217 lines
7.1 KiB
C
217 lines
7.1 KiB
C
#include <stdio.h>
|
||
#include <stdlib.h>
|
||
#include <sys/types.h>
|
||
#include <sys/socket.h>
|
||
#include <netinet/in.h>
|
||
#include <ctype.h>
|
||
#include <string.h>
|
||
#include <assert.h>
|
||
#include <arpa/inet.h>
|
||
#include <netdb.h>
|
||
#include <limits.h>
|
||
|
||
#include "helpers.h"
|
||
|
||
// UDP server-related mostly lifted from https://cs.nyu.edu/~mwalfish/classes/16sp/classnotes/handout01.pdf
|
||
|
||
void panic(const char* s) {
|
||
perror(s);
|
||
exit(1);
|
||
}
|
||
|
||
// TODO check max app name length
|
||
#define MSG_APP_LEN 64
|
||
|
||
struct Message {
|
||
int priority;
|
||
char application[MSG_APP_LEN];
|
||
};
|
||
|
||
#define DF_MONTH_LEN 9
|
||
|
||
struct Datefields {
|
||
char month[DF_MONTH_LEN]; // TODO numeric indicator?
|
||
int day;
|
||
int hour;
|
||
int minute;
|
||
int second;
|
||
};
|
||
|
||
|
||
int parse_priority(char* message, int* priority, int* position) {
|
||
/*
|
||
Given a string that begins with a message something like: <123>foo
|
||
Parse out the number (123) and place it in the passed `priority` int pointer
|
||
The position after the final `>` will be placed in the passed `position` int pointer
|
||
Returns 0 on success or something else on failure
|
||
*/
|
||
// Must have >3 chars to form <x> priority
|
||
if (strlen(message) < 3) return 1;
|
||
// Must start with <
|
||
if (message[0] != '<') return 1;
|
||
char digits[4];
|
||
memset(&digits, '\0', sizeof(digits));
|
||
int num_digits = 0;
|
||
int pos = 1;
|
||
//bool found_priority_end = false; // TODO
|
||
while (pos < 4) {
|
||
if(!isdigit(message[pos])) return 1; // priority must be numeric
|
||
digits[num_digits] = message[pos];
|
||
num_digits++;
|
||
pos++;
|
||
if (message[pos] == '>') {
|
||
break;
|
||
}
|
||
}
|
||
// TODO if escape the loop because pos >= 4, we never found '>'
|
||
if (num_digits == 0) return 1; // empty priority <> ?
|
||
*priority = atoi(digits);
|
||
*position = pos;
|
||
return 0;
|
||
}
|
||
|
||
|
||
int parse_datefield(char* message, struct Datefields* date, int* position) {
|
||
/*
|
||
Given a message+position pointers, where message + position in a string like:
|
||
May 10 03:09:59 filterlog: 5,,,....
|
||
Parse out the date and place the fields in the passed datefields struct pointer
|
||
Position will be advanced to the character after the parsed data
|
||
*/
|
||
// char month[8];
|
||
// memset(&month, '\0', sizeof(month)); // makes valgrind happy as the above char contains uninitialized memory
|
||
int date_length;
|
||
if(sscanf(message + *position, "%"STR(DF_MONTH_LEN)"s %d %d:%d:%d%n",
|
||
date->month, &(date->day), &(date->hour), &(date->minute), &(date->second), &date_length) != 5) {
|
||
return 1; // Failed to parse all desired fields
|
||
}
|
||
*position += date_length;
|
||
return 0;
|
||
}
|
||
|
||
|
||
int parse_application(char* message, char* application, int* position) {
|
||
int app_length;
|
||
if(sscanf(message + *position, "%"STR(MSG_APP_LEN)"s%n", application, &app_length) != 1) { // %n not counted in returned field count
|
||
return 1; // Failed to parse all desired fields
|
||
}
|
||
if(strlen(application) < 2) return 1; // Expect at least chars
|
||
application[app_length-1] = '\0'; // Remove the trailing :
|
||
*position += app_length;
|
||
return 0;
|
||
}
|
||
|
||
|
||
int parse_message(struct Message* result, char* message) {
|
||
/*
|
||
parse a message like:
|
||
<134>May 10 03:09:59 filterlog: 5,,,1000000103,cpsw0,match,block,in,4,0x20,,239,27547,0,none,6,tcp,40,185.216.140.37,24.4.129.164,57159,11111,0,S,3919167832,,1024,,
|
||
Format:
|
||
<priority>VERSION ISOTIMESTAMP HOSTNAME APPLICATION PID MESSAGEID STRUCTURED-DATA MSG
|
||
Assumes null termed string
|
||
*/
|
||
int priority = 0;
|
||
int position = 0;
|
||
if(parse_priority(message, &priority, &position) != 0) return 1;
|
||
result->priority = priority;
|
||
position++; // Now sits on the first character of the ISOTIMESTAMP
|
||
|
||
// Parse ISOTIMESTAMP
|
||
// Note: does not parse a full iso timestamp, only the format above
|
||
struct Datefields date;
|
||
if(parse_datefield(message, &date, &position) != 0) {
|
||
return 1;
|
||
}
|
||
position++; // position now at beginning of HOSTNAME field
|
||
|
||
// Parse APPLICATION
|
||
// filterlog: 5,,,1000000103,cpsw0,match....
|
||
char application[MSG_APP_LEN];
|
||
if(parse_application(message, application, &position) != 0) return 1;
|
||
memcpy(result->application, application, sizeof(application));
|
||
position += 1; // pass over the space
|
||
|
||
printf("remaining: '%s'\n", message + position);
|
||
return 0;
|
||
|
||
// char msg_remaining[4096];
|
||
// memset(&msg_remaining, '\0', sizeof(msg_remaining));
|
||
// memcpy(msg_remaining, &message[position], strlen(message) - position);
|
||
// printf("'%s'\n", msg_remaining);
|
||
// or
|
||
// memmove(message, &message[position], strlen(message) - position);
|
||
// printf("'%s'\n", message);
|
||
|
||
}
|
||
|
||
|
||
|
||
int main(int argc, char** argv) {
|
||
int sock_fd;
|
||
struct sockaddr_in my_addr, my_peer_addr;
|
||
char* endptr;
|
||
unsigned int portl;
|
||
unsigned short port;
|
||
char msg[4096];
|
||
socklen_t addrlen;
|
||
|
||
if (argc != 2) {
|
||
fprintf(stderr, "usage: %s <port>\n", argv[0]);
|
||
exit(1);
|
||
}
|
||
|
||
/* convert from string to int */
|
||
portl = strtol(argv[1], &endptr, 10);
|
||
if (endptr == NULL || portl == 0)
|
||
panic("strtol");
|
||
|
||
assert(portl < USHRT_MAX);
|
||
port = (unsigned short)portl;
|
||
|
||
/*
|
||
* Note! This code is not the same as what you need to do in lab1.
|
||
*/
|
||
if ((sock_fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
|
||
panic("socket");
|
||
int one = 1;
|
||
setsockopt(sock_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
|
||
|
||
memset(&my_addr, 0, sizeof(my_addr));
|
||
my_addr.sin_family = AF_INET;
|
||
my_addr.sin_addr.s_addr = INADDR_ANY;
|
||
my_addr.sin_port = htons(port);
|
||
|
||
if (bind(sock_fd, (struct sockaddr*)&my_addr, sizeof(struct sockaddr_in)) < 0)
|
||
panic("bind failed");
|
||
|
||
while (1) {
|
||
addrlen = sizeof(struct sockaddr_in);
|
||
int size_recvd;
|
||
if ((size_recvd = recvfrom(sock_fd, /* socket */
|
||
msg, /* buffer */
|
||
sizeof(msg), /* size of buffer */
|
||
0, /* flags = 0 */
|
||
(struct sockaddr*)&my_peer_addr, /* who’s sending */
|
||
&addrlen /* length of buffer to receive peer info */
|
||
)) < 0)
|
||
panic("recvfrom");
|
||
assert(size_recvd < sizeof(msg)); // messages can't be longer than our buffer
|
||
|
||
assert(addrlen == sizeof(struct sockaddr_in));
|
||
printf("Got message: %s\n", msg);
|
||
|
||
// TODO should we check that msg[size_recvd] == \0 ?
|
||
// printf("From host %s src port %d got message %.*s\n",
|
||
// inet_ntoa(my_peer_addr.sin_addr), ntohs(my_peer_addr.sin_port), size_recvd, msg);
|
||
struct Message result;
|
||
// printf("XXXsize: %lu", sizeof(result)); // curious how big the struct gets
|
||
//printf("msg[size_recvd] is: %d", msg[size_recvd]);
|
||
msg[size_recvd] = '\0'; // We receive 1 full string at a time
|
||
if(parse_message(&result, msg) != 1) {
|
||
printf("message is valid:\n\tpriority: %d\n\tapplication: %s\n", result.priority, result.application);
|
||
}
|
||
}
|
||
|
||
exit(EXIT_SUCCESS);
|
||
}
|