proxy_parse.h

/*
 * proxy_parse.h -- a HTTP Request Parsing library
 *
 * Written by: Matvey Arye
 * For: COS 518
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <errno.h>
#include <ctype.h>

#ifndef PROXY_PARSE
#define PROXY_PARSE

#define DEBUG 1

/*
 * ParsedRequest objects are created from parsing a buffer containing a HTTP 
 * request. The request buffer consists of a request line followed by a number 
 * of headers. Request fields such as method, protocol etc. are stored 
 * explicitly. Headers such as "Content-Length" and their values are maintained
 * in a linked list. Each node is a ParsedHeadera dn contains a key-value pair.
 *
 * The buf and buflen fields are used internally to maintain the parsed request
 * line.
 */

struct ParsedRequest {
    char* method;
    char* protocol;
    char* host;
    char* port;
    char* path;
    char* version;
    char* buf;
    size_t buflen;
    struct ParsedHeader* headers;
    size_t headersused;
    size_t headerslen;
};

/*
 * ParsedHeader: any header after the request line is a key-value pair with 
 * the format "key:value\r\n" and is maintained in the ParsedHeader linked
 * list within ParsedRequest
 */

struct ParsedHeader {
    char* key;
    size_t keylen;
    char* value;
    size_t valuelen;
};

/*
 * Create an empty parsing object to be used exactly once for parsing a single 
 * request buffer. 
 */
struct ParsedRequest* ParsedRequest_create();

// Parse the reqeust buffer in buf given that buf is of length buflen
int ParsedRequest_parse(struct ParsedRequest* Parse, const char* buf, int buflen);

// Destroy the parsing object
void ParsedRequest_destroy(struct ParsedRequest* pr);

/*
 * Retrive the entire buffer from a parsed request object. buf must be an 
 * allocated buffer of size buflen, with enough space to write the request line,
 * headers and the trailing \r\n. buf will not be NUL terminated by unparse()
 */
int ParsedRequest_unparse(struct ParsedRequest* pr, char* buf, size_t buflen);

/*
 * Retrive the entire buffer 
 */

size_t ParsedRequest_unparse_headers(struct ParsedRequest* pr, char* buf, 
        size_t buflen);

size_t ParsedRequest_totalLen(struct ParsedRequest* pr);

// 
size_t ParsedHeader_headersLen(struct ParsedHeader* pr);

// SET, GET and REMOVE NULL-terminated header keys and values
int ParsedHeader_set(struct ParsedRequest* pr, const char* key, 
        const char *value);

struct ParsedHeader* ParsedHeader_get(struct ParsedRequest* pr, const char* key);

int ParsedHeader_remove(struct ParsedRequest *pr, const char* key);

// debug() prints out debugging info if DEBUG is set to 1
void debug(const char* format, ...);

/*
 * Example Usage :
 *
 * const char *c = 
 * "GET http://www.google.com:80/index.html/1.0\r\n"
 * "Content-Length:80\r\n"
 * "If-Modified-Since: Sat, 29 Oct 2994 19:43:31 MT\r\n\r\n";
 *
 * int len = strlen(c);
 *
 * // 1. Create a Parsedreques to use. This  ParsedRequest is dynamically 
 *       allocated. 
 *  =====================================================================
 *  ParsedRequest *pr = ParsedRequest_create();
 *  if (ParsedRequest_parse(req, c, len) < 0){
 *      printf("parse-failed\n");
 *      return -1;
 *  }
 *
 *
 *
 *  // 2. Turn ParsedRequest into a string.
 *  =======================================
 *  // NOTE: Be sure that you need to dynamically allocate string and if you do, 
 *     remember to free it when you are done. DMA was not necessary here but 
 *     is used as an example
 *
 *  int rlen = ParsedRequest_totalLen(req);
 *  char* b = (char *)malloc(rlen + 1);
 *  if (ParsedRequest_unparse(req, b, rlen) < 0){
 *      printf("unparse failed\n");
 *      return -1;
 *  }
 *  b[rlen] = '\0';
 *  // print out b for text request
 *  free(b);
 *
 *
 *
 *  // 3. Turn the headers from the request into a string
 *  =====================================================
 *  rlen = ParsedHeader_headersLen(req);
 *  char buf[rlen + 1];
 *  if(ParsedRequest_unparse_headers(req, buf, rlen) < 0){
 *      printf("unparse failed\n");
 *      return -1;
 *  }
 *  buf[rlen] = '/0';
 *  // NOTE : printing out buf for text headers only
 *
 *
 *
 * // 4. Get a specific header (key) from the headers.
 * ===================================================
 * A key is a header field such as "If-Modified-Since" which is followed by ":"
 *
 *  struct ParsedHeader *r = ParsedHeader_get(req, "If-Modified-Since");
 *  printf("Modified value: %s\n", r -> value);
 * 
 *
 *
 *  // 5. Remove a specific header by name. 
 *  =======================================
 *  In this case, remove the "If-Modified-Since" header.
 *
 *  if (ParsedHeader_remove(req,"If-Modified-Since") < 0){
 *      printf("remove header key not work\n");
 *      return -1;
 *  }
 *
 * // 6. Set a specific header (key) to a value. 
*  =============================================
*  In this case, we set the "Last-Modified" key to be set ot have as value - 
*  a date in Feb 2014
*
 *  if (ParsedHeader_set(req, "Last-Modified", "Wed, 12 Feb 2014 12:43:31 GMT")){
 *      printf("set header key not work\n");     
 *      return -1;
 *  }
 *
 *
 * // 7. Check the modified header key value pair
 * ==============================================
 * r = ParsedHeader_get(req, "Last-Modified");
 * printf("Last-Modified value: %s\n", r -> value);
 *
 * // 8. Call to free on any ParsedRequests that you create once done. DMA
 * ==========================================================================
 * ParsedRequest_destroy(req);
 *
 */

#endif