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proxy: refactor and implement simple state machine

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This commit is contained in:
Kevin J. 2024-08-06 00:00:14 +02:00
parent d61315d438
commit 4fc6665e44
2 changed files with 176 additions and 136 deletions
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298
proxy.c
View File

@ -11,10 +11,16 @@
#include "structs.h"
int debug = 1;
struct http_msg *child_msg;
struct request *child_msg;
regex_t preg;
regmatch_t pmatch[REGEX_MATCHN];
int par_line = 0;
int statem;
int clt_sock = -1;
int srv_sock = -1;
char *clt_msg = NULL;
char *srv_msg = NULL;
void *extractsub(const char *msg, regmatch_t match) {
int buflen = match.rm_eo - match.rm_so;
@ -37,7 +43,7 @@ int parse_header(char *msgbuff) {
ret = regexec(&preg, msgbuff, REGEX_MATCHN, pmatch, 0);
if (ret != 0)
goto _err;
goto _ok;
char *key = extractsub(msgbuff, pmatch[1]);
if (key == NULL)
@ -60,6 +66,8 @@ int parse_header(char *msgbuff) {
child_msg->headers[last_index] = new_header;
_ok:
regfree(&preg);
return 0;
@ -146,159 +154,179 @@ char *getheader(char *key) {
return ret;
}
char *doforward(char *host, char *msgbuff) {
struct addrinfo hints;
struct addrinfo *res;
int client_socket;
int ret;
char *host_response = NULL;
void do_err(void) {
int statem_code = statem & (~STATEM_ERR);
fprintf(stderr, "[%d,%d,%d] Errored out!\n", statem, statem_code, STATEM_ERR);
}
memset(&hints, 0, sizeof(hints));
hints.ai_family = AF_INET;
int do_fwd_clt(void) {
int bytes = 0;
do {
bytes += send(clt_sock, srv_msg+bytes, PROXY_MAX_MSGLEN-bytes, 0);
} while (bytes < PROXY_MAX_MSGLEN);
return 0;
}
// TODO: add parsing ability
int do_prs_srv(void) {
int ret = 0;
return ret;
}
int do_rcv_srv(void) {
int ret = recv(srv_sock, srv_msg, PROXY_MAX_MSGLEN, 0);
if (ret < 0)
return -1;
if (debug) {
fprintf(stdout, "[%d] Received server message: %s\n", statem, clt_msg);
}
return 0;
}
int con_srv(void) {
int ret;
char *host = getheader("Host");
if (!host)
return -1;
struct addrinfo hints;
struct addrinfo *res;
memset(&hints, 0, sizeof(hints));
hints.ai_family = AF_INET;
hints.ai_socktype = SOCK_STREAM;
ret = getaddrinfo(host, "80", &hints, &res);
if (ret < 0) {
fprintf(stderr, "Failed to determine host '%s'\n", host);
goto _return;
}
if (ret < 0)
return -1;
ret = client_socket = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
if (ret < 0) {
fprintf(stderr, "Failed to create a client socket\n");
goto _return;
}
ret = srv_sock = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
if (ret < 0)
return -1;
ret = connect(client_socket, res->ai_addr, res->ai_addrlen);
if (ret < 0) {
fprintf(stderr, "Failed to connect to destination host '%s'\n", host);
goto _return;
}
ret = connect(srv_sock, res->ai_addr, res->ai_addrlen);
if (ret < 0)
return -1;
int bytes = 0;
do {
bytes += send(client_socket, msgbuff+bytes,
PROXY_MAX_MSGLEN-bytes, 0);
} while (bytes < PROXY_MAX_MSGLEN);
host_response = (char *) calloc(1, PROXY_MAX_MSGLEN);
if (host_response == NULL) {
fprintf(stderr, "Not enough dynamic memory\n");
goto _free_sock;
}
/*bytes = 0;
while (bytes < PROXY_MAX_MSGLEN) {
fprintf(stdout, "bytes 2 -> %d\n", bytes);
int new_bytes = recv(client_socket, host_response+bytes, PROXY_MAX_MSGLEN-bytes, 0);
bytes += new_bytes;
fprintf(stdout, "New bytes -> %d, bytes -> %d\n", new_bytes, bytes);
if (!new_bytes)
break;
}*/
recv(client_socket, host_response, PROXY_MAX_MSGLEN, 0);
if (debug) {
fprintf(stdout, "RECEIVED %s\n", host_response);
}
_free_sock:
close(client_socket);
_return:
return host_response;
return 0;
}
void handle_request(int sockfd) {
int do_fwd_srv(void) {
int ret = 0;
if (srv_sock < 0)
ret = con_srv();
if (ret < 0)
return -1;
int bytes = 0;
do {
bytes += send(srv_sock, clt_msg+bytes, PROXY_MAX_MSGLEN-bytes, 0);
} while (bytes < PROXY_MAX_MSGLEN);
return 0;
}
int do_prs_clt(void) {
int ret;
int ln_cnt = 0;
char *msgbuff = (char *) calloc(1, PROXY_MAX_MSGLEN);
if (msgbuff == NULL) {
fprintf(stderr, "Not enough dynamic memory\n");
goto end_sock;
}
ret = recv(sockfd, msgbuff, PROXY_MAX_MSGLEN, 0);
if (ret < 0) {
fprintf(stderr, "Failed to receive data from client\n");
goto end_sock;
}
// prepare structs
child_msg = (struct http_msg *) calloc(1, sizeof(struct http_msg));
if (child_msg == NULL) {
fprintf(stderr, "Failed to allocate memory for client structs\n");
goto end_sock;
}
if (debug) {
fprintf(stdout, "Received buffer: %s\n", msgbuff);
}
char *ln = strdup(msgbuff);
if (!ln) {
fprintf(stderr, "Not enough dynamic memory\n");
goto free_msg;
}
char *ln = strdup(clt_msg);
if (!ln)
return -1;
ln = strtok(ln, "\n");
while (ln) {
parse_line(ln, par_line);
par_line++;
ln = strtok(NULL, "\n");
ret = parse_line(ln, ln_cnt);
if (ret < 0)
return -1;
ln_cnt++;
ln = strtok(NULL, "\n");
}
// logic
fprintf(stdout,
"=====PARSE=RESULTS=====\n"
" * Method value: '%s'\n"
" * URI value: '%s'\n"
" * Version value: '%s'\n"
" * Number of headers: %d\n"
" * Headers:\n",
child_msg->method,
child_msg->uri,
child_msg->ver,
child_msg->header_num
);
for (int i = 0; i < child_msg->header_num; i++) {
struct header *hdr = &child_msg->headers[i];
fprintf(stdout, " * Key: '%s', Value: '%s'\n", hdr->key, hdr->value);
}
fprintf(stdout, "=====PARSE=RESULTS=====\n");
return 0;
}
char *host = getheader("Host");
char *response = doforward(host, msgbuff);
if (debug) {
fprintf(stdout, "Response from host '%s': %s\n", host, response);
}
// reply to client
int bytes = 0;
do {
bytes += send(sockfd, response+bytes,
PROXY_MAX_MSGLEN-bytes, 0);
} while (bytes < PROXY_MAX_MSGLEN);
int do_rcv_clt(void) {
int ret;
ret = recv(clt_sock, clt_msg, PROXY_MAX_MSGLEN, 0);
if (ret < 0)
return -1;
if (debug) {
fprintf(stdout, "Sent response from host '%s' to client. Totaling %d bytes of transfer\n", host, bytes);
fprintf(stdout, "[%d] Received client message: %s\n", statem, clt_msg);
}
free(response);
return 0;
}
free_message();
int do_alloc(void) {
clt_msg = (char *) calloc(1, PROXY_MAX_MSGLEN);
if (!clt_msg)
return -1;
free_msg:
free(msgbuff);
srv_msg = (char *) calloc(1, PROXY_MAX_MSGLEN);
if (!srv_msg)
return -1;
end_sock:
close(sockfd);
child_msg = (struct request *) calloc(1, sizeof(struct request));
if (!child_msg)
return -1;
return 0;
}
void dostatem() {
int ret = do_alloc();
if (ret < 0) {
do_err();
return;
}
for (int counter = 0; counter < MAX_BOUND; counter++) {
switch (statem & (~STATEM_ERR)) {
case STATEM_RCV_CLT:
ret = do_rcv_clt();
break;
case STATEM_PRS_CLT:
ret = do_prs_clt();
break;
case STATEM_FWD_SRV:
ret = do_fwd_srv();
break;
case STATEM_RCV_SRV:
ret = do_rcv_srv();
break;
case STATEM_PRS_SRV:
ret = do_prs_srv();
break;
case STATEM_FWD_CLT:
ret = do_fwd_clt();
break;
default:
ret = -1;
break;
}
if (ret < 0)
statem |= STATEM_ERR;
if (statem & STATEM_ERR) {
do_err();
break;
}
if (statem & STATEM_FWD_CLT) {
statem = STATEM_RCV_CLT;
continue;
}
statem <<= 1;
}
}
void dohelp() {
@ -374,12 +402,14 @@ int doserver(void) {
return -1;
break;
case 0:
handle_request(client_socket);
clt_sock = client_socket;
statem = STATEM_RCV_CLT;
dostatem();
return 0;
break;
default:
fprintf(stdout, "[PROGRAM] Successfully forked a new child process"
"with PID %d\n", ret);
" with PID %d\n", ret);
break;
}
}

14
structs.h
View File

@ -1,6 +1,8 @@
#ifndef STRUCTS_H
#define STRUCTS_H
#define MAX_BOUND 100
#define SERVER_MODE "server"
#define CLIENT_MODE "client"
@ -18,12 +20,20 @@
"Host: google.com\n"\
"Authorization: Bearer ffja2439gjawgjgojserg\n"
#define STATEM_RCV_CLT 0b00000001
#define STATEM_PRS_CLT 0b00000010
#define STATEM_FWD_SRV 0b00000100
#define STATEM_RCV_SRV 0b00001000
#define STATEM_PRS_SRV 0b00010000
#define STATEM_FWD_CLT 0b00100000
#define STATEM_ERR 0b10000000
struct header {
char *key;
char *value;
};
struct http_msg {
struct request {
char *method;
char *uri;
char *ver;
@ -31,4 +41,4 @@ struct http_msg {
struct header *headers;
};
#endif
#endif