another sscanf Q

jnusa · 10-26-2004, 04:28 AM

Hey... I'm trying to make some utility func, to interpret headers. I've haven't really been able to find any libraries that have the ability to process http headers, so I'm making my own (ne1 know any?)
Here my problem in a nutshell

Code:

char buf[2000];
sscanf("include1\r\ninclude2\r\ninclude3\r\n\r\ndonotinclude", "%[^:]\r\n\r\n%*", buf);
printf("\n%s", buf);

My delimter is "\r\n\r\n" and i don't need anything else from this point forward.
This is probably a "must know" question, but I've not been able to figure out sscanf with a string as a delimiter. Any information will be greatly appriciated.

Regards J.

jlliagre · 10-26-2004, 05:01 AM

There are tons of http libraries available, see for example:
http://curl.haxx.se/libcurl/competitors.html
http://www.webdav.org/neon/

Beyond that, I'm not sure what precisely your question is ... can you elaborate ?

jnusa · 10-26-2004, 05:23 AM

If you look at my string, I need to get everything before the "\r\n\r\n" into the buf variable (including the \r\n's).

itsme86 · 10-26-2004, 05:51 AM

strcpy(buf, "include1\r\ninclude2\r\ninclude3\r\n\r\ndonotinclude");

jnusa · 10-26-2004, 06:04 AM

Ehm... guess you misunderstod it:

I have a string (well... a whole http request actually, but lets keep it simple):

Code:

"include1\r\ninclude2\r\ninclude3\r\n\r\ndonotinclude"

What I need to extract out of this string is:

Code:

"include1\r\ninclude2\r\ninclude3"

and discard

Code:

"\r\n\r\ndonotinclude"

I've been messing around with sscanf, but no luck. With the following code, I just get the entire string saved in buf

Code:

sscanf("include1\r\ninclude2\r\ninclude3\r\n\r\ndonotinclude", "%[^:]\r\n\r\n%*", buf);

output:

Code:

include1
include2
include3


donotinclude

I'm not completly sure how to use the brackets [] and I have read the man page

jlliagre · 10-26-2004, 06:46 AM

Try this instead:

Code:

  char *source="include1\r\ninclude2\r\ninclude3\r\n\r\ndonotinclude";
  char *s=strstr(source,"\r\n\r\n");
  printf("%*.*s\n",0,s-source,source);

jnusa · 10-26-2004, 08:55 AM

Thanks jlliagre.. this will work, but I don't understand your syntax (it works though). I would really like to use sscanf, if possible. Ne1 know what is wrong with my syntax?

jlliagre · 10-26-2004, 09:43 AM

I'm afraid you want to push scanf beyond its limits ...

Is your goal doing it with scanf, and I'm out of the game, or to extract the HTTP header, and I can explain how to do it with my approach ?

jnusa · 10-27-2004, 01:31 AM

Please do. I really don't need to display the string, but return it from a function. I tried using sprintf to save it into a varible.

Code:

 
char* ptr;
sprintf(ptr, "%*.*s", 0,s-source, source);

It does work, but can you try to explain it further? Or if there's another way to do this. I also thought og readoing the buffer one char at a time, and look for the combination "\r\n\r\n" and return the index. With that number you could just read the nessary header information with the index number. Which would take less time/resources. The function will only be called 1 time pr. request, so I don't know if this will have any impact.
Anyway please do elaborate your ideas

jlliagre · 10-27-2004, 02:19 AM

Here's a commented code, I guess it says it all:

Code:

char *getHTTPHeader(char *s)
{
  char *trailer=strstr(s,"\r\n\r\n");
  // trailer points now to the first occurrence of an empty CRLF terminated line.
  char *header;
  int len=trailer-s; // len is the HTTP header length
  header=(char *)malloc(len+1); // allocate memory for the reply
  strncpy(header,s,len);  // copy the header part to the reply string
  header[len]='\0'; // terminate the string
  return(header); // that's it
}
main()  // test the function
{
  printf("%s\n",
    getHTTPHeader("include1\r\ninclude2\r\ninclude3\r\n\r\ndonotinclude"));
}

jnusa · 10-27-2004, 02:33 AM

I appriciate it jlliagre. Thx