decode_hdr.c

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#include "stralloc.h"
#include "error.h"
#include "case.h"
#include "byte.h"
#include "uint_t.h"
#include "mime.h"
#include "errtxt.h"
#include "idx.h"
#include "logmsg.h"
 
#define WHO "decode_hdr"

 
static void die_nomem() { logmsg(WHO,111,FATAL,ERR_NOMEM); }
 
void decode_hdr(const char *indata,unsigned int n,stralloc *outdata)
{
  unsigned int pos;
  const char *cp,*cpnext,*cpstart,*cpenc,*cptxt,*cpend,*cpafter;
 
  cpnext = indata;
  cpafter = cpnext + n;
  cpstart = cpnext;
  if (!stralloc_copys(outdata,"")) die_nomem();
  if (!stralloc_ready(outdata,n)) die_nomem();
  for (;;) {
    cpstart = cpstart + byte_chr(cpstart,cpafter-cpstart,'=');
    if (cpstart == cpafter)
      break;
    ++cpstart;
    if (*cpstart != '?') continue;
    ++cpstart;
    cpenc = cpstart + byte_chr(cpstart,cpafter-cpstart,'?');
    if (cpenc == cpafter) continue;
    cpenc++;
    cptxt = cpenc + byte_chr(cpenc,cpafter-cpenc,'?');
    if (cptxt == cpafter) continue;
    cptxt++;
    cpend = cptxt + byte_chr(cptxt,cpafter-cptxt,'?');
    if (cpend == cpafter || *(cpend + 1) != '=') continue;
 
        /* We'll decode anything. On lists with many charsets, this may */
        /* result in unreadable subjects, but that's the case even if   */
        /* no decoding is done. This way, the subject will be optimal   */
        /* for threading, but charset info is lost. We aim to correctly */
        /* decode us-ascii and all iso-8859/2022 charsets. Exacly how   */
        /* these will be displayed depends on dir/charset.              */
 
    cp = cpnext;
                                                        /* scrap lwsp between coded strings */
    while (*cp == ' ' || *cp == '\t')
      cp++;
    if (cp != cpstart - 2)
      if (!stralloc_catb(outdata,cpnext,cpstart - cpnext - 2)) die_nomem();
     cpnext = cp + 1;
     cpstart = cpnext;
       switch (*cpenc) {
         case 'b': case 'B':
           pos = outdata->len;
           decode_b64(cptxt,cpend-cptxt,outdata);
           cpnext = cpend + 2;
           cpstart = cpnext;
           break;
         case 'q': case 'Q':
           decode_qp(cptxt,cpend-cptxt,outdata);
           cpnext = cpend + 2;
           cpstart = cpnext;
           break;
         default:                                /* shouldn't happen, but let's be reasonable */
           cpstart = cpend + 2;
           break;
       }
  }
  if (!stralloc_catb(outdata,cpnext,indata-cpnext+n)) die_nomem();
}