ipc.cc

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/*
 * Copyright (C) 1996-2025 The Squid Software Foundation and contributors
 *
 * Squid software is distributed under GPLv2+ license and includes
 * contributions from numerous individuals and organizations.
 * Please see the COPYING and CONTRIBUTORS files for details.
 */
 
/* DEBUG: section 54    Interprocess Communication */
 
#include "squid.h"
#include "comm/Connection.h"
#include "compat/pipe.h"
#include "fd.h"
#include "fde.h"
#include "globals.h"
#include "ip/Address.h"
#include "ipc/Kid.h"
#include "rfc1738.h"
#include "SquidConfig.h"
#include "SquidIpc.h"
#include "tools.h"
 
#include <chrono>
#include <thread>
#include <cstdlib>
 
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
 
static const char *hello_string = "hi there\n";
#ifndef HELLO_BUF_SZ
#define HELLO_BUF_SZ 32
#endif
static char hello_buf[HELLO_BUF_SZ];
 
static int
ipcCloseAllFD(int prfd, int pwfd, int crfd, int cwfd)
{
    if (prfd >= 0)
        comm_close(prfd);
 
    if (prfd != pwfd)
        if (pwfd >= 0)
            comm_close(pwfd);
 
    if (crfd >= 0)
        comm_close(crfd);
 
    if (crfd != cwfd)
        if (cwfd >= 0)
            comm_close(cwfd);
 
    return -1;
}
 
static void
PutEnvironment()
{
#if HAVE_PUTENV
    char *env_str;
    int tmp_s;
    env_str = (char *)xcalloc((tmp_s = strlen(Debug::debugOptions) + 32), 1);
    snprintf(env_str, tmp_s, "SQUID_DEBUG=%s", Debug::debugOptions);
    putenv(env_str);
#endif
}
 
pid_t
ipcCreate(int type, const char *prog, const char *const args[], const char *name, Ip::Address &local_addr, int *rfd, int *wfd, void **hIpc)
{
    pid_t pid;
    Ip::Address ChS;
    Ip::Address PaS;
    struct addrinfo *AI = nullptr;
    int crfd = -1;
    int prfd = -1;
    int cwfd = -1;
    int pwfd = -1;
    int fd;
    int t1, t2, t3;
    int x;
    int xerrno;
 
#if USE_POLL && _SQUID_OSF_
    assert(type != IPC_FIFO);
#endif
 
    if (rfd)
        *rfd = -1;
 
    if (wfd)
        *wfd = -1;
 
    if (hIpc)
        *hIpc = nullptr;
 
// NP: no wrapping around d and c usage since we *want* code expansion
#define IPC_CHECK_FAIL(f,d,c) \
    if ((f) < 0) { \
        debugs(54, DBG_CRITICAL, "ERROR: Failed to create helper " d " FD: " << c); \
        return ipcCloseAllFD(prfd, pwfd, crfd, cwfd); \
    } else void(0)
 
    if (type == IPC_TCP_SOCKET) {
        crfd = cwfd = comm_open_listener(SOCK_STREAM,
                                         0,
                                         local_addr,
                                         COMM_NOCLOEXEC,
                                         name);
        prfd = pwfd = comm_open(SOCK_STREAM,
                                0,          /* protocol */
                                local_addr,
                                0,          /* blocking */
                                name);
        IPC_CHECK_FAIL(crfd, "child read", "TCP " << local_addr);
        IPC_CHECK_FAIL(prfd, "parent read", "TCP " << local_addr);
    } else if (type == IPC_UDP_SOCKET) {
        crfd = cwfd = comm_open(SOCK_DGRAM,
                                0,
                                local_addr,
                                COMM_NOCLOEXEC,
                                name);
        prfd = pwfd = comm_open(SOCK_DGRAM,
                                0,
                                local_addr,
                                0,
                                name);
        IPC_CHECK_FAIL(crfd, "child read", "UDP" << local_addr);
        IPC_CHECK_FAIL(prfd, "parent read", "UDP" << local_addr);
    } else if (type == IPC_FIFO) {
        int p2c[2];
        int c2p[2];
 
        if (pipe(p2c) < 0) {
            xerrno = errno;
            debugs(54, DBG_CRITICAL, "ipcCreate: pipe: " << xstrerr(xerrno));
            return -1; // maybe ipcCloseAllFD(prfd, pwfd, crfd, cwfd);
        }
        fd_open(prfd = p2c[0], FD_PIPE, "IPC FIFO Parent Read");
        fd_open(cwfd = p2c[1], FD_PIPE, "IPC FIFO Child Write");
 
        if (pipe(c2p) < 0) {
            xerrno = errno;
            debugs(54, DBG_CRITICAL, "ipcCreate: pipe: " << xstrerr(xerrno));
            return ipcCloseAllFD(prfd, pwfd, crfd, cwfd);
        }
        fd_open(crfd = c2p[0], FD_PIPE, "IPC FIFO Child Read");
        fd_open(pwfd = c2p[1], FD_PIPE, "IPC FIFO Parent Write");
 
        IPC_CHECK_FAIL(crfd, "child read", "FIFO pipe");
        IPC_CHECK_FAIL(prfd, "parent read", "FIFO pipe");
 
#if HAVE_SOCKETPAIR && defined(AF_UNIX)
 
    } else if (type == IPC_UNIX_STREAM) {
        int fds[2];
        int buflen = 32768;
 
        if (socketpair(AF_UNIX, SOCK_STREAM, 0, fds) < 0) {
            xerrno = errno;
            debugs(54, DBG_CRITICAL, "ipcCreate: socketpair: " << xstrerr(xerrno));
            return -1;
        }
 
        errno = 0;
        if (setsockopt(fds[0], SOL_SOCKET, SO_SNDBUF, (void *) &buflen, sizeof(buflen)) == -1)  {
            xerrno = errno;
            debugs(54, DBG_IMPORTANT, "ERROR: setsockopt failed: " << xstrerr(xerrno));
            errno = 0;
        }
        if (setsockopt(fds[0], SOL_SOCKET, SO_RCVBUF, (void *) &buflen, sizeof(buflen)) == -1) {
            xerrno = errno;
            debugs(54, DBG_IMPORTANT, "ERROR: setsockopt failed: " << xstrerr(xerrno));
            errno = 0;
        }
        if (setsockopt(fds[1], SOL_SOCKET, SO_SNDBUF, (void *) &buflen, sizeof(buflen)) == -1) {
            xerrno = errno;
            debugs(54, DBG_IMPORTANT, "ERROR: setsockopt failed: " << xstrerr(xerrno));
            errno = 0;
        }
        if (setsockopt(fds[1], SOL_SOCKET, SO_RCVBUF, (void *) &buflen, sizeof(buflen)) == -1) {
            xerrno = errno;
            debugs(54, DBG_IMPORTANT, "ERROR: setsockopt failed: " << xstrerr(xerrno));
            errno = 0;
        }
        fd_open(prfd = pwfd = fds[0], FD_PIPE, "IPC UNIX STREAM Parent");
        fd_open(crfd = cwfd = fds[1], FD_PIPE, "IPC UNIX STREAM Parent");
        IPC_CHECK_FAIL(crfd, "child read", "UDS socket");
        IPC_CHECK_FAIL(prfd, "parent read", "UDS socket");
 
    } else if (type == IPC_UNIX_DGRAM) {
        int fds[2];
 
        if (socketpair(AF_UNIX, SOCK_DGRAM, 0, fds) < 0) {
            xerrno = errno;
            debugs(54, DBG_CRITICAL, "ipcCreate: socketpair: " << xstrerr(xerrno));
            return -1;
        }
 
        fd_open(prfd = pwfd = fds[0], FD_PIPE, "IPC UNIX DGRAM Parent");
        fd_open(crfd = cwfd = fds[1], FD_PIPE, "IPC UNIX DGRAM Parent");
 
        IPC_CHECK_FAIL(crfd, "child read", "UDS datagram");
        IPC_CHECK_FAIL(prfd, "parent read", "UDS datagram");
#endif
 
    } else {
        assert(IPC_NONE);
    }
 
    debugs(54, 3, "ipcCreate: prfd FD " << prfd);
    debugs(54, 3, "ipcCreate: pwfd FD " << pwfd);
    debugs(54, 3, "ipcCreate: crfd FD " << crfd);
    debugs(54, 3, "ipcCreate: cwfd FD " << cwfd);
 
    if (type == IPC_TCP_SOCKET || type == IPC_UDP_SOCKET) {
        Ip::Address::InitAddr(AI);
 
        if (getsockname(pwfd, AI->ai_addr, &AI->ai_addrlen) < 0) {
            xerrno = errno;
            Ip::Address::FreeAddr(AI);
            debugs(54, DBG_CRITICAL, "ipcCreate: getsockname: " << xstrerr(xerrno));
            return ipcCloseAllFD(prfd, pwfd, crfd, cwfd);
        }
 
        PaS = *AI;
 
        debugs(54, 3, "ipcCreate: FD " << pwfd << " sockaddr " << PaS);
 
        Ip::Address::FreeAddr(AI);
 
        Ip::Address::InitAddr(AI);
 
        if (getsockname(crfd, AI->ai_addr, &AI->ai_addrlen) < 0) {
            xerrno = errno;
            Ip::Address::FreeAddr(AI);
            debugs(54, DBG_CRITICAL, "ipcCreate: getsockname: " << xstrerr(xerrno));
            return ipcCloseAllFD(prfd, pwfd, crfd, cwfd);
        }
 
        ChS = *AI;
 
        Ip::Address::FreeAddr(AI);
 
        debugs(54, 3, "ipcCreate: FD " << crfd << " sockaddr " << ChS );
 
    }
 
    if (type == IPC_TCP_SOCKET) {
        if (listen(crfd, 1) < 0) {
            xerrno = errno;
            debugs(54, DBG_IMPORTANT, "ipcCreate: listen FD " << crfd << ": " << xstrerr(xerrno));
            return ipcCloseAllFD(prfd, pwfd, crfd, cwfd);
        }
 
        debugs(54, 3, "ipcCreate: FD " << crfd << " listening...");
    }
 
    /* flush or else we get dup data if unbuffered_logs is set */
    logsFlush();
 
    if ((pid = fork()) < 0) {
        xerrno = errno;
        debugs(54, DBG_IMPORTANT, "ipcCreate: fork: " << xstrerr(xerrno));
        return ipcCloseAllFD(prfd, pwfd, crfd, cwfd);
    }
 
    if (pid > 0) {      /* parent */
        /* close shared socket with child */
        comm_close(crfd);
 
        if (cwfd != crfd)
            comm_close(cwfd);
 
        cwfd = crfd = -1;
 
        if (type == IPC_TCP_SOCKET || type == IPC_UDP_SOCKET) {
            if (comm_connect_addr(pwfd, ChS) == Comm::COMM_ERROR)
                return ipcCloseAllFD(prfd, pwfd, crfd, cwfd);
        }
 
        if (type == IPC_UDP_SOCKET)
            x = comm_udp_recv(prfd, hello_buf, sizeof(hello_buf)-1, 0);
        else
            x = read(prfd, hello_buf, sizeof(hello_buf)-1);
        xerrno = errno;
        if (x >= 0)
            hello_buf[x] = '\0';
 
        if (x < 0) {
            debugs(54, DBG_CRITICAL, "ERROR: ipcCreate: PARENT: hello read test failed");
            debugs(54, DBG_CRITICAL, "--> read: " << xstrerr(xerrno));
            return ipcCloseAllFD(prfd, pwfd, crfd, cwfd);
        } else if (strcmp(hello_buf, hello_string)) {
            debugs(54, DBG_CRITICAL, "ERROR: ipcCreate: PARENT: hello read test failed");
            debugs(54, DBG_CRITICAL, "--> read returned " << x);
            debugs(54, DBG_CRITICAL, "--> got '" << rfc1738_escape(hello_buf) << "'");
            return ipcCloseAllFD(prfd, pwfd, crfd, cwfd);
        }
 
        commUnsetFdTimeout(prfd);
        commSetNonBlocking(prfd);
        commSetNonBlocking(pwfd);
 
        if (rfd)
            *rfd = prfd;
 
        if (wfd)
            *wfd = pwfd;
 
        fd_table[prfd].flags.ipc = 1;
 
        fd_table[pwfd].flags.ipc = 1;
 
        if (Config.sleep_after_fork)
            std::this_thread::sleep_for(std::chrono::microseconds(Config.sleep_after_fork));
 
        return pid;
    }
 
    /* child */
    TheProcessKind = pkHelper;
    no_suid();          /* give up extra privileges */
 
    /* close shared socket with parent */
    close(prfd);
 
    if (pwfd != prfd)
        close(pwfd);
 
    pwfd = prfd = -1;
 
    if (type == IPC_TCP_SOCKET) {
        debugs(54, 3, "ipcCreate: calling accept on FD " << crfd);
 
        if ((fd = accept(crfd, nullptr, nullptr)) < 0) {
            xerrno = errno;
            debugs(54, DBG_CRITICAL, "ipcCreate: FD " << crfd << " accept: " << xstrerr(xerrno));
            _exit(1);
        }
 
        debugs(54, 3, "ipcCreate: CHILD accepted new FD " << fd);
        close(crfd);
        cwfd = crfd = fd;
    } else if (type == IPC_UDP_SOCKET) {
        if (comm_connect_addr(crfd, PaS) == Comm::COMM_ERROR)
            return ipcCloseAllFD(prfd, pwfd, crfd, cwfd);
    }
 
    if (type == IPC_UDP_SOCKET) {
        x = comm_udp_send(cwfd, hello_string, strlen(hello_string) + 1, 0);
 
        if (x < 0) {
            xerrno = errno;
            debugs(54, DBG_CRITICAL, "sendto FD " << cwfd << ": " << xstrerr(xerrno));
            debugs(54, DBG_CRITICAL, "ERROR: ipcCreate: CHILD: hello write test failed");
            _exit(1);
        }
    } else {
        if (write(cwfd, hello_string, strlen(hello_string) + 1) < 0) {
            xerrno = errno;
            debugs(54, DBG_CRITICAL, "write FD " << cwfd << ": " << xstrerr(xerrno));
            debugs(54, DBG_CRITICAL, "ERROR: ipcCreate: CHILD: hello write test failed");
            _exit(1);
        }
    }
 
    PutEnvironment();
 
    // A dup(2) wrapper that reports and exits the process on errors. The
    // exiting logic is only suitable for this child process context.
    const auto dupOrExit = [prog,name](const int oldFd) {
        const auto newFd = dup(oldFd);
        if (newFd < 0) {
            const auto savedErrno = errno;
            debugs(54, DBG_CRITICAL, "ERROR: Helper process initialization failure: " << name <<
                   Debug::Extra << "helper (CHILD) PID: " << getpid() <<
                   Debug::Extra << "helper program name: " << prog <<
                   Debug::Extra << "dup(2) system call error for FD " << oldFd << ": " << xstrerr(savedErrno));
            _exit(EXIT_FAILURE);
        }
        return newFd;
    };
 
    /*
     * This double-dup stuff avoids problems when one of
     *  crfd, cwfd, or DebugStream() are in the rage 0-2.
     */
 
    do {
        /* First make sure 0-2 is occupied by something. Gets cleaned up later */
        x = dupOrExit(crfd);
    } while (x < 3);
 
    close(x);
 
    t1 = dupOrExit(crfd);
 
    t2 = dupOrExit(cwfd);
 
    t3 = dupOrExit(fileno(DebugStream()));
 
    assert(t1 > 2 && t2 > 2 && t3 > 2);
 
    close(crfd);
 
    close(cwfd);
 
    close(fileno(DebugStream()));
 
    dup2(t1, 0);
 
    dup2(t2, 1);
 
    dup2(t3, 2);
 
    close(t1);
 
    close(t2);
 
    close(t3);
 
    /* Make sure all other filedescriptors are closed */
    for (x = 3; x < SQUID_MAXFD; ++x)
        close(x);
 
#if HAVE_SETSID
    if (opt_no_daemon)
        setsid();
#endif
 
    execvp(prog, (char *const *) args);
    xerrno = errno;
 
    ResyncDebugLog(fdopen(2, "a+"));
 
    debugs(54, DBG_CRITICAL, "ipcCreate: " << prog << ": " << xstrerr(xerrno));
 
    _exit(1);
 
    return 0;
}