An rfc compliant irc parser in C.

irc.c

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>

enum symbols    { NEWLINE, SPACE, COLON     };
#define SYMBOLS {  '\n',    ' ',   ':', '\0'};

char line[32][256];

int delim(FILE *fp, char *dest, char *delims, char **pos) {
	int c;
	char *p;

	while ((c = fgetc(fp)) != EOF) {
		if ((p = strchr(delims, c)) != NULL) {
			*pos = dest;
			return p - delims;
		}
		*dest++ = c;
	}
	return -1;
}

int parse(FILE *fp) {
	char sym[] = SYMBOLS 
	char *p;
	int i;

	i = 0;
	p = line[0];

	for (;;) {
		switch (delim(fp, p, sym, &p)) {
			case EOF:
				goto FAIL;
				break;
			case NEWLINE:
				if (p != line[i] && *(p - 1) == '\r') {
					*(p - 1) = '\0';
					goto DONE;
				}
				break;
			case SPACE:
				*p = '\0';
				p = line[++i];
				break;
			case COLON: 
				*p = ':';
				if (i != 0 && p == line[i]) {
					sym[SPACE] = '\0'; /* truncate */
				}
				p++;
				break;
		}
	}

DONE:
	return i+1;

FAIL:
	return EOF;
}

/*-\-\-----------------------------------------------------------------/-/-*/
/*-/-/-----------------------------------------------------------------\-\-*/


int main (int argc, char *argv[]) {

	FILE *fp;

	int t, i, j, n;

	if (argc < 2) {
		fputs("no arguments\n", stderr);
		exit(EXIT_FAILURE);
	}
	for (t = 1; argv[t]; t++) {
	
		fp = fopen(argv[t], "r");

		if (!fp) {
			fprintf(stderr, "failed to open file: %s\n", argv[t]);
			continue;
		}
		printf("opened: %s\n", argv[t]);

		for (; !feof(fp); puts("\n")) {
			memset(line, '\0', sizeof line);
			n = parse(fp);

			if (n <= 0) {
				continue;
			}
			printf("Message, %d parts:\n", n);	
			i = 0;

			if (line[0][0] == ':') {
				printf("prefix: %s\n", line[0]);
				i++;
			}

			printf("command: %s\n", line[i++]);
			n--;
			for (j = 0; i+j < n; j++) {
				printf("\t[%-.2d] => '%s'\n", j, line[i + j]);
			}
			
			if (line[n][0] == ':') {
				printf("trailing: %s\n", line[n]);
			} else {
				printf("\t[%-.2d] => '%s'\n", j, line[n]);
			}

		}
	}

	exit(EXIT_SUCCESS);
}

out

$ ./a.out <(echo -en ':nick!user@net COMMAND a b:ds :b b adas lasda\r\n')
opened: /dev/fd/63
Message, 5 parts:
prefix: :nick!user@net
command: COMMAND
	[00] => 'a'
	[01] => 'b:ds'
trailing: :b b adas lasda

need to fix up the output
too lazy tho