;
}
