parslib/tinyparser.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "tinyparser.h"
#include "streecmp/streecmp.h"

extern char *headers;

enum errs err = err_init;
enum states state = state_init;
enum methods method = method_init;
char *uri = NULL; 
char *ver = NULL;
int uri_len = 0;
int ver_len = 0;

struct nod *header_tree = NULL;
char **header_table = NULL; 

int read_line(char **buffer, char **buffer_limit) {
    int diff = 0; 
    if ((*buffer) >= (*buffer_limit)) {
        return diff;
    }

    int ret = 0; 
    char *match = strstr(*buffer, "\r\n");
    if (match) {
        ret = match-(*buffer);
        *buffer += 2;
    } else {
        ret = (*buffer_limit)-(*buffer);
    }
    *buffer += ret;
    return ret;
}

int cmp_orig(char *ch, char *orig, char *limit) {
    int diff = 0;
    for (; *orig != '\0' && *ch != '\0' && ch < limit; orig++, ch++, diff++) 
        if (*orig != *ch)
            return -1;

    return diff;
}

int cmp_ascii(char *ch, char *limit) {
    int diff = 0; 
    for (; *ch != '\0' && *ch != ' ' && ch < limit; ch++, diff++) {
        if (*ch >= '0' && *ch <= '9')   continue;
        if (*ch >= 'A' && *ch <= 'Z')   continue;
        if (*ch >= 'a' && *ch <= 'z')   continue;
        if (*ch >= '#' && *ch <= '/')   continue;
        if (*ch == '!')                 continue;
        if (*ch == ':')                 continue;
        if (*ch == ';')                 continue;
        if (*ch == '=')                 continue;
        if (*ch == '?')                 continue;
        if (*ch == '@')                 continue;
        if (*ch == '[')                 continue;
        if (*ch == ']')                 continue;
        if (*ch == '_')                 continue;
        if (*ch == '~')                 continue;

        return -1;
    }

    return diff;
}

int parse_header(char *offset, int len) {
    int cursor = 0;
    int ret = 0; 
    char *header_limit = offset+len;
    char *sep = strchr(offset, ':');
    if (!sep) {
        return -1;
    }

    if (sep > header_limit) {
        return -1;
    }

    int htitle_len = sep-offset;
    ret = streencmp(header_tree, offset, htitle_len); 
    if (ret == 0) {
        return -1;
    }

    char *hvalue = sep+1;
    header_table[ret] = hvalue;

    return 0;
}

int parse_title(char *offset, int len) {
    int cursor = 0;

    while (state != state_title_ok && state != state_title_err) {
        if (cursor >= len) {
            state = state_title_err;
            err = err_parse_title;
        }

        int ret = 0; 
        char *ch = offset+cursor;
        char *lim = offset+len-1;

        switch (state) {
        case state_init: 
            state = state_title_method;
            break;
        case state_title_method: 
            if ((ret = cmp_orig(ch, "GET", lim))) {
                cursor += ret;
                state = state_title_after_method;
                method = method_get;
                break;
            }
            if ((ret = cmp_orig(ch, "POST", lim))) {
                cursor += ret;
                state = state_title_after_method;
                method = method_post;
                break;
            }
            if ((ret = cmp_orig(ch, "HEAD", lim))) {
                cursor += ret;
                state = state_title_after_method;
                method = method_head;
                break;
            }

            state = state_title_err;
            err = err_parse_title_method;
            break;
        case state_title_after_method: 
            cursor++;
            state = state_title_uri;
            break;
        case state_title_uri: 
            if ((ret = cmp_ascii(ch, lim)) <= 0) {
                state = state_title_err;
                err = err_parse_title_uri;
                break;
            }

            if (!(uri = strndup(ch, ret))) {
                state = state_title_err;
                err = err_memory;
                break;
            }

            uri_len = ret;
            cursor += ret;
            state = state_title_after_uri;
            break;
        case state_title_after_uri: 
            cursor++; 
            state = state_title_version;
            break;
        case state_title_version: 
            if ((ret = cmp_ascii(ch, lim)) <= 0) {
                state = state_title_err;
                err = err_parse_title_version;
                break;
            }

            if (!(ver = strndup(ch, ret))) {
                state = state_title_err;
                err = err_memory;
                break;
            }

            ver_len = ret;
            cursor += ret;
            state = state_title_ok;
            break;
        case state_title_ok: 
            for (;ch < lim;ch++) {
                if (*ch == ' ') continue;
                if (*ch == '\t') continue;
                if (*ch == '\0') continue;
                if (*ch == '\r') continue;

                state = state_title_err;
                err = err_parse_title;
                break;
            }
            break;
        case state_title_err:
            fprintf(stderr, "failed\n");
            return -1;
            break;
        default: 
            break;
        }
    }

    return 0;
}

int parse_request(char *buffer) {
    int ret; 
    char *buffer_limit = buffer+strlen(buffer);

    char *title_offset = buffer;
    int title_len = read_line(&buffer, &buffer_limit);
    if ((ret = parse_title(title_offset, title_len)) < 0) {
        fprintf(stderr, "Failed parsing title\n");
        return -1;
    }

    for (int bound = 0; bound < MAX_BOUND; bound++) {
        char *header_offset = buffer; 
        int header_len = read_line(&buffer, &buffer_limit);
        char *header_limit = header_offset+header_len;
        
        // IF END OF MESSAGE
        if (!header_len) {
            state = state_fin;
            break;
        }

        if ((ret = parse_header(header_offset, header_len)) < 0) {
            fprintf(stderr, "Failed parsing header\n");
            return -1;
        }
    }

    free(uri);
    free(ver);

    return 0;
}

int main(void) {
    int ret; 
    char *str = strdup(TEST_ONE);

    header_table = (char **) calloc(header_count, sizeof(char *));
    if (!header_table) {
        fprintf(stderr, "Not enough dynamic memory\n");
        return -1;
    }

    header_tree = allocnod();
    if (!header_tree) {
        fprintf(stderr, "Not enough dynamic memory\n");
        return -1;
    }

    ret = gentree(header_tree, headers, NULL);
    if (gentree < 0) {
        fprintf(stderr, "Failed generating the header comparison tree\n");
        return -1;
    }

    ret = parse_request(str);
    if (ret < 0) {
        fprintf(stderr, "Failed parsing request\n");
        return -1;
    }

    fprintf(stderr, "Finished parsing request\n");

    frenod(header_tree);
    free(header_table);
    free(str);
    
    return 0;
}