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sesimos/src/lib/rev_proxy.c

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C
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/**
* Necronda Web Server
* Reverse proxy
* src/lib/rev_proxy.c
* Lorenz Stechauner, 2021-01-07
*/
#include "rev_proxy.h"
#include "utils.h"
#include "compress.h"
#include "../necronda-server.h"
#include <openssl/ssl.h>
#include <string.h>
#include <errno.h>
#include <openssl/err.h>
#include <arpa/inet.h>
#include <sys/time.h>
sock rev_proxy;
char *rev_proxy_host = NULL;
struct timeval server_timeout = {.tv_sec = SERVER_TIMEOUT, .tv_usec = 0};
int rev_proxy_preload() {
rev_proxy.buf = NULL;
rev_proxy.buf_len = 0;
rev_proxy.buf_off = 0;
rev_proxy.ctx = SSL_CTX_new(TLS_client_method());
return 0;
}
int rev_proxy_request_header(http_req *req, int enc) {
char buf1[256];
char buf2[256];
int p_len;
http_remove_header_field(&req->hdr, "Connection", HTTP_REMOVE_ALL);
http_add_header_field(&req->hdr, "Connection", "keep-alive");
char *via = http_get_header_field(&req->hdr, "Via");
sprintf(buf1, "HTTP/%s %s", req->version, DEFAULT_HOST);
if (via == NULL) {
http_add_header_field(&req->hdr, "Via", buf1);
} else {
p_len = snprintf(buf2, sizeof(buf2), "%s, %s", via, buf1);
if (p_len < 0 || p_len >= sizeof(buf2)) {
print(ERR_STR "Header field 'Via' too long" CLR_STR);
return -1;
}
http_remove_header_field(&req->hdr, "Via", HTTP_REMOVE_ALL);
http_add_header_field(&req->hdr, "Via", buf2);
}
char *host = http_get_header_field(&req->hdr, "Host");
char *forwarded = http_get_header_field(&req->hdr, "Forwarded");
int client_ipv6 = strchr(client_addr_str, ':') != NULL;
int server_ipv6 = strchr(server_addr_str, ':') != NULL;
p_len = snprintf(buf1, sizeof(buf1), "by=%s%s%s;for=%s%s%s;host=%s;proto=%s",
server_ipv6 ? "\"[" : "", server_addr_str, server_ipv6 ? "]\"" : "",
client_ipv6 ? "\"[" : "", client_addr_str, client_ipv6 ? "]\"" : "",
host, enc ? "https" : "http");
if (p_len < 0 || p_len >= sizeof(buf1)) {
print(ERR_STR "Appended part of header field 'Forwarded' too long" CLR_STR);
return -1;
}
if (forwarded == NULL) {
http_add_header_field(&req->hdr, "Forwarded", buf1);
} else {
p_len = snprintf(buf2, sizeof(buf2), "%s, %s", forwarded, buf1);
if (p_len < 0 || p_len >= sizeof(buf2)) {
print(ERR_STR "Header field 'Forwarded' too long" CLR_STR);
return -1;
}
http_remove_header_field(&req->hdr, "Forwarded", HTTP_REMOVE_ALL);
http_add_header_field(&req->hdr, "Forwarded", buf2);
}
char *xff = http_get_header_field(&req->hdr, "X-Forwarded-For");
if (xff == NULL) {
http_add_header_field(&req->hdr, "X-Forwarded-For", client_addr_str);
} else {
sprintf(buf1, "%s, %s", xff, client_addr_str);
http_remove_header_field(&req->hdr, "X-Forwarded-For", HTTP_REMOVE_ALL);
http_add_header_field(&req->hdr, "X-Forwarded-For", buf1);
}
char *xfh = http_get_header_field(&req->hdr, "X-Forwarded-Host");
if (xfh == NULL) {
if (forwarded == NULL) {
http_add_header_field(&req->hdr, "X-Forwarded-Host", host);
} else {
char *ptr = strchr(forwarded, ',');
unsigned long len;
if (ptr != NULL) len = ptr - forwarded;
else len = strlen(forwarded);
ptr = strstr(forwarded, "host=");
if ((ptr - forwarded) < len) {
char *end = strchr(ptr, ';');
if (end == NULL) len -= (ptr - forwarded);
else len = (end - ptr);
len -= 5;
sprintf(buf1, "%.*s", (int) len, ptr + 5);
http_add_header_field(&req->hdr, "X-Forwarded-Host", buf1);
}
}
}
char *xfp = http_get_header_field(&req->hdr, "X-Forwarded-Proto");
if (xfp == NULL) {
if (forwarded == NULL) {
http_add_header_field(&req->hdr, "X-Forwarded-Proto", enc ? "https" : "http");
} else {
char *ptr = strchr(forwarded, ',');
unsigned long len;
if (ptr != NULL) len = ptr - forwarded;
else len = strlen(forwarded);
ptr = strstr(forwarded, "proto=");
if ((ptr - forwarded) < len) {
char *end = strchr(ptr, ';');
if (end == NULL) len -= (ptr - forwarded);
else len = (end - ptr);
len -= 6;
sprintf(buf1, "%.*s", (int) len, ptr + 6);
http_add_header_field(&req->hdr, "X-Forwarded-Proto", buf1);
}
}
}
return 0;
}
int rev_proxy_response_header(http_req *req, http_res *res) {
char buf1[256];
char buf2[256];
int p_len;
char *via = http_get_header_field(&res->hdr, "Via");
p_len = snprintf(buf1, sizeof(buf1), "HTTP/%s %s", req->version, DEFAULT_HOST);
if (p_len < 0 || p_len >= sizeof(buf1)) {
print(ERR_STR "Appended part of header field 'Via' too long" CLR_STR);
return -1;
}
if (via == NULL) {
http_add_header_field(&res->hdr, "Via", buf1);
} else {
p_len = snprintf(buf2, sizeof(buf2), "%s, %s", via, buf1);
if (p_len < 0 || p_len >= sizeof(buf2)) {
print(ERR_STR "Header field 'Via' too long" CLR_STR);
return -1;
}
http_remove_header_field(&res->hdr, "Via", HTTP_REMOVE_ALL);
http_add_header_field(&res->hdr, "Via", buf2);
}
return 0;
}
int rev_proxy_init(http_req *req, http_res *res, host_config *conf, sock *client, http_status *custom_status,
char *err_msg) {
char buffer[CHUNK_SIZE];
long ret;
int tries = 0;
int retry = 0;
if (rev_proxy.socket != 0 && strcmp(rev_proxy_host, conf->name) == 0 && sock_check(&rev_proxy) == 0) {
goto rev_proxy;
}
retry:
if (rev_proxy.socket != 0) {
print(BLUE_STR "Closing proxy connection" CLR_STR);
sock_close(&rev_proxy);
}
retry = 0;
tries++;
rev_proxy.socket = socket(AF_INET6, SOCK_STREAM, 0);
if (rev_proxy.socket < 0) {
print(ERR_STR "Unable to create socket: %s" CLR_STR, strerror(errno));
res->status = http_get_status(500);
return -1;
}
server_timeout.tv_sec = SERVER_TIMEOUT;
server_timeout.tv_usec = 0;
if (setsockopt(client->socket, SOL_SOCKET, SO_RCVTIMEO, &server_timeout, sizeof(server_timeout)) < 0)
goto rev_proxy_timeout_err;
if (setsockopt(client->socket, SOL_SOCKET, SO_SNDTIMEO, &server_timeout, sizeof(server_timeout)) < 0) {
rev_proxy_timeout_err:
res->status = http_get_status(500);
print(ERR_STR "Unable to set timeout for socket: %s" CLR_STR, strerror(errno));
sprintf(err_msg, "Unable to set timeout for socket: %s", strerror(errno));
goto proxy_err;
}
struct hostent *host_ent = gethostbyname2(conf->rev_proxy.hostname, AF_INET6);
if (host_ent == NULL) {
host_ent = gethostbyname2(conf->rev_proxy.hostname, AF_INET);
if (host_ent == NULL) {
res->status = http_get_status(503);
print(ERR_STR "Unable to connect to server: Name or service not known" CLR_STR);
sprintf(err_msg, "Unable to connect to server: Name or service not known.");
goto proxy_err;
}
}
struct sockaddr_in6 address = {.sin6_family = AF_INET6, .sin6_port = htons(conf->rev_proxy.port)};
if (host_ent->h_addrtype == AF_INET6) {
memcpy(&address.sin6_addr, host_ent->h_addr_list[0], host_ent->h_length);
} else if (host_ent->h_addrtype == AF_INET) {
unsigned char addr[16] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xFF, 0xFF, 0, 0, 0, 0};
memcpy(addr + 12, host_ent->h_addr_list[0], host_ent->h_length);
memcpy(&address.sin6_addr, addr, 16);
}
inet_ntop(address.sin6_family, (void *) &address.sin6_addr, buffer, sizeof(buffer));
print(BLUE_STR "Connecting to " BLD_STR "[%s]:%i" CLR_STR BLUE_STR "..." CLR_STR, buffer, conf->rev_proxy.port);
if (connect(rev_proxy.socket, (struct sockaddr *) &address, sizeof(address)) < 0) {
if (errno == ETIMEDOUT) {
res->status = http_get_status(504);
} else if (errno == ECONNREFUSED) {
res->status = http_get_status(503);
} else {
res->status = http_get_status(500);
}
print(ERR_STR "Unable to connect to [%s]%i: %s" CLR_STR, buffer, conf->rev_proxy.port, strerror(errno));
sprintf(err_msg, "Unable to connect to server: %s.", strerror(errno));
goto proxy_err;
}
if (conf->rev_proxy.enc) {
rev_proxy.ssl = SSL_new(rev_proxy.ctx);
SSL_set_fd(rev_proxy.ssl, rev_proxy.socket);
SSL_set_connect_state(rev_proxy.ssl);
ret = SSL_do_handshake(rev_proxy.ssl);
rev_proxy._last_ret = ret;
rev_proxy._errno = errno;
rev_proxy._ssl_error = ERR_get_error();
rev_proxy.enc = 1;
if (ret < 0) {
res->status = http_get_status(502);
print(ERR_STR "Unable to perform handshake: %s" CLR_STR, sock_strerror(&rev_proxy));
sprintf(err_msg, "Unable to perform handshake: %s.", sock_strerror(&rev_proxy));
goto proxy_err;
}
}
rev_proxy_host = conf->name;
print(BLUE_STR "Established new connection with " BLD_STR "[%s]:%i" CLR_STR, buffer, conf->rev_proxy.port);
rev_proxy:
ret = rev_proxy_request_header(req, (int) client->enc);
if (ret != 0) {
res->status = http_get_status(500);
return -1;
}
ret = http_send_request(&rev_proxy, req);
if (ret < 0) {
res->status = http_get_status(502);
print(ERR_STR "Unable to send request to server (1): %s" CLR_STR, sock_strerror(&rev_proxy));
sprintf(err_msg, "Unable to send request to server: %s.", sock_strerror(&rev_proxy));
retry = tries < 4;
goto proxy_err;
}
char *content_length = http_get_header_field(&req->hdr, "Content-Length");
if (content_length != NULL) {
unsigned long content_len = strtoul(content_length, NULL, 10);
if (client->buf_len - client->buf_off > 0) {
unsigned long len = client->buf_len - client->buf_off;
if (len > content_len) {
len = content_len;
}
ret = sock_send(&rev_proxy, client->buf, len, 0);
if (ret <= 0) {
res->status = http_get_status(502);
print(ERR_STR "Unable to send request to server (2): %s" CLR_STR, sock_strerror(&rev_proxy));
sprintf(err_msg, "Unable to send request to server: %s.", sock_strerror(&rev_proxy));
retry = tries < 4;
goto proxy_err;
}
content_len -= len;
}
if (content_len > 0) {
ret = sock_splice(&rev_proxy, client, buffer, sizeof(buffer), content_len);
if (ret <= 0) {
if (ret == -1) {
res->status = http_get_status(502);
print(ERR_STR "Unable to send request to server (3): %s" CLR_STR, sock_strerror(&rev_proxy));
sprintf(err_msg, "Unable to send request to server: %s.", sock_strerror(&rev_proxy));
goto proxy_err;
} else if (ret == -2) {
res->status = http_get_status(400);
print(ERR_STR "Unable to receive request from client: %s" CLR_STR, sock_strerror(client));
sprintf(err_msg, "Unable to receive request from client: %s.", sock_strerror(client));
return -1;
}
res->status = http_get_status(500);
print(ERR_STR "Unknown Error" CLR_STR);
return -1;
}
}
}
ret = sock_recv(&rev_proxy, buffer, sizeof(buffer), MSG_PEEK);
if (ret <= 0) {
res->status = http_get_status(502);
print(ERR_STR "Unable to receive response from server: %s" CLR_STR, sock_strerror(&rev_proxy));
sprintf(err_msg, "Unable to receive response from server: %s.", sock_strerror(&rev_proxy));
goto proxy_err;
}
char *buf = buffer;
unsigned short header_len = (unsigned short) (strstr(buffer, "\r\n\r\n") - buffer + 4);
if (header_len <= 0) {
res->status = http_get_status(502);
print(ERR_STR "Unable to parse header: End of header not found" CLR_STR);
sprintf(err_msg, "Unable to parser header: End of header not found.");
goto proxy_err;
}
for (int i = 0; i < header_len; i++) {
if ((buf[i] >= 0x00 && buf[i] <= 0x1F && buf[i] != '\r' && buf[i] != '\n') || buf[i] == 0x7F) {
res->status = http_get_status(502);
print(ERR_STR "Unable to parse header: Header contains illegal characters" CLR_STR);
sprintf(err_msg, "Unable to parse header: Header contains illegal characters.");
goto proxy_err;
}
}
char *ptr = buf;
while (header_len != (ptr - buf)) {
char *pos0 = strstr(ptr, "\r\n");
if (pos0 == NULL) {
res->status = http_get_status(502);
print(ERR_STR "Unable to parse header: Invalid header format" CLR_STR);
sprintf(err_msg, "Unable to parse header: Invalid header format.");
goto proxy_err;
}
if (ptr == buf) {
if (strncmp(ptr, "HTTP/", 5) != 0) {
res->status = http_get_status(502);
print(ERR_STR "Unable to parse header: Invalid header format" CLR_STR);
sprintf(err_msg, "Unable to parse header: Invalid header format.");
goto proxy_err;
}
int status_code = (int) strtol(ptr + 9, NULL, 10);
res->status = http_get_status(status_code);
if (res->status == NULL && status_code >= 100 && status_code <= 999) {
custom_status->code = status_code;
strcpy(custom_status->type, "");
snprintf(custom_status->msg, sizeof(custom_status->msg), "%.*s",
(int) (strchr(ptr, '\r') - ptr - 13), ptr + 13);
res->status = custom_status;
} else if (res->status == NULL) {
res->status = http_get_status(502);
print(ERR_STR "Unable to parse header: Invalid or unknown status code" CLR_STR);
sprintf(err_msg, "Unable to parse header: Invalid or unknown status code.");
goto proxy_err;
}
} else {
ret = http_parse_header_field(&res->hdr, ptr, pos0);
if (ret != 0) {
res->status = http_get_status(502);
print(ERR_STR "Unable to parse header" CLR_STR);
sprintf(err_msg, "Unable to parse header.");
goto proxy_err;
}
}
if (pos0[2] == '\r' && pos0[3] == '\n') {
break;
}
ptr = pos0 + 2;
}
sock_recv(&rev_proxy, buffer, header_len, 0);
ret = rev_proxy_response_header(req, res);
if (ret != 0) {
res->status = http_get_status(500);
return -1;
}
return 0;
proxy_err:
if (retry) goto retry;
return -1;
}
int rev_proxy_send(sock *client, unsigned long len_to_send, int flags) {
// TODO handle websockets
long ret;
char buffer[CHUNK_SIZE];
char comp_out[CHUNK_SIZE];
char buf[256];
long len, snd_len;
int finish_comp = 0;
char *ptr;
compress_ctx comp_ctx;
if (flags & REV_PROXY_COMPRESS_BR) {
flags &= ~REV_PROXY_COMPRESS_GZ;
if (compress_init(&comp_ctx, COMPRESS_BR) != 0) {
print(ERR_STR "Unable to init brotli: %s" CLR_STR, strerror(errno));
flags &= ~REV_PROXY_COMPRESS_BR;
}
} else if (flags & REV_PROXY_COMPRESS_GZ) {
flags &= ~REV_PROXY_COMPRESS_BR;
if (compress_init(&comp_ctx, COMPRESS_GZ) != 0) {
print(ERR_STR "Unable to init gzip: %s" CLR_STR, strerror(errno));
flags &= ~REV_PROXY_COMPRESS_GZ;
}
}
do {
snd_len = 0;
if (flags & REV_PROXY_CHUNKED) {
char *pos;
ret = sock_recv(&rev_proxy, buffer, 16, MSG_PEEK);
if (ret <= 0) goto err0;
len_to_send = strtol(buffer, NULL, 16);
pos = strstr(buffer, "\r\n");
len = pos - buffer + 2;
sock_recv(&rev_proxy, buffer, len, 0);
if (ret <= 0) {
err0:
print("Unable to receive from server: %s", sock_strerror(&rev_proxy));
break;
}
if (len_to_send == 0 && (flags & REV_PROXY_COMPRESS)) {
finish_comp = 1;
len = 0;
goto out;
finish:
compress_free(&comp_ctx);
}
}
while (snd_len < len_to_send) {
unsigned long avail_in, avail_out;
ret = sock_recv(&rev_proxy, buffer, CHUNK_SIZE < (len_to_send - snd_len) ? CHUNK_SIZE : len_to_send - snd_len, 0);
if (ret <= 0) {
print("Unable to receive from server: %s", sock_strerror(&rev_proxy));
break;
}
len = ret;
ptr = buffer;
out:
avail_in = len;
void *next_in = ptr;
do {
long buf_len = len;
if (flags & REV_PROXY_COMPRESS) {
avail_out = sizeof(comp_out);
compress_compress(&comp_ctx, next_in + len - avail_in, &avail_in, comp_out, &avail_out,
finish_comp);
ptr = comp_out;
buf_len = (int) (sizeof(comp_out) - avail_out);
snd_len += (long) (len - avail_in);
}
if (buf_len != 0) {
len = sprintf(buf, "%lX\r\n", buf_len);
ret = 1;
if (flags & REV_PROXY_CHUNKED) ret = sock_send(client, buf, len, 0);
if (ret <= 0) goto err;
ret = sock_send(client, ptr, buf_len, 0);
if (ret <= 0) goto err;
if (!(flags & REV_PROXY_COMPRESS)) snd_len += ret;
if (flags & REV_PROXY_CHUNKED) ret = sock_send(client, "\r\n", 2, 0);
if (ret <= 0) {
err:
print(ERR_STR "Unable to send: %s" CLR_STR, sock_strerror(client));
break;
}
}
} while ((flags & REV_PROXY_COMPRESS) && (avail_in != 0 || avail_out != sizeof(comp_out)));
if (ret <= 0) break;
if (finish_comp) goto finish;
}
if (ret <= 0) break;
if (flags & REV_PROXY_CHUNKED) sock_recv(&rev_proxy, buffer, 2, 0);
} while ((flags & REV_PROXY_CHUNKED) && len_to_send > 0);
if (ret <= 0) return (int) -1;
if (flags & REV_PROXY_CHUNKED) {
ret = sock_send(client, "0\r\n\r\n", 5, 0);
if (ret <= 0) {
print(ERR_STR "Unable to send: %s" CLR_STR, sock_strerror(client));
return -1;
}
}
return 0;
}
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