msg.c

   1 #include <ctype.h>
   2 #include <stdlib.h>
   3 #include <string.h>
   4 #include "mail.h"
   5
   6 static char *hdrnext(char *s, char *e)
   7 {
   8         char *r;
   9         while (s + 1 < e && s[0] != '\n' && (s[0] != '\r' || s[1] != '\n')) {
  10                 if (!(r = memchr(s, '\n', e - s - 1)))
  11                         return NULL;
  12                 if (isalpha((unsigned char) r[1]))
  13                         return r + 1;
  14                 s = r + 1;
  15         }
  16         return NULL;
  17 }
  18
  19 /* return 1 if r starts with s */
  20 int startswith(char *r, char *s)
  21 {
  22         while (*s)
  23                 if (tolower((unsigned char) *s++) != tolower((unsigned char) *r++))
  24                         return 0;
  25         return 1;
  26 }
  27
  28 char *msg_get(char *msg, long msz, char *hdr)
  29 {
  30         char *s = msg;
  31         char *e = msg + msz;
  32         while (s && s < e) {
  33                 if (startswith(s, hdr))
  34                         return s;
  35                 s = hdrnext(s, e);
  36         }
  37         return NULL;
  38 }
  39
  40 int msg_set(char *msg, long msz, char **mod, long *modlen, char *hdr, char *val)
  41 {
  42         char *h = msg_get(msg, msz, hdr);
  43         int off;
  44         int hlen = h ? hdrlen(h, msg + msz - h) : 0;
  45         int vlen = strlen(val);
  46         if (!h) {
  47                 h = msg;
  48                 while (hdrnext(h, msg + msz))
  49                         h = hdrnext(h, msg + msz);
  50                 h = h + hdrlen(h, msg + msz - h);
  51         }
  52         off = h - msg;
  53         *modlen = msz - hlen + vlen;
  54         *mod = malloc(*modlen + 1);
  55         if (!*mod)
  56                 return 1;
  57         memcpy(*mod, msg, off);
  58         memcpy(*mod + off, val, vlen);
  59         memcpy(*mod + off + vlen, msg + off + hlen, msz - off - hlen + 1);
  60         (*mod)[*modlen] = '\0';
  61         return 0;
  62 }
  63
  64 int hdrlen(char *hdr, long len)
  65 {
  66         char *r, *s = hdr;
  67         do {
  68                 if (!(r = strchr(s, '\n')))
  69                         return strchr(s, '\0') - hdr;
  70                 s = r + 1;
  71         } while (s[0] && (s[0] == ' ' || s[0] == '\t'));
  72         return s - hdr;
  73 }