[9fans] URL Encode/Decode Verb

["matt" <matt@proweb.co.uk>]

Hi,

I've spent plenty of today sidetracked by this so I hope someone uses it :)

It's a verb for printing char* data as a URL encoded string.

It also does URL decoding

I must admit I've been having a bit of trouble with UTF (I think) as what
Windows types into drawterm seems different from the decoded strings. If
someone can offer some help there I'd appreciate it. That aside, well
behaved input produces well behaved output.

Because there is some UTF in the examples I don't trust the copy and paste
to work but it's only in the examples.
I've put the files on the web too.
http://www.proweb.co.uk/~matt/plan9/url_encode.c
or
http://www.proweb.co.uk/~matt/plan9/url_encode.c.gz

I'm quite impressed I'm picking up this c stuff fairly easily.
I've got some user level file servers in development as well.

Whoever thought of user defined verbs was inspired. Well done to them.

Comments suggestions welcome. As always.

Is the static int url_trans_flag array the best way to do this btw. ?

M

#include <u.h>
#include <libc.h>
#include <ctype.h>

int url_encode(Fmt *fmt) {
 int cnt;
 uchar c, e;
 char *str_start;
 char *str_index;

 static int url_trans_flag[] = { [32] 0, [33] 0, [34] 0, [35] 0, [36] 0,
[37] 0, [38] 0, [39] 0, [40] 0, [41] 0, [42] 0, [43] 0, [44] 0, [45] '-',
[46] '.', [47] 0, [48] '0', [49] '1', [50] '2', [51] '3', [52] '4', [53]
'5', [54] '6', [55] '7', [56] '8', [57] '9', [58] 0, [59] 0, [60] 0, [61] 0,
[62] 0, [63] 0, [64] 0, [65] 'A', [66] 'B', [67] 'C', [68] 'D', [69] 'E',
[70] 'F', [71] 'G', [72] 'H', [73] 'I', [74] 'J', [75] 'K', [76] 'L', [77]
'M', [78] 'N', [79] 'O', [80] 'P', [81] 'Q', [82] 'R', [83] 'S', [84] 'T',
[85] 'U', [86] 'V', [87] 'W', [88] 'X', [89] 'Y', [90] 'Z', [91] 0, [92] 0,
[93] 0, [94] 0, [95] '_', [96] 0, [97] 'a', [98] 'b', [99] 'c', [100] 'd',
[101] 'e', [102] 'f', [103] 'g', [104] 'h', [105] 'i', [106] 'j', [107] 'k',
[108] 'l', [109] 'm', [110] 'n', [111] 'o', [112] 'p', [113] 'q', [114] 'r',
[115] 's', [116] 't', [117] 'u', [118] 'v', [119] 'w', [120] 'x', [121] 'y',
[122] 'z', [123] 0, [124] 0, [125] 0, [126] 0, [127] 0 };

 str_start = str_index= smprint("%s", va_arg(fmt->args, char *));
 if (fmt->flags & FmtSign)
  url_trans_flag[32] = '+';
 else
  url_trans_flag[32] = 0;

 cnt = 0;
 while(c = *(str_index++)) {
  if (c > 127 || c < 32) {
   cnt += fmtprint(fmt, "%%%02x", c);
   continue;
  }

  e = url_trans_flag[c];
  if(e)
   cnt += fmtprint(fmt, "%c", e);
  else
   cnt += fmtprint(fmt, "%%%02x", c);
 }
 free(str_start);
 return cnt;
}

int
url_decode(Fmt *fmt) {
 char *str_arg;
 char *str_start;
 char * token;
 int token_index;
 int str_length;
 int ante_token_length;
 int c, cnt, t;
 Rune r;


 str_start = str_arg = smprint("%s", va_arg(fmt->args, char *));
 for (token = str_arg ; *token; token++) if (*(token) == '+') *token = ' ';

 cnt = 0;
 while(token =  strchr(str_arg, '%')) {
  str_length = strlen(str_arg);
  token_index = str_length - strlen(token);
  ante_token_length = str_length - token_index - 1;

  if (token_index) {
   str_arg[token_index] = 0;
   cnt += fmtprint(fmt, "%s", str_arg);
  }

  if (ante_token_length < 1) {
   str_arg = token +1;
   continue;
  }

  if(token[1] == '%') {
   cnt += fmtprint(fmt, "%%");
   str_arg = &token[2];
   continue;
  }

  if ((ante_token_length > 1) && isxdigit(token[1]) && isxdigit(token[2]) )
{
   t = token[3];
   token[3] = 0;
   r = strtol(&token[1], nil, 16);
   cnt += fmtprint(fmt, "%C",r);
   token[3] = t;
   str_arg = &token[3];
   continue;
  }

  // if we get here the string is malformed, I'll silently drop it
  str_arg++;
 }
 if(*str_arg)
  cnt += fmtprint(fmt, "%s", str_arg);
 free(str_start);
 return cnt;

}


int
url_encoding(Fmt *fmt) {
 if(fmt->flags & FmtLeft)
  return url_decode(fmt);
 else
  return url_encode(fmt);
}






/*

here's an example

8c url_encode.c && 8l url_encode.8 && mv 8.out url_encode && ./url_encode

output is :

fancy : caf€ bl€nc
+enc : caf%e9+bl%e1nc
%20 enc : caf%e9%20bl%e1nc
plain : café blánc
oh_no : %c3%b3h%20n%c3%b3
óh nó

*/


void
main (void) {
 char *fancy_string = "cafe blanc";
 char *prev_estring = "caf%E9%20bl%E1nc";
 char *plus_enc_string;
 char *p20_enc_string;
 char *plain_string;

 fancy_string[3] = 0xE9;
 fancy_string[7] = 0xE1;

 fmtinstall('R', url_encoding);

 plus_enc_string = smprint("%+R", fancy_string);
 p20_enc_string = smprint("%R", fancy_string);
 plain_string = smprint("%-R", prev_estring);

 print("fancy : %s\n+enc : %s\n%%20 enc : %s\nplain : %s\n", fancy_string,
plus_enc_string, p20_enc_string, plain_string);


 print("oh_no : %R\n%-R\n", "óh nó", "%c3%b3h%20n%c3%b3");


 exits(0);
}